Geology's topics - tribe.net

Geologic Evidence for a Biblical Flood

Thanos — Thu, 09 Apr 2009 20:41:38 GMT

I'm the Moderator for the Science Vs religion tribe. I seriously doubt there is any evidence of this, but if there is a shred of it anyone knows about, i'd like to hear it.
Thanks-t

posted in Geology - 12 replies

Earth Heartbeat & Seismic Activity

Phoenix — Sat, 07 Feb 2009 16:47:06 GMT

Some of you may have an interest in checking out the work Curtis has been engaged in relative to seismic activity and the earth's heartbeat. He has animated his graphs and contains audio.

Some of you will know what what you are looking at.

http://flyingsnail.com/index2.html

posted in Geology - 0 replies

Question -

Plokk D Rainbo — Wed, 31 Dec 2008 01:54:06 GMT

I became interested in watching the earthquake movements when I started looking at Google earth, it shows fault lines and earthquakes then I added the widget on my g mail homepage so I watched the earthquakes build and release in China.. there is still alot of energy around the inner edge of the continents shown here http://neic.usgs.gov/neis/qed/

With the current event (swarm) in Yellowstone , which is in the middle of the continent occurring is it more likely to have a larger event along the faults? to release the pressure? Can you explain if yes or no?

posted in Geology - 8 replies

Quake swarm in Yellowstone

Will The Dancer — Sun, 28 Dec 2008 16:11:38 GMT

http://earthquake.usgs.gov/eqcenter/recenteqsus/Maps/US2/44.46.-111.-109_eqs.php

A substantial earthquake swarm is in progress at Yellowstone lake.

posted in Geology - 7 replies

Plate tectonics started over 4 billion years ago, geochemists report

bobs — Thu, 27 Nov 2008 07:46:17 GMT

(PhysOrg.com) -- A new picture of the early Earth is emerging, including the surprising finding that plate tectonics may have started more than 4 billion years ago — much earlier than scientists had believed, according to new research by UCLA geochemists reported Nov. 27 in the journal Nature.

"We are proposing that there was plate-tectonic activity in the first 500 million years of Earth's history," said geochemistry professor Mark Harrison, director of UCLA's Institute of Geophysics and Planetary Physics and co-author of the Nature paper. "We are reporting the first evidence of this phenomenon."

"Unlike the longstanding myth of a hellish, dry, desolate early Earth with no continents, it looks like as soon as the Earth formed, it fell into the same dynamic regime that continues today," Harrison said. "Plate tectonics was inevitable, life was inevitable. In the early Earth, there appear to have been oceans; there could have been life — completely contradictory to the cartoonish story we had been telling ourselves."

"We're revealing a new picture of what the early Earth might have looked like," said lead author Michelle Hopkins, a UCLA graduate student in Earth and space sciences. "In high school, we are taught to see the Earth as a red, hellish, molten-lava Earth. Now we're seeing a new picture, more like today, with continents, water, blue sky, blue ocean, much earlier than we thought."

The Earth is 4.5 billion years old. Some scientists think plate tectonics — the geological phenomenon involving the movement of huge crustal plates that make up the Earth's surface over the planet's molten interior — started 3.5 billion years ago, others that it began even more recently than that.

The research by Harrison, Hopkins and Craig Manning, a UCLA professor of geology and geochemistry, is based on their analysis of ancient mineral grains known as zircons found inside molten rocks, or magmas, from Western Australia that are about 3 billion years old. Zircons are heavy, durable minerals related to the synthetic cubic zirconium used for imitation diamonds and costume jewelry. The zircons studied in the Australian rocks are about twice the thickness of a human hair.

Hopkins analyzed the zircons with UCLA's high-resolution ion microprobe, an instrument that enables scientists to date and learn the exact composition of samples with enormous precision. The microprobe shoots a beam of ions, or charged atoms, at a sample, releasing from the sample its own ions, which are then analyzed in a mass spectrometer. Scientists can aim the beam of ions at specific microscopic areas of a sample and conduct a high-resolution isotope analysis of them without destroying the object.

"The microprobe is the perfect tool for determining the age of the zircons," Harrison said.

The analysis determined that some of the zircons found in the magmas were more than 4 billion years old. They were also found to have been formed in a region with heat flow far lower than the global average at that time.

"The global average heat flow in the Earth's first 500 million years was thought to be about 200 to 300 milliwatts per meter squared," Hopkins said. "Our zircons are indicating a heat flow of just 75 milliwatts per meter squared — the figure one would expect to find in subduction zones, where two plates converge, with one moving underneath the other."

"The data we are reporting are from zircons from between 4 billion and 4.2 billion years ago," Harrison said. "The evidence is indirect, but strong. We have assessed dozens of scenarios trying to imagine how to create magmas in a heat flow as low as we have found without plate tectonics, and nothing works; none of them explain the chemistry of the inclusions or the low melting temperature of the granites."

Evidence for water on Earth during the planet's first 500 million years is now overwhelming, according to Harrison.

"You don't have plate tectonics on a dry planet," he said.

Strong evidence for liquid water at or near the Earth's surface 4.3 billion years ago was presented by Harrison and colleagues in a Jan. 11, 2001, cover story in Nature.

"Five different lines of evidence now support that once radical hypothesis," Harrison said. "The inclusions we found tell us the zircons grew in water-saturated magmas. We now observe a surprisingly low geothermal gradient, a low rate at which temperature increases in the Earth. The only mechanism that we recognize that is consistent with everything we see is that the formation of these zircons was at a plate-tectonic boundary. In addition, the chemistry of the inclusions in the zircons is characteristic of the two kinds of magmas today that we see at place-tectonic boundaries."

"We developed the view that plate tectonics was impossible in the early Earth," Harrison added. "We have now made observations from the Hadean (the Earth's earliest geological eon) — these little grains contain a record about the conditions under which they formed — and the zircons are telling us that they formed in a region with anomalously low heat flow. Where in the modern Earth do you have heat flow that is one-third of the global average, which is what we found in the zircons? There is only one place where you have heat flow that low in which magmas are forming: convergent plate-tectonic boundaries."

Three years ago, Harrison and his colleagues applied a technique to determine the temperature of ancient zircons.

"We discovered the temperature at which these zircons formed was constant and very low," Harrison said. "You can't make a magma at any lower temperature than what we're seeing in these zircons. You look at artists' conceptions of the early Earth, with flying objects from outer space making large craters; that should make zircons hundreds of degrees centigrade hotter than the ones we see. The only way you can make zircons at the low temperature we see is if the melt is water-saturated. There had to be abundant water. That's a big surprise because our longstanding conception of the early Earth is that it was dry."

Source: University of California - Los Angeles

http://www.physorg.com/news146924511.html

posted in Geology - 2 replies

Expedition set for 'ghost peaks'

bobs — Wed, 15 Oct 2008 07:20:34 GMT

By Jonathan Amos
Science reporter, BBC News

It is perhaps the last great Antarctic expedition - to find an explanation for why there is a great mountain range buried under the White Continent.

The Gamburtsevs match the Alps in scale but no-one has ever seen them because they are covered by up to 4km of ice.

Geologists struggle to understand how such a massif could have formed and persisted in the middle of Antarctica.

Now, an international team is setting out on a deep-field survey to try to get some answers.

The group comprises scientists, engineers, pilots and support staff from the UK, the US, Germany, Australia, China and Japan.

The ambitious nature of the project - working in Antarctica's far interior - has required an exceptional level of co-ordination and co-operation.

"You can almost think about it as exploring another planet - but on Earth," said Dr Fausto Ferraccioli from the British Antarctic Survey.

"This region is a complete enigma. It's in the middle of the continent. Most mountain ranges are on the edges of continents, and we really can't understand what these mountains are doing in the centre."

The AGAP (Antarctica's Gamburtsev Province) project will establish two camps from where the team will map the subglacial range using surface and airborne instruments.

The Gamburtsevs were discovered by a Soviet team making a traverse across the ice in the late 1950s. The rocky prominence was totally unexpected; scientists thought the interior of the continent would be relatively flat.

"There are two easy ways to make mountains," explained Dr Robin Bell, from the Lamont-Doherty Earth Observatory, who is a lead US researcher on the expedition.

"One is colliding continents, but after they collide they tend to erode; and the last collision was 500-million-plus years ago. They shouldn't be there.

"The other way is a hotspot, [with volcanoes punching through the crust] like in Hawaii; but there's no good evidence for underneath the ice sheet being that hot.

"I like to say it's rather like being an archaeologist and opening up a tomb in a pyramid and finding an astronaut sitting inside. It shouldn't be there."

The mountains are believed to have been a key nucleation point for the vast East Antarctic Ice Sheet.

It is thought that as Earth's climate cooled just over 30 million years ago, the snows that fell on the mountains produced mighty glaciers, which then merged to form one giant spreading ice-mass.

A better understanding of these events could give clues as to how Antarctica might evolve in the coming centuries if, as expected, the Earth continues its current warming trend.

The aerogeophysical survey of Antarctica's Gamburtsev Province (AGAP) is a flagship endeavour of International Polar Year - the global science community's concerted push to try to answer the big questions about the Earth's northern and southern extremes.

The challenging nature of the expedition has required that expertise be drawn from across polar community. Supplying such remote camps is a major logistical exercise; working in them - at temperatures 30-40 degrees below zero Celsius - is bound to be physically demanding.

Two survey aircraft will sweep back and forth across the ice to map the shape of the mountains. The planes will be equipped with ice-penetrating radar and instruments to measure the local gravitational and magnetic fields.

Information on the deeper structure of the Gamburtsevs will come from a network of seismometers that will listen to earthquake signals passing through the rock from the other side of the globe.

"We'll map everything from the detailed ripples on the surface of the ice sheet down to the temperature structure hundreds of kilometres in the Earth, so we'll have everything from the layering in the ice to what the nature of the rocks are," said Dr Bell.

Another important aim of the project is to find a place to drill for ancient ices. By examining bubbles of air trapped in compacted snow, it is possible for researchers to glean details about past environmental conditions.

Not only can they see concentrations of carbon dioxide and methane - the two principal human-produced gases now blamed for global warming - but they can also gauge past temperatures from the samples.

Somewhere in the Gamburtsev region there could be a location were it is possible to drill down to ices that are more than a million years old. This is at least 200,000 years older than the most ancient ices currently in the possession of scientists.

The expedition gets under way in the next few weeks and will take some two-and-a-half months to complete.

Maps, pics and video : http://news.bbc.co.uk/1/hi/sci/tech/7668070.stm

posted in Geology - 0 replies

Team finds Earth's 'oldest rocks'

bobs — Sun, 28 Sep 2008 19:33:07 GMT

By James Morgan
Science reporter, BBC News

Earth's most ancient rocks, with an age of 4.28 billion years, have been found on the shore of Hudson Bay, Canada.

Writing in Science journal, a team reports finding that a sample of Nuvvuagittuq greenstone is 250 million years older than any rocks known.

It may even hold evidence of activity by ancient life forms.

If so, it would be the earliest evidence of life on Earth - but co-author Don Francis cautioned that this had not been established.

"The rocks contain a very special chemical signature - one that can only be found in rocks which are very, very old," he said.

The professor of geology, who is based at McGill University in Montreal, added: "Nobody has found that signal any place else on the Earth."

"Originally, we thought the rocks were maybe 3.8 billion years old.

"Now we have pushed the Earth's crust back by hundreds of millions of years. That's why everyone is so excited."

Ancient rocks act as a time capsule - offering chemical clues to help geologists solve longstanding riddles of how the Earth formed and how life arose on it.

But the majority of our planet's early crust has already been mashed and recycled into Earth's interior several times over by plate tectonics.

Before this study, the oldest whole rocks were from a 4.03 billion-year-old body known as the Acasta Gneiss, in Canada's Northwest Territories.

The only things known to be older are mineral grains called zircons from Western Australia, which date back 4.36 billion years.

Date range

Professor Francis was looking for clues to the nature of the Earth's mantle 3.8 billion years ago.

He and colleague Jonathan O'Neil, from McGill University, travelled to remote tundra on the eastern shore of Hudson Bay, in northern Quebec, to examine an outcrop of the Nuvvuagittuq greenstone belt.

They sent samples for chemical analysis to scientists at the Carnegie Institution of Washington, who dated the rocks by measuring isotopes of the rare earth elements neodymium and samarium, which decay over time at a known rate.

The oldest rocks, termed "faux amphibolite", were dated within the range from 3.8 to 4.28 billion years old.

"4.28 billion is the figure I favour," says Francis.

"It could be that the rock was formed 4.3 billion years ago, but then it was re-worked into another rock form 3.8bn years ago. That's a hard distinction to draw."

The same unit of rock contains geological structures which might only have been formed if early life forms were present on the planet, Professor Francis suggested.

Early habitat?

The material displays a banded iron formation - fine ribbon-like bands of alternating magnetite and quartz.

This feature is typical of rock precipitated in deep sea hydrothermal vents - which have been touted as potential habitats for early life on Earth.

"These ribbons could imply that 4.3 billion years ago, Earth had an ocean, with hydrothermal circulation," said Francis.

"Now, some people believe that to make precipitation work, you also need bacteria.

"If that were true, then this would be the oldest evidence of life.

"But if I were to say that, people would yell and scream and say that there is no hard evidence."

Fortunately, geologists have already begun looking for such evidence, in similar rocks found in Greenland, dated 3.8 billion years.

"The great thing about our find, is it will bring in people here to Lake Hudson to carry out specialised studies and see whether there was life here or not," says Francis.

"Regardless of that, or the exact date of the rocks, the exciting thing is that we've seen a chemical signature that's never been seen before. That alone makes this an exciting discovery."

http://news.bbc.co.uk/1/hi/sci/tech/7639024.stm

posted in Geology - 1 reply

San Andreas Fault Cores Go Live, Online

bobs — Fri, 30 May 2008 16:00:00 GMT

Larry O'Hanlon, Discovery News

May 30, 2008 -- For the first time ever, the thrashed and jumbled innards of the notorious San Andreas Fault are now available online for anyone to see.

The new Google Maps-based "Core Viewer" allows scientists and the general public to peer at high-resolution images of the rock cores drilled and extracted directly from the steadily slipping section of the infamous fault two kilometers (1.2 miles) beneath Parkfield, Calif.

"That's where all the action is," said U.S. Geological Survey geophysicist Steve Hickman. At Parkfield, that action is already contorting the metal casing installed in the San Andreas Fault Observatory at Depth (SAFOD) borehole at a rate of two centimeters (0.8 inches) per year.

The core viewer shows the fronts and backs of the long cylindrical rocks, marked in centimeters, drilled out with circular drill heads. The cores reveal two sub-faults of the San Andreas where rocks are currently being ground up by the sidewise meeting of the Pacific and the North American tectonic plates.

The most important parts of the core show not only highly ground-up rocks, but rocks that have been polished by the shearing forces in the fault. There are also chunks of green rocks made of a very weak, slippery mineral called serpentine, which has long been a suspect in the lubricating of the San Andreas along this section in central California.

"The serpentine is really an important find for us," said Hickman, referring to a section shown in the Core Viewer under Hole G, Run 2, sections 7 through 9. "It allows the fault to creep. The presence of that serpentine is kind of a smoking gun."

Section 8 of the same area reveals dark rocks that appear to shimmer like opals. These rocks were essentially ground smooth by the fault, like stones polished by a rock tumbler, Hickman explained.

The bright white minerals in the same sections are calcite, a sign that water as been present and plays a role in the fault as well. These and other important sections of the core will be marked with bubbles containing scientific information as more work is done, Hickman told Discovery News.

"The core viewer is to show the scientific community what the core looks like," said Stanford University's Charley Weiland, who serves as SAFOD's data manager. Already there are 800 samples requested from researchers who want to conduct all sorts of research on the rocks.

"The core is a very scarce commodity," Weiland told Discovery News. The actual core is locked away at 4 degrees Centigrade with ocean drilling cores in a store facility in Texas, he said.

SAFOD is one of three "observatories" encompassed by the EarthScope project. The other two are the Plate Boundary Observatory, which measures the ongoing tectonic mangling of the crust throughout the Western United States, and the U.S. Array, which is moving a high-density network of seismic stations across North America to uncover the physical structure of the continent.

http://www.earthscope.org/data/safod_core_viewer

http://dsc.discovery.com/news/2008/05/30/san-andreas-fault.html

posted in Geology - 4 replies

ETS event happening under Puget Sound

Will The Dancer — Wed, 21 May 2008 00:46:36 GMT

The Episodic Tremor and Slip event is going on now beneath Puget Sound. The estimated energy dissipated by
some of the previous events are equivalent to a 6.7 subduction zone roller, but drawn out over several weeks.
Last tell during this event The Olympic mountains moved west about 5 mm as well.

It is concerning that my neighborhood part of the Cascadia S.Z. is locked, and has been for 300 years or so.

http://www.pnsn.org/WEBICORDER/DEEPTREM/winter2008.html

posted in Geology - 4 replies

A single boulder..........

bobs — Thu, 17 Jul 2008 22:16:35 GMT

.............may prove that Antarctica and North America were once connected

A lone granite boulder found against all odds high atop a glacier in Antarctica may provide additional key evidence to support a theory that parts of the southernmost continent once were connected to North America hundreds of millions of years ago.

Writing in the July 11 edition of the journal Science, an international team of U.S. and Australian investigators describe their findings, which were made in the Transantarctic Mountains, and their significance to the problem of piecing together what an ancient supercontinent, called Rodinia, looked like. The U.S. investigators were funded by the National Science Foundation (NSF).

Previous lines of scientific evidence led researchers to theorise that about 600-800 million years ago a portion of Rodinia broke away from what is now the southwestern United States and eventually drifted southward to become eastern Antarctica and Australia.

The team's find, they argue, provides physical evidence that confirms the so-called southwestern United States and East Antarctica (SWEAT) hypothesis.

"What this paper does is say that we have three main new lines of evidence that basically confirm the SWEAT idea," said John Goodge, an NSF-funded researcher with the Department of Geological Sciences at the University of Minnesota-Duluth.

Added Scott Borg, director of the division of Antarctic sciences in NSF's Office of Polar Programs, "this is first-rate work and a fascinating example of scientists at work putting together the pieces of a much larger puzzle. Not only do the authors pull together a diverse array of data to address a long-standing question about the evolution of the Earth's crust during a critical time for biological evolution, but the research shows how the ideas surrounding the SWEAT hypothesis have developed over time."

As a field researcher during the late 1980's and early 1990's, Borg authored papers on the SWEAT hypothesis.

The boulder find came by serendipity while the researchers were picking though rubble carried through the Transantarctic Mountains by ice streams-rivers of ice-that flow at literally a glacial pace from East Antarctica.

Goodge and his team were searching for rocks that might provide keys to the composition of the underlying continent crust of Antarctica, which in most places is buried under almost two miles of ice.

"We were picking up boulders in the moraines that looked interesting," Goodge said. "It was basically just a hodge-podge of material."

One rock in particular, small enough to heft in one hand, found atop the Nimrod Glacier, was later determined to be a very specific form of granite with, as Goodge describes it, "a particular type of coarse-grained texture."

Subsequent chemical and isotopic tests conducted in laboratories in the United States revealed that the boulder had a chemistry "very similar to a unique belt of igneous rocks in North America" that stretches from what is now California eastward through New Mexico to Kansas, Illinois and eventually through New Brunswick and Newfoundland in Canada.

That belt of rocks is known to have been a part of what is called Laurentia, which was a component of the supercontinent of Rodinia.

"There is a long, linear belt of these igneous rocks that stretches across Laurentia. But 'bang' it stops, right there at the (western) margin where we knew that something rifted away" from what is now the West Coast of the United States," Goodge said.

"It just ends right where that ancient rift margin is," Goodge said. "And these rocks are basically not found in any other part of the world."

That it should turn up on a glacier high up in the mountains of Antarctica is strong evidence in support of the SWEAT model that parts of North America continue into part of the frozen continent at the bottom of the Earth.

"There's no other explanation for how it got where we found it," Goodge said. "It was bull-dozed over from that interior region of Antarctica."

The find itself is compelling to geologists, Goodge noted, because little other physical evidences exists to allow them directly to put together the jigsaw puzzle of the long-disappeared Rodinia.

But because the supercontinent existed at a key time in the development of multi-cellular life on Earth, it also helps provide a geological context in which this massive biotic change took place.

"During the Cambrian explosion about 520 million years ago we started seeing this huge expansion in the diversity of life forms," Goodge said. "This was also a time when the Earth was undergoing tremendous geologic changes."

He added that "something helped trigger that big radiation in life."

The shifting configuration of the continents, accompanied by collisions between landmasses, erosion and the influx of chemicals into the seas may well have provided the nutrients to that growing diversity of lifeforms.

"There are ideas developing about these connections between the geo-tectonic world on the one hand and biology on the other.

The job of geoscientists in this context, he said "is to reconstruct what the world was like at the time."

Source: National Science Foundation

http://www.physorg.com/news135518754.html

posted in Geology - 0 replies

Rocks under the northern ocean are found to resemble ones far south

bobs — Wed, 30 Apr 2008 21:23:20 GMT

Scientists probing volcanic rocks from deep under the frozen surface of the Arctic Ocean have discovered a special geochemical signature until now found only in the southern hemisphere. The rocks were dredged from the remote Gakkel Ridge, which lies under 3,000 to 5,000 meters of water; it is Earth’s most northerly undersea spreading ridge. The study appears in the May 1 issue of the leading science journal Nature.

The Gakkel extends some 1,800 kilometers beneath the Arctic ice between Greenland and Siberia. Heavy ice cover prevented scientists from getting at it until the 2001 Arctic Mid-Ocean Ridge Expedition, in which U.S and German ice breakers cooperated. This produced data showing that the ridge is divided into robust eastern and western volcanic zones, separated by an anomalously deep segment. That abrupt boundary contains exposed unmelted rock from earth’s mantle, the layer that underlies the planet’s hardened outer shell, or lithosphere.

By studying chemical trace elements and isotope ratios of the elements lead, neodymium, and strontium, the paper’s authors showed that the eastern lavas, closer to Siberia, display a typical northern hemisphere makeup. However, the western lavas, closer to Greenland, show an isotopic signature called the Dupal anomaly. The Dupal anomaly, whose origin is intensely debated, is found in the southern Indian and Atlantic oceans, but until now was not known from spreading ridges of the northern hemisphere. Lead author Steven Goldstein, a geochemist at Columbia University’s Lamont-Doherty Earth Observatory (LDEO), said that this did not suggest the rocks came from the south. Rather, he said, they might have formed in similar ways. “It implies that the processes at work in the Indian Ocean might have an analog here,” said Goldstein. Possible origins debated in the south include upwelling of material from the deep earth near the core, or shallow contamination of southern hemispheric mantle with certain elements during subduction along the edges of the ancient supercontinent of Pangea.

At least in the Arctic, the scientists say they know what happened. Some 53 million years ago, what are now Eurasia and Greenland began separating, with the Gakkel as the spreading axis. Part of Eurasia’s “keel”—a relatively stable layer of mantle pasted under the rigid continent and enriched in certain elements that are also enriched in the continental crust—got peeled away. As the spreading continued, the keel material got mixed with “normal” mantle that was depleted in these same elements. This formed a mixture resembling the Dupal anomaly. The proof, said Goldstein, is that the chemistry of the western Gakkel lavas appear to be mixtures of “normal” mantle and lavas coming from volcanoes on the Norwegian/Russian island of Spitsbergen. Although Spitsbergen is an island, it is attached to the Eurasian continent, and its volcanoes are fueled by melted keel material.

“This is unlikely to put an end to the debate about the origin of the southern hemisphere Dupal signature, as there may be other viable explanations for it,” said Goldstein. “On the other hand, this study nails it in the Arctic. Moreover, it delineates an important process within Earth’s system, where material associated with the continental lithospheric keel is transported to the deeper convectiing mantle.”

Source: The Earth Institute at Columbia University

http://www.physorg.com/news128778940.html

posted in Geology - 0 replies

How deep is Europe?

bobs — Wed, 30 Apr 2008 21:22:04 GMT

(Also posted at: http://awesomenature.tribe.net/ )

The Earth's crust is, on global average around 40 kilometres deep. In relation to the total diameter of the Earth with approx. 12800 kilometres this appears to be rather shallow, but precisely these upper kilometres of the crust, the human habitat, is of special interest for us.

Europe's crust shows an astonishing diversity: for example the crust under Finland is as deep as one only expects for crust under a mountain range such as the Alps. It is also amazing that the crust under Iceland and the Faroer-Islands is considerably deeper than a typical oceanic crust. This is explained by M. Tesauro und M. Kaban from GeoForschungsZentrum Potsdam (GFZ) and S. Cloetingh from the Vrije Universiteit in Amsterdam in a recent publication in the renowned scientific journal "Geophysical Research Letters". GFZ is the German Research Centre for Geosciences and a member of the Helmholtz Association.

For many years intensive investigation of the Earth's crust has been underway. However, different research groups in Europe have mostly been concentrating on individual regions. Hence, a high-resolution and consistent overall picture has not been available to date. With the present study this gap can now be filled. By incorporating the latest seismological results a digital model of the European crust has been created. This new detailed picture also allows for the minimization of interfering effects of the crust when taking a glance at the deeper Earth's interior.

A detailed model of the Earth's crust, i.e. from the upper layers to approx. a depth of 60 km is essential to understand the many millions of years of development of the European Continent. This knowledge supports the discovery of the commercial importance of ore deposits or crude oil in the continental shelf or in general with the use of the subterranean e.g. for the sequestration of CO2. It also contributes to the identification of geological hazards such as earthquakes.

Citation: Tesauro, M., M. K. Kaban, and S. A. P. L. Cloetingh (2008), EuCRUST-07: A new reference model for the European crust, Geophys. Res. Lett., 35, L05313, doi:10.1029/2007GL032244.

Source: Helmholtz Association of German Research Centres

http://www.physorg.com/news128774944.html

posted in Geology - 0 replies

Discovery sheds light on mantle formation

bobs — Fri, 11 Apr 2008 19:47:53 GMT

Uncovering a rare, two-billion-year-old window into the Earth’s mantle, a University of Houston professor and his team have found our planet’s geological history is more complex than previously thought.

Jonathan Snow, assistant professor of geosciences at UH, led a team of researchers in a North Pole expedition, resulting in a discovery that could shed new light on the mantle, the vast layer that lies beneath the planet’s outer crust. These findings are described in a paper titled “Ancient, highly heterogeneous mantle beneath Gakkel Ridge, Arctic Ocean,” appearing recently in Nature.

These two-billion-year-old rocks that time forgot were found along the bottom of the Arctic Ocean floor, unearthed during research voyages in 2001 and 2004 to the Gakkel Ridge, an approximately 1,000-mile-long underwater mountain range between Greenland and Siberia. This massive underwater mountain range forms the border between the North American and Eurasian plates beneath the Arctic Ocean, where the two plates diverge.

These were the first major expeditions ever undertaken to the Gakkel Ridge, and these latest published findings are the fruit of several years of research and millions of dollars spent to retrieve and analyze these rocks.

The mantle, the rock layer that comprises about 70 percent of the Earth’s mass, sits several miles below the planet’s surface. Mid-ocean ridges like Gakkel, where mantle rock is slowly pushing upward to form new volcanic crust as the tectonic plates slowly move apart, is one place geologists look for clues about the mantle. Gakkel Ridge is unique because it features – at some locations – the least volcanic activity and most mantle exposure ever discovered on a mid-ocean ridge, allowing Snow and his colleagues to recover many mantle samples.

“I just about fell off my chair,” Snow said. “We can’t exaggerate how important these rocks are – they’re a window into that deep part of the Earth.”

Venturing out aboard a 400-foot-long research icebreaker, Snow and his team sifted through thousands of pounds of rocks scooped up from the ocean floor by the ship’s dredging device. The samples were labeled and cataloged and then cut into slices thinner than a human hair to be examined under a microscope. That is when Snow realized he found something that, for many geologists, is as rare and fascinating as moon rocks – mantle rocks devoid of sea floor alteration. Analysis of the isotopes of osmium, a noble metal rarer than platinum within the mantle rocks, indicated they were two billion years old. The use of osmium isotopes underscores the significance of the results, because using them for this type of analysis is still a new, innovative and difficult technique.

Since the mantle is slowly moving and churning within the Earth, geologists believe the mantle is a layer of well-mixed rock. Fresh mantle rock wells up at mid-ocean ridges to create new crust. As the tectonic plates move, this crust slowly makes its way to a subduction zone, a plate boundary where one plate slides underneath another and the crust is pushed back into the mantle from which it came.

Because this process takes about 200 million years, it was surprising to find rocks that had not been remixed inside the mantle for two billion years. The discovery of the rocks suggests the mantle is not as well-mixed or homogenous as geologists previously believed, revealing that the Earth’s mantle preserves an older and more complex geologic history than previously thought. This opens the possibility of exploring early events on Earth through the study of ancient rocks preserved within the Earth’s mantle.

The rocks were found during two expeditions Snow and his team made to the Arctic, each lasting about two months. The voyages were undertaken while Snow was a research scientist at the Max Planck Institute in Germany, and the laboratory study was done by his research team that now stretches from Hawaii to Houston to Beijing.

Since coming to UH in 2005, Snow’s work stemming from the Gakkel Ridge samples has continued, with more research needed to determine exactly why these rocks remained unmixed for so long. Further study using a laser microprobe technique for osmium analysis available only in Australia is planned for next year.

Source: University of Houston

http://www.physorg.com/news127124384.html

posted in Geology - 0 replies

Grand Canyon may be as old as dinosaurs, says new study

bobs — Thu, 10 Apr 2008 22:59:09 GMT

New geological evidence indicates the Grand Canyon may be so old that dinosaurs once lumbered along its rim, according to a study by researchers from the University of Colorado at Boulder and the California Institute of Technology.

The team used a technique known as radiometric dating to show the Grand Canyon may have formed more than 55 million years ago, pushing back its assumed origins by 40 million to 50 million years. The researchers gathered evidence from rocks in the canyon and on surrounding plateaus that were deposited near sea level several hundred million years ago before the region uplifted and eroded to form the canyon.

A paper on the subject will be published in the May issue of the Geological Society of America Bulletin. CU-Boulder geological sciences Assistant Professor Rebecca Flowers, lead author and a former Caltech postdoctoral researcher, collaborated with Caltech geology Professor Brian Wernicke and Caltech geochemistry Professor Kenneth Farley on the study.

"As rocks moved to the surface in the Grand Canyon region, they cooled off," said Flowers. "The cooling history of the rocks allowed us to reconstruct the ancient topography, telling us the Grand Canyon has an older prehistory than many had thought."

The team believes an ancestral Grand Canyon developed in its eastern section about 55 million years ago, later linking with other segments that had evolved separately. "It's a complicated picture because different segments of the canyon appear to have evolved at different times and subsequently were integrated," Flowers said.

The ancient sandstone in the canyon walls contains grains of a phosphate mineral known as apatite -- hosting trace amounts of the radioactive elements uranium and thorium -- which expel helium atoms as they decay, she said. An abundance of the three elements, paired with temperature information from Earth's interior, provided the team a clock of sorts to calculate when the apatite grains were embedded in rock a mile deep -- the approximate depth of the canyon today -- and when they cooled as they neared Earth's surface as a result of erosion.

Apatite samples from the bottom of the Upper Granite Gorge region of the Grand Canyon yield similar dates as samples collected on the nearby plateau, said Caltech's Wernicke. "Because both canyon and plateau samples resided at nearly the same depth beneath the Earth's surface 55 million years ago, a canyon of about the same dimensions of today may have existed at least that far back, and possibly as far back as the time of dinosaurs at the end of the Cretaceous period 65 million years ago."

One of the most surprising results from the study is the evidence showing the adjacent plateaus around the Grand Canyon may have eroded away as swiftly as the Grand Canyon itself, each dropping a mile or more, said Flowers. Small streams on the plateaus appear to have been just as effective at stripping away rock as the ancient Colorado River was at carving the massive canyon.

"If you stand on the rim of the Grand Canyon today, the bottom of the ancestral canyon would have sat over your head, incised into rocks that have since been eroded away," said Flowers. The ancestral Colorado River was likely running in the opposite direction millions of years ago, she said.

When the canyon was formed, it probably looked like a much deeper version of present-day Zion Canyon, which cuts through strata of the Mesozoic era dating from about 250 million to 65 million years ago, Wernicke said. From 28 million to 15 million years ago, a pulse of erosion deepened the already-formed canyon and also scoured surrounding plateaus, stripping off the Mesozoic strata to reveal the Paleozoic rocks visible today, he said.

The prevailing belief is that the canyon was incised by an ancient river about six million years ago as the surrounding plateau began rising from sea level to the current elevation of about 7,000 feet. The new scenario described in the GSA Bulletin by Flowers and her colleagues is consistent with recent evidence by other geologists using radiometric dating techniques indicating the Grand Canyon is significantly older than scientists had long believed.

Source: University of Colorado at Boulder

http://www.physorg.com/news127055332.html

posted in Geology - 0 replies

New Findings From Tibetan Plateau Suggest Uplift Occurred In Stages

bobs — Tue, 25 Mar 2008 07:41:25 GMT

by Staff Writers
Santa Cruz CA (SPX) Mar 25, 2008
The vast Tibetan Plateau--the world's highest and largest plateau, bordered by the world's highest mountains--has long challenged geologists trying to understand how and when the region rose to such spectacular heights. New evidence from an eight-year study by U.S. and Chinese researchers indicates that the plateau rose in stages, with uplift occurring first in the central plateau and later in regions to the north and south.
"The middle part of the plateau was uplifted first at least 40 million years ago, while the Himalayan Range in the south and also the mountains to the north were uplifted significantly later," said Xixi Zhao, a research scientist at the University of California, Santa Cruz.

The team found marine fossils suggesting that the now lofty Himalayas remained below sea level at a time when the central plateau was already at or near its modern elevation, Zhao said. The average elevation of the plateau today is more than 4,500 meters (14,850 feet).

The researchers published their findings in the Proceedings of the National Academy of Sciences (online the week of March 24 and later in print). Zhao, who is affiliated with the Institute of Geophysics and Planetary Physics at UCSC, is the second author of the paper. First author Chengshan Wang of the China University of Geosciences in Beijing has been collaborating with Zhao and other UCSC researchers since 1996.

Known as "the roof of the world," the Tibetan Plateau was created by the ongoing collision of tectonic plates as India plows northward into Asia. Coauthor Robert Coe, a professor of Earth and planetary sciences at UCSC, said ideas about how the uplift of the plateau occurred have been evolving since well before his first visit to Tibet in 1988.

"People used to talk about the whole plateau coming up at once, but it has become clear that different parts of the plateau were elevated at different times," Coe said. "Our work shows that the central part of the plateau was uplifted first, and it seems to fit pretty well with other studies."

The rise of the Tibetan Plateau led to dramatic changes in the climate, both regionally and globally. For climate researchers trying to understand major episodes of global climate change in Earth's past, the timing of the uplift is a crucial piece of information.

"One of the traditional views of when Tibet became a high plateau is that it's a relatively recent phenomenon that happened in the last 15 million years," said coauthor Peter Lippert, a UCSC graduate student who has spent five field seasons studying the geology of the plateau. "The existence of a high plateau at least 40 million years ago could have important climatic implications."

The team of U.S. and Chinese geologists based their findings on extensive field studies conducted mostly in a remote interior region of the Tibetan Plateau. They focused on an area called the Hoh Xil Basin in the north-central part of the plateau. The area's geologic history is recorded in layers of sedimentary rock 5,000 meters thick. Now a part of the high plateau, it was once a basin on the northern edge of the central plateau, Lippert said.

"The structure of the basin and way the sediments were deposited show that it is the type of basin that forms at the base of large mountains. So we've shown that there was high topography to the south of the Hoh Xil Basin at least 40 million years ago," he said.

Several lines of evidence support the team's conclusions. In addition to field studies, the researchers used a variety of laboratory techniques to analyze and date the rocks. Past changes in Earth's magnetic field, recorded in the magnetization of the rocks, provide one method of dating. Called magnetostratigraphy, this analysis was performed in Coe's laboratory at UCSC. Another dating technique used in the study, called apatite fission-track analysis, is based on the damage trails left in apatite crystals by the decay of radiogenic isotopes.

The researchers also discovered volcanic rock in an area of the central plateau south of the Hoh Xil Basin. The flat bed of hardened lava lies on top of tilted and folded layers of sedimentary rocks; geochronology techniques dated it to 40 million years ago.

"The presence of these flat-lying volcanic rocks tells us that the sedimentary rock was deformed prior to the volcanism, and it extends the age of volcanism in this part of Tibet from 15 million to 40 million years ago," Lippert said.

In the Himalayas, the team found fossils of marine plankton called radiolarians that turned out to be 5 million years younger than any previously discovered marine fossils from that area. The discovery narrows the window of time during which the Himalayas could have been uplifted. When the central part of the Tibetan plateau was uplifted more than 40 million years ago, Mount Everest and the rest of the Himalayas were still part of a deep ocean basin, Zhao said.

The Himalayan region is very complicated, however, and other groups are working to determine the timing of its uplift more precisely, said Lippert. "Our main contribution has been the data we gathered from the north-central part of the plateau, which has not been well studied," he said.

Zhao noted that the U.S. researchers could not have gained access to this area without the support of their Chinese colleagues. This long-term collaboration has included exchanges of graduate students between UCSC and Chinese universities, as well as opportunities for UCSC undergraduates to conduct field research in Tibet. "It has been a very good research collaboration, with a strong educational component as well," Zhao said.

http://www.terradaily.com/reports/New_Findings_From_Tibetan_Plateau_Suggest_Uplift_Occurred_In_Stages_999.html

posted in Geology - 0 replies

10 questions shaping 21st-century earth science identified

bobs — Wed, 12 Mar 2008 20:59:42 GMT

Ten questions driving the geological and planetary sciences were identified today in a new report by the National Research Council. Aimed at reflecting the major scientific issues facing earth science at the start of the 21st century, the questions represent where the field stands, how it arrived at this point, and where it may be headed.

"With all the advancements over the last 20 years, we can now get a better picture of Earth by looking at it from micro- to macro-perspectives, such as discerning individual atoms in minerals or watching continents drift and mountains grow," said Donald J. DePaolo, professor of geochemistry at the University of California at Berkeley and chair of the committee that wrote the report. "To keep the field moving forward, we have to look to the past and ask deeper fundamental questions, about the origins of the Earth and life, the structure and dynamics of planets, and the connections between life and climate, for example."

The report was requested by the U.S. Department of Energy, National Science Foundation, U.S. Geological Survey, and NASA. The committee selected the question topics, without regard to agency-specific issues, and covered a variety of spatial scales -- subatomic to planetary -- and temporal scales -- from the past to the present and beyond.

The committee canvassed the geological community and deliberated at length to arrive at 10 questions. Some of the questions present challenges that scientists may not understand for decades, if ever, while others are more tractable, and significant progress could be made in a matter of years, the report says. The committee did not prioritize the 10 questions -- listed with associated illustrative issues below -- nor did it recommend specific measures for implementing them.

HOW DID EARTH AND OTHER PLANETS FORM?
While scientists generally agree that this solar system's sun and planets came from the same nebular cloud, they do not know enough about how Earth obtained its chemical composition to understand its evolution or why the other planets are different from one other. Although credible models of planet formation now exist, further measurements of solar system bodies and extrasolar objects could offer insight to the origin of Earth and the solar system.

WHAT HAPPENED DURING EARTH'S "DARK AGE" (THE FIRST 500 MILLION YEARS)?
Scientists believe that another planet collided with Earth during the latter stages of its formation, creating debris that became the moon and causing Earth to melt down to its core. This period is critical to understanding planetary evolution, especially how the Earth developed its atmosphere and oceans, but scientists have little information because few rocks from this age are preserved.

HOW DID LIFE BEGIN?
The origin of life is one of the most intriguing, difficult, and enduring questions in science. The only remaining evidence of where, when, and in what form life first appeared springs from geological investigations of rocks and minerals. To help answer the question, scientists are also turning toward Mars, where the sedimentary record of early planetary history predates the oldest Earth rocks, and other star systems with planets.

HOW DOES EARTH'S INTERIOR WORK, AND HOW DOES IT AFFECT THE SURFACE?
Scientists know that the mantle and core are in constant convective motion. Core convection produces Earth's magnetic field, which may influence surface conditions, and mantle convection causes volcanism, seafloor generation, and mountain building. However, scientists can neither precisely describe these motions, nor calculate how they were different in the past, hindering scientific understanding of the past and prediction of Earth's future surface environment.

WHY DOES EARTH HAVE PLATE TECTONICS AND CONTINENTS?
Although plate tectonic theory is well established, scientists wonder why Earth has plate tectonics and how closely it is related to other aspects of Earth, such as the abundance of water and the existence of the continents, oceans, and life. Moreover, scientists still do not know when continents first formed, how they remained preserved for billions of years, or how they are likely to evolve in the future. These are especially important questions as weathering of the continental crust plays a role in regulating Earth's climate.

HOW ARE EARTH PROCESSES CONTROLLED BY MATERIAL PROPERTIES?
Scientists now recognize that macroscale behaviors, such as plate tectonics and mantle convection, arise from the microscale properties of Earth materials, including the smallest details of their atomic structures. Understanding materials at this microscale is essential to comprehending Earth's history and making reasonable predictions about how planetary processes may change in the future.

WHAT CAUSES CLIMATE TO CHANGE -- AND HOW MUCH CAN IT CHANGE?
Earth's surface temperature has remained within a relatively narrow range for most of the last 4 billion years, but how does it stay well-regulated in the long run, even though it can change so abruptly" Study of Earth's climate extremes through history -- when climate was extremely cold or hot or changed quickly -- may lead to improved climate models that could enable scientists to predict the magnitude and consequences of climate change.

HOW HAS LIFE SHAPED EARTH -- AND HOW HAS EARTH SHAPED LIFE?
The exact ways in which geology and biology influence each other are still elusive. Scientists are interested in life's role in oxygenating the atmosphere and reshaping the surface through weathering and erosion. They also seek to understand how geological events caused mass extinctions and influenced the course of evolution.

CAN EARTHQUAKES, VOLCANIC ERUPTIONS, AND THEIR CONSEQUENCES BE PREDICTED?
Progress has been made in estimating the probability of future earthquakes, but scientists may never be able to predict the exact time and place an earthquake will strike. Nevertheless, they continue to decipher how fault ruptures start and stop and how much shaking can be expected near large earthquakes. For volcanic eruptions, geologists are moving toward predictive capabilities, but face the challenge of developing a clear picture of the movement of magma, from its sources in the upper mantle, through Earth's crust, to the surface where it erupts.

HOW DO FLUID FLOW AND TRANSPORT AFFECT THE HUMAN ENVIRONMENT?
Good management of natural resources and the environment requires knowledge of the behavior of fluids, both below ground and at the surface, and scientists ultimately want to produce mathematical models that can predict the performance of these natural systems. Yet, it remains difficult to determine how subsurface fluids are distributed in heterogeneous rock and soil formations, how fast they flow, how effectively they transport dissolved and suspended materials, and how they are affected by chemical and thermal exchange with the host formations.

Source: The National Academies

http://www.physorg.com/news124539902.html

posted in Geology - 4 replies

Scientist answers how Peruvian meteorite made it to Earth

bobs — Tue, 11 Mar 2008 21:51:18 GMT

It made news around the world: On Sept. 15, 2007, an object hurtled through the sky and crashed into the Peruvian countryside. Scientists dispatched to the site near the village of Carancas found a gaping hole in the ground.

Peter Schultz, professor of geological sciences at Brown University and an expert in extraterrestrial impacts, went to Peru to learn more. For the first time, he will present findings from his travels at the 39th annual Lunar and Planetary Science Conference in League City, Texas, in a talk scheduled for 2 p.m. on March 11, 2008. Brown graduate student Robert “Scott” Harris collaborated on the research, joined by Jose Ishitsuka, a Peruvian astrophysicist, and Gonzalo Tancredi, an astronomer from Uruguay.

What Schultz and his team found is surprising. The object that slammed into a dry riverbed in Peru was a meteorite, and it left a 49-foot-wide crater. Soil ejected from the point of impact was found nearly four football fields away. When Schultz’s team analyzed the soil where the fireball hit, he found “planar deformation features,” or fractured lines in sand grains found in the ground. Along with evidence of debris strewn over a wide area, the shattered sand grains told Schultz that the meteorite had maintained a high rate of speed as it shot through the atmosphere. Scientists think it was traveling at roughly 15,000 miles per hour at the moment of impact.

“Normally with a small object like this, the atmosphere slows it down, and it becomes the equivalent of a bowling ball dropping into the ground,” Schultz said. “It would make a hole in the ground, like a pit, but not a crater. But this meteorite kept on going at a speed about 40 to 50 times faster than it should have been going.”

Scientists have determined the Carancas fireball was a stony meteorite – a fragile type long thought to be ripped into pieces as it enters the Earth’s atmosphere and then leaves little more than a whisper of its journey.

Yet the stony meteorite that struck Peru survived its passage mostly intact before impact.

“This just isn’t what we expected,” Schultz said. “It was to the point that many thought this was fake. It was completely inconsistent with our understanding how stony meteorites act.”

Schultz said that typically fragments from meteorites shoot off in all directions as the object speeds to Earth. But he believes that fragments from the Carancas meteorite may have stayed within the fast-moving fireball until impact. How that happened, Schultz thinks, is due to the meteorite’s high speed. At that velocity, the fragments could not escape past the “shock-wave” barrier accompanying the meteorite and instead “reconstituted themselves into another shape,” he said.

That new shape may have made the meteorite more aerodynamic – imagine a football passing through air versus a cinderblock – meaning it encountered less friction as it sped toward Earth, hitting the surface as one large chunk.

“It became very streamlined and so it penetrated the Earth’s atmosphere more efficiently,” Schultz said.

Schultz’s theory could upend the conventional wisdom that all small, stony meteorites disintegrate before striking Earth. If correct, it could change the thinking about the size and type of extraterrestrial objects that have bombarded the Earth for eons and could strike our planet next.

“You just wonder how many other lakes and ponds were created by a stony meteorite, but we just don’t know about them because when these things hit the surface they just completely pulverize and then they weather,” said Schultz, director of the Northeast Planetary Data Center and the NASA/Rhode Island University Space Grant Consortium.

Schultz’s research could have implications for Mars, where craters have been discovered in recent missions. “They could have come from anything,” he said. “It would be interesting to study these small craters and see what produced them. Perhaps they also will defy our understanding.”

Source: Brown University

http://www.physorg.com/news124466115.html

posted in Geology - 0 replies

Rock: Electrons Run Through It

bobs — Tue, 11 Mar 2008 09:51:45 GMT

ScienceDaily (Mar. 11, 2008) — If the Flintstones had electricity, their wires might have been made of rock. New results in Science Express show that a chunk of hematite can conduct electrons under certain chemical conditions. In addition, the current causes some mineral surfaces to build up while others degrade. These results with iron oxide might be important for water quality, soil evolution, and environmental cleanup.

"Considering iron as an important nutrient, the finding could help us understand how soils evolve from nutrient rich to nutrient poor," says lead investigator Kevin Rosso, a chemist at the Department of Energy's Pacific Northwest National Laboratory. "And it has implications for other common minerals such as pyrite and manganese oxides -- even particles in the atmosphere."

Mineral surfaces are linked by electrons traveling through mineral's bulk. Scientists have long known that electrons can travel through some iron oxides when a voltage is applied, but they have assumed that electrons stemming from chemical reactions alone won't move spontaneously through the mineral's bulk. That long-standing assumption has caused chemists to treat different faces of a hunk of mineral as independent entities that don't 'communicate' with each other. New results, published online March 6, 2008 in Science Express, suggest otherwise.

"Now we know reactions at different faces of these minerals can couple together and yield behavior unique to semiconducting minerals," says Rosso.

Minerals often exist as individual crystals in rocks at a stream's bottom, where they keep busy reacting with the water flowing around them. Understanding this chemistry is central to understanding how elements move through sediments, maintaining good water quality, and cleaning up pollution. To elicit the details, scientists study what effect acids and other forms of chemicals have on mineral surfaces.

When Rosso and PNNL colleague Svetlana Yanina immersed a cube-shaped hematite crystal in an acid solution in the absence of oxygen, they expected all surfaces to degrade. But when the chemists examined the surfaces at high magnification, they found one surface that didn't. This surface grew pyramid-like mounds rising from the top. "The whole crystal wants to dissolve, thermodynamically," says Rosso. "So we didn't expect to see that growth."

No one had previously reported this buildup, so the team modified their experiments to try to prevent the pyramids from growing. "In fact, we spent a year trying to get rid of it," Rosso says.

One path to getting rid of something is to understand how it got there in the first place, so they decided to explore how the pyramids formed. The researchers performed atomic force, scanning electron and transmission electron microscopy at the DOE's Environmental Molecular Sciences Laboratory on the PNNL campus, as well as electrical potential measurements of the individual surfaces.

Because hematite is a crystal of iron oxide, the sides and the top (and bottom) are structurally different, and therefore have different chemical properties. The team wondered if the iron being deposited on the top came from iron dissolving from the sides, building up in solution, and then redepositing.

To test this, they separated the six cube surfaces into groups: They took two cubes, protected four sides from the solution on one, and on the other, protected the top and bottom. The acidic solution chewed away the unprotected surfaces, as expected. But the chemists didn't see any buildup on the unprotected top and bottom faces and instead saw degradation. This indicated the breakdown and buildup were not independent of each other.

"The hematite won't grow pyramids without that surface being connected to the dissolving ones," says Rosso.

The required physical connection hinted at electron conduction. Iron in solution, or Fe(II), contains one more electron than the iron in the crystal, Fe(III). If Fe(II) landed on the top, it might react with the surface, incorporate into the crystal and give up its electron. The electron could then flow through the crystal to the sides, where an atom of Fe(III) could pick up the electron and dissolve into the solution.

To prove this, the chemists connected the electron flow with a wire. When they repeated the first experiment but connected the two cubes with a dab of silver, the team restored the pyramid buildup. Additional experiments allowed them to measure the electrical potential driving the current flow, which came out to 200 millivolts -- about 6% of the power needed for a keychain LED light, or about twice as much as in a nerve cell.

Reference: S. V. Yanina and K. M. Rosso, "Linked reactivity at mineral-water interfaces through bulk crystal conduction," published online at Science Express, March 6, 2008, 10.1126/science.1151614.

This work was supported by the Department of Energy's Office of Basic Energy Sciences Geosciences Program.

Adapted from materials provided by DOE/Pacific Northwest National Laboratory.

http://www.sciencedaily.com/releases/2008/03/080306183140.htm

posted in Geology - 0 replies

Researchers confirm discovery of Earth's inner, innermost core

bobs — Mon, 10 Mar 2008 22:16:05 GMT

Geologists at the University of Illinois have confirmed the discovery of Earth’s inner, innermost core, and have created a three-dimensional model that describes the seismic anisotropy and texturing of iron crystals within the inner core.

“For many years, we have been like blind men touching different parts of an elephant,” said U. of I. geologist Xiaodong Song. “Now, for the fist time, we have a sense of the entire elephant, and see what the inner core of Earth really looks like.”

Using both newly acquired data and legacy data collected around the world, Song and postdoctoral research associate Xinlei Sun painstakingly probed the shape of Earth’s core. The researchers report their findings in a paper accepted for publication in the journal Earth and Planetary Science Letters.

Composed mainly of iron, Earth’s core consists of a solid inner core about 2,400 kilometers in diameter and a fluid outer core about 7,000 kilometers in diameter. The inner core plays an important role in the geodynamo that generates Earth’s magnetic field.

The solid inner core is elastically anisotropic; that is, seismic waves have different speeds along different directions. The anisotropy has been found to change with hemisphere and with radius. In the latest work, Sun and Song describe another anomaly – a global structure – found within the inner core.

“To constrain the shape of the inner core anisotropy, we needed a uniform distribution of seismic waves traveling in all directions through the core,” Sun said. “Since the seismic waves we studied were generated by earthquakes, one challenge was acquiring enough seismic waves recorded at enough stations.”

In their analysis, Sun and Song used a three-dimensional tomography technique to invert the anisotropy of the inner core. They parameterized the anisotropy of the inner core in both radial and longitudinal directions. The researchers then used a three-dimensional ray tracing method to trace and retrace the seismic waves through the inner core iteratively.

What they found was a distinct change in the inner core anisotropy, clearly marking the presence of an inner inner core with a diameter of about 1,180 kilometers, slightly less than half the diameter of the inner core.

The layering of the core is interpreted as different texturing, or crystalline phase, of iron in the inner core, the researchers say.

“Our results suggest the outer inner core is composed of iron crystals of a single phase with different degrees of preferred alignment along Earth’s spin axis,” Sun said. “The inner inner core may be composed of a different phase of crystalline iron or have a different pattern of alignment.”

Although the anisotropy of the inner core was proposed 20 years ago, “this is the first time we have been able to piece everything together to create a three-dimensional view,” Song said. “This view should help us better understand the character, mineral properties and evolution of Earth’s inner core.”

Source: University of Illinois at Urbana-Champaign

http://www.physorg.com/news124372414.html

posted in Geology - 0 replies

You Can't Make This Stuff Up....

Badger — Tue, 26 Feb 2008 00:29:04 GMT

Well, actually it seems you can. From the same folks who bring us the Creation Museum in Knuckle Drag, Kentucky we now have a peer reviewed journal of Scientific papers anchored in creationist science.

"I’m not making this up, I swear. “Answers in Genesis,” the same nonsensical outlet that has given us Ken Ham’s “Creation Museum,” recently launched a “peer reviewed” “technical” journal, called, of course, “Answers Research Journal.” The idea, we learn from the “About” section of the journal’s web page, is to provide an outlet for “interdisciplinary scientific and other relevant research from the perspective of the recent Creation and the global Flood within a biblical framework.” See, apparently “there has been a pressing need for such a journal,” because “people want to know they can trust what is published on the Internet,” and they “can give you absolute assurance that the papers we will be publishing in Answers Research Journal are of the highest scientific and theological standard.” Of course, a high theological standard is a bit of an oxymoron, but let’s not quibble on the details."

I checked out the web site and the first thing I stumble across here: http://www.answersingenesis.org/arj/

is a paper on Catastrophic Granite Formation ( http://www.answersingenesis.org/articles/arj/v1/n1#catastrophic-granite-formation) which suggests - no PROVES - that batholithic granites can emplace into country rock and cool in periods of hundred of years.

With this in mind have a laugh. The reading's worth it.

posted in Geology - 4 replies

Tiny pieces of 'deep time' brought to the surface

bobs — Mon, 03 Mar 2008 22:19:20 GMT

Three-billion-year-old zircon microcrystals found in northern Ontario are proving to be a new record of the processes that form continents and their natural resources, including gold and diamonds.

The discovery was made recently by an international research team led by Earth Sciences professor Desmond Moser at The University of Western Ontario. Measuring no more than the width of a human hair, the 200-million-year growth span of these ancient microcrystals is longer than any previously discovered.

The findings provide a new record of planetary evolution and contradict previous experimental predictions that the crystals would change when exposed to heat and pressure upon burial in the deep Earth. Instead, they have an incredible ‘memory’ of their time below volcanoes, of transport to the shores of ancient oceans and of their burial beneath now-extinct mountain ranges billions of years before the time of dinosaurs. “This research shows that these crystals are incredibly resistant to change and proves for the first time that the growth zones we see inside them contain an accurate record of their movements through and around the Earth,” says Moser.

Containing trace amounts of uranium, the crystals continued to grow over hundreds of millions of years, even as the planet evolved and underwent a series of dramatic shifts. “The oldest pieces of our planet are crystals of zircon,” says Moser. “These crystals are the memory cells of the Earth and with our study we can now say they are an accurate recorder of planetary evolution over eons – in the same way that rings on an old growth tree can record changes in a forest over hundreds of years.”

Keeping with the tree analogy, Moser found that these crystals had roughly circular growth zones that he was able to date and analyze with specialized ion probes. These zones track the formation of the early North American continent, from its beginning as a series of volcanic island chains, to its eventual fusion into a large, thick continental plate that became the core of North America.

As the crystals formed around the same time as gold, diamond and other metal deposits, this research provides not only insight into the formation of Earth itself, it can also help answer the question, “Did plate tectonics operate early in our planet’s history or did some other process create the large metal and diamond deposits of the Canadian Shield?” “It also provides a new tool for dating the appearance of oceans on other rocky planets like Mars, where Rover results indicate zircon crystals should exist” says Moser.

Over the course of millions of years, the crystals have been pushed back to the surface from depths of 30 kilometres by a series of pushes on the edges of the original continent, which give us globally-rare exposures in northern Ontario. “It’s not every day you find a piece of the deep Earth that you can walk around on and explore,” Moser says.

Moser’s findings are further detailed in the March issue of Geology, published by the Geological Society of America.

Source: University of Western Ontario

http://www.physorg.com/news123768995.html

posted in Geology - 0 replies

Earthquake theory stretched in Central Asia study

bobs — Mon, 25 Feb 2008 23:38:06 GMT

(Also posted in : http://awesomenature.tribe.net/ )

The entrenched political instability in Pakistan and Afghanistan is of grave concern to many in the West – but now geologists at ANU have suggested a new cause for the seismic instability that regularly rocks the region.

Scientists from the Research School of Earth Sciences at ANU argue that the frequent and dramatic earthquakes in the Hindu Kush mountain range are likely to be the result of a slow, elastic stretching of a sub-surface feature called a boudin. Their findings, published in the journal Nature Geoscience today, run contrary to the theory that earthquakes usually result from the abrasive collisions between tectonic plates.

“We’ve always thought of earthquakes as being brittle, but our research that the slow, ductile stretching of certain geological features can build up energy that is then suddenly released, causing major seismic upheaval,” said lead author Professor Gordon Lister.

Using computer modelling, the researchers were able to show that the long, hard boudin that sits vertically beneath the Hindu Kush is being stretched as its lower parts are pulled into the Earth’s mantle. “It’s like a metal rod that is being pulled at both ends,” Professor Lister explained. “Eventually the stretching will suddenly accelerate, releasing energy in the process.”

The boudin is thought to be a remnant of the oceanic plate that was pushed into the Earth’s mantle when India collided with Asia. Professor Lister said that eventually it too will eventually drop into the deeper mantle, but that is likely to take thousands, if not millions, of years.

“This is important work, as it suggests a new way of understanding how earthquakes happen. It feeds into the potential for us to eventually develop new and innovative long-range forecasting techniques” Professor Lister said.

“It’s no accident that nations like Afghanistan and Pakistan are places of unrest, because the people there are living in constant hardship, and this results in part from periodic catastrophe’s they must endure, for example related to earthquakes. If we don’t put more effort into understanding the how and why, and also into how we might eventually better forecast earthquakes, humankind is forever doomed to deal with the consequences.”

The researchers have developed a software program called eQuakes that allows them to model earthquake patterns against geological features.

Source: Australian National University

http://www.physorg.com/news123171934.html

posted in Geology - 0 replies

Request: Modeling textbook

Inaras — Tue, 05 Feb 2008 02:53:01 GMT

I'm looking for a good textbook on glacial modeling. Anyone have any recommendations?

posted in Geology - 1 reply

Man-made changes bring about new epoch in Earth's history

bobs — Sat, 26 Jan 2008 14:16:30 GMT

"Geologists from the University of Leicester propose that humankind has so altered the Earth that it has brought about an end to one epoch of Earth’s history and marked the start of a new epoch.

Jan Zalasiewicz and Mark Williams at the University of Leicester and their colleagues on the Stratigraphy Commission of the Geological Society of London have presented their research in the journal GSA Today.

In it, they suggest humans have so changed the Earth that on the planet the Holocene epoch has ended and we have entered a new epoch - the Anthropocene.

They have identified human impact through phenomena such as:

-- Transformed patterns of sediment erosion and deposition worldwide
-- Major disturbances to the carbon cycle and global temperature
-- Wholesale changes to the world’s plants and animals
-- Ocean acidification

The scientists analysed a proposal made by Nobel Prize-winning chemist Paul Crutzen in 2002. He suggested the Earth had left the Holocene and started the Anthropocene era because of the global environmental effects of increased human population and economic development.

The researchers argue that the dominance of humans has so physically changed Earth that there is increasingly less justification for linking pre- and post-industrialized Earth within the same epoch - the Holocene.

The scientists said their findings present the scholarly groundwork for consideration by the International Commission on Stratigraphy for formal adoption of the Anthropocene as the youngest epoch of, and most recent addition to, the Earth's geological timescale.

They state: “Sufficient evidence has emerged of stratigraphically significant change (both elapsed and imminent) for recognition of the Anthropocene—currently a vivid yet informal metaphor of global environmental change—as a new geological epoch to be considered for formalization by international discussion.”

Source: University of Leicester

http://www.physorg.com/news120484292.html

posted in Geology - 1 reply

fault maps

Chili_Bonbons — Sat, 19 Jan 2008 21:02:37 GMT

does anyone know of any links to world (quake/plate) fault maps besides the ones through the usgs website that they would recommend?

posted in Geology - 6 replies

Hot springs microbes hold key to dating sedimentary rocks, researchers say

bobs — Tue, 22 Jan 2008 22:22:02 GMT

Scientists studying microbial communities and the growth of sedimentary rock at Mammoth Hot Springs in Yellowstone National Park have made a surprising discovery about the geological record of life and the environment.

Their discovery could affect how certain sequences of sedimentary rock are dated, and how scientists might search for evidence of life on other planets.

“We found microbes change the rate at which calcium carbonate precipitates, and that rate controls the chemistry and shape of calcium carbonate crystals,” said Bruce Fouke, a professor of geology and of molecular and cellular biology at the University of Illinois.

In fact, the precipitation rate can more than double when microbes are present, Fouke and his colleagues report in a paper accepted for publication in the Geological Society of America Bulletin.

The researchers’ findings imply changes in calcium carbonate mineralization rates in the rock record may have resulted from changes in local microbial biomass concentrations throughout geologic history.

A form of sedimentary rock, calcium carbonate is the most abundant mineral precipitated on the surface of Earth, and a great recorder of life.

“As calcium carbonate is deposited, it leaves a chemical fingerprint of the animals and environment, the plants and bacteria that were there,” said Fouke, who also is affiliated with the university’s Institute for Genomic Biology.

The extent to which microorganisms influence calcium carbonate precipitation has been one of the most controversial issues in the field of carbonate sedimentology and geochemistry. Separating biologically precipitated calcium carbonate from non-biologically precipitated calcium carbonate is difficult.

Fouke’s research team has spent 10 years quantifying the physical, chemical and biological aspects of the hot springs environment. The last step in deciphering the calcium carbonate record was performing an elaborate field experiment, which drew water from a hot springs vent and compared deposition rates with and without microbes being present.

“Angel Terrace at Mammoth Hot Springs in Yellowstone National Park is an ideal, natural laboratory because of the high precipitation rates and the abundance of microbes,” Fouke said. “Calcium carbonate grows so fast – millimeters per day – we can examine the interaction between microorganisms and the calcium-carbonate precipitation process.”

The researchers found that the rate of precipitation drops drastically – sometimes by more than half – when microbes are not present.

“So one of the fingerprints of calcium carbonate deposition that will tell us for sure if there were microbes present at the time it formed is the rate at which it formed,” Fouke said. “And, within the environmental and ecological context of the rock being studied, we can now use chemistry to fingerprint the precipitation rate.”

In a second paper, to appear in the Journal of Sedimentary Research, Fouke and colleagues show how the calcium carbonate record in a spring’s primary flow path can be used to reconstruct the pH, temperature and flux of ancient hot springs environments. The researchers also show how patterns in calcium carbonate crystallization can be used to differentiate signatures of life from those caused by environmental change.

“This means we can go into the rock record, on Earth or other planets, and determine if calcium carbonate deposits were associated with microbial life,” Fouke said.

Source: University of Illinois at Urbana-Champaign

http://www.physorg.com/news120228971.html

posted in Geology - 1 reply

Shrinking ice means Greenland is rising fast

bobs — Fri, 02 Nov 2007 21:45:50 GMT

18:06 02 November 2007
NewScientist.com news service
Catherine Brahic

Greenland appears to be floating upwards – its landmass is rising up to 4 centimetres each year, scientists reveal.
And the large country's new-found buoyancy is a symptom of Greenland's shrinking ice cap, they add.
"The Earth is elastic and if you put a load on top of it, then the surface will move down; if you remove the load, then the surface will start rising again," explains Shfaqat Khan of the Danish National Space Center in Copenhagen.
In the case of Greenland, the "load" is its ice cap, he says.
Such uplift is not an unknown phenomenon. Relic "raised beaches" are relatively common in some areas, where the loss of ice after the last Ice Age caused the land to rise, leaving beaches often metres above the water.
Khan and his team detected the country's uplift using measurements from GPS stations located on the bedrock, underneath the ice.
Khan and his colleagues have been monitoring data from these stations since 2001 and have found that the southeastern tip of the country is definitely rising upwards. They have also found that the rate of rise has dramatically accelerated in recent years.
Sudden acceleration"Before 2004, the uplift was about 0.5 cm to 1 cm per year," Khan told New Scientist. Since then, however, the land has been rising four times faster. "This means that since 2004, Greenland has been losing four times more ice than before," he says.
These figures roughly correspond to other measurements of how much ice is being lost by the ice sheet.
In 2006, a team led by Eric Rignot from NASA's Jet Propulsion Laboratory in Pasadena, California, US, published findings suggesting that there had been a sudden acceleration in the rate at which Greenland was losing ice during 2004.
Khan says they are unsure what caused the acceleration and cautions that it is impossible to say if this speedy loss will be maintained in the long-term.
"It could be that more melt water is flowing into crevasses, which is making the glaciers flow into the ocean faster," he says. Research done at NASA has shown that warmer temperatures due to global warming are melting ice at the surface of Greenland's glaciers.
Vertical riversThe warm water is boring holes through the glaciers, creating vertical rivers whose water lubricates the bottom of the glaciers once it reaches the bedrock. This process makes glaciers speed faster towards the sea, where they break off and eventually melt.
Calculations by Khan and his team land suggest the uplift is mostly due to glaciers flowing out to the sea and breaking off. They calculated that some ice is also lost through melting, however.
This is consistent with a review of the polar meltdown which was published in March 2007.
At the time, Duncan Wingham of University College London in the UK had told New Scientist: "It has become very clear over the past 5 years that these sheets are not losing most of their mass through melting. They are losing it because the ice is flowing into the ocean faster than the snow is replacing it."

Journal reference: Geophysical Research Letters (DOI: 10.1029/2007GL031468)

http://technology.newscientist.com/channel/tech/dn12872-shrinking-ice-means-greenland-is-rising-fast.html?feedId=online-news_rss20

posted in Geology - 0 replies

Nano-coatings grease earthquake zones

bobs — Wed, 31 Oct 2007 22:48:48 GMT

Samples of rock from deep inside the San Andreas Fault could shake up scientists' notions about why some fault zones move slowly and steadily while others balk for a time and then shift suddenly and violently, producing major earthquakes.

'There's been strong interest in finding signatures in rocks that would characterize a fault as creeping or seismic,' said University of Michigan geological sciences professor Ben van der Pluijm, who will discuss recent findings today (Oct. 30) in a symposium during the 119th annual meeting of the Geological Society of America in Denver.

Some scientists have speculated that fluids facilitate slippage; others have focused on bits of serpentine—a greenish mineral that can crystallize as slippery talc under certain conditions—which were found in core samples retrieved from the San Andreas Fault.

But van der Pluijm and coworkers at U-M and the University of Strasbourg in France aren't convinced of those explanations for slippery fault behavior. 'We think the answer is in clay,' he said.

He bases his opinion on analyses of material brought up from a depth of two miles below the fault's surface as part of the San Andreas Fault Observatory at Depth (SAFOD) project. SAFOD, which is establishing the world's first underground earthquake observatory, is a major research component of EarthScope, an ambitious, $197-million federal program to investigate the forces that shape the North American continent and the physical processes controlling earthquakes and volcanic eruptions.

Earth scientists are especially interested in the San Andreas Fault—that notorious fracture running 800 miles along the length of California—because major earthquakes occur on such plate boundaries. The SAFOD site, near Parkfield, Calif., sits on a creeping section of the fault that moves regularly and incrementally, but does not produce large earthquakes.

Van der Pluijm's samples are 'not glamorous to look at. They're not spectacular to showcase; they just look like dirt.' But it's how the 'dirt' forms and behaves in active fault zones that makes it noteworthy. Through a combination of chemical and mechanical processes, the grains making up the rock develop 'nano-coatings' of clay on their surfaces, which act something like grease on ball bearings.

'We can show that these nano-coatings, which are only a few hundred nanometers thick, occur all around broken-up, fractured grains, and they occur exactly in the places where they can affect the 'weakness' of the fault,'—how easily it moves. We think that as these grains move past one another, the coatings facilitate the displacement.'

By dating the first suite of samples collected in 2005, the researchers show that these coatings are relatively recent. 'They form in actively creeping fault zones,' van der Pluijm said, 'creating a dynamic environment where rocks change while faulting occurs,' Finding signatures that reveal whether a fault is creeping or seismic won't immediately aid in earthquake prediction, van der Pluijm said. 'But it will help us understand what processes govern this behavior.'

Source: University of Michigan

http://www.physorg.com/news113067833.html

posted in Geology - 0 replies

Seismologists see Earth's interior as interplay........

bobs — Thu, 25 Oct 2007 21:42:36 GMT

.......... between temperature, pressure and chemistry.

Seismologists in recent years have recast their understanding of the inner workings of Earth from a relatively benign homogeneous environment to one that is highly dynamic and chemically diverse. This new view of Earth’s inner workings depicts the planet as a living organism where events that happen deep inside can affect what happens at its surface, like the rub and slip of tectonic plates and the rumble of the occasional volcano.

New research into these dynamic inner workings are now showing that Earth’s upper mantle (an area that extends down to 660 km) exhibits how far more than just temperature and pressure play a role in the dynamics of the deep interior.

A study by Nicholas Schmerr, a doctoral student in Arizona State University’s School of Earth and Space Exploration is shedding light on these processes and showing that they are not just temperature driven. His work helps assess the role chemistry plays in the structure of Earth’s mantle.

The simplest model of the mantle — the layer of the Earth’s interior just beneath the crust — is that of a convective heat engine. Like a pot of boiling water, the mantle has parts that are hot and welling up, as in the mid-Atlantic rift, and parts that are cooler and sinking, as in subduction zones. There, crust sinks into the Earth, mixing and transforming into different material “phases,” like graphite turning into diamond.

“A great deal of past research on mantle structure has interpreted anomalous seismic observations as due to thermal variations within the mantle,” Schmerr said. “We’re trying to get people to think about how the interior of the Earth can be not just thermally different in different regions but also chemically different.”

The research, which Schmerr conducted with Edward Garnero, a professor in ASU’s School of Earth and Space Exploration, was published in the October 26 issue of the journal Science. Their article is titled “Upper Mantle Discontinuity Topography from Thermal and Chemical Heterogeneity.”

Schmerr’s work shows that Earth’s interior is far from homogeneous, as represented in traditional views, but possesses an exotic brew of down and upwelling material that goes beyond simply hot and cold convection currents. His work demonstrates the need for a chemical component in the convection process.

At key depths within Earth, rock undergoes a compression to a denser material where its atoms rearrange due to the ever-increasing pressure. Earth scientists have long known that the dominant mineral olivine in Earth’s outer shell, compresses into another mineral named wadsleyite at 410 km (255 mile) depth, which then changes into ringwoodite around 520 km (325 mile) depth and then again into perovskite + magnesiowüstite at 660 km (410 mile) depth.

These changes in crystal structure, called phase transitions, are sensitive to temperature and pressure, and the transition depth moves up and down in the mantle in response to relatively hot or cold material.

Beneath South America, Schmerr’s research found the 410 km phase boundary bending the wrong way. The mantle beneath South America is predicted to be relatively cold due to cold and dense former oceanic crust and the underlying tectonic plate sinking into the planet from the subduction zone along the west coast. In such a region, the 410 km boundary would normally be upwarped, but using energy from far away earthquakes that reflect off the deep boundaries in this study area, Schmerr and Garnero found that the 410 km boundary significantly deepened.

“Our discovery of the 410 boundary deflecting downwards in this region is incompatible with previous assumptions of upper mantle phase boundaries being dominantly modulated by the cold temperature of the subducting crust and plate,” Garnero said.

Geologists and geochemists have long suspected that subduction processes are driven by more than temperature alone. A sinking oceanic plate is compositionally distinct from the mantle, and brings with it minerals rich in elements that can alter the range of temperatures and pressures at which a phase change takes place.

“We’re not the first to suggest chemical heterogeneities in the mantle, however, we are the first to suggest hydrogen or iron as an explanation for an observation at this level of detail and over a geographical region spanning several thousands of kilometers,” Schmerr said.

Hydrogen from ocean water can be bonded to minerals within the crust and carried down as it is subducted into the mantle, Schmerr explained. When the plate reaches the 410 km phase boundary, the hydrogen affects the depth of the olivine to wadsleyite phase transition, reducing the density of the newly formed wadsleyite, and making it relatively more buoyant than its surrounding material. This hydrated wadsleyite then “pools” below the 410 km boundary, and the base of the wet zone reflects the seismic energy observed by Schmerr.

Alternatively, subduction can bring the iron-poor and magnesium-enriched residues of materials that melted near the surface to greater depths. Mantle mineral compositions enriched in magnesium are stable to greater depths than usual, resulting in a deeper phase transition.

“Either hypothesis explains our observation of a deep 410-km boundary beneath South American subduction, and both ideas invoke chemical heterogeneity,” Schmerr said. “However, if we look deeper, at the 660-km phase transition, we find it at a depth consistent with the mantle being colder there. This tells us that the mantle beneath South America is both thermally cold and chemically different.”

To make their observations, Schmerr and Garnero used data from the USArray, which is part of the National Science Foundation-funded EarthScope project.

“The USArray essentially is 500 seismometers that are deployed in a movable grid across the United States,” Schmerr said. “It’s an unheard of density of seismometers.”

Schmerr and Garnero used seismic waves from earthquakes to measure where phase transitions occur in the interior of Earth by looking for where waves reflect off these boundaries. In particular, they used a set of seismic waves that reflect off the underside of phase transitions halfway between the earthquake and the seismometer. The density and other characteristics of the material they travel through affect how the waves move, and this gives geologists an idea of the structure of the inner Earth.

“Seismic discontinuities are abrupt changes in density and seismic wave speeds that usually occur where a mineral undergoes a phase change -- such as when olivine transitions to wadsleyite, or ringwoodite transforms into perovskite and magnesiowüstite. The transformed mineral is generally denser, and typically seismic waves travel faster through it as well. Discontinuities reflect seismic energy, which allows us to figure out how deep they are. They are found throughout the world at certain average depths -- in this case, at 410 and 660 km,” Schmerr said. “Because these phase transitions are not always uniform, these layers are bumpy with ridges and troughs.”

http://www.physorg.com/news112541343.html
“Right now the big question that we have is about Earth’s thermal state and its chemical state, and there are a lot of ways we can go about getting at that information,” Schmerr said. “This study lets us look at one particular area in Earth and constrain the temperature and composition to a certain degree, imaging this structure inside the Earth and saying, These are not just thermal effects -- there’s also some sort of chemical aspect to it as well.”

Source: Arizona State University

posted in Geology - 0 replies

Geological science "debunked" in the new Creation Museum

captaincracklins — Tue, 26 Jun 2007 19:22:17 GMT

I visited the new $27 million Creation Museum in Petersburg Kentucky (just south of Cincinnati) last weekend. I didn’t go in order to gawk, or to argue with people, or to protest. I went because I have a genuine interest in how museum space can be used and what museums can do, and I went because I thought I could take one for the team (you all) and come back to report on it. What follows is divided into two parts: first, a summation of the social conditions which led to such a museum to exist in modern America (I assume that most of the comparatively educated and progressive members of the tribe are not all that familiar with the ins and outs of Biblical fundamentalism as a social movement; this section is pulled largely from a paper I wrote some months ago), and second, a description of the museum, section by section, with some of my personal comments. If you’re not interested in a long prologue, then skip down to the series of dashed lines. But if you have an interest in trying to understand what these fundamentalists are trying to accomplish, then read the prologue. Hopefully, this will stimulate some discussion.

…………………………………………………………………………………………….

The recent proliferation of so-called Creation Science museums in the United States is the result of a kind of anticolonialist social action; not anticolonialist in terms of foreign domination, but rather in terms of cognitive domination. The preponderance of evolutionary and geological science in the social discourse has alienated much of the fundamentalist Christian population, and it has traditionally responded by challenging the practice of teaching evolutionary theory in public schools, most famously in the Scopes “Monkey Trial” of 1925. Since their defeat in that trial, the Biblical literalists have continued to seek legal injunctions against evolution in the public sphere while simultaneously constructing their own epistemological framework for insertion into the social discourse. One of the latest manifestations of this epistemological framework is the museum of creation science. Creation Science is a conscious effort to appropriate elements of sound science into a pre-existing narrative about the origins and operations of the universe. These museums are the site of social resistance against prevailing scientific norms, repositories of collective memory, tools of legitimization for a particular narrative, and the latest front in the “Culture Wars.”

Museums are the repositories of knowledge and ways of knowing in society. They reflect and perpetuate social discourse in such a way as to enshrine narratives of history, society, and the relationship of the individual to that society. They are the site of social power and enforcement, particularly when they are sustained by ruling political institutions. Chief among the powers of the museum is its role as archive, and the primary archive in museums of creation science is the King James translation of the Bible.

An archive is any system of statements articulating conditions for reality; it constitutes the rules for what can be said and what can be learned. As such, the archive is a collection of judgments through which mediation guides discourse. An archive is necessarily a physical thing resulting from cognitive realities; it has a location, it contains data, but it is inscribed in a sociological framework. It contains iconic and indexical references, and it therefore has a wide range of meanings due to these connections. Though an archive is consciously constructed, its meanings are contingent upon interpretation and association. Control of the organization of the archive and control of the meaning of the archive constitute a potent form of social power which is manifest in the institution of the museum.

Museums themselves represent imposed order. The establishment of an archive in a museum is an effort to etch it into permanent memory. The regimes of truth underlying an archive determine the production of knowledge and define correct knowledge. For example, China’s Cultural Revolution sought to create archives which rearticulated social order and relegated parts of the consciousness of its citizens (i.e. religious belief) to elements of the past. That which is relegated to the past is defined as having passed, no matter how present it may yet be. Social narratives and museums in Japan have excluded the presence and culture of the native Ainu people because their existence in Japan before the formulation of traditional ethnic Japanese mythology was unthinkable. The archive can both mirror collective memories and erase others through its function as the site of mediation.

In contrast to historical memory, which is subject to verification, analysis, and revision, collective memory is based upon social myth. Collective memory reduces the human experience to its essentials, retaining the useful and reinforcing elements while discarding those elements which are perceived as dangerous or uncomfortable. Because collective memory is so mutable, the archive is a social technology to enshrine memory in ostensibly unchanging forms. Thus collective memory is codified and canonized into a social discourse.

Traditional Foucaldian views of museums as sites of social power tend to interpret that power as being foisted upon colonial subjects. This is the metaphor of modernity itself (or “globalization”) as a colonizing influence and the model of museums as a “top-down” imposition of power. Under this model, the powerful otherize the less powerful and perpetuate their own social discourse. However, museums can be important statements of power by disadvantaged groups who attempt to reclaim and reestablish their own discourse. The community-based museum can serve to bolster and legitimize local or disenfranchised groups. New Museology, informed by the effects of colonialism (and reactions against it), is focused not on the practices of museums but rather their political dimensions and social implications, focusing on the museum’s relationship to the community and maintaining the curator’s role as facilitator. The museum becomes the site of resistance to power as well as a purveyor of power.

New Museology frames museums as necessarily “ideas-based” rather than “object-based.” As such, the creation of a museum begins with narratives as a representation of a story rather than with objects as a representation of a people. Visiting a museum is a social activity which not only recovers the past but also explains the present. The important part is not the collections of things, but rather the collections of people and their shared experience.

The development of museums has not followed a linear progression; each museum has its own origin and function. Creation museums grew out of an existing epistemological framework and social discourse which took shape shortly after the Scopes “Monkey” trial in 1925, in which evolutionary theory was officially sanctioned in public schools. The fundamentalist Christian community reacted strongly to the ruling because they saw evolutionary theory as conflicting with their religious beliefs. The perceived assault from courts and secular interests galvanized the fundamentalist community. William Jennings Bryan, despite having lost the case, was elevated to hero (martyr?) status in Christian fundamentalist circles.

Briefly, fundamentalist Christians adhere to a strict and literal interpretation of the Biblical narrative. Their holy texts form the epistemological foundation for their worldview, which can not be falsified in their view. They approach the universe and their place in it from a deductive standpoint (wherein the Bible forms the only absolute truth and objective reality is subject to that truth), rather than an inductive viewpoint (wherein facts and evidence are collected and truth is based on a preponderance of evidence). According to the strict creationist model, the earth and all life were created willfully by supernatural forces, the earth’s history is dominated by catastrophism rather than gradual change, and the complexity of the universe has steadily decayed since the perfect original creation. According to creationists, the geologic time scale is a construction of the minds of geologists and that humankind is the purpose of the natural world rather than a result of it. A complete evaluation of the creationist arguments is beyond the scope of this discussion, and it is irrelevant to the way in which the museums of creation science function. The creation science movement is a social reality, regardless of its merits. However, the relevant elements are how scientific creationism appropriates and re-classifies scientific knowledge for its own purposes and for its museums.

Creationists are strongly motivated to promote antievolutionism because they believe it to be a matter of their (and others’) eternal souls. For them, scientific knowledge is only acceptable insofar as it is able to pass through a screen of preexisting ideology, whether religious or political. William Jennings Bryan, perennial presidential candidate and lead prosecutor in the Scopes trial, famously remarked in 1925, “When the Bible and the microscope disagree, the microscope is wrong.” Even when scientific ideas do not directly contradict religious views and are instead conflated with undesirable political associations, they are rejected out of hand. Henry R. Morris, a creationist leader and author, wrote in 1963, “Evolution is at the foundation of communism, fascism, Freudianism, social Darwinism, behaviorism, Kinseyism, materialism, atheism, and in the religious world, modernism and neo-orthodoxy.” This litany of fearful “isms” well articulates the visceral reaction of creationists to principles even remotely connected (or perceived to be connected) with evolutionary thought.

Since 1925, creationists have been assembling and disseminating their own message to combat what they perceive as the danger of evolutionism. This siege mentality among creationists strengthened after the US reaction to the Soviet launch of Sputnik in the 1950s. In order to close the knowledge gap between the Soviets and the United States, the federal government enhanced funding of K-12 public education, including explicit education in school textbooks of evolution as the cornerstone of the biological sciences. Even worse for the creationists, these moves were given the National Science Foundation’s seal of approval. From the perspective of the creationists, they had been betrayed by the government and its endorsement of evolutionary principles. Both the government and its associated agencies became enemies, and all faith in public education was lost.

The response of the creationists was threefold. First, they adopted a stance of social action. Because the scientific community at large was wary of the popularization of scientific knowledge, it was loath to engage in social discourse directly. This social vacuum was readily filled by a plethora of creationist writings which situated pseudoscientific arguments as social imperatives. Second, the creationists began appropriating scientific knowledge and terminology into their own parallel discourse in order to compete with science in the marketplace of ideas; in other words, they began to look at where the Bible and the microscope agreed. Third, they continued legal challenges to evolution education and embarked on a political campaign to disparage those who ruled against them.

Scientific Creationist literature developed into its own genre throughout the 20th century. George McCready’s The New Geology (1923) promoted the idea of a literal six-day creation of the universe and contested the old-earth model of James Hutton, who famously wrote that the earth, with all its layered history has “No vestige of a beginning and no prospect of an end” in the 18th century. Excavations by Langdona at Kish and Wooley at Ur purported to show evidence of the Biblical flood in ancient Mesopotamia. Henry M. Morris, the director of the Institution for Creation Research, published Scientific Creationism (1974), Many Infallible Proofs (1974), and The Beginning of the World (1977), in which he included carefully chosen aspects of science, Biblical prophecy, history, and personal witnessing as evidence of creation. Phillip Johnson, who still holds an endowed chair at UC-Berkeley, published Darwin on Trial in 1991 and Reason in the Balance in 1995.

These publications cherrypicked the discourse of scientific thought in formulating the discourse of scientific creationism. To begin with, the appropriation of the very word “science” serves to legitimize and bolster the arguments of creationism by its association with rigor, peer review, and the strength of falsifiability, even though scientific creationism bears none of it. Falsifiability is completely anathema to creation science because it is based upon the eternal and unerring truth of a literal reading of the King James Bible. Furthermore, “science” carries with it the promise of status, recognition, and advancement. It also has an attractive predicative quality which is transferred to divine prophecy within the space of a Creation Science museum. Scientific creationists attempted to win “equal time” for creationism in public school classrooms as a topic of equal merit to evolution, and some others backpedaled to the position of “Intelligent Design,” which is an essentially deist and non-denominational philosophy.

Established scientific arguments were cherry picked for bits of evidence which could help verify creationist ideas such as the cataclysmic Flood. The fossil record, particularly those fossils of marine origin embedded in sedimentary rock, was re-interpreted as victims of the Flood while ignoring such scientific evidence as plate tectonics, radioisotope dating, and stratigraphy. They championed the Paluxy River hoax in which human footprints were carved alongside Cretaceous dinosaur tracks in Texas, claiming it as proof that humans and dinosaurs coexisted. They offered the 2nd Law of Thermodynamics as evidence against evolution. The 2nd law states that the entropy of the universe is steadily increasing, and the creationists argued that because evolution represents increasing levels of order, then it is in violation of that Law. However, they did not consider that the earth is not a closed system (it receives a constant influx of energy and material from the sun and from space), and it is therefore in thermal equilibrium.

These arguments, combined with the frustration of receiving little governmental money for research as a form of recognition, formed the intellectual foundation and conditions for the emergence of museums of Creation Science by constructing an alternate worldview which challenged the hegemony of science.

As a site of resistance, museums of Creation Science challenge rationalism and otherize secularism while legitimizing creationism and directing social discourse. As “bottom-up” museums, their social contexts are more present. The entire construction of meaning is intended to fetishize the narrative; the narrative of literalist Biblical creation and its inerrant truth is the essential quality of these museums. Unlike other museums, there is complete suspension of disbelief in a museum of Creation Science: a retention, reinforcement, and affirmation of a specific belief. The gaze of visitors does not operate independently, but rather it is directed as a reflection of an internalized narrative. The museum is not a window on the natural world, but rather a mirror on the visitors. Only the “others” of rationality, materialism, and evolutionism are challenged. Archives are constructed and reflective of an epistemological framework, and the archive of a creationist museum is more explicit in its agenda than most.

Creation Science museums are organized from a necessarily essentialist viewpoint dependent upon the assumption of the unchanging truth of the Bible. As such, the objects within the museum only have power and meaning insofar as they can fit into this narrative of a universal history. Stones, fossils, animals, and human artifacts are interpreted relative to their assigned role according to a literalist reading of the Bible. As with any museum collection, the display of objects entails a recoding and valuation of those objects. These objects are contextualized not as natural objects, but as artifacts of a creator. This recoding means that items which would otherwise have no intrinsic value are inserted in to the archive as demonstrative of elements of the overarching narrative. Just as a text can be read, objects can be read as mirroring and verifying the text. The only means of verification are the extent to which the objects can be interpreted to be in agreement with the narrative.

The narrative myth of a museum of Creation Science can be interpreted as a way to exploit the mental capacities that are neglected as a result of the current domination of by scientific thought. The narrative is intended to be comforting rather than merely explanatory. It preserves the emotional response to the universe which is lacking in a materialistic viewpoint. It represents understanding by means of intuition and faith rather than analysis, and it forms an alternate way of knowing.

In terms of objects originating from human material culture, museums of Creation Science form a type of folk archaeology. Mainstream archaeology draws its authority from connections with the hard sciences: chemistry, geology, physics, etc. Folk archaeology like those of Creation Science, Graham Hancock, and Eric Van Daniken, challenges archaeology’s authority to interpret the past. Emotional, ideological, and political factors contribute to the adoption of folk archaeology, whether Scientific Creationism or neo-paganism. It appeals to those who are not satisfied with the scientific narrative and those who find no comforting presence in the scientific model. Folk archaeology is a construction of meaning. Folk archaeology is not to be confused with traditional Biblical archaeology, however. The discipline of Biblical archaeology relies upon historical documents and artifacts which are more subject to the rigors of archaeological dating methods and interpretation. Biblical archaeology lies somewhere between folk archaeology and academic archaeology; it relies upon data and evidence, but it is still subject to a preexisting narrative.

Museums of natural history are essentially tombs. What lies within them cannot be resurrected. The objects within them are dead, and the narrative has been enacted. By contrast, museums of Creation Science are alive to visitors, filled with prophecy, revelation, inspiration, and evidence of a divine living presence. The museum speaks directly to visitors in a familiar and internalized dialogue rather than challenging them.

Contrary to what many secularists may believe, those who espouse Creation Science are not stupid. They understand the power and the social role of the museum, and they have been very successful in maintaining popular support in the United States. They use their museums as vehicles of creation and perpetuation of a particular kind of epistemology. These museums grew out of creationists’ failure to legally impose creationism in the public arenas of schools, libraries, museums, research facilities, and the courts. Meanwhile, evolution continues to merely be an academic discourse as Creation Science becomes a stronger social and political discourse. A 1996 poll of Americans found that only 44% of the population agreed with the following statement: Human beings, as we know them today, developed from earlier species of animals.” If scientists want to increase that number, they will need to use their well-funded museums as springboards into the social arena, despite their reluctance to enter the field of politics.

--------------------------------------------------------------------------------------------------------

So, about the Creation Museum. You can visit the museum website here: http://www.creationmuseum.org/

The museum is out in the middle of nowhere (some might say both physically and intellectually). A series of billboards and road signs along the highway direct visitors to the museum. The building is expansive, and the stone walls are lined with steel silhouettes of dinosaurs. I visited the day before Father’s Day, and I can’t say whether the packed parking lot was a result of having visited on a Saturday, whether it was a weekend, or whether the museum has been so busy since the opening. But the lots were filled with minivans and urban assault vehicles; bumpers were plastered with the ichthus and the “Truth” fish devouring the “Darwin” fish.

After stepping through the front doors, visitors face a high wall of moulded imitation stone mimicking the strata of the Grand Canyon. Following the wall to the ticket counter, visitors pass several tables with religious literature.

A word about admission: Here in New York, people scoff at high museum admissions prices. Unless a museum has a particularly amazing or valuable exhibit (such as AMNH’s “Gold!” exhibit), admission of $15 or more is seen as excessive. The cost of admission to the Creation Museum is $20 for adults (13 and up), $15 for seniors, $10 for children aged 5-12, and free for children under five. So, a family of five (many families I saw had more than three children) may have to shell out $80 just to get in the door. $120 if Grandma and Grandpa wish to join them. And if they want to see the 30 minute planetarium show, it’s another $5 per seat (I didn’t see the planetarium show because all tickets had been sold out by the time I got there shortly before 11 am). Granted, a table in front offers $5 off each ticket, but only if patrons give their name, address, and phone number to the museum (I’m looking forward to getting some creationist mail).

After having my ticket scanned, I enter into the main foyer of the museum. It is a high room with a preview of the life-sized Eden diorama: children sit near a babbling brook, with dinosaurs peacefully grazing nearby. The museum tour begins with a series of panels clearly outlining the organization of the tour. The tour, unguided and proceeding at the pace of each patron, is divided into sections based upon the “Seven Cs:” Creation, Corruption, Catastrophe, Confusion, Christ, Cross, and Consummation.

But before explaining the Seven Cs, a section with several rooms undermines the process of scientific inquiry and elevates literalist interpretation of the Bible above all other lines of reasoning. Chief among the aims of the museum is to promote the idea that the universe and the earth are only 6,000 years old and that the earth in its present form (post-flood), with its present flora and fauna, are only 4,300 years old.

The museum, like many others, crystallizes its message in the panels. Because this museum is an exposition of ideas rather than an exposition of objects, the panels are even more important. The panels are the true site of the museum, where all the ideas it tries to promote are articulated and where the complex intellectual acrobatics necessary in reconciling the observed natural world with Biblical narratives are laid out for all to read. The museum has an open photography policy, so I was able to get some good shots of the panels and exhibits.

One of the first sections of the “doubt factory” part of the museum features a large diorama of a paleontologist excavating a dinosaur fossil. The panels in this section are written to cast doubt on the scientifically determined age of the earth. One panel features an artificial sapphire and asks if this sapphire could have been assembled in a lab in a matter of days, then all sapphires in the earth could have formed in such a short time.

The next section is composed of a series of panels pitting “Human Reason” vs “God’s Word.” In one panel, a photograph of a stack of books (the usual suspects: Origin of Species, Newton’s Laws, The Communist Manifesto, Hutton’s Theory of the Earth, etc.) is juxtaposed against a singular Bible. This section clearly states that reason has no place in the proper approach to study of the natural world, and it explains that, depending upon one’s assumptions, she or he will reach different conclusions about the universe. If a person assumes that the universe developed over billions of years as a result of natural processes, she or he will lead a different sort of life than one who assumes that the Bible is the Word of God.

The museum organizers were quick in their display strategy to engage the emotions of the visitors. A wall-length panel titled “Do Different Starting Points Matter in Our Personal Lives?” has a series of pictures with subtitles: a woman crouched in an empty hallway (Does anyone care?), an old man slumped in a wheelchair (Am I alone?), Hurricane devastation and debris (Why do I suffer?), angry parents gesticulating at one another as a small boy holds his head in his hands (Is there any hope?).

The next room shows the role of the Bible and states that it is inerrant, eternal, consistent, and most importantly, constantly under siege. Visitors are first greeted with well-made, life-sized, and very European-looking models of the Patriarchs. The rest of the room explains the various attempts to “undermine” the truth of the Bible (or at least the interpretation of the truth of the Bible as interpreted by the museum creators). The panels explain how wrong and sinful it is to question the truth of the Bible in any way or to interpret the Bible as metaphor rather than an accurate ant literal account. Another life-sized diorama shows Martin Luther nailing his Theses to the church door, and an accompanying panel explains how, for centuries, demonic forces led the church (i.e., the Catholic Church) to “elevate tradition above God’s Word.” A wall mural and accompanying video on a flat screen television explain the evil unleashed in the Scopes Trial of 1925.

The Scopes exhibit then leads visitors into a dark hallway showing the depravity of the modern condition in which “God has been forcibly removed.” Visitors pass a graveyard mural with headstones reading “God is Dead,” “Truth,” “God’s Word,” and “Genesis.” Next, visitors walk down a corridor designed to look like an inner-city street, complete with graffiti, garbage, and audio of police sirens, violent crime, and the like. Two walls are plastered with photos and articles from popular magazines which touch on the hot-button issues for Christian fundamentalists in the US today: gay marriage, prayer in schools, abortion, stem cells, etc. Many of these pages are taken from publications like Newsweek (I am uploading a photo of one of these walls to the tribe album). At the end of the hallway is an installation of two structures: on the left is a suburban home with televisions set behind the windows, as if the viewers are looking inside the home. The televisions show family dissolution (kids playing violent video games and ignoring their parents, parents screaming at one another, a baby crying, etc). On the right is a section of a church wall being demolished by a wrecking ball labeled “Millions of Years.”

The next room of the museum presents an alternative model. It frames the natural world as a result of special creation. The room is bright, hopeful, and engaging. A series of backlit panels and explanatory videos on flat screens offer alternative views of the universe. This room kicks off the “Creation” section of the museum.

The next exhibit is a centerpiece of the museum: the walk-through Eden scene. You may have seen pictures of this section in articles about the museum. Life-sized animals, including dinosaurs and other extinct animals, populate the exhibit. Adam and Eve, with discreetly shielded naughty bits, repose peacefully in several scenes (there was some controversy recently over the man used as the model for Adam. Apparently, he had appeared in several gay porn films). The last scene shows Adam and Eve (clearly not Adam and Steve) bathing in a pool. Overhead, you-know-who looms in a tree. A panel describes the Biblical form of marriage: “Doctrine of Marriage – The special creation of Adam and Eve is the foundation for marriage: one man and one woman. The fact that they were one flesh is the basis for the oneness of marriage.” No mention of the fact that most Biblical marriage involved polygyny.

Visitors are then directed to a black hallway with no text, no labels, and no lighting. In the middle of the hallway is a plexiglass case with a copy of the Satan snake just in case everyone missed it. This begins the “Corruption” section of the museum. In the next room are examples of earthly misery with no labels or text: still posters of piles of skulls from genocide in Cambodia, a woman in pained childbirth, a tornado laying waste to the countryside, and a heroin user shooting up. On the other wall are projected images of NAZI atrocities, the horrors of war, devastation, and the like.

The next room is another diorama of a couple sacrificing lamb in order to make atonement for sin. After that is a natural scene in stark contrast to the idyllic Eden a few rooms earlier. It shows a “cursed” world. In this room are some of the most interesting labels because they attempt to explain why nature can be harmful or dangerous. One panel labeled “Venom” states the following:

“Though nothing harmed animals before Adam’s sin, venom harms animals in the present. We do not know exactly how venoms first entered the world. Possibilities include:
*Changed use of chemicals (chemicals that once had non-harmful functions at the creation changed to venoms after the Curse).
*Revealed information (the potential to make venoms was built into the original creation, but not revealed until after the Curse).”

Don’t try to reason it out. As stated earlier, reason has no place in the Creation Museum. Visitors are expected to accept the explanations because they do not conflict with the literalist interpretation of the Bible. Moving on, another label titled “Carnivores” explains how, before the Curse, all animals ate plants:

“Though all animals ate plants before Adam’s sin, some are carnivores in this present fallen world. We do not know how meat eating first entered the world. Possibilities include:
*Changed diet (the diet of some animals merely changed)
*Revealed information (the potential for meat eating was placed into the original creation, but not revealed until after the Curse.
By removing the weakest and diseased, carnivores help keep the fallen world functioning despite sin.”

Another long panel justifies the Biblical practice of incest. Truly. The text is too long to type verbatim at the moment, but I’m uploading a picture to the tribe photo album. This panel clearly demonstrates a woeful and willful ignorance of genetics, and it employs entirely self-referential logic, as in most of the rest of the museum.

The next section of the museum deals with “Catastrophe.” The original nucleus of the museum was a model of Noah’s ark assembled by the museum’s chief funder, an Australian named Ken Ham. He made several more models “to scale,” and his design is featured in the section on Noah’s Ark and the Flood. A huge, full-scale section of the ark rises over three stories high, and animatronic figures talk about Noah and his construction. Visitors can walk through the ark section, passing other smaller models showing the various floor of the ark. Several small dioramas, painstakingly assembled in the old AMNH diorama style, show the ark sequence: construction, loading of animals (including dinosaurs), riding the waves, and perched atop Mount Ararat as the floodwaters receded.

After the ark display is a series of rooms filled with panels going into more detail about the catastrophe. Remember, according to this brand of Christian fundamentalism, the earth in its present form is a result of the Flood and its aftermath. One wall uses the eruption of Mt St Helens as an example of how catastrophism shapes the surface of the earth. The reasoning goes something like this: since the eruption buried trees and animals, carved gorges, and deposited meters of sediment in a matter of hours, all buried plants and gorges and sediments across the earth are also the result of a global catastrophe in the Flood. Another panel explains plate tectonics as a result of the flood: before the Flood, the continent of Rodinia dominated the earth’s surface. Rodinia broke up during the Flood and formed Pangaea. Late in the Flood, Pangaea broke up under water and formed the continents as we know them today. The waters receded and exposed the continents. All of this happened in the year of the Flood.

Another equally baffling panel explains how, in the fossil record (interpreted here as evidence of the Flood), plants and animals appear to be arranged in the strata from simplest to most complex. It offers a theory I’ve never heard before: the Floating Forest. Basically, before the flood, there were huge forests floating on the ocean, with their roots tangled in a thick mat. From the label: “4350 years ago, When Flood waves grew large enough, they began ripping apart the floating forest, from the outside edge inward. In a sequence reflecting the forest structure, plants torn off the forest became waterlogged, sank, and were buried on the ocean bottom.” Accompanying these panels is a wall-sized mural of the Floating Forest.

The next section deals with “Confusion.” The various cultures, traditions, and languages of people of the earth are described as a result of the Babel incident. Various cultures are portrayed as exhibiting various levels of corruption, with, of course, fundamentalist Christians being the only ones as having the true account of world and human history.

As for the other “Cs,” there really isn’t much. Christ, Cross, and Consummation are all but absent. I was disappointed that there was no apocalyptic eschatology on display, but I suppose it was a Creation museum after all. Perhaps in the future; construction around the museum is ongoing.

Several friends have asked me whether the Creation Museum is actually a museum, and I maintain that it is, based upon the discussion above. The space is used as a place for the display and dissemination of knowledge; it’s irrelevant whether that knowledge happens to be factual. You might se the same kinds of spurious lines of reasoning in museums built to glorify the state, but that doesn’t make it any less of a museum.

It was interesting to listen to the conversations in the course of the tour. Most visitors, as most other museum goers, simply wandered through the exhibits in a somewhat zombified state. Others were very excited to see “scientific” verification of what they had believed all along. The explanations of the natural world which would have cost any other museum its funding and support were enthusiastically accepted without further question. Several old men leading their families became armchair geologists, explaining the panels to their grandchildren and quoting Scripture.

Much to my surprise, my two friends and I were the only “infiltrators” I was able to recognize. Most everyone else seemed completely accepting of the museum and the message.

posted in Geology - 10 replies

Fulgurites!

yingfriman — Sun, 22 Jul 2007 21:41:31 GMT

I am watching the lightning march up the valley and all I can think is: FULGURITES!
Hopefully I'll have some quality pics here in the next coupla days...

Fulgurites are the lightning-fused sand and gravel glass which forms multicolor, tubular to tabular bodies.

I saw some sparks down valley so I know at least one volt achieved 'touchdown'. I'll leave the shovel in camp for now!

Wish me luck!

posted in Geology - 6 replies

Experiments challenge models about the deep Earth

bobs — Thu, 20 Sep 2007 21:30:06 GMT

(Also posted in Power and beauty of nature tribe)

In the first experiments able to mimic the crushing, searing conditions found in Earth’s lower mantle, and simultaneously probe tell-tale properties of iron, scientists have discovered that material there behaves very differently than predicted by models. The research also points to the likelihood of a new zone deep in the Earth. The work is published in the September 21, 2007, issue of Science.

Surface phenomena such as volcanoes and earthquakes are generated by what goes on in Earth’s interior. To understand some of these surface dynamics, scientists have to probe deep into the planet. The lower mantle is between 400 and 1,740 miles deep (650 km- 2,800 km) and sits atop the outer core.

Coauthor of the paper, Viktor Struzhkin of the Carnegie Institution’s Geophysical Laboratory explains: “The deeper you go, the higher the pressures and temperatures become. Under these extreme conditions, the atoms and electrons of the rocks become squeezed so close together that they interact very peculiarly. In fact, spinning electrons in iron, which is prevalent throughout the inner Earth, are forced to pair up. When this spin state changes from unpaired electrons—called a high-spin state—to paired electrons—a low-spin state—the density, sound velocities, conductivity, and other properties of the materials can change. Understanding these conditions helps scientists piece together the complex puzzle of the interior/surface interactions.”

The pressures in the lower mantle are brutal, ranging from about 230,000 times the atmospheric pressure at sea level (23 GPa), to almost 1.35 million times sea-level pressure (135 GPa). The heat is equally extreme—from about 2,800 to 6,700 degrees Fahrenheit (1800 K–4000 K).

Using a laser-heated diamond anvil cell to heat and compress the samples, the scientists subjected ferropericlase to almost 940,000 atmospheres and 3,140 °F. They analyzed it using so-called X-ray emission spectroscopy. As its name suggests, ferropericlase is iron-laden. It is also the second most prevalent material found in the lower mantle. Previous to this study, ferropericlase has been subjected to high pressures, but only to room temperatures. The new experiments are the highest pressures and temperatures attained to probe the spin state of iron in the mineral at lower-mantle conditions.

Under the less-intense conditions of the former experiments, the high-spin to low-spin transition occurs in a narrow pressure range. In the new study, however, both spin states coexisted in the same crystal structure and the spin transition was also continuous over a large pressure range, indicating that the mineral is in a complex state over a large range in depth in the planet.

“We were expecting to find a transition zone, but did not know how extended it may be in the Earth’s mantle,” commented Struzhkin. “Our findings suggest that there is a region or ‘spin-transition zone’ from about 620 miles to 1,365 miles deep, where high spin, unpaired electrons, transition to low spin, paired electrons. The transitioning appears to be continuous over these depths. At pressures representing a lower depth of about 1,365 miles the transition stops and ferropericlase is dominated by low-spin electrons.”

Since measurements that scientists use to determine the composition and density of the inner Earth, such as sound velocities, are influenced by the ratio of high-spin/low- spin states, the new finding calls into question the traditional techniques for modeling this region of the planet.

In addition, a continuous spin transition zone may explain some interesting experimental findings including why there has been no significant iron partitioning, or separating, into ferropericlase or perovskite, the most prevalent mineral in the region. The research also suggests that the depth of the transition zone is less than scientists had speculated.

The existence of this transition zone may also account for seismic-wave behavior at those depths. The fact that the lowermost area is dominated by denser low-spin material could also affect the temperature stability of mantle upwellings—the generators of volcanic hotspots, such as those in Hawaii.

“This paper solves only part of the puzzle,” cautioned Struzhkin. “Since the major lower mantle mineral perovskite has not been measured yet with this technique, we know there are more surprises to come.”

Source: Carnegie Institution

http://www.physorg.com/news109517518.html

posted in Geology - 0 replies

If you see this man, spit on him

yingfriman — Wed, 08 Aug 2007 17:48:53 GMT

I would like to think the fate of my chosen profession doesn't, can't, rest in the hands of one negligent, smarmy prick.

The wisdom of that naive statement was severely tested by the unworldly events that unfolded during those tense weeks in February of 1997. My life changed dramatically at that point. My chosen industry changed dramatically at that point. The belt tightening, the navel gazing, the what-ifs. The uneasy and fragile balance now maintained in what was once a forum of honorable and intrepid wayfarers.

The fate of John Felderhof, former Vice President of Exploration for Bre-X Minerals, was announced on July 31, 2007. For perpretrating the largest fraud in the history of mineral exploration and causing the financial ruination of thousands of people and shaking a grand industry to its very roots: NOTHING.

John Felderhof was acquitted of all charges. As the only one charged in the Bre-X fiasco, Felderhof is now absolved of all responsibility in all insider trading and securities charges. The trail ends here, there will be no accountability, no one to point the finger at. No one to say 'sorry' for affecting such a disgrace upon my industry - no one to be held financially responsible for the ruined lives and broken dreams...

If you see this man, spit on him.

http://www.cbc.ca/money/story/2007/07/31/felderhof.html?ref=rss

posted in Geology - 2 replies

Mud Volcano Off Trinidad.

bobs — Sat, 28 Jul 2007 14:11:40 GMT

(Also posted in Power and beauty of nature tribe)

Hardbeatnews, PORT-OF-SPAIN, Trinidad.

An apparent underwater volcano is sending 50 feet high mud spewing into the sea about five miles east of Trinidad, scientists at the University of the West Indies' Seismic Unit said last night.

All the observations suggest the source ia an underwater mud volcano, officials said, adding that the spewing has been happening slightly over a period of about two months and appears to have built up a 15 metre or 50 feet high mount that is now just below the water surface.

Scientists said te mud could form a new temporary island, noting that the phenomenon is very similar to the activity at Chatham Island, which produced short-lived islands in 1964 and 2001, added the scientists.

They also warned boaters and sailors approaching the area to adopt a cautious approach and stay more than one mile from the disturbance. But insisted hazards are generally very localized.

The term "mud-volcano" is applied to a more or less violent eruption or surface extrision of watery mud or clay which almost invariebly is accompanied by methane gas, and which commonly tends to build up a solid mud or clay deposit around it's orifice which may have a conical or volcano-like shape the T&T Geological Society said.

The source of a mud volcano commonly may be traced to a substantial layer of highly plastic, and under compacted mud or shale. Mud volcanoes also commonly appear to be related to lines of fracture, faulting or sharp folding. The mud of the volcanoes is a mixture of clay and salt water which is kept in a state of slurry by the boiling or churning activity of escaping methane gas, geologists added.
Hardbeatnews.com

http://www.hardbeatnews.com/editor/RTE/my_documents/my_files/details.asp?newsid=13283&title=Top%20Stories

posted in Geology - 0 replies

Without hot rock, much of North America would be underwater

bobs — Mon, 25 Jun 2007 21:51:19 GMT

A University of Utah study shows how various regions of North America are kept afloat by heat within Earth’s rocky crust, and how much of the continent would sink beneath sea level if not for heat that makes rock buoyant.

Of coastal cities, New York City would sit 1,427 feet under the Atlantic, Boston would be 1,823 feet deep, Miami would reside 2,410 feet undersea, New Orleans would be 2,416 underwater and Los Angeles would rest 3,756 feet beneath the Pacific.

Mile-high Denver’s elevation would be 727 feet below sea level and Salt Lake City, now about 4,220 feet, would sit beneath 1,293 feet of water. But high-elevation areas of the Rocky Mountains between Salt Lake and Denver would remain dry land.

“If you subtracted the heat that keeps North American elevations high, most of the continent would be below sea level, except the high Rocky Mountains, the Sierra Nevada and the Pacific Northwest west of the Cascade Range,” says study co-author Derrick Hasterok, a University of Utah doctoral student in geology and geophysics.

“We have shown for the first time that temperature differences within the Earth’s crust and upper mantle explain about half of the elevation of any given place in North America,” with most of the rest due to differences in what the rocks are made of, says the other co-author, David Chapman, a professor of geology and geophysics, and dean of the University of Utah Graduate School.

People usually think of elevations being determined by movements of “tectonic plates” of Earth’s crust, resulting in volcanism, mountain-building collisions of crustal plates, stretching apart and sinking of inland basins, and sinking or “subduction” of old seafloor. But Hasterok and Chapman say those tectonic forces act through the composition and temperature of rock they move. So as crustal plates collide to form mountains like the Himalayas, the mountains rise because the collision makes less dense crustal rock get thicker and warmer, thus more buoyant.

The study – published online in the June issue of Journal of Geophysical Research-Solid Earth – is more than just an entertaining illustration of how continents and mountains like the Rockies are kept afloat partly by heat from Earth’s deep interior and heat from radioactive decay of uranium, thorium and potassium in Earth’s crust.

Scientists usually attribute the buoyancy and elevation of various continental areas to variations in the thickness and mineral composition (and thus density) of crustal rocks. But Chapman says researchers have failed to appreciate how heat makes rock in the continental crust and upper mantle expand to become less dense and more buoyant.

“We found a good explanation for the elevation of continents,” Hasterok says. “We now know why some areas are higher or lower than others. It’s not just what the rocks are made of; it’s also how hot they are.”

Chapman says it will take billions of years for North American rock to cool to the point it becomes denser, sinks and puts much of the continent underwater. Coastal cities face flooding much sooner as sea levels rise due to global warming, he adds.

Why it is Important to Know How Heat Affects Elevation

The new study’s scientific significance is that by accounting for composition, thickness and, now, temperature of crustal rock in North America, scientists can more easily determine how much elevation is explained by forces such as upwelling plumes of molten rock like the “hotspot” beneath Yellowstone, and places where vast areas of mantle rock “dripped” down, letting mountains like the Sierras rise higher.

The new method also will make it easier to identify areas where crustal rocks are unusually hot due to higher-than-average concentrations of radioactive isotopes.

Chapman says temperatures in Earth’s crust and upper mantle often are inferred from measurements in boreholes drilled near the surface, while elevation reflects average rock temperatures down to 125 miles beneath Earth’s surface. Inconsistencies in both measurements can be used to reveal the extent to which borehole temperatures are affected by global warming or changes in groundwater flow.

Elevation increases in a given area could provide notice – tens of millions of years in advance – of volcanic processes beginning to awake deep in the lithosphere, he adds.

Most Regions Would Sink, but Seattle would Soar

Some locations – sitting atop rock that is colder than average – actually would rise without the temperature effect, which in their case means without refrigeration.

Instead of its current perch along saltwater Puget Sound, Seattle would soar to an elevation of 5,949 feet. Seattle sits above a plate of Earth’s crust that is diving or “subducting” eastward at an angle. That slab of cold, former seafloor rock insulates the area west of the Cascades from heat deeper beneath the slab. Removing that effect would warm the Earth’s crust under Seattle, so it would expand and become more buoyant.

To calculate how elevations of different regions would change if temperature effects were removed, the researchers did not remove all heat, but imagined that region’s rock was as cold as some of North America’s coldest crustal rock, which still is 750 degrees Fahrenheit at the base of the crust in Canada. Here are other locations, their elevations and how they would sink if their crust had the same temperature:

-- Atlanta, 1,000 feet above sea level, 1,416 feet below sea level.

-- Dallas, 430 feet above sea level, 1,986 feet below sea level.

-- Chicago, 586 feet above sea level, 2,229 feet below sea level.

-- St. Louis, 465 feet above sea level, 1,499 feet below sea level.

-- Las Vegas, 2,001 feet above sea level, 3,512 feet below sea level.

-- Phoenix, 1,086 feet above sea level, 4,345 feet below sea level.

-- Albuquerque, 5,312 feet above sea level, 48 feet above sea level.

-- Mount Whitney, Calif., tallest point in the lower 48 states, 14,496 feet above sea level, 11,877 feet above sea level.

A Lesson from the Abyssal Ocean Depths

Chapman says it may seem paradoxical, but “the answer to questions about the elevation of Earth’s continental areas starts in the oceans.”

The Earth’s crust averages 4 miles thick beneath the oceans and 24 miles thick under continents. The crust and underlying layer, the upper mantle, together are known as the lithosphere, which has a maximum thickness of 155 miles. The lithosphere is broken up into “tectonic plates” that slowly drift, changing the shapes, locations and configurations of continents over the eons.

Ice floats on water because when water freezes it expands and becomes less dense. Rock and most other materials expand and become less dense when heated. Hasterok says it has been well known for years that “elevations of different regions of the continents sit higher or lower relative to each other as a result of their density and thickness. Most elevation that we can observe at the surface is a result of the buoyancy of the crust and upper mantle.”

He adds that elevation changes also can stem from heating and expansion of rocks that makes them more buoyant – a phenomenon named “thermal isostasy” that explains “why the hot mid-ocean ridges are much higher relative to the cold abyssal plains.”

New ocean floor crust is produced by volcanic eruptions at undersea mountain ranges known as mid-ocean ridges. Molten and hot rock emerges to form new seafloor, which spreads away from a ridge like two conveyor belts moving opposite directions. As new seafloor crust becomes older and cooler over millions of years, it becomes denser and loses elevation. Chapman and Hasterok say there is a 10,000-foot elevation difference between the peaks of the mid-ocean ridges and older seafloor.

Given that, Chapman says he has been puzzled that differences in rock temperature never have been used to explain elevations on continents.

“Our goal was to show that temperature variations add a significant contribution, not only to the ocean floor, but also to continental elevation,” Hasterok says. “For example, the Colorado Plateau sits 6,000 feet above sea level, while the Great Plains – made of the same rocks [at depth] – are much lower at 1,000 feet. We propose this is because, at the base of the crust, the Colorado Plateau is significantly warmer [1,200 degrees Fahrenheit] than the Great Plains [930 degrees Fahrenheit].”

When You’re Hot You’re High in North America

Chapman says that in the study, he and Hasterok “removed the effects of composition of crustal rocks and the thickness of the crust to isolate how much a given area’s elevation is related to the temperature of the underlying rock.”

First, they analyzed results of previous experiments in which scientists measured seismic waves moving through Earth’s crust due to intentional explosions. The waves travel faster through colder, denser rock, and slower through hotter, less dense rock. Then they used published data in which various kinds of rocks were measured in the laboratory to determine both their density and how fast seismic waves travel through them.

The data allowed researchers to calculate how rock density varies with depth in the crust, and thus how much of any area’s elevation is due to the thickness and composition of its rock, and how much is due to heating and expansion of the rock.

Seafloor crust has the same composition and thickness most places away from the tall mid-ocean ridges, so it is easy for scientists to observe how elevations vary with ocean crust temperature. But to determine the temperature effect on continents, “we wave this wand and create a transformed continental crust that is everywhere the same thickness [24 miles] and composition [2.85 times the density of water],” Chapman says. “Once we’ve done that, we can see the thermal effect.”

That, in turn, made it possible to calculate how much heat flow contributes to elevation in each of 36 tectonic provinces – sort of “mini-plates” – of North America.

For example, the New England (Central) Appalachians Province has an average elevation of 897 feet, but if its rocky crust were cooled to that of old, colder continental crust like the Canadian Shield, the province would sit 563 feet below sea level, a drop of 1,460 feet. New York City, within that province, has an elevation listed as 33 feet. Subtract 1,460 feet and the Big Apple gets dunked 1,427 feet below sea level.

Source: University of Utah

http://www.physorg.com/news101952315.html

posted in Geology - 0 replies

The state of mineral exploration in light of current violence in northern Sonora, Mexico_redacted for content...

yingfriman — Sun, 20 May 2007 03:17:35 GMT

Hey _________,
This is to address any fears about northwest Sonora State, Mexico. I do appreciate the concern! We are kept abreast of developments with radio, newsprint and internet (yes, we've left the Bronze-age behind here on property and have air-conditioning as well as internet access!). If I am reading the situation right, and I think I am, what is happening is essentially a civil war, of sorts. With the decline in the last 5 years of the Milenio cartel, fighting between the Sinaloa cartel and the east coast Gulfo cartel to establish control of the lucrative corridors east of ________ is heating up. Generally, civilians are left to their own devices. Mind you, I did work in Nicaragua (where civilians and crypto-socialist, sandal-wearing gringos were the targets) and certainly have read about El Salvador and Guatemala; I am not stupid enough to think that 'civilians' aren't targeted in civil wars. But our situation is unique for several reasons:
Firstly, we act as a kind of cover for illegal activity in the immediate area. The only reason that this corridor is used is because increased activity in the area is masked by our own legitimate activity. To begin targeting the gringos would bring about an end to a very lucrative and peaceful corridor. As you can see, everything is happening out east of us - that's not a mistake or an oversight. These people aren't, at their base, opposed to our presence here; we help the local economy (and regardless of what _______ thinks, pay wages that are 5 to 6 times what the average in the area is). This isn't Saudi Arabia and the narcos aren't jihadists - they're businessmen. Not to put too fine a point on it (or mix metaphors), fucking with us would bring the full hammer weight of the Mexican and to some extent American law on their heads; they won't shit where they eat when it's been proven that the kitchen is always open and the chow is top shelf.
Secondly, one of the most powerful families in Sonora state are the landowners (they hold surface rights where they can run cattle and grow date palms) of our property. If you look at a map of Sonora, you'll see that not one single incident has happened west of the ___________ corridor - once again, this is no accident and is a hard border of control within the realm of the _______ family sphere of influence. Not one illegal immigrant or ounce of drug moves north within this corridor without their blessing. One of Eduardo Bours (the longstanding governor of Sonora State) closest friends is the patriarch of the _________ clan - _________. I had the opportunity 2 weeks ago to sit in his palatial dining room and shared a pleasant meal with him and his extended family when I was in _____ - I saw the photos of them hugging and laughing like brothers. I also got a lesson in negotiating with powerful Mexicans as well, but that's another story. After our meal, which was entirely fried things by the way, we chatted about activity in the area...he was pumping me to see if I was connecting the dots concerning low flying planes and fast moving one-ton pickup trucks...after telling him that it was none of my business one way or the other, he said I could expect to be safer than if I was in California again.
Thirdly, I am not a drug dealer. That would a good way to wind up dead. I am certainly paid well enough to not feel any urges. Experience tells these people that recruiting a gringo is bad business anyways; they consider us too greedy and frankly too cowardly to make efficient operatives - they're probably right. And no, I have not been approached by anyone...I have had 'hey, bodyguard!' yelled at me several times by smiling narco types when we make into town. That's a new fad in the area - I've seen some ex-Rhodesian and buzz cut American military types that apparently are working as bodyguards. They mostly seem to chauffeur around old ladies draped in layer-upon-layer of makeup and gold chains. Why I could be confused with one of them is a mystery - I mean, when was the last time you saw a bodyguard wearing flip-flops?
Asking me to be careful is inherently redundant, in the final analysis. I know this area as good as most any gringo has after the Mexican revolution. To tell me to watch myself implies I don't know what I'm doing...fear not, I know exactly what I'm doing...
Vigilantly yours,
Jim

posted in Geology - 5 replies

book recommendation

buddyboy76 — Wed, 06 Jun 2007 21:25:55 GMT

hey all,

i used to have a book "rocks and minerals" when i was a kid. i've seen it on every geologists book shelf -- red cover.

alas, i lost the book years ago.

an amazon search yields gajillions of hits that aren't what i'm looking for -- can't remember the publisher or editor.

does a book titled "rocks and minerals" with a red cover ring a bell with any of you?

posted in Geology - 2 replies

Bulge under Yellowstone Lake

Greg — Thu, 11 Mar 2004 19:51:14 GMT

This topic was brought up in a very unrelated tribe. I thought I'd bring it up here, since it's more fitting...doesn't anyone know anything about this or have any further information or theories, aprt from what's below?

"Fairly" recent info about a large bulge that has formed under Yellowstone Lake. Info from the USGS and various other sources:

"We're thinking this structure could be a precursor to an hydrothermal explosive event," Morgan said last week. "But we don't think this is a volcano."

"If the bulge should explode, "we think it would create a large crater." But such an explosion, smaller versions of which created Indian Pond, Duck Lake and Mary Bay itself, would probably heat up the water temporarily, create high waves, spew poison gasses and other materials into the lake for a time, and leave a rimmed underwater crater."

"Or it could do nothing."

"Professor Bob Smith at the University of Utah and his students reported at the American Geophysical Union meeting that they have done seismic tomographic imaging of the bulge which covers 19 x 25 miles. Their seismic velocity data suggest there is leakage of gas, maybe carbon dioxide, causing some of the ground to lift. There is a possibility that there might be some magma movement, but the seismic tomography shows magma only in small amounts under the Mallard Lake and Sour Creek resurgent domes in Yellowstone. The University of Utah data suggests that 90% of the large bulge is solidified. Another possibility for the slowly rising bulge could be superheated water moving underground."

http://www.earthfiles.com/news/news.cfm?ID=612&category=Environment

http://dax.geo.arizona.edu/earthscope/news/yellowstone.html

posted in Geology - 23 replies

The Klyuchevskaya Sopka volcano

captaincracklins — Tue, 29 May 2007 18:11:34 GMT

http://www.russiannewsroom.com/content.aspx?id=11565_Science&date=2007-5-28

he Klyuchevskaya Sopka volcano on Russia’s Kamchatka Peninsula is spewing a major ash column to a height of up to 6.5-seven kilometres above sea level
The Klyuchevskaya Sopka volcano on Russia’s Kamchatka Peninsula is spewing a major ash column to a height of up to 6.5-seven kilometres above sea level, there is no danger to nearby settlements, head of the Klyuchevskaya volcanic station Yuri Demyanchuk told Itar-Tass from the Klyuchi settlement (located 32 kilometres from the volcano) on Monday.

He pointed out that on Sunday the giant mount spewed volcanic dust columns to a height of up to nine kilometres above sea level. “It is seen from Klyuchi today that the ash column is permanently above it,” the expert said. According to the scientist, the ash plume drifts away from the settlement with a population of about 5,000, but “a very small amount of ash” nevertheless falls there.

Major incandescence is observed at nighttime above the volcano summit. Hot volcanic bombs are spewed from the crater every five-ten seconds. The spews height reaches 500 metres, Demyanchuk noted. According to him, several lava flows heated to 1,000 degrees Celsius are descending on the slopes. “At least three such flows are clearly visible,” the scientist said. The longest of them descended to the mark three kilometres above sea level. Lava is melting the glacier and water and mudflows are coming down the volcano slopes, but they pose no direct danger for the Klyuchi settlement.

The volcano roar and explosions could be heard in this settlement. House windows were trembling from them.

The so-called phreatic explosions occur when the hot lava with comes in contact with ice. Volcanic bombs are spewed from the crater to a height of up to 500 metres.

The Klyuchevskaya Sopka volcano is regarded the highest active volcano in Eurasia (4,750 metres above sea level). Its eruption started on February 15 and its activity has considerably grown since then, specialists pointed out. The giant mount spews ash clouds that spread in plumes to a distance of hundreds of kilometres. Last Tuesday, such a plume moving along an arc of a circle above the Bering Sea about 500 kilometres reached the Korf settlement in the Koryak Autonomous Area in the northern part of the Kamchatka Peninsula.

The Klyuchevskaya Sopka usually erupts once in five-six years. The previous major eruption was registered in winter-spring 2005. Specialists are permanently monitoring the volcano. They believe the volcano presents no danger for nearby populated localities.

Experts of the Kamchatka volcanic eruption response group said “there is a danger in the area of the volcano for international and local flights caused by possible ash and aerosol plumes.” All the organizations concerned have been warned about the hazard.

------------------------------

posted in Geology - 0 replies

New Photomicrographs posted

Missouri-Rhino — Tue, 24 Apr 2007 19:54:25 GMT

Both of the photomicrographs posted today illustrate petrographic textures of granites in the North American midcontinent. The Troy Granite is from Meridian Aggregates' quarry near Mill Creek, Oklahoma; while the Tishomingo Granite is from Meridian Aggregates' quarry near Snyder, OK. These were part of a study I did in-house to characterize the compositions of both granites, both chemically and petrographically. A new correlation was found which is published in Chapter G, USGS Bulletin 2209 - Contributions to Industrial Minerals Research. This bulletin is available on the Internet.

Comments are welcome.

^Rhino!

posted in Geology - 6 replies

Geologists to test theory that Asia is being 'stuffed' under Tibetan Plateau

bobs — Wed, 09 May 2007 16:59:29 GMT

(Also posted on: http://awesomenature.tribe.net/ )

For nearly a decade and a half, Cornell geologist Larry Brown has been leading an international seismic profiling effort in Tibet, using explosions to probe the deep earth and discover how continents formed millions of years ago.

The project, called INDEPTH -- for International Deep Profiling of Tibet and the Himalayas -- has gone through several stages and now is a major international collaboration among scientists from the United States, China, Germany, Canada and, most recently, Ireland.

The National Science Foundation recently renewed funding for the project with a grant of $1.3 million to Cornell to finish the survey. Brown, professor of earth and atmospheric sciences, has been leading the project across the Tibetan plateau, located in the southwestern corner of China, since its inception in the early 1990s.

Tibet is one of the world's best examples of what happens when continents smash together, Brown explained, because of its famously high elevation and sprawling terrain. The Himalayas are thought to be have formed when the Indian continent slammed into Asia beginning about 50 million years ago.

The ultimate goal, according to Brown, is to piece together what happens when continents collide to form supercontinents like Eurasia. A common theory is that the Tibetan Plateau formed when India was pushed under Asia from the south.

"We'll be testing the hypothesis that, in fact, Asia is also being stuffed under the northern part of the plateau," Brown said.

In order to do that, scientists must understand the geometry of rock layers under the Earth's surface.

The researchers use echo sounding, which is the same basic technology used to map the ocean bottom and explore for oil and gas. In Tibet, the scientists set up explosions that generate sound waves, whose echoes off the deep rock layers are recorded and analyzed.

This allows an "acoustic photograph" to be taken as deep as 100 miles, but typically between 20 and 30 miles deep, said Brown, whose current work also involves deep imaging of major earthquake faults in Taiwan and an active volcano on the Caribbean island of Montserrat.

Future targets of Brown's work include sites in Brazil, Africa, Madagascar and India.

Source: Cornell University

http://www.physorg.com/news97515051.html

posted in Geology - 0 replies

Why Supercontinents Self-Destruct

bobs — Tue, 01 May 2007 19:56:30 GMT

Larry O'Hanlon, Discovery News

May 1, 2007 — Earth's mega-volcanic eruptions may be the direct result of mega continents getting in the way.

A new computer simulation that looks at how heat moves out from the center of our planet confirms the idea that the supercontinent Pangea could have acted like a thermal dam to that heat flow.

When the dam burst, Pangea experienced a gigantic, continent-melting flood of basalt lava that not only busted the place up, but likely vented enormous amounts of carbon into the atmosphere and caused rapid global warming — all at the time of the dinosaurs' demise.

"(Pangea) was sort of a blanket that prevented cooling," said Ben Phillips, a geophysical modeler at Los Alamos National Laboratory in New Mexico. "It was insulating almost a hemisphere." Phillips coauthored a paper on the new simulation in the May issue of the journal Geology.

What's more, when there are many land masses, there is more cooling in the mantle because there's more crust being pushed into the mantle, explained Phillips. It's a lot like dropping ice cubes in hot tea. But when there's just one big continent, he said, there's less cooling in the mantle.

The big question, of course, is whether the big continental blanket and fewer ice cubes could build up enough heat to melt a lot of rock and split up Pangea. The computer simulation indicates it could.

If it's correct, then supercontinents are their own worst enemies — literally creating the conditions which lead to their own demise.

On the other hand, the biggest breach in Pangea — today’s Atlantic Ocean — may hold clues to another continent-wrecker. The Atlantic has quite a few volcanic hot spots that indicate that there are plumes of extra heat rising from deeper in the Earth, says geochemist Kent Condie of New Mexico State University in Socorro.

These hot spots — like the Azores, Bermuda and Iceland — might be the leftovers of a much larger plume and upwelling that was the cause of the continental break-up.

This plume and upwelling idea is the way geologists have previously explained the massive flood basalt eruptions that wrenched the continent apart and might have led to global warming that killed the dinosaurs.

"(Phillips and his colleagues) have suggested that you don't need to have a mantle plume to have flood basalt," said Condie. What seems more likely, he said, is that there was a combination of things going on — including plumes.

More evidence that plumes are at work is the fact that parts of Pangea are still in the process of breaking up, said Condie. Places like the east African Rift or the ever-widening Red Sea are examples of the continuing break up of Pangea.

Either way, figuring out what ended Pangea is important because its story could help explain other massive events. A billion years ago there was another supercontinent, Rodinia, which didn't last either, said Phillips.

http://dsc.discovery.com/news/2007/05/01/supercontinent_pla.html?category=earth&guid=20070501094500

posted in Geology - 0 replies

'Kryptonite' discovered in mine

bobs — Tue, 24 Apr 2007 08:22:16 GMT

Kryptonite is no longer just the stuff of fiction feared by caped superheroes.
A new mineral matching its unique chemistry - as described in the film Superman Returns - has been identified in a mine in Serbia.

According to movie and comic-book storylines, kryptonite is supposed to sap Superman's powers whenever he is exposed to its large green crystals.

The real mineral is white and harmless, says Dr Chris Stanley, a mineralogist at London's Natural History Museum.

"I'm afraid it's not green and it doesn't glow either - although it will react to ultraviolet light by fluorescing a pinkish-orange," he told BBC News.

Rock heist

Researchers from mining group Rio Tinto discovered the unusual mineral and enlisted the help of Dr Stanley when they could not match it with anything known previously to science.

Once the London expert had unravelled the mineral's chemical make-up, he was shocked to discover this formula was already referenced in literature - albeit fictional literature.

"Towards the end of my research I searched the web using the mineral's chemical formula - sodium lithium boron silicate hydroxide - and was amazed to discover that same scientific name, written on a case of rock containing kryptonite stolen by Lex Luther from a museum in the film Superman Returns.

"The new mineral does not contain fluorine (which it does in the film) and is white rather than green but, in all other respects, the chemistry matches that for the rock containing kryptonite."

The mineral is relatively hard but is very small grained. Each individual crystal is less than five microns (millionths of a metre) across.

Elementary clash

Identifying its atomic structure required sophisticated analytical facilities at Canada's National Research Council and the assistance and expertise of its researchers, Dr Pamela Whitfield and Dr Yvon Le Page.

"'Knowing a material's crystal structure means scientists can calculate other physical properties of the material, such as its elasticity or thermochemical properties," explained Dr Le Page.

"Being able to analyse all the properties of a mineral, both chemical and physical, brings us closer to confirming that it is indeed unique."

Finding out that the chemical composition of a material was an exact match to an invented formula for the fictitious kryptonite "was the coincidence of a lifetime," he added.

The mineral cannot be called kryptonite under international nomenclature rules because it has nothing to do with krypton - a real element in the Periodic Table that takes the form of a gas.

Power possibilities

Instead, it will be formally named Jadarite when it is described in the European Journal of Mineralogy later this year.

Jadar is the name of the place where the Serbian mine is located.

Dr Stanley said that if deposits occurred in sufficient quantity it could have some commercial value.

It contains boron and lithium - two valuable elements with many applications, he explained.

"Borosilicate glasses are used to encapsulate processed radioactive waste, and lithium is used in batteries and in the pharmaceutical industries."

http://news.bbc.co.uk/1/hi/sci/tech/6584229.stm

posted in Geology - 0 replies

2004 Quake Wounded Earth's Crust

bobs — Mon, 23 Apr 2007 16:20:08 GMT

Also posted in: http://awesomenature.tribe.net/

Larry O'Hanlon, Discovery News

April 23, 2007 — Deep water may be healing the portion of Earth's crust ruptured by the deadly 2004 Sumatra-Andaman earthquake, say Japanese scientists who have detected changes deep in the quake zone with orbiting, gravity-measuring spacecrafts.

The researchers propose that moving water in Earth's mantle — below the crust — explains the relatively quick fading of a "dent" in Earth's gravity caused by the rare mega-thrust earthquake that launched the terrible 2004 Indian Ocean Tsunami. If so, it means water plays a surprisingly big role in the dynamics of Earth's mantle.

A "dent" in gravity is really a change in the geoid, the invisible global contour map of the lumpy variations in gravitational force. Those variations are caused by differences in the mass of the planet in different places.

Even on a big planet, massive objects like chunks of crust or mountains can still exert their own measurable local gravity, however small compared to cumulative gravity of the entire Earth. This can now be measured from space using the two Gravity Recovery and Climate Experiment (GRACE) satellites.

A mountain range, for instance, positions more mass closer to Earth's surface, and so it has a different gravitational tug than a spot in the middle of the ocean, where Earth's crust is thin and all the gravity-making mass is far below.

In the case of the Sumatra-Andaman earthquake, the downward lurch of one crustal plate under another caused the gigantic quake.

"Geoid changes are due to the vertical movement of mass," explained geoscientist Kosuke Heki of the University of Hokkaido in Japan. He and his colleagues published their study on the changes at Sumatra-Andaman rupture zone in the latest issue of Geophysical Research Letters.

"That alone is a pretty remarkable thing," said geophysicist Paul Segall of Stanford University in California, commenting on the detection of the gravity change, and the subsequent geoid rebound. "It's a real achievement. The data looks pretty good."

As for whether it's really the shifting of mantle water that accounts for the rebound, Heki suspects it is, comparing the phenomenon to the way a body responds to injury.

"A bruise in the human body is often associated with swelling caused by internal bleeding," Heki explained. In the Earth, the "bruise is caused by the quake, the swelling is like the change in the geoid," he said and the internal bleeding is the movement of water freed from rocks by the injury.

"Although it may take longer time for the scar itself to heal, swellings (the geoid) may heal earlier," Heki added.

The quick changes the Japanese team are seeing are indeed unusual, said Segall. However, the healing of the geoid could also be from silent slippages in the crust after the giant quake.

"I have to say that in many cases it's been very difficult to untangle" the possibilities, Segall told Discovery News. That said, he's not ready to rule out water.

"It's thought-provoking," said Segall. "It will be interesting to see what happens with more time."

http://dsc.discovery.com/news/2007/04/23/sumatracrust_pla.html?category=earth&guid=20070423094530&dcitc=w19-502-ak-0000

posted in Geology - 0 replies

Drillers target earthquake zone

bobs — Wed, 18 Apr 2007 10:45:23 GMT

Also posted at: http://awesomenature.tribe.net/

By Jonathan Amos
Science reporter, BBC News, Vienna

It promises to be one of the grand scientific challenges of this decade.

Researchers are about to drill down into an earthquake zone at the Nankai Trough off the coast of Japan.

The project, which will cost hundreds of millions of dollars over the next 10 years, is being coordinated by the Integrated Ocean Drilling Programme.

It seeks to understand the causes of deadly quakes and tsunami by pulling up cores for study and by putting down sensors to monitor changes in the rock.

The Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE) expects to get under way in September.

There is a strong need in the Japanese community to know what is going on under the sea floor

Masataka Kinoshita, Jamstec
It is focused on a region of the sea floor that has been responsible for immense tremor events, including the 1944 Tonankai (Magnitude 8.1) and 1946 Nankaido (Magnitude 8.3) earthquakes.

"The place we are going to has a history of disastrous earthquakes and tsunami every 100 or 200 years; and these have resulted in the deaths of many people," explained Chief Project Scientist Masataka Kinoshita, from the Japan Agency for Marine-Earth Science and Technology (Jamstec).

"There is a strong need in the Japanese community to know what is going on under the sea floor," he told BBC News.

He was speaking here at the European Geosciences Union General Assembly meeting.

Real-time data

NanTroSEIZE is focussed on an area of subduction, where a huge slab of Pacific oceanic crust is being pulled down under the continental rock on which Japan sits.

The drilling effort will attempt to cut directly into the faults that trace the grinding interface - the seismogenic zone.

The project has great relevance for Japan - but goes wider
"These are complex structures," said Cesar Ranero, from the Spanish research council, Icrea. "They have areas that are very sticky - where the two plates are strongly mechanically coupled - and these are typically the areas where strong earthquakes nucleate.

"And they have other areas which are less sticky, but which may still be involved in the propagation of the quake. One of the goals of the project is to understand why an earthquake will rupture across a smaller or larger area, producing a smaller or larger earthquake."

Drilling operations will be conducted from a new 57,000-tonne ship, the Chinkyu.

It will have to sit atop 2,500m of water, holding a steady position as the drill head cuts a series of holes up to 7km under the sea floor.

Core samples will be returned to the laboratory for study and the holes themselves will be instrumented to monitor changes.

Seismometers and tilt meters will follow how the rocks in the faulting zone are moving. The sensor package will also measure changes in temperature and pressure, and provide information to assess any geochemical reactions taking place.

"We'd like to know something about what fluids do at that position," said Nathan Bangs, from University of Texas at Austin, US.

"If there are a lot of fluids there that are under very high pressure, they can essentially act like lubricants and not allow stresses to build up. But if the fluids are not present, the rocks can build up big stresses that can eventually rupture as an earthquake."

Extreme environment

Data from the instruments will be stored by logging devices at nodes on the sea floor. Submersible vehicles will return year after year to retrieve the data packages, although it is hoped that eventually the nodes can be cabled, to bring the information straight on to shore and to the scientists' PCs.

The Integrated Ocean Drilling Programme (IODP) is aware that the venture is a risky one. The instruments will have to be built to survive searing heat, crushing pressures and corrosive fluids. They could fail at anytime.

There are places on the surface of the Earth that scientists can study the types of rocks being sought by the Nankai Trough experiment - but there is no substitute for seeing the true setting, researchers believe.

"To get those rocks up to the surface, they have been exhumed, which means, for example, that any fluids involved in an earthquake will have been lost," explained Paola Vannucchi, from the University of Florence, Italy.

"The process that brings these rocks to the surface from eight kilometres down is also a process of deformation, so you get one superimposed on the other. You don't get a pure signal."

As part of the IODP project, a second series of holes will be drilled off Costa Rica in Central America.

The scientists say the results from both experiments should be applicable to all major subduction zone earthquakes and related tsunami, as well as earthquakes generally.

http://news.bbc.co.uk/1/hi/sci/tech/6566039.stm

posted in Geology - 1 reply

Scientists Discover First Seafloor Vents on Ultraslow-Spreading Ridge

bobs — Mon, 16 Apr 2007 20:49:34 GMT

(Also posted in: http://awesomenature.tribe.net/ )

Scientists have found one of the largest fields of seafloor vents gushing super-hot, mineral-rich fluids on a mid-ocean ridge that, until now, remained elusive to the ten-year hunt to find them.

“The discovery of the first active vents ever found on an ultraslow-spreading ridge is a significant milestone event,” said Jian Lin, leader of a team of Woods Hole Oceanographic Institution (WHOI) scientists who participated in a Chinese expedition to the remote Southwest Indian Ridge in the Indian Ocean in February and March.

Since deep-sea hydrothermal vents were first discovered 30 years ago in the Pacific Ocean, scientists have studied them all along the Mid-Ocean Ridge, a 40,000-mile-long mountain range that zigzags through the middle of the world’s ocean basins like a giant zipper. The ridge marks the area where the Earth’s giant tectonic plates spreads apart and new ocean crust forms from hot lava rising from deep within Earth’s mantle.

Most studies of the chimney-like vent structures have taken place along ridges in the “fast-spreading” East Pacific Rise (100 to 200 millimeters per year) and the “slow-spreading” Mid-Atlantic Ridge (20 to 40 millimeters per year). Only in recent years have scientists explored “ultraslow-spreading ridges” (less than 20 millimeters per year) in the Arctic and Indian Oceans—remote areas tough to get to, and therefore the least studied.

Scientists initially thought ultraslow-spreading ridges would be too cold to host large hot vents. But in the past decade, some scientists began to hypothesize that the slower a ridge spreads, the fewer vents it would have—but the bigger the vent fields would be.

“This cruise confirmed that hypothesis,” said Lin, a marine geophysicist and U.S. Coordinator of the 20-day expedition aboard the Chinese research vessel Dayang 1. “People have been looking for active hot vents on ultraslow ridges for more than 10 years,” Lin said.

In 2005-06, as part of China’s first around-the-world oceanographic expedition, Lin had sailed as a US chief scientist on Dayang 1 to the Southwest Indian Ridge, where scientists found tantalizing evidence of active hydrothermal venting. They gathered critical data that led them back to the site this year.

During the February-March expedition, the team nailed the discovery with the aid of ABE, WHOI’s Autonomous Benthic Explorer, which has been instrumental in recent years in helping scientists find vents on the bottom of the ocean much quicker than ever before. ABE acts like a robotic deep-sea bloodhound: In a sequence of dives, its sensors “sniff out” clues indicating a plume of fluids emanating from a vent and collect data scientists use to home in on the vent.

ABE also uses sonar to create maps of vent fields and takes photographs about 5 meters above them. ABE snapped 5,000 images of the robust Southwest Indian Ridge vent site, which is among the largest known to date. It is larger than a football field (120 meters by 100 meters).

The discovery was a first for China. “This discovery reflects China’s increasing contribution to ocean science in general, and ridge science in particular,” Lin said.

The China Ocean Mineral Resources R&D Association (COMRA) in Beijing, China, funded the 2005-06 expedition and ABE’s participation in the current one. COMRA, which represents China in the International Seabed Authority, has been exploring the deep sea for mineral resources since the early 1990s.

China is increasing investments in ocean science, Lin said. COMRA’s primary interests lay in the large sulfide deposits created by hydrothermal vents, which are rich in copper, zinc, gold, and other minerals, he said.

“Our Chinese colleagues were the happiest people I’ve ever seen at sea when they brought the first samples aboard,” said Dana Yoerger, scientist in the WHOI Deep Submergence Laboratory and co-designer of ABE, who participated in the expedition. Once ABE pinpointed the site’s exact location, the Chinese team sent down its “TV grab”— a grappling device guided by a television camera—and retrieved a reddish chunk of a vent chimney, Yoerger said.

The researchers outran a tropical cyclone and collected the data they needed in just six days and three ABE dives. “It was the most ruthlessly efficient science we’ve ever done,” said Christopher German, chief scientist of the WHOI-operated National Deep Submergence Facility, who also participated in the expedition. “We had no margin for error.”

The Chinese science party was led by chief scientist Chunhui Tao, a geophysicist at the Second Institute of Oceanography in Hanzhou, China.

“The two international teams worked exceedingly well for this kind of complex operation,” Lin said.

Source: Woods Hole Oceanographic Institution

http://www.physorg.com/news95941712.html

posted in Geology - 0 replies

Giant crystals enjoyed perfection

bobs — Thu, 05 Apr 2007 16:04:48 GMT

With lengths over 11m, the giant gypsum crystals found in Mexico's Cueva de los Cristales are a great natural wonder.
Now, a Spanish-Mexican team thinks it can explain how these marvels acquired their immense form.

The scientists studied tiny pockets of fluid trapped in the crystals and conducted back-up lab experiments.

They report in the journal Geology that the solution from which the crystals grew must have been kept in a very narrow, stable temperature range.

The researchers' analysis leads them to believe there are other dramatic caves waiting to be discovered in the Naica mine complex south-east of Chihuahua city.

"If the theory we propose for the 'genetic' mechanisms of the crystals is right, then I would not be surprised if miners find more of these caves in the next few years," Juan Manuel Garcia-Ruiz, from the University of Granada, Spain, told BBC News.

Bigger than 'swords'

Already two remarkable caves are known at Naica, which has yielded some of the world's most significant deposits of silver and lead.

The 120m-deep Cueva de las Espadas (Cave of Swords), discovered in 1912, is named for its metre-long shafts of gypsum (a calcium sulphate mineral that incorporates water molecules into its chemical formula).

And although individually there are fewer crystals in the 290m-deep Cueva de los Cristales, its beams are considerably bigger.

Professor Garcia-Ruiz and colleagues believe they can now show how these differences emerged.

The team studied tiny fluid samples embedded inside the crystals themselves.

These watery inclusions record tell-tale chemical details of the saline and temperature conditions of the saturated solution from which the mammoth structures developed.

'Perfect conditions'

Both caves owe their origin to the volcanism which laid down the metal sulphides - the ores - that have proved so valuable.

Copious amounts of calcium sulphate would also have been created towards the end of this mineralisation process more than 20 million years ago - but in the hot fluids that infused the cracks and cavities in the rock, this calcium sulphate would have taken the form of anhydrite.

Anhydrite has the same chemical formula as gypsum, except that it excludes water. Only as the magma chamber deep under the Naica mountain cool sufficiently for the hot fluids above to fall to a temperature at which anhydrite could switch to gypsum.

Professor Garcia-Ruiz and colleagues say their studies indicate that the deeper of the two caves - Cueva de los Cristales - must have been kept just below the transition temperature for many hundreds of thousands of years.

"The conditions were perfect. By maintaining the temperature just below 58 degrees for a very long time you get a few, very big crystals," said Professor Garcia-Ruiz.

"You can see that many areas on the cave's walls are empty; they have no crystals. The walls are red because of the iron oxide. The reason we know this happened for many years is because we studied the fluid inclusions inside the crystals."

It is likely the upper cave - Cueva de las Espadas - fell below the transition temperature much more rapidly and consequently grew many, smaller crystals.

Heritage future?

The particular crystalline form taken by the gypsum is selenite which is known for its translucency.

Their future will be dependent on the fate of the mine.

At the moment, access is restricted to prevent damage to the soft crystals.

And the only reason humans can get in the caves at all is because of the ongoing pumping operations that keep them clear of water.

If, when Naica's ores are no longer viable, the mine is closed and the pumping is stopped, then the caves will be submerged - and the crystals will start growing again.

"I've recommended to the mining company that they try to preserve them and I would like to see Unesco get involved," explained Professor Garcia-Ruiz.

"Later on we should decide whether to keep them available for people to visit and enjoy, or let the natural scenario return."

http://news.bbc.co.uk/1/hi/uk/6518161.stm

posted in Geology - 2 replies

Mineral Physics Illuminates Lower Mantle Hypothesis

bobs — Sun, 25 Mar 2007 12:06:18 GMT

Scientists have shown increased interest in a mantle layer known as D", presumed to be just above the core-mantle boundary, since laboratory experiments in 2004 revealed a possible new high-temperature, high-pressure, crystal packing structure derived from the common mantle mineral perovskite.

Noting that recent research has also hypothesized the existence above and below the D" layer of discontinuities in the velocities of seismic waves, Hernlund and Labrosse investigate whether such discontinuities are theoretically predicted by mineral physics.

Using independent constraints for a lower bound on temperature in the Earth's deep mantle and for the temperature of the Earth's inner core boundary, the authors examine the nature of the transition between perovskite phases, as hypothesized by the existence of the D" layer and the observed seismic velocity anomalies. They find it consistent only with part of the range of uncertainties in current knowledge of the pressure-temperature behavior of minerals at such depths.

Title: Geophysically consistent values of the perovskite to post-perovskite transition Clapeyron slope

Authors: J. W. Hernlund: Institute de Physique du Globe de Paris, Paris, France; S. Labrosse: Laboratoire des Sciences de la Terre, École Normale Supérieure de Lyon, Lyon, France

Source: Geophysical Research Letters (GRL) paper 10.1029/2006GL028961, 2007

Note: This story has been adapted from a news release issued by American Geophysical Union.

http://www.sciencedaily.com/releases/2007/03/070322110408.htm

posted in Geology - 1 reply

Sea floor records ancient Earth

bobs — Fri, 23 Mar 2007 09:46:41 GMT

(Also posted in: http://awesomenature.tribe.net/ )

By Jonathan Fildes
Science and technology reporter, BBC News

A sliver of four-billion-year-old sea floor has offered a glimpse into the inner workings of an adolescent Earth.
The baked and twisted rocks, now part of Greenland, show the earliest evidence of plate tectonics, colossal movements of the planet's outer shell.

Until now, researchers were unable to say when the process, which explains how oceans and continents form, began.

The unique find, described in the journal Science, shows the movements started soon after the planet formed.

"Since the plate tectonic paradigm is the framework in which we interpret all modern-day geology, it is important to know how far back in time it operated," said Professor Minik Rosing of the University of Copenhagen and one of the authors of the paper.

Professor John Valley, a geologist at the University of Wisconsin, Madison described the work as "significant" and "exciting".

"If these observations are substantiated it will be a significant line of new evidence indicating that plate tectonics was active and familiar as early as 3.8 million years ago," he said.

"That really is an important conclusion."

Crack and spread

Plate tectonics is a geological theory used to explain the observed large-scale motions of the Earth's surface.

The relatively thin outer shell of the planet is composed of two layers: the lithosphere and the asthenosphere.

The lithosphere - made up of the outer crust and the top-most layer of the underlying mantle - is broken up into huge plates; seven major plates and several smaller ones.

These float above the asthenosphere and move in relation to one another.

Today, oceanic crust is created at plate boundaries known as mid-ocean ridges, where magma rises from the asthenospehere through cracks in the ocean floor, cools and spreads away.

As it moves away from the spreading centre towards the edges of the oceans it becomes cooler, denser and eventually starts to sink back into the mantle to be recycled.

"Sea floor is not normally preserved for more than 200 million years," said Professor Rosing.

Most is destroyed at subduction zones, such as those found along the edge of the Pacific Ocean, where oceanic crust plunges under the buoyant and long-lived continental crust.

Water world

However, in certain circumstances, fragments of the sea floor known as ophiloites are preserved when they are scraped on to the land.

This exceptional process typically occurs when continental crust begins to be sucked into a subduction zone, clogging the system.

"It goes down into the subduction zone until the buoyancy of the continent arrests the process of subduction," explained Eldridge Moores, emeritus professor of geology at the University of California, Davis.

"The continent then pops back up, preserving a little bit of the overriding wedge of oceanic crust and mantle that was on the overriding plate."

Ophiolites are found today in Cyprus and Oman and show a distinctive structure.

At their base, crystalline rocks preserve the top layer of the mantle. Above, "fossilised" magma chambers give way to a layer of stacked vertical pipes, known as sheeted dykes.

These represent the conduits through which magma is extruded onto the sea floor as pillow lavas, bulbous lobes of basaltic rock that form when lava cools quickly in contact with water.

Racing rocks

The rocks analysed in Greenland come form an area known as the Isua Belt, a zone of intensely deformed rocks in the southwest of the island that geologists have pored over for decades.

The ophiolite structure was mapped between outcrops covering 4-5km (2.5-3 miles) and shows the correct sequence of layers found in an ophiolite, except the lowest mantle portion.

"You can actually recognise features that formed in a couple of minutes, 3.8 billion years ago - a quarter of all time - and you can actually go and touch them with your hand," said Professor Rosing.

Crucially, they show well preserved sheeted dykes and pillow lavas, clear evidence to many that these are the ancient remains of sea floor created by processes seen today.

"What this tells you unequivocally is that the process of sea-floor spreading that we observe today appears to be present in one of, if not the, oldest sequence of rocks on Earth," said Professor Moores. "That is a significant milestone."

In particular, it pushes back the oldest known evidence of plate tectonics by at least 1.3 billion years and gives scientists clues to the processes that formed the surface of the Earth today.

Although the structures and processes that led to their formation would be similar to the modern era, they would not be exactly the same.

The young Earth was much hotter than now, and as it shed heat, it put many of the tectonic processes into overdrive.

"If you had plate tectonics you probably would have had more plates, moving faster, and they probably would have been thinner," said Professor Moores.

The rate of recycling of oceanic crust would therefore have been even quicker than today, making the fact that the rocks in Isua are preserved at all even more extraordinary.

"These fragments are extremely rare," said Professor Rosing. "It's just very exciting when you get one of these glimpses when you can look back nearly four billion years in time."

http://news.bbc.co.uk/1/hi/sci/tech/6479289.stm

posted in Geology - 0 replies

Scientists Read Rocks’ History With Unprecedented Precision

bobs — Mon, 12 Mar 2007 21:37:42 GMT

Assigning dates to the events in the life of a rock—for example, a collision with a piece of continent, or a journey through the Earth’s crust—has long challenged geologists, as the events themselves can confound evidence of the past.

But now, armed with a custom-built machine known as the Ultrachron, University of Massachusetts Amherst scientists are refining a technique that allows them to pin dates to geologic processes with unprecedented precision. The research is already providing new information on the expansion of the North American continent and the growth of the Himalayas, and could help geologists re-evaluate current debates such as the “Snowball Earth” hypothesis.

UMass Amherst geologists Michael Williams and Michael Jercinovic will discuss the new technique at the 42nd annual meeting of the Northeastern Section of the Geological Society of America Monday, March 12, in Durham, N.H. The work also appears in the current Annual Review of Earth and Planetary Sciences.

The life of a rock is often filled with drama—there may be collisions, deforming pressures, intense heat or the scrape and weight of glaciers. Figuring out when something happened to a particular piece of rock has been difficult—methods exist for dating a rock’s absolute age—but scientists trying to determine the dates of a rock’s experiences have had to settle on ballpark figures often many millions of years apart.

In the past decade however, researchers discovered that nature has a version of an airplane’s black box, in the form of a little-known mineral called monazite. Common in a wide variety of rocks, monazite contains uranium and thorium—elements that decay to lead over a predictable length of time—allowing scientists to read the ratios of these elements like a clock. Moreover, monazite grows in distinct layers, or “domains,” and a new domain is added each time the parent rock is altered, making the mineral a powerful tool for dating geologic processes, says Williams.

“It grows a bit like an onion, a new layer is added each time the host rock undergoes some geologic event,” he says. When a new domain forms, its uranium clock begins ticking, so by carefully analyzing each domain in a fleck of monazite, the researchers can set dates to processes that affected the host rock—a collision or a period of melting, for example. “It’s acting like a petrologic tape recorder,” says Williams.

As Williams and Jercinovic continued to work with the mineral, they realized that an instrument built precisely for monazite analysis would be a very powerful tool for getting at all kinds of geologic questions, such as when the oceans formed and how the continents grew. With such a machine scientists could shed new light on current debates, such as the controversial “Snowball Earth” hypothesis, which posits that between 500 million and 700 million years ago, the planet experienced an ice age so severe that the oceans froze over and life on earth was nearly brought to a halt.

So the scientists began discussions with Cameca, the French analytical instrumentation company, and applied for National Science Foundation (NSF) funding to custom-build an instrument for monazite analysis. Typically for this kind of work, researchers would cut and polish a chunk of rock and analyze it with an electron-probe—a machine that directs an electron beam onto a mineral sample and then measures the X-rays and electrons that bounce back. But regular probes couldn’t deal with the tiny samples the researchers were working with—sometimes a mere 20 microns in size, a fraction of the size of a grain of salt. And they needed it optimized for monazite, which is very dense, so its electrons don’t scatter very far, explains Jercinovic.

“We went to the drawing board with Cameca,” he says. “We wanted to take more advantage of our beam so they refined the optics. They improved the brightness of the electron gun and altered the lenses.” The researchers needed high current, but low voltage. Extra large diffracting crystals were made to catch more of the cone of X-rays coming from the sample. After two and a half years of discussion, construction and adjustments, the “Ultrachron” was dedicated at UMass Amherst, an event celebrated in Paris.

As Jercinovic and Williams use the Ultrachron, they continue to refine their technique and the machine. And they are unraveling the complicated history of some very old rocks. A slab of rock from Colorado had a fleck of monazite with a 1.64 billion-year-old domain, a 1.66 billion year-old one and 1.4 billion-year-old tip, likely formed when the host rock was stretched during an ancient faulting event. Former graduate student Kevin Mahan wanted to more precisely date when a chunk of rock in Saskatchewan was thrust through the Earth’s crust to the surface—some evidence said 2.5 billion years ago, some said 1.9 billion years ago. Monazite analyses determined that the host rock’s journey took place around 1.85 billion years ago—leading to new ideas about what the environment was like in the deep crust of North America.

The scientists received additional NSF funding supporting the exploration of this technique, says Jercinovic, giving them a freedom to really develop the best possible methods and parameters for analyses.

“When you look closely the monazite has a meaningfully complicated structure,” says Jercinovic. “And we now have a powerful tool to extract information from that structure—it’s very exciting.”

Source: University of Massachusetts Amherst

http://www.physorg.com/news92898446.html

posted in Geology - 0 replies

Scientists set to rock the world

bobs — Fri, 09 Mar 2007 19:24:17 GMT

The world's geologists are to bring together all their maps, producing the first truly global resource on rocks.
Known as the OneGeology project, it will pool existing knowledge about what lies under our feet, and present it through one web portal.

Led by the British Geological Survey (BGS), the effort calls on scientists from more than 55 nations.

It hopes to be able to display searchable rock data for the entire Earth down to the scale of 1:1,000,000.

"There is currently a problem of accessibility," said Ian Jackson, the OneGeology Project Leader from BGS.

"We know the data exists; but it's not always clear where it is, and some of it is still in paper form. We want to make more available the data that has already being surveyed, modelled and paid for."

'Big' issues

The project is expected to drive new science by showing up gaps in knowledge.

It should also become a key support tool for cross-national agencies and companies that want to investigate and understand the Earth's exploitable resources, such as its mineral and water reserves.

Professor John Ludden, executive director of BGS, cited the example of carbon capture and storage, which is being proposed as a possible solution to global warming.

This would see carbon dioxide (CO2), one of the main greenhouse gases, captured at power stations and buried deep underground.

"Some of this is what I call 'big science' - science that no one country or geological survey can do on its own," he said.

"Geological surveys across the world are involved in trying to work out how you put CO2 underground and keep it there, and these sorts of databases are going to be required."

The project, which has the backing of Unesco and five other global umbrella bodies, will be a centrepiece of the International Year of Planet Earth in 2008.

Scientists would expect have the first release of their portal up and running by then. It will present the information with the use of a "virtual globe", in much the same way as Google Earth now presents satellite images.

National differences

Although the 1:1,000,000 scale is the goal, the project realises that for some parts of the world this simply may not be possible.

"Some nations may take a view that 1:1,000,000 is too commercially sensitive to release," concedes Ian Jackson.

"We hope not - but at least if they can make available 1:5,000,000 scale, we can put that up, and some details about where you could go for more details."

It is also envisaged that some work will need to be done to marry up the maps at national boundaries where geologists of connecting countries have interpreted their surface rocks slightly differently.

The portal will work on a distributed model, with national surveys retaining their data but allowing it to be interrogated through the portal using a common computer mark up language such as GeoSciML.

Much of the content - although not all of it - will be free to browse.

The OneGeology's inaugural event is a meeting in Brighton, UK, from 12-16 March.

http://news.bbc.co.uk/1/hi/sci/tech/6434011.stm

posted in Geology - 2 replies

Mysteries of the Atlantic

bobs — Fri, 02 Mar 2007 09:12:43 GMT

Also posted in: http://awesomenature.tribe.net/

Cardiff University scientists will shortly set sail (March 5) to investigate a startling discovery in the depths of the Atlantic

Scientists have discovered a large area thousands of square kilometres in extent in the middle of the Atlantic where the Earth's crust appears to be missing. Instead, the mantle - the deep interior of the Earth, normally covered by crust many kilometres thick - is exposed on the seafloor, 3000m below the surface.

Marine geologist Dr Chris MacLeod, School of Earth, Ocean and Planetary Sciences said: "This discovery is like an open wound on the surface of the Earth. Was the crust never there? Was it once there but then torn away on huge geological faults? If so, then how and why?"

To answer some of these questions Dr MacLeod with a team of scientists, led by marine geophysicist Professor Roger Searle, Durham University, will travel to the area which lies mid-way between the Cape Verde Islands and the Caribbean.

The expedition will be the inaugural research cruise of a new UK research ship RRS James Cook. The team intends to use sonars to image the seafloor and then take rock cores using a robotic seabed drill. The samples will provide a rare opportunity to gain insights into the workings of the mantle deep below the surface of the Earth.

Source: Cardiff University

http://www.physorg.com/news91970657.html

posted in Geology - 0 replies

New Data Shakes Accepted Models Of Collisions Of Earth's Crust

bobs — Fri, 09 Feb 2007 14:11:04 GMT

(Also posted at: http://awesomenature.tribe.net/ )

New research findings may help refine the accepted models used by earth scientists over the past 30 years to describe the ways in which continents clash to form the Earth's landscape.

Eric Calais, an associate professor of geophysics at Purdue University, in collaboration with Ming Wang and Zenghang Shen from the Institute for Geology and Earthquake Science in China, used global positioning systems to record the precise movements of hundreds of points on the continent of Asia over a 10-year period.

"Prior to this, we had only partial regional views that were sometimes inconsistent with each other," Calais said. "With this work, we addressed a fundamental question that geologists have been debating for the past 40 years: Are continents strong and brittle or weak and viscous?"

The "strong and brittle" theory suggests continents break into pieces during collisions of the tectonic plates, pieces of the Earth's crust into which the continents are embedded. The "weak and viscous" theory suggests, on the contrary, that continents thicken and flow upon collision.

The data collected by Calais and his team, reported in the Dec. 30 issue of Geophysical Research Letters, suggests the answer is a combination of both theories. His team found that the surface of the Asian continent behaves differently in areas of high elevation, such as mountains.

"We found that most of Asia is very strong and breaks like a ceramic plate, much like what would be predicted by classic plate tectonics, but there also are large chunks like Tibet and the Tien Shan mountains that seem to deform more like Play-Doh," he said.

The Indian and Eurasian tectonic plates collide at a rate of 38 millimeters, or about one and one-half inches, per year. This slow-motion crash is responsible for the formation of the Himalayas and holds up the Tibetan Plateau, Calais said.

"These movements happen slowly over millions of years, but the impact is tremendous because of the huge masses involved," he said. "When the Earth's crust is put under stress, it deforms. Like a rubber band, the crust can only take so much stress before it breaks, causing an earthquake. We must understand the stresses and their accumulation in the Earth's crust to better understand earthquakes and, eventually, save lives."

The continent of Asia, home to more than 3 billion people, has had some of the largest earthquakes in the recent past, but areas in the United States also are deforming.

"The western third of North America is seismically active," Calais said. "The most well-known area is along the San Andreas Fault in California, but there also is deformation occurring across the Nevada desert, along the Wasatch Mountains in Utah, and further south in Colorado and New Mexico. The National Science Foundation is currently funding a large research effort called the "Plate Boundary Observatory" to apply this same method to study the Western United States."

Calais and his team gathered data from geodetic markers, metal pins about the size of a pen, that they placed in some of the most remote areas of the world, including Siberia and Mongolia. The markers remain in place for use in future studies. They are surveyed for a few days every year by GPS tracking equipment, which is then removed once the data is collected. The tops of the markers have a 1-millimeter-wide dimple that is the actual point tracked by the equipment.

The team tracked changes in height and horizontal movements and compared each site to those surrounding it to determine if the larger area responded to forces as a rigid or malleable segment. If the movement of sites within an area was consistent with a rigid rotation, it could be confirmed that the area fit the strong and brittle theory. However, a change in height did not necessarily mean an area fit the weak and viscous theory, Calais said.

"The change in height of an individual site could be a sign of thickening or it could mean that a rigid block is uplifting as a whole," he said. "We had to look at the behavior of the neighboring sites as well to accurately understand what was happening to the area as a whole."

The team also pulled data from existing tracking stations and through contributions from collaborators, including scientists in Russia and Kirgistan.

"International collaboration was essential for us to achieve a complete view of the surface deformation of the continent," Calais said.

The precision of the team's techniques and use of GPS allowed researchers to track movement as small as 1 millimeter per year. The team plans to place additional GPS tracking points to increase the resolution of their continentwide measurements in the future.

"This is beyond plate tectonics and theories," he said. "We now have the ability to directly measure how continents deform and to use that information to validate or invalidate theories of why this happens."

The National Science Foundation funded this research.

Note: This story has been adapted from a news release issued by Purdue University.

http://www.sciencedaily.com/releases/2007/02/070208100925.htm

posted in Geology - 0 replies

Scientists use seismic waves to locate missing rock under Tibet

bobs — Wed, 07 Feb 2007 23:09:07 GMT

(Also posted in the power and beauty of nature)

Geologists at the University of Illinois at Urbana-Champaign have located a huge chunk of Earth's lithosphere that went missing 15 million years ago. By finding the massive block of errant rock beneath Tibet, the researchers are helping solve a long-standing mystery, and clarifying how continents behave when they collide.

The Tibetan Plateau and adjacent Himalayan Mountains were created by the movements of vast tectonic plates that make up Earth's outermost layer of rocks, the lithosphere. About 55 million years ago, the Indian plate crashed into the Eurasian plate, forcing the land to slowly buckle and rise. Containing nearly one-tenth the area of the continental U.S., and averaging 16,000 feet in elevation, the Tibetan Plateau is the world's largest and highest plateau.

Tectonic models of Tibet vary greatly, including ideas such as subduction of the Eurasian plate, subduction of the Indian plate, and thickening of the Eurasian lithosphere. According to this last model, the thickened lithosphere became unstable, and a piece broke off and sank into the deep mantle.

"While attached, this immense piece of mantle lithosphere under Tibet acted as an anchor, holding the land above in place," said Wang-Ping Chen, a professor of geophysics at the U. of I. "Then, about 15 million years ago, the chain broke and the land rose, further raising the high plateau."

Until recently, this tantalizing theory lacked any clear observation to support it. Then doctoral student Tai-Lin (Ellen) Tseng and Chen found the missing anchor.

"This remnant of detached lithosphere provides key evidence for a direct connection between continental collision near the surface and deep-seated dynamics in the mantle," Tseng said.

"Moreover, mantle dynamics ultimately drives tectonism, so the fate of mantle lithosphere under Tibet is fundamental to understanding the full dynamics of collision."

Through a project called Hi-CLIMB -- an integrated study of the Himalayan-Tibetan Continental Lithosphere during Mountain Building, Tseng analyzed seismic signals collected at a number of permanent stations and at many temporary stations to search for the missing mass.

Hi-CLIMB created a line of seismic monitoring stations that extended from the plains of India, through Nepal, across the Himalayas and into central Tibet. "With more than 200 station deployments, Hi-CLIMB is the largest broadband (high-resolution) seismic experiment conducted to date," said Chen, who is one of the project's two principal investigators.

Using high-resolution seismic profiles recorded at many stations, Tseng precisely measured the velocities of seismic waves traveling beneath the region at depths of 300 to 700 kilometers. Because seismic waves travel faster through colder rock, Tseng was able to discern the positions of detached, cold lithosphere from her data. "We not only found the missing piece of cold lithosphere, but also were able to reconstruct the positions of tectonic plates back to 15 million years ago," Tseng said. "It therefore seems much more likely that instability in the thickening lithosphere was partially responsible for forming the Tibetan Plateau, rather than the wholesale subduction of one of the tectonic plates."

Other evidence, including the age and the distribution of volcanic rocks and extrapolation of current ground motion in Tibet, the researchers say, also indicates the remnant lithosphere detached about 15 million years ago.

Chen and Tseng present their findings in a paper to appear in the Journal of Geophysical Research.

Source: University of Illinois at Urbana-Champaign

http://www.physorg.com/news90088929.html

posted in Geology - 0 replies

Scientists Observe Drumlin Beneath Ice Sheet

bobs — Thu, 25 Jan 2007 11:46:48 GMT

Scientists have discovered a warehouse-sized drumlin -- a mound of sediment and rock -- actively forming and growing under the ice sheet in Antarctica. Its discovery, and the rate at which it was formed, sheds new light on ice-sheet behaviour. This could have implications for predicting how ice sheets contribute to sea-level rise. The results are published this week in the journal Geology.

Drumlins are well known features of landscape scoured by past ice sheets and can be seen in Scotland and Northern England where they were formed during the last ice age. They form underneath the ice as it scrapes up soil and rock, and they slow down the rate at which the ice can flow.

Scientists from British Antarctic Survey (BAS), Swansea University and NASA's Jet Propulsion Laboratory Pasadena used a new technique of time-lapse seismic surveys to find the drumlin, and how it formed over time.

Lead author Dr Andy Smith of BAS says, "This is the first time anyone has observed a drumlin actually forming under the ice. These results will help us interpret the way ice sheets behaved in the past, and crucially, will help predict how they might change in the future".

To the team's surprise the drumlin grew ten times faster than they had ever expected, giving a new and important insight into the drag on the underside of the ice and hence how fast ice sheets are able to flow. The study took place on the Rutford Ice Stream -- a 2-km thick, fast flowing ice stream draining part of the West Antarctic ice sheet.

The team used seismic reflection data gathered three times over the last 13 years to map the changes beneath the ice.

Second author Professor Tavi Murray of Swansea University's School of the Environment and Society says, "The new study was recently described at a conference as 'hunting drumlins in the wild'. The analogy with wildlife is good. We learn a lot more from seeing an animal born and growing up, than just dissecting an ancient body. The same is true of drumlins. By observing the birth and growth of this drumlin, we can see that the landscape beneath an ice sheet is changing at a rate faster than previously thought".

The paper, ' Rapid Erosion and Drumlin Formation Beneath an Antarctic Ice Stream' by A.M. Smith1, T. Murray2, K.W. Nicholls1, K. Makinson1, G. Aðalgeirsdóttir2 A.E. Behar3, D.G. Vaughan1 is published in the journal Geology on 23 January.

Background

Today thousands of relict drumlins cover parts of northern England, Canada and Russia -- countries that experienced glacial conditions. Drumlins are formed as sediment and water from the surrounding area gets picked up by a groove in the base of an ice sheet. The rate of formation is controlled by the speed of the ice. Dr Smith and his colleagues also observed the ice sheet eroding huge amounts of sediment, 10 times faster than normally encountered. This rate is comparable to glaciers from a previous Ice Age and indicates unsteady glacier dynamics.

The Rutford Ice Stream is about 150 km long 25 km wide and 2-3 km thick. It is a fast flowing ice stream, which drains part of the West Antarctic ice sheet. Ice Streams are a bit like gigantic rivers of ice. They can be as much as a few hundred km long, tens of km wide, and they typically move by a meter or more every day. Almost all of the ice from the interior of the Antarctic Ice Sheet is drained towards the sea through these ice streams. As the ice enters the ocean, it forms large floating ice shelves. The ice streams can be considered to form the link between the ocean and the more slowly moving ice in the interior of the Antarctic continent.

Ice sheet -- is the huge mass of ice, up to 4 km thick, that covers Antarctica's bedrock. It flows from the centre of the continent towards the coast where it feeds ice shelves. Scientists need to understand the processes going on below ice sheets to predict the behaviour of the world's ice masses and their impact on sea levels. The Antarctic ice sheet is the layer of ice up to 5 km thick covering the Antarctic continent. The ice sheet slowly moves towards the coast, eventually breaking away as icebergs that gradually melt into the sea.

Note: This story has been adapted from a news release issued by British Antarctic Survey.

http://www.sciencedaily.com/releases/2007/01/070123111035.htm

posted in Geology - 0 replies

Silent tremor episode-Csacadia

Will The Dancer — Tue, 02 Jan 2007 02:37:15 GMT

Looks like its finally happening now. 2 months late. 'bout time

check out www.pnsn.org Look at the news, and go to the silent tremor listing (CAFE)

Will

posted in Geology - 1 reply

Grand Canyon National Park is not permitted to give an official estimate of the geologic age of its principal feature

zeth — Mon, 15 Jan 2007 18:55:48 GMT

http://www.peer.org/news/news_id.php?row_id=801

posted in Geology - 5 replies

Pacific Toy Spill Fuels Ocean Current Pathways Research

mofo — Wed, 17 Jan 2007 02:57:28 GMT

I love this story!

http://www.agu.org/sci_soc/ducks.html

posted in Geology - 1 reply

Geologists Discover Origin Of Mysterious Black Diamonds

bobs — Mon, 15 Jan 2007 08:25:38 GMT

by Staff Writers
Upton NY (SPX) Jan 15, 2007
If indeed "a diamond is forever," the most primitive origins of Earth's so-called black diamonds were in deep, universal time, geologists have discovered. Black diamonds came from none other than interstellar space. In a paper published online on December 20, 2006, in the journal Astrophysical Journal Letters, scientists Jozsef Garai and Stephen Haggerty of Florida International University, along with Case Western Reserve University researchers Sandeep Rekhi and Mark Chance, claim an extraterrestrial origin for the unique black diamonds, also called carbonado diamonds.
Infrared synchrotron radiation at Brookhaven National Laboratory was used to discover the diamonds' source.

"Trace elements critical to an 'ET' origin are nitrogen and hydrogen," said Haggerty. The presence of hydrogen in the carbonado diamonds indicates an origin in a hydrogen-rich interstellar space, he and colleagues believe.

The term carbonado was coined by the Portuguese in Brazil in the mid-18th century; it's derived from its visual similarity to porous charcoal. Black diamonds are found only in Brazil and the Central African Republic.

"Conventional diamonds are mined from explosive volcanic rocks [kimberlites] that transport them from depths in excess of 100 kilometers to the Earth's surface in a very short amount of time," said Sonia Esperanca, program director in the National Science Foundation's Division of Earth Sciences, which funded the research. "This process preserves the unique crystal structure that makes diamonds the hardest natural material known."

From Australia to Siberia, from China to India, the geological settings of conventional diamonds are virtually identical, said Haggerty. None of them are compatible with the formation of black diamonds.

Approximately 600 tons of conventional diamonds have been mined, traded, polished and adorned since 1900. "But not a single black/carbonado diamond has been discovered in the world's mining fields," Haggerty said.

The new data support earlier research by Haggerty showing that carbonado diamonds formed in stellar supernovae explosions. Black diamonds were once the size of asteroids, a kilometer or more in diameter when they first landed on Earth.

Related Links
Brookhaven National Laboratory
Case Western Reserve University
The Iron and Ice Of Our Solar System

http://www.spacedaily.com/reports/Geologists_Discover_Origin_Of_Mysterious_Black_Diamonds_999.html

posted in Geology - 0 replies

The Bicentennial of the Geological Society of London

bobs — Sat, 13 Jan 2007 16:54:25 GMT

http://www.geolsoc.org.uk/template.cfm?name=Bicentenary

Click on: Public lectures for a list of the free monthly lectures for this event. Some top speakers there! I think tickets need to be booked!

posted in Geology - 1 reply

Drilling 'boosts Homeric theory'

bobs — Sat, 13 Jan 2007 12:41:29 GMT

(Also posted on http://awesomenature.tribe.net/)

The Mediterranean island of Kefalonia was probably once two separate islands, new geophysical studies suggest.
A British-led team is amassing evidence that indicates Kefalonia's western peninsula, Paliki, was only recently joined to the main landmass.

The team believes a huge in-fall of rock in the last 3,000 years may have built a land-bridge between the two.

If correct, the researchers say, it would support their view that Paliki was the real site for Homer's Ithaca.

The location was supposedly home to Odysseus, whose mythical 10-year journey back from the Trojan War was chronicled in the Greek poet's epic tale The Odyssey.

New results from a test borehole and other survey work in the region lend support to the Paliki hypothesis, the team claims.

"Unlike many historical speculations, our answer to the age-old mystery of Ithaca's location makes a specific prediction that can be scientifically tested by geological techniques," said Robert Bittlestone, the businessman who first made the contention in a book published in 2005.

Most people think modern-day Ithaki on the eastern side of the Ionian island group is the proper geographical setting for Ithaca; but the research team, which includes geologists, classicists and archaeologists, begs to differ.

It argues the Ithaki interpretation is inconsistent with Homer's own descriptions of a low-lying terrain to the west of all land.

Click here to read Homer's Ithaca description http://news.bbc.co.uk/1/hi/sci/tech/6256807.stm#map

Mr Bittlestone and colleagues - James Diggle, Professor of Greek and Latin at Cambridge University and John Underhill, Professor of Geology at Edinburgh University - have sought to test whether Paliki's position furthest from Greece is a plausible explanation.

They propose that recent, huge earthquakes triggered catastrophic landslides and rockfalls, and this material has covered over a narrowmarine channel which separated the peninsula from Kefalonia during the Bronze Age.

Professor Underhill was initially highly sceptical of this idea, because it requires huge volumes of rock to have come off the hills that flank what is now the Thinia isthmus.

But the latest results obtained from a 122m (400ft) borehole drilled in October at the southern end of the land connection lend support to the hypothesis.

It found only loose aggregations of rock as it cut down to - and beyond - current sea level.

"Crucially, we didn't hit limestone bedrock, which means that the theory still holds," explains Professor Underhill.

"The second key thing is we have found that the landslide and rockfall debris of the right type extends to at least 40m below the surface, and, vitally, scanning electron microscopy undertaken at the Academy of Sciences in Sofia shows that it contains Holocene microfossils - it's in the right timeframe," he told BBC News.

And other evidence points the same way, Professor Underhill says.

A marine seismic survey shot jointly with the Greek Institute of Geology and Mineral Exploration (IGME) immediately offshore from the southern Thinia area indicates that the underlying bedrock does have a valley shape in the neighbouring gulf, and its contours fit one-for-one with the presumed course of the marine channel suggested by the onshore geology.

Ancient roads interrupted by landslides and major rockfall deposits are also still visible on the surface.

"We now want to shoot a land-based seismic survey to get a 3D image of the subsurface along the whole extent of the valley onshore, and on the basis of that drill further boreholes where the theory is most challenged - i.e. where the topography of the valley is at its highest level, in the saddle," said Professor Underhill.

Applications for funding will be made to UK and Greek authorities.

The Odyssey seems to have been composed in about the 8th Century BC.

Its descriptions of Gods and giants are clearly fanciful, but the poem has had a huge influence on Western culture, and the team says it is perfectly reasonable to suppose the story had a real geographical setting.

The city of Troy featured in Homer's other epic, The Iliad, is now widely recognised to have been in north-western Turkey.

A study of river sediments in the region would even seem to fit with aspects of the military campaign that Homer's story says eventually led to the destruction of the city.

"Until about the 1850s and 60s, when [the German archaeologist Heinrich] Schliemann discovered Troy, people thought that the Iliad was a work of fiction. Now, they're not so sure because it describes a real landscape; it's been excavated," said Mr Bittlestone.

"If it is the case that The Odyssey and the return home to Ithaca also described a real landscape, this is of monumental significance for our understanding of where our culture's come from and what its routes really have been," he told Channel 4 News.

Commentators say that if the Paliki theory is eventually proven, it is likely to initiate renewed archaeological interest in the peninsula, which has long and perhaps unfairly been considered a backwater.

--------------------------------------------------------------------------------
I am Odysseus, Laertes' son, world-famed
For stratagems: my name has reached the heavens.
Bright Ithaca is my home: it has a mountain,
Leaf-quivering Neriton, far visible.
Around are many islands, close to each other,
Doulichion and Same and wooded Zacynthos.
Ithaca itself lies low, furthest to sea
Towards dusk; the rest, apart, face dawn and sun.
Odyssey 9, 19-26 (trans. James Diggle)

http://news.bbc.co.uk/1/hi/sci/tech/6256807.stm

posted in Geology - 1 reply

Open forum

yingfriman — Fri, 21 Jul 2006 14:31:07 GMT

Thought I'd give a try to initiating some kind of dialog for exploration geologists to share ideas about what's new or cool about the systems you're looking at and where you're looking at it...

Probably barking up the wrong thread here, not to mix metaphors, but thought I'd give it a shot anyways.

I'm currently working on a 10 million ounce resource in an Archean volcanic greenstone belt. Syngenetic harbingers in equal measure with epigenetic. I'm not so dense to assume exclusivity in either scenario considering it is a metamorphic belt from that age - I have worked in Archean BIF's before - just wanted to talk to someone about it besides the same old geo's I've rolled it over a thousand times with...

I am in work mode now which seems to be the wrong worldview to bring to these kinds of forums but a guy can be hopeful. Maybe it would be more appropriate to let everyone know that in spite of my mineral exploration work, I am also an artistically minded, bed-wetting liberal from the U of Oregon in Eugene - there, now the howling chorus can desend - how can u work for those animals? Welllll, I am getting paid to look at rocks and consider myself the inside guy trying to change the way things work from the 'inside'. Anyways, that's how I justify it to myself...

Anyone a working mineral geo out there or prof type who would like to cross swords?

See ya in the funny papers...

posted in Geology - 2 replies

Geologists Make Better Estimates Of Rock Ages, Study Global Climate Change

bobs — Wed, 25 Oct 2006 15:10:35 GMT

Ohio State University geologists have found that important rocks from Niagara Gorge -- rock formations that are used to judge the ages of rocks and fossils around North America -- formed five times faster than previously thought.

The finding means that scientists will have to re-examine studies of sedimentary rock deposited across North America during the Silurian period, from 416 to 443 million years ago.

Ultimately, the geologists hope to perform similar studies of rock from other time periods, to better pinpoint periods of global climate change in Earth's history. Just as tree rings, coral reefs, and ice cores contain chemical records of Earth's history, sedimentary rocks such as limestone vary in composition according to the climate in which they formed.

Bradley Cramer, a doctoral student in earth sciences at Ohio State , reported the study October 22 at the Geological Society of America meeting in Philadelphia.

Cramer and his advisor, Matthew Saltzman, professor of earth sciences, and their colleagues used a relatively new technique called high-resolution carbon isotope stratigraphy to determine the age of rocks in Niagara Gorge in New York .

Rocks that were originally estimated to have formed as sediments built up over 10 million years' time actually formed in only 2 million years, they found. That means that instead of forming between 428 and 418 million years ago, the rocks actually formed between 428 and 426 million years ago.

What do a few million years matter, when they happened so long ago? Saltzman and his team need to make precise time measurements as they search for evidence of ancient climate change.

"We have this great geological record of climate changes in the past," Cramer said. "The problem is, the rate of change that we're worried about in the modern day is on a very short time scale. And when we look into the deep past, our ability to know where we are in time isn't that precise. If we can get our time constraints down more precisely, we can begin to ask the same sort of questions of the past that we're asking of the modern era."

Ancient sedimentary rocks contain chemicals such as carbon that are indicators of atmospheric conditions at the time the rocks formed. During times of apparent rapid climate change at other locations around the globe, the rock composition shows a change as well, and pinpointing exactly when things happened can be difficult.

That's why the Ohio State geologists decided to re-examine the rock formations of Niagara Gorge, which had originally been studied in the 1800s.

"That very set of rocks contains a global extinction event -- one of the largest in Earth's history," Saltzman said, "and it hadn't been examined with the most modern techniques available."

Scientists believe this extinction event, the Ireviken event, happened approximately 428 million years ago, and may have been caused by climate change. Some 80 percent of conodont species -- wormlike sea creatures -- and 50 percent of trilobite species went extinct during that time.

The event was recorded in the rock composition of Niagara Gorge, and carbon isotope stratigraphy is the ideal technique to study it.

Cramer explained how the technique works. Scientists measure the ratio between two isotopes of carbon, carbon-13 and carbon-12, in a rock sample. Normally, the ratio is zero or one, but in certain times throughout history, such as during and after a great extinction, the ratio markedly increases. Scientists call the increase an "excursion" from the normal value of zero or one.

"What is so useful about these excursions is that they are time markers," Cramer said. "If you find an excursion in Ohio , and then the same one in Sweden , you know that the intervals containing the excursion are coincident in time. Essentially, we match the markers from one place to another. This is a chemical way of telling time."

The Niagara Gorge rocks contained a marker from the Ireviken extinction. That marker had been well documented in rocks in sites around the United States, Canada, and Sweden. In all those locations, the rocks that contain the marker formed at the same time in Earth's history.

The Niagara Gorge rocks were among the first North American rocks to be dated by geologists in the 1800s, and the gorge has been a treasure trove for scientists ever since. From the top of the escarpment, down to the floor of the gorge where the Niagara River cascades, scientists have thought that the gorge represented as much as 10 million years of history.

Cramer's analysis revealed that most of the formations originated during the Ireviken event, which lasted for only 1 million years or so.

Given this new information, the geologists decided that the formations of Niagara Gorge only represent 2 million years of history. Rock formations there are used as a frame of reference to judge the ages of rocks throughout North America . So these new results mean that many scientists will have to revise their work. Estimates of when certain animals went extinct may change.

"Unfortunately, this means that a lot of people are going to have to re-examine work that they thought was done," Cramer said.

Next, he wants to look further back in time, to the period before the Silurian: the Ordovician, which began 488 million years ago. Geologists disagree on where exactly the boundary between the Ordovician and the Silurian should be placed, and carbon isotope stratigraphy is an ideal tool to help solve the problem.

Ohio State coauthors on the presentation included Mark Kleffner, an associate professor, Stig Bergström, a professor emeritus, and Seth Young, a doctoral student, all of earth sciences.

The Friends of Orton Hall Fund -- a fund provided by Ohio State earth sciences alumni -- and the Geological Society of America funded this work. A laboratory at the University of Erlangen-Nuremberg in Germany analyzed the Niagara Gorge rock samples.

http://www.sciencedaily.com/releases/2006/10/061023193403.htm

posted in Geology - 2 replies

New Madrid Seismic Zone May Be Cold And Dying, New Evidence Shows

bobs — Fri, 29 Dec 2006 11:40:29 GMT

(Also posted in Power & Beauty of Nature)

Science Daily — New results about the temperatures of rock deep below the New Madrid Seismic Zone in the central United States shed light on the puzzling questions of why large earthquakes happened there in 1811 and 1812 and when they may happen again.

Scientists from Northwestern University, the U.S. Army Engineer Research and Development Center and the University of Illinois at Chicago have found that New Madrid appears to be cold and dying. They presented their findings Dec. 13 at the annual meeting of the American Geophysical Union (AGU) in San Francisco.

"Hot rocks are weak," says Seth A. Stein, William Deering Professor of Geological Sciences in the Weinberg College of Arts and Sciences at Northwestern and a coauthor of the study. "So people suggested that the reason large earthquakes occur in the New Madrid area rather than in the many similar geologic settings in other parts of the eastern United States is that the New Madrid rocks are hotter."

But the researchers discovered this is not the case. They looked at data used in the new edition of the Geothermal Map of North America (American Association of Petroleum Geologists, 2004), which shows all the measurements of the heat coming to the Earth's surface (heat flow) taken from boreholes. They found that thermally New Madrid is surprisingly similar to other areas of the eastern United States.

"The New Madrid data are essentially no different from other sites in the eastern United States," explains coauthor Jason R. McKenna from the U.S. Army Engineer Research and Development Center. "Although we'd like to have more measurements to be sure, at this point, there's no reason to believe New Madrid rocks are hotter and therefore weaker than rock in other parts of the eastern United States."

One of the most difficult aspects of assessing the earthquake hazard is deciding whether New Madrid is a special place or simply where central U.S. earthquakes have occurred in the past few thousand years. "When we look at things like geology, gravity or the magnetic field, there's no obvious difference between New Madrid and similar places in the eastern United States that haven't had large earthquakes recently," McKenna notes. "Now we see the same for heat flow."

The new heat flow results fit into a growing idea that earthquakes can migrate among similar faults, some of which -- such as the Meers fault in Oklahoma -- appear to have been active about 10,000 years ago but show no activity today. Geological studies find that New Madrid earthquakes comparable to those of 1811-1812 occurred about 1450 and 900 AD. However, because this fault system has not generated significant topography, it is likely to have "turned on" relatively recently, perhaps within the past few thousand years.

With this view, say the researchers, prior earthquakes were concentrated on other faults, and future earthquakes will occur somewhere else when the New Madrid system "shuts down." Once this happens, it may be a very long time -- thousands of years or longer -- before New Madrid becomes active again.

"Although we don't know when the New Madrid fault system will shut down, it may be dying today," says Stein. "The recent cluster of earthquakes may be coming to an end."

Migrating earthquakes also occur in the interior of other continents, such as Australia. This is very different from the way earthquakes occur on boundaries between plates, like the San Andreas fault along the boundary between the Pacific and North American plates. Because the plates keep moving, earthquakes continue to occur on the boundaries in the same places.

Precise measurements taken by Stein, coworkers and other investigators using the Global Positioning System (GPS) show that motion across the New Madrid Seismic Zone currently is either very slow or at zero. Because this motion has to accumulate for many years to cause a large earthquake, it will be at least hundreds of years, and perhaps much longer, before another large earthquake happens.

"Until recently about all we could say was that future earthquakes might occur in places where past ones had," says Stein. "Now we can actually test that idea by looking at the motion accumulating for possible future earthquakes. Although we can't be sure yet, the longer the GPS data continue to show essentially no motion, the more likely it seems that the fault is shutting down and won't cause large earthquakes for a very long time. It's time to start thinking about this possibility and to use what we're learning to improve estimates of the hazard from future earthquakes."

The possibility of the fault shutting down is important for assessing the earthquake hazard in the central United States. Large earthquakes (magnitude 7) occurred in 1811 and 1812, causing shaking across much of the area. Houses collapsed in the tiny Mississippi river town of New Madrid, Mo., and minor damage occurred in St. Louis, Louisville and Nashville. The smaller earthquakes that continue in the area today are typically more of a nuisance than a catastrophe, say the researchers. The largest in the past century, the 1968 southern Illinois earthquake (magnitude 5.5), was widely felt and caused some damage but no fatalities. However, if large earthquakes like those of 1811-12 occurred again, they would be very destructive.

The third coauthor of the study, "No thermal weakening under the New Madrid Seismic Zone," is Carol A. Stein, professor of Earth and environmental sciences at the University of Illinois at Chicago.

Note: This story has been adapted from a news release issued by Northwestern University.

NaN

http://www.sciencedaily.com/releases/2006/12/061211221056.htm

posted in Geology - 1 reply

Thoughts on global warming?

Snowlover — Tue, 19 Dec 2006 23:21:36 GMT

I'm curious as to what some of you other rock lickers think about global warming. I have my thoughts but will save them for a bit later as I don't want to sway any answers. I'm not looking for a dissertation or anything here, just some candid thoughts...

posted in Geology - 3 replies

Abstract for peer review of large, epithermal-like gold deposit, Canada.

yingfriman — Wed, 08 Nov 2006 17:39:40 GMT

The _____ deposit is a strataform series of near-vertical, elongate lenticular ore domains hosted in Archean tuffaceous clastic rocks and ash-flow tuff. Gold mineralization is interpreted to be a product of an episodic, epithermal-like, submarine and subaerial, hydrothermal system. Regional deformation has imparted minor metamorphic mineralogical and geometric modification to the deposit. The hydrothermal system is interpreted to have formed within an emerging, peraluminous, calc-alkaline rhyolite to rhyodacite volcanic edifice. Although there is no strict lithological control to the gold distribution in the _____ deposit, each of the identified ore domains has a consistent stratigraphic architecture that distinguishes them. Gold concentrations are associated with:

• intense (>20%) alkali depletion of the volcanic rocks.
• K-metasomatism manifested as sericitic alteration.
• strataform quartz zones accompanied by broad, variably intense silicic alteration.
• concentrations of acicular arsenopyrite crystals.

posted in Geology - 3 replies

Evidence from Hawaiian volcanoes shows that Earth recycles its crust

bobs — Thu, 30 Nov 2006 11:05:18 GMT

(Also posted in Power & beauty of nature)

A geologist at Rutgers, The State University of New Jersey, has come up with evidence our planet practices recycling on a grand scale.

Writing in the prestigious British science journal Nature, geological sciences professor Claude Herzberg offers new evidence that parts of the Earth’s crust that long ago dove hundreds or thousands of kilometers into the Earth’s interior have resurfaced in the hot lava flow of Hawaiian volcanoes.

“This concept has been a big issue in the earth sciences,” Herzberg said. While it had been proposed earlier by some geologists, the profession hasn’t embraced it because evidence until now remained sketchy. “Many geologists felt that when Earth’s crust was forced deep into the mantle, a process called subduction, it would simply stay there.”

Herzberg claims to have found telltale chemical evidence at Mauna Kea that pieces of this submerged crust have been forced up through plumes and now make up most of this volcano’s lava flow. “The low calcium in the Hawaiian magma pegs it as crust that had melted and been forced to the surface,” he said. The calcium levels in traditional magma, which comes from melting the Earth’s mantle layer below the crust, are much higher.

Herzberg said his research doesn’t stop in Hawaii and that his chemical findings will be useful in understanding the makeup and action of other volcanoes around the world. These findings extend beyond calcium and include sulfur, along with isotopes of the heavier elements hafnium and lead that are tracers for clays and other materials that originated close to the surface prior to subduction.

“Chemical patterns we’ve found elsewhere used to be puzzles but are now starting to make sense,” he said.

Still, the big island of Hawaii remains the prime site for uncovering the secrets of volcanic action, as it has the largest volcanoes on Earth and is the most productive in terms of lava outpouring. Herzberg believes the information he’s uncovered about magma chemistry might one day help scientists predict eruptions, as different chemical abundances show up at different times in the volcanoes’ eruption cycles.

Source: Rutgers, the State University of New Jersey

http://www.physorg.com/news84029104.html

posted in Geology - 0 replies

Geologists Find New Origins of Appalachian Mountains

bobs — Fri, 17 Nov 2006 10:30:51 GMT

(Also posted in: http://awesomenature.tribe.net/ )

Geologists have developed a new theory to explain how and when the Appalachian Mountain range was created. Their research redraws the map of the planet from 420 million years ago.

The scientists recently discovered a piece of the Appalachian Mountains in southern Mexico, a location geologists long had assumed was part of the North American Cordillera. The Cordillera is a continuous sequence of mountain ranges that includes the Rocky Mountains. It stretches from Alaska to Mexico and continues into South America.

For the past decade, geologists have collected information from Mexico’s Acatlán Complex, a rock outcropping the size of Massachusetts. As they uncovered each new piece of data from the complex, evidence contradicting earlier assumptions about the origins of that part of Mexico emerged.

“It was a story that had the Appalachians written all over it,” said Damian Nance, Ohio University professor of geological sciences and lead author of an article detailing the findings, which was published in the October issue of Geology. “This will change the way geologists look at Mexico.”

It also changes existing theory regarding the creation of the Appalachians, which has radically altered scientists’ understanding of the planet’s geography, said Nance. Age data, newly unearthed fossils and chemical analysis of the rocks show that the complex is much younger than previously thought. It records a pivotal part of the Appalachian story not preserved elsewhere.

According to the conventional map of 420 million years ago, two main land masses were separated by the Rheic Ocean. In the south sat Gondwana, a supercontinent consisting of South America, Africa, India, Australia and Antarctica. To the north was Laurussia, made up of North America, Greenland, Europe and part of Asia. The old map showed the Acátlan Complex attached to Laurussia. The complex broke off Gondwana about 80 million years earlier, drifted toward North America along with the other land masses, closing an older ocean, known as the Iapetus Ocean, as it did so. The collision created the Appalachian Mountains.

The new map looks rather different.

Evidence collected by Nance and his colleagues from rocks in the Acatlán Complex shows that its collision with Laurussia actually occurred about 120 million years later. The rocks once existed on an ancient ocean floor, but this ocean has proven to be the Rheic, not Iapetus as previously thought.

The explanation, Nance and his fellow authors say, is that the Acatlán Complex was originally attached to Gondwana. Gondwana and the complex eventually slammed into North America, closing the Rheic Ocean in the process. This cataclysmic crunch of continental plates formed the goliath land mass known as Pangea, Nance said, and created the Appalachian Mountains.

“We believe we have found the missing piece of the Rheic suture where Gondwana and North America converged,” said Nance. “All the evidence point to that and, as far as we know, it is the best preserved piece of this puzzle in North America.”

Now geologists from around the world, funded by the United Nations Educational, Scientific and Cultural Organization (UNESCO), are expanding the search for evidence of the Rheic Ocean in order to unravel its history from initial opening to final closure.

“We want to see if the ocean opened and closed everywhere at the same time or at different times like a jaw opening and closing. We want to understand the mechanics of these processes,” said Nance.

Source: Ohio University

http://www.physorg.com/news82919989.html

posted in Geology - 2 replies

Seismolgists get handle on heat flow deep in Earth

bobs — Sat, 25 Nov 2006 21:46:49 GMT

(Also posted in "The Power and Beauty of Nature)

Earth's interior is not a benign world that only stores the geologic history of our planet. Geologists now see the normally assumed placid inner Earth as a dynamic environment filled with exotic materials and substances roiling under intense heat and pressures. It is an environment that continues to evolve in interesting ways and one that has an impact on what happens at its surface.

The latest evidence of this dynamic inner Earth is revealed in a recent series of measurements that peered deep within Earth, halfway to its center. The new experiments have yielded important results that help determine temperature halfway to the center of Earth. It also has implications for the age of Earth's solid inner core and how its magnetic field may be generated.

"We have found unexpected rock layering in Earth's deepest mantle," said Edward Garnero of ASU's School of Earth and Space Exploration and one of the researchers on the team. "The implications of the layering are far reaching, with intimate connections to the rock chemistry, temperature and convective flow, all of which have been previously inaccessible."

"Understanding of Earth's core-mantle boundary environment puts us in the position of answering a host of important questions, such as how much heat from the molten outer core cooks the overlying mantle," Garnero explained. "While this might seem distant and esoteric, it actually relates to the vigor of convective mantle flow that ultimately jostles Earth's surface with volcanic and earthquake processes."

Garnero, and his fellow researchers (Thorne Lay of the University of California, Santa Cruz; John Hernlund of the Institut de Physique du Globe de Paris; and Michael Thorne of the University of Alaska, Fairbanks) report their findings in the Nov. 24, 2006 issue of Science magazine.

In "A post-perovskite lens and D" heat flux beneath the central Pacific," the researchers discuss measurements that have led them to determine temperatures at different levels deep within Earth. The researchers, for the first time, have been able to measure the flow of heat emanating from Earth's core into the base of its mantle, which can help determine the age of the core and help understand how Earth's magnetic field is generated.

Earth is made up of several layers. The crust, which includes the surface of Earth, extends only 40 km (25 mi) deep. Below the crust is the mantle area that extends to about 2900 km (1800 mi) into Earth, the D" layer is the deepest 200 to 300 km of the mantle. The outer core is beneath that and extends to 5150 km (3200 mi) and the inner core to about 6400 km (4000 mi). The researchers probed the D" layer, which lies at the bottom of the mantle.

The boundary between the Earth's core and mantle lies halfway to the center of Earth, to a depth of 2900 km. The seismologists were able to probe the structure of this region by studying its effects on seismic waves generated by large earthquakes.

"What we have found are various layers deep within Earth under the central Pacific Ocean, near the edge of what appears to be a pile of hot, chemically distinct material," Garnero said. "In this 'thermochemical pile' the layering is consistent with a new high pressure phase of a compound called perovskite, a material that exists specifically under high pressures that cause new arrangements of atoms to be formed."

Using seismic waves generated by earthquakes in the Tonga-Fiji region of the southwest Pacific Ocean, the seismologists were able to probe the structure of the D" region inside Earth by studying the patterns of waves reflecting from any distinct objects in the deep Earth. They detected the waves with a new array of highly sensitive instruments deployed by the EarthScope project (a National Science Foundation initiative), located throughout the Western U.S.

What they detected was a novel material alternating between two distinct forms, Garnero said. The material they detected is called post-perovskite, a modified version of perovskite. Separate laboratory mineral physics tests set the temperatures and pressures that would be required to change perovskite material to post-perovskite material.

Temperature measurements in Earth were obtained by relating seismic observations to the mineral transformations of perovskite/post-perovskite material, which occurs under extremely high pressures and temperatures that the researchers say prevail near the core-mantle boundary.

"Perovskite refers to a specific arrangement of the silicon-iron-oxygen-magnesium atoms," Garnero said. "Post-perovskite happens at the highest pressures in the deep mantle of Earth, so if we can pinpoint a depth where that occurs it will allow us to determine the temperature (as determined in laboratory tests) required to make this phase transition from perovskite to post-perovskite."

"We not only found a boundary marking an entrance into this material, but an additional boundary showing an exit from the material back to its original structure as well," Garnero added. "It is like a lens or a cloud that is hovering in the lower most mantle above Earth's core."

Because the research team was able to determine the temperature at two different depths, one right above the other, it gave them a temperature gradient, "which tells us the amount of heat flowing from the core into the base of the mantle," said UC Santa Cruz's Thorne Lay, lead author of the Science paper.

"Heat flow is the Holy Grail because it tells us how much energy powers the geodynamo, and it tells us how much the mantle is being heated from below," Lay added. The geodynamo is the convective motion in Earth's fluid outer core that generates the magnetic field we observe at Earth's surface.

As heat flows from the outer core into the mantle, it drives important processes in the mantle and the core. The mantle is a thick layer of silicate rock and surrounds a dense, predominantly iron core.

The high heat flow found within Earth supports the idea that mantle convection, the slow turnover of mantle material that moves Earth's tectonic plates at its surface, is strongly controlled by this intense degree of heating at the mantle's base by the upwelling of hotter material from near the core mantle boundary.

"The implication from this study is that the flow of heat from the core to the mantle suggests that the inner core of Earth is not as old as the Earth itself," Garnero said.

"The core must have been pretty hot in the past for this much heat to still be coming out, and the inner core, which is slowly solidifying from the inside out as it cools, may be only 1 billion years old," Lay added.

The age of Earth itself is generally regarded as 4.6 billion years old.

The researchers suspect that an upwelling of hot mantle material may be taking place near the edges of the lens of the post-perovskite material. They detected the lens in the lowermost mantle southeast of Hawaii, an area where previous studies have suggested there is a root of a hot upwelling plume from near the core mantle boundary that is ultimately responsible for volcanism that created and continues to create the chain of the Hawaiian Islands.

Garnero said overall this new finding adds an important missing piece to the puzzle of what is going on deep in Earth's interior, adding to the larger picture emerging of a dynamic interior that affects what happens at the surface.

"These glimpses into Earth are revealing key pieces of Earth as a system," Garnero added. "They beckon for a larger understanding of larger scale cycles of our planet."

Source: Arizona State University

http://www.physorg.com/news83515537.html

posted in Geology - 0 replies

FESTIVAL OF GEOLOGY

bobs — Sat, 28 Oct 2006 15:41:00 GMT

The Geologists' Association annual event

Saturday November 4th and Sunday November 5th

10.00–4.30 at University College London

Details: http://www.geologist.demon.co.uk/festival.html

posted in Geology - 0 replies

Amazon river 'switched direction'

bobs — Tue, 24 Oct 2006 19:07:46 GMT

The world's largest river, the Amazon, once flowed from the Atlantic Ocean to the Pacific - the opposite of its present direction, a study shows.
Sedimentary rocks in the central part of South America contain ancient mineral grains that must have come from the eastern part of the continent.

Geologist Russell Mapes says this must mean that about 145-65 million years ago, the Amazon flowed east to west.

Mr Mapes will present his findings at a geology meeting in Philadelphia.

The age of rocks on the South American continent differs between east and west.

Rocks as old as 2.5 billion years are found on the eastern side of the continent. Because of continual geological activity in the Andes, on the western side, rocks there are much younger.

Changing landscape

If the Amazon had continuously flowed eastward, as it does now, much younger mineral grains would be found in the sediments, because they would have been washed down from the Andes.

"We didn't see any. All along the basin, the ages of the mineral grains all pointed to very specific locations in central and eastern South America," said Mr Mapes, a graduate student from the University of North Carolina (UNC), US.

He explained that these sediments of eastern origin were washed down from a highland area that formed in the Cretaceous Period, when the South American and African tectonic plates broke away from each other.

That might have tilted the river's flow westward, sending sediment as old as two billion years toward the centre of the continent.

Current course

Afterwards, a relatively low ridge, called the Purus Arch, rose in the middle of the continent, running north and south. This divided the Amazon's flow, so that one half flowed eastward toward the Atlantic and the other westward toward the Andes.

In the late Cretaceous, mineral grains younger than 500 million years old began to fill in the basin between the Andes mountains - in the west - and the arch running down the centre of the continent.

After millions of years of build up, the Amazon river finally broke through these sediments and flowed past the Purus arch and into the eastern side of South America. This established the river's current course.

The new data comes from zircons, a type of mineral grain that can be dated in order to determine the age of the sediment.

Previous research has identified a reverse flow, but only in segments of the river. Mr Mapes and his colleague Drew Coleman from UNC traversed about 80% of the Amazon basin, collecting samples of zircon.

Their data supported the previous findings, and illustrate the continent-wide shift of the river's flow over millions of years.

The results will be presented at the Geological Society of America's annual meeting in Philadelphia, which runs from 22-25 October.

http://news.bbc.co.uk/1/hi/sci/tech/6080232.stm

posted in Geology - 0 replies

San Jacinto Fault

bobs — Tue, 24 Oct 2006 12:01:00 GMT

Also posted in The Power and Beauty of Nature tribe:

San Jacinto Fault Is Younger Than Thought, Rises In Seismic Importance

by Staff Writers
Eugene OR (SPX) Oct 24, 2006
A detailed study of sedimentary rocks exposed along a portion of southern California's San Jacinto fault zone shows the fault to be no older than 1.1 million to 1.3 million years and that its long-term slip rate is probably faster than previously thought.
Researchers at three universities conducted a National Science Foundation-funded study of the earthquake-active region, concluding that sedimentation related to slip in the San Jacinto fault zone began about 1 million years ago, significantly later than predicted by many models for faulting in southern California. Their findings appear in the November-December issue of the Geological Society of America Bulletin.

"Our findings suggest that the San Jacinto fault absorbs a large share of the relative motion between the Pacific and North American plates," said principal investigator Rebecca J. Dorsey, a professor of geological sciences at the University of Oregon. "This is important both for understanding the development of this active plate boundary and for helping to constrain estimates of seismic hazards in southern California."

Until now the birth of the San Jacinto fault in the area of Anza-Borrego Desert State Park had not been pinned down.

Geologists from the University of Oregon, Western Washington University and Utah State University carried out detailed geologic mapping, measuring and analysis of samples from Pleistocene (12,000 to 1.8 million years ago) sedimentary rocks in the western Salton Trough, including the Ocotillo Formation and the Font's Point Sandstone in the Borrego Badlands.

Using geologic, stratigraphic and paleomagnetic techniques, they determined that sedimentation related to slip in this fault zone began about 1 million years ago; the fault itself could have started a little earlier than that. A second fault reorganization about 400,000 years later produced a thin sheet-like alluvial deposit that created the Font's Point Sandstone, triggering modern uplift and erosion that has produced the popular Font's Point escarpment.

"The revised younger age of the San Jacinto fault indicates it is an important player in southern California's seismically active fault zones," Dorsey said.

However, she noted, "a rigorous assessment of long-term slip rate on this fault must await a complete analysis of the total offset on the fault," which already is underway. "Based on our current knowledge, it appears that the geologic slip rate could be as high as about 20 millimeters a year," she said.

Slip rate is the speed at which one side of a fault moves with respect to the other. Any rate over 10 millimeters a year is considered "fast," although the movement measured is an average occurring over long periods of time and many earthquakes. Previous studies concluded that fault has slipped about 25 kilometers (15.5 miles) in a right-lateral sense, at a rate of 10-12 millimeters a year during the last 2.0 million to 2.4 million years.

Related Links
http://www.uoregon.edu/

http://www.terradaily.com/reports/San_Jacinto_Fault_Is_Younger_Than_Thought_Rises_In_Seismic_Importance_999.html

posted in Geology - 0 replies

Scientists Explain Giant Holes in China

bobs — Wed, 18 Oct 2006 19:10:27 GMT

(Also posted in "Power and Beauty of nature")

By Larry O'Hanlon, Discovery News

Oct. 18, 2006 — The secrets to the steepest, deepest, most bizarre sinkholes in the world have been worked out by geologists who recently visited the "tiankeng," or "sky holes" near the southern Chinese city of Guilin.

The tiankeng are steep-walled wonders unlike any other sinkholes on Earth, said geologist William White, an emeritus professor at Pennsylvania State University.

"You could fit a couple of Empire State Buildings in and they’d disappear," said White of the more than 2,000-foot-deep wonders.

Yet until recently, no one outside China had even heard of them. "Even the Chinese didn’t know about these until about 15 years ago," said White.

That’s because the tiankeng are in the boonies. Until recently there were no roads to them, just footpaths through the other-worldly conical hills of China's scenic Guilin region.

"These are pretty unique features," White told Discovery News. "The key factor you need is an underground river."

And not just a trickle, but a pretty good-sized flow of water, he said. As in other cavern-riddled places, it’s the water that dissolves limestone to make caves, the roofs of which can collapse to form sinkholes. Usually, large sinkholes look like valleys with no outlets.

But due to the way the exceptionally thick limestone of Guilin is fractured, the tiankeng tend to form along vertical cracks — creating the steep walls.

As the caverns collapse over time, the hundreds to millions of cubic yards of rubble on the floor of the cavern is continually dissolved and carried away by the river, White explained. Over eons the cavern opens to the sky and a tiankeng is born.

White is slated to give a report on the tiankeng to fellow geologists on Tuesday, Oct. 24, at the meeting of the Geological Society of America in Philadelphia.

"It’s a hole through which you can see the sky," said Arthur Palmer, a cave expert at the State University of New York at Oneonta. He was on the same tour of the tiankeng as White in 2005 and recalled that you could even walk into a cavern, through the dark and into the bottom of a tiankeng.

In Tennessee there are some sinkholes on a similar scale, said Palmer, but they are not steep-sided and look like normal valleys — until you notice that there’s no outlet. In Guilin, on the other hand, the entire landscape is dominated by tiankeng and conical hills.

"You have the impression someone took a giant cookie cutter to the land," said Palmer. "You are impressed by how abrupt they are. These do tend to be the biggest in the world."

The provincial government is hoping more people make the trip to see the tiankeng. They’ve already built roads and paths so people can walk down into the holes, said White.

"This is kind of hot-off-the-press," said Palmer of how unknown tiankeng are outside of China.

"I didn't figure there would be that much scientific value," he said. "It is interesting history."

posted in Geology - 0 replies

A Continent Splits Apart

bobs — Fri, 17 Mar 2006 09:07:23 GMT

AFRICA'S NEW OCEAN

By Axel Bojanowski

Normally new rivers, seas and mountains are born in slow motion. The Afar Triangle near the Horn of Africa is another story. A new ocean is forming there with staggering speed -- at least by geological standards. Africa will eventually lose its horn.

Geologist Dereje Ayalew and his colleagues from Addis Ababa University were amazed -- and frightened. They had only just stepped out of their helicopter onto the desert plains of central Ethiopia when the ground began to shake under their feet. The pilot shouted for the scientists to get back to the helicopter. And then it happened: the Earth split open. Crevices began racing toward the researchers like a zipper opening up. After a few seconds, the ground stopped moving, and after they had recovered from their shock, Ayalew and his colleagues realized they had just witnessed history. For the first time ever, human beings were able to witness the first stages in the birth of an ocean.

Normally changes to our geological environment take place almost imperceptibly. A life time is too short to see rivers changing course, mountains rising skywards or valleys opening up. In north-eastern Africa's Afar Triangle, though, recent months have seen hundreds of crevices splitting the desert floor and the ground has slumped by as much as 100 meters (328 feet). At the same time, scientists have observed magma rising from deep below as it begins to form what will eventually become a basalt ocean floor. Geologically speaking, it won't be long until the Red Sea floods the region. The ocean that will then be born will split Africa apart.

The Afar Triangle, which cuts across Ethiopia, Eritrea and Djibouti, is the largest construction site on the planet. Three tectonic plates meet there with the African and Arabian plates drifting apart along two separate fault lines by one centimeter a year. A team of scientists working with Christophe Vigny of the Paris Laboratory of Geology reported on the phenomenon in a 2006 issue of the Journal of Geophysical Research. While the two plates move apart, the ground sinks to make room for the Red Sea and the Gulf of Aden.

Bubbling magma and the smell of sulphur

A third crevice cuts south, splitting not far from Lake Victoria. One branch of the rift runs to the east, the other to the west of the lake. The two branches of this third crevice are moving apart by about one millimeter a year.

The dramatic event that Ayalew and his colleagues witnessed in the Afar Desert on Sept. 26, 2005 was the first visual proof of this process -- and it was followed by a week-long series of earthquakes. During the months that followed, hundreds of further crevices opened up in the ground, spreading across an area of 345 square miles. "The earth has not stopped moving since," geophysicist Tim Wright of the University of Oxford says. The ground is still splitting open and sinking, he says; small earthquakes are constantly shaking the region.

Scientists have made repeated trips to the area since the drama of last September. Locals have reported a number of new cracks opening in the ground, says geologist Cynthia Ebinger from the University of London, and during each visit, new crevices are discovered. Fumes as hot as 400 degrees Celsius (752 degrees Fahrenheit) shoot up from some of them; the sound of bubbling magma and the smell of sulphur rise from others. The larger crevices are dozens of meters deep and several hundred meters long. Traces of recent volcanic eruptions are also visible.

In a number of places, cracks have opened up beneath the thin layer of volcanic ash that covers the region. As there is no ash in the fissures, it's clear that they opened up after the volcanic eruptions, most of which took place at the end of September or in October, 2005. A number of locals who fled the eruptions have reported that a black cloud of ash -- spewed out of the Dabbahu volcano -- darkened the sky for three days.

A new ocean floor on the Earth's surface

Basalt magma has risen into some of the crevices. For the moment, Ayalew explains, the lava seems not to be rising further. A number of recent eruptions, though, have left layers of new basalt lava on the Earth's surface. And it's the exact same kind of lava that spews out of volcanic ridges deep under the ocean -- a process which slowly pushes older lava sediments away on either side. The process has only just begun in the Afar Triangle -- and scientists for the first time can witness the birth of a new ocean floor.

The source of the African magma looks to be a gigantic stream of molten rock rising from beneath the Earth's crust and slicing through the African continental plate like a blow torch. It's a process that began thirty million years ago when lava broke through the continent for the first time, separating the Arabian Peninsula from Africa and creating the Red Sea.

Now, it's the Afar Triangle's turn and it's sinking rapidly. Large areas are already more than 100 meters (328 feet) below sea level. For now, the highlands surrounding the Denakil Depression prevent the Red Sea from flooding these areas, but erosion and tectonic plate movement are continually reducing the height of this natural barrier. The Denakil Depression, which lies to the east of Afar, is already prey to regular floods -- each flood leaving behind a crust of salt.

Africa to lose its horn

The chain of volcanoes that runs along the roughly 6,000 kilometer (3,730 mile) long East African Rift System offers further testimony to the breaking apart of the continent. In some areas around the outer edges of the Rift System, the Earth's crust has already cracked open, making room for the magma below. From the Red Sea to Mozambique in the south, dozens of volcanoes have formed, the best known being Mt. Kilimanjaro and Mt. Nyiragongo.

These fiery mountains too will one day sink into the sea. Geophysicists have calculated that in 10 million years the East African Rift System will be as large as the Red Sea. When that happens, Africa will lose its horn.

http://service.spiegel.de/cache/international/spiegel/0,1518,405947,00.html

posted in Geology - 5 replies

Volcano (La Palma) in Canary Islands: Tsunami 30 mi.->N.Y.

Deborah — Mon, 09 Jan 2006 16:16:56 GMT

The Next time this volcano erupts AFTER a big rainstorm, the whole side of it will come down, causing a tsunami that will strike from Florida to Boston, and probably going inland an estimated 30 miles at New York or south of there.

It is estimated that it will be in the next 12 eruptions, but it doesn't blow often, so it could be 10 or 50 years... or just maybe 1000.

Why? Well, it is built of a sheet of solid rock, then basalt (like sponge, for holding water), then another layer...and then maybe hundreds of layers. The heat will turn the water to steam, and the WHOLE volcano will explode into the sea.

A smart terrorist could drop a bomb after a big rainstorm, too. Then it could easily be in the next few years, and it would make 9/11, Florida, Indonesia and Pakistan together look rather small. ... The last one from there reshaped islands - not facing a continent at the time.

WHY DON'T THEY just drill some drain holes? Anything could help - maybe even just to aim it in a safer direction.

Every article and show I've seen on this takes the attitude of helplessness. I may not know much but ONE of my ideas got pushed up to national level (Mount Vesuvius, due to go off any day in the next 50 or 75 years -or as the guy on the phone said, yesterday).

If there is anything I'll stand for, it is that not trying only gets you One type of help, and I have yet to see Him interfer with as sure a bet as a volcano. .......But we could.

posted in Geology - 3 replies

Pillow Basalt

Jeff — Tue, 11 Jul 2006 22:38:02 GMT

Does anyone know what the fasted recorded accumulation of pillow basalt is? I would also like to know if anyone knows the average depth of the pillow basalt formations on the acretian wedge in California. Most of my family are "young earthers". I need ammo for the fight, and this seems like a good possibility. I don't think that "40 days and 40 nights would do it for the formations that I see in road cuts and landslides around me.

posted in Geology - 11 replies

epigenesis vs. syngenesis

yingfriman — Wed, 19 Jul 2006 19:23:43 GMT

I'm looking to dispute the metallogenesis of a large gold occurence. Multi-sulfide mineral assemblages, strataform qtz zones, lack of shearing. I'm looking at a classic epithermal-like Archaen system in calc-alkaline pyroclastics - not a shear hosted metamorphogenic system. Any suggestions for threads to follow up?

posted in Geology - 2 replies

Signs that you might be an amateur geologist

bobs — Sun, 27 Nov 2005 15:40:11 GMT

Unashamedly pinched from another site! I won't admit to how many of these ring a bell with me!

Signs that you might be an amateur geologist

1 - when people ask you "what have you got in that bag - rocks?" - the answer is "yes!"
2 - you take more pictures of your hammer than of your family.
3 - members of your family only appear in your pictures standing next to rocks.
4 - there is always sand at the bottom of your pockets.
5 - all available work surfaces are covered with specimens.
6 - your family know that when you say "I'll just be a few minutes looking at this exposure" it is time to get out the sandwiches and sleeping bags.
7 - you have a good collection of hammers and chisels and can explain the special uses for each one.
8 - you have to keep going back to sites "just to see if they have changed".
9 - on the way home your headlights point up to the sky.
10 - you have a list of geology books that you want for Christmas!

posted in Geology - 5 replies

Fossil mounds may be oldest life on Earth

lunataylor — Wed, 07 Jun 2006 21:32:53 GMT

I wanna go.

http://www.cnn.com/2006/TECH/science/06/07/oldest.life.ap/index.html

posted in Geology - 2 replies

A Rock Nearly Knocked Off The Chart

bobs — Mon, 19 Jun 2006 09:25:42 GMT

Also posted in "the power and beauty of nature"

by Staff Writers
Moffett Field CA (SPX) Jun 19, 2006
Researchers are scratching their heads after unearthing a 25-centimeter-wide chondritic meteorite from the 145-million-year-old Morokweng impact crater in South Africa. The team found the meteorite within the crater's impact melt sheet about 770 meters (half a mile) down a drilling borehole.
Its existence is puzzling, they said, given its low chance of surviving the high shock pressures and temperatures normally associated with large impact events.

The mystery is its unusual composition, which suggests it is a sample from a previously unknown part of the parent body, or perhaps it originated from an entirely different asteroid population than other known meteorites.

The Morokweng crater is at the edge of the Kalahari Desert in northern South Africa. It has a diameter of at least 70 kilometers (43 miles) and is one of the largest terrestrial impact craters known.

Worn by erosion and obscured by sediments and Kalahari sands, the crater is unrecognizable on the surface. It was discovered by Marco Andreoli as a circular pattern of magnetic anomalies during early-1990s mining explorations.

In 1997, researchers from the University of the Witwatersrand reported that boreholes drilled into the center of the crater hit an impact melt sheet at least 870 meters thick.

The melt sheet is rock at the base of the crater that was liquefied by heat of the impact, and then re-crystallized. It shows high abundances of chromium, nickel, cobalt and the platinum-group elements.

The researchers determined the age of the crater by isotopic age-dating of zircons plucked from the impact melt rock. Ion microprobe analyses for uranium-thorium-lead isotopic compositions placed the age of the crater at about 145-million years - the same age as a major geological boundary, the Jurassic-Cretaceous.

The Morokweng melt sheet is out of the ordinary for a few reasons. First, it contains more meteorite fragments than melt sheets of most other impact craters - fragments thought to be relics of the impactor that created the crater.

In Morokweng the fragments are pebble-sized - less than 1 centimeter - and represent 5 percent to 6 percent chondritic contamination of the melt sheet. That percentage is so high, only one other crater's melt sheet - the Clearwater East crater in Quebec, Canada - has come close to that figure.

Second, the impact melt is unusually rich in nickel (up to 0.25 percent NiO in pyroxene) and chromium (up to 0.35 percent Cr2O3 in the orthopyroxene, and 0.69 percent in clinopyroxene).

Third, and unique to Morokweng's melt sheet is the new discovery reported by Wolf Maier and colleagues of a large (25-centimeter) fossil meteorite. Never before has such a boulder-sized chuck of the impactor been found within a large crater.

Previously, researchers have found fossil meteorites in crater ejecta deposits, but finding a large fragment inside a huge crater had been deemed nearly impossible.

Reporting in the June 15 issue of Nature, Maier's team said the Morokweng meteorite is chemically unaltered except for a thin (1 millimeter) coating of brown alteration minerals. Their laboratory analyses show the meteorite has chondritic chromium isotope ratios and identical platinum-group element ratios to the bulk impact melt.

The researchers found diagnostic features of a highly equilibrated chondrite breccia, including well-preserved chondrules of various textures: porphyritic, excentroradial (see images), and barred. These textures are produced by different degrees of melting and are typical of chondrules in chondrites.

Olivines with 120-degree triple junctions indicate that recrystalization occurred in the parent asteroid as the result of thermal metamorphism. Maier and his co-authors report that the fossil meteorite resembles an LL6 chondrite breccia, yet its atypical composition and texture do not fit exactly into any of the known chondrite groups.

The platinum-group element contents of the Morokweng meteorite are lower than in normal LL chondrites. It contains unusually iron-rich silicates and iron-nickel sulfide, but does not have troilite (an iron sulfide) and there is no metal, which would be expected in this type of meteorite. It seems they have found some thing a little different.

The Morokweng fossil meteorite is a rare find. It is a surviving remnant of a much larger projectile that blasted out the crater.

Its existence challenges the accepted idea that large bodies hit with such energy that they are melted or vaporized within seconds of impact.

Laboratory modeling experiments and numerical simulations of the cratering process support this idea. For example, at high impact angles (close to vertical), the predicted peak shock pressures are 200-500 GPa. Predicted temperatures exceed 2,000K (1,700 oC). If any bits survived, they would be melted and chemically altered.

Until now, craters larger than 4 kilometers in diameter have not yielded any large remnant meteorites. In these cases, the composition of the original impacting body is usually determined indirectly by analyzing chemical tracers of metals, such as nickel, cobalt, and the platinum-group elements. What were the special conditions that made it possible to preserve this unaltered meteorite in the Morokweng melt sheet?

Was it slower than the normal 15-20 kilometers/second (maybe Earth's escape velocity of 11 kilometers/second)? Was it an asteroid rubble pile, hence weak?

Running more cratering experiments and finding similar fossil meteorites on Earth in large impact craters, particularly those with melt sheets that contain an elevated dissolved platinum-group element component, would help to answer such questions. Perhaps future explorers will find projectile pieces in the impact melts of large lunar craters.

The discovery of the Morokweng fossil meteorite is a new piece of information that may help us better understand the bombardment history in the inner solar system.

The unusual composition of Morokweng might suggest that the nature of meteorites may have changed through time - types of impactors hitting Earth 145 million years ago were not the same as bodies hitting more recently. Morokweng may represent a sample of a different asteroid population from any other meteorite collected so far.

Maier's team said they found no evidence to suggest the absence of metal and abundance of sulfide are the result of contamination from interaction with the impact melt. They attribute the mineralogy to metamorphism in the parent body.

If the mineralogy reflects metamorphism in the parent body, then the Morokweng fossil meteorite could have come from a previously unknown interior portion of the LL chondrite parent body.

http://www.spacedaily.com/reports/A_Rock_Nearly_Knocked_Off_The_Chart.html

posted in Geology - 0 replies

Minerals go 'dark' near Earth's core

bobs — Thu, 25 May 2006 21:27:18 GMT

Minerals crunched by intense pressure near the Earth's core lose much of their ability to conduct infrared light, according to a new study from the Carnegie Institution's Geophysical Laboratory. Since infrared light contributes to the flow of heat, the result challenges some long-held notions about heat transfer in the lower mantle, the layer of molten rock that surrounds the Earth's solid core. The work could aid the study of mantle plumes--large columns of hot upwelling magma believed to produce features such as the Hawaiian Islands and Iceland.

Crystals of magnesiowüstite, a common mineral within the deep Earth, can transmit infrared light at normal atmospheric pressures. But when squashed to over half a million times the pressure at sea level, these crystals instead absorb infrared light, which hinders the flow of heat. The research will appear in the May 26, 2006 issue of the journal Science.

Carnegie staff members Alexander Goncharov and Viktor Struzhkin, with postdoctoral fellow Steven Jacobsen, pressed crystals of magnesiowüstite using a diamond anvil cell--a chamber bound by two superhard diamonds capable of generating incredible pressure. They then shone intense light through the crystals and measured the wavelengths of light that made it through. To their surprise, the compressed crystals absorbed much of the light in the infrared range, suggesting that magnesiowüstite is a poor conductor of heat at high pressures.

"The flow of heat in Earth's deep interior plays an important role in the dynamics, structure, and evolution of the planet," Goncharov said. There are three primary mechanisms by which heat is likely to circulate in the deep Earth: conduction, the transfer of heat from one material or area to another; radiation, the flow of energy via infrared light; and convection, the movement of hot material. "The relative amount of heat flow from these three mechanisms is currently under intense debate," Goncharov added.

Magnesiowüstite is the second most common mineral in the lower mantle. Since it does not transmit heat well at high pressures, the mineral could actually form insulating patches around much of the Earth's core. If that is the case, radiation might not contribute to overall heat flow in these areas, and conduction and convection might play a bigger role in venting heat from the core.

"It's still too early to tell exactly how this discovery will affect deep-Earth geophysics," Goncharov said. "But so much of what we assume about the deep Earth relies on our models of heat transfer, and this study calls a lot of that into question."

Source: Carnegie Institution

http://www.physorg.com/news67788052.html

posted in Geology - 0 replies

Herkimer Quartz scepters in Little Falls, NY

uncletim — Tue, 23 May 2006 18:07:46 GMT

Anyone visiting central NY this summer is welcome to contact me and come dig for diamonds and try their luck in finding the elusive "sceptimer" on these beautiful ledges overlooking the Mohawk river. Guaranteed to leave with at least a sore back , filthy clothes and a greater appreciation of the home planet. Chances of success commensurate with experience and a measure of dumb luck.

Tip: bring all the tool steel you can get yer mitts on and an energetic and enthusiastic apprentice or two !

posted in Geology - 0 replies

The Inescapable Vibrating Quartz Crystal

uncletim — Tue, 23 May 2006 17:37:28 GMT

During WWII the gubmint of these here very fine United States did indeed have cause to operate one very secretive and mostly hush hush kinda mining operation in the southern part of California. It's called the Pacifica Silica Quarry and produced some enormous quartz points essential to some top secret program absolutely vital to America's war effort. Now although the crystals there were sought for their vibratory abilities please don't assume that they possessed any particular "vibratrional energies".
As I stated they were quartz crystals. Big ol' gigantical momma honkin' jammies indeed, but good ol' SiO2 none the less. Different in size only from most any crystal you might spy on the key chain of your typical middle aged "I was at Woodstock" lady.
So "why" you may wonder, "were these crystals so sought after by the arsenal of democracy?" How was it that the fate of the entire free world hinged upon the contribution of these remarkable geological specimens?
For the answer to that we need to examine that curios ability of quartz to convert energy from one form to another. You see, our friend the humble quartz crystal is enslaved all around us doing the bidding of its Babylonian masters faithfully and without hesitation or complaint.
When one applies physical force to a quartz crystal some of the energy is converted into an electrical current. The piezoelectric effect. Conversely, applying an electromagnetic field to a crystal will cause it to vibrate, and vibrate at an extraordinarily steady and predictable frequency to boot. That vibration by the way is an expression of mechanical energy.
The battery in a quartz watch energizes a tiny micro crystal whose steady vibrations keep perfect time for millennia. The silicon wafer chip in your computer is an extraordinarily cleverly engineered synthetic quartz crystal whose structure facilitates it assuming myriad on/off positions within its molecular crystalline latticework.
Oh, and the giant crystals from the Pacifica Silica Quarry? They were deployed in ships and submarines to locate and destroy other ships and submarines. They were installed in the hull with an enormous electromagnetic coil around the crystal. When the coil was jolted with power the crystal would vibrate. PING!!!!!PING!!!!!PING!!!!! Sonar operators could then echolocate the enemy vessels by the return signals and blow them into naval jelly.
See? Crystals really do have some practical uses and they're not just a bunch of meta-
physical healy-feely flapdoodle after all. I'll just hang on to my collection and see what else evolves.

posted in Geology - 0 replies

Slab of sunken ocean floor found deep within Earth

bobs — Thu, 18 May 2006 07:59:55 GMT

(Also posted in The Power and Beauty of nature)

Deep within Earth, halfway to its center in an area where Earth's core meets its mantle, lies a massive folded slab of rock that once was the ocean floor, reports a team of researchers in the current issue of Nature.

The slab, which sank beneath North America some 50 million years ago, holds important clues as to the behavior and composition of the deep interior of Earth and it could help explain how surface features such as volcanos and earthquakes form, the researchers say.

The research team, led by seismologists at the University of California, Santa Cruz, detected the slab by analyzing seismic waves reflected from the deepest layer of the mantle beneath an area off the west coast of Central America. The team includes Edward Garnero of Arizona State University, Alexander Hutko and Thorne Lay of UC-Santa Cruz, and Justin Revenaugh of the University of Minnesota. They describe their discovery in "Seismic detection of folded, subducted lithosphere at the core-mantle boundary," in the May 18 issue of Nature.

"In this one location we see quite strong evidence for whole mantle circulation," said Garnero, an ASU seismologist. "Slabs descending deep into the mantle are thought to drive the convective system found within Earth. They are dense and fall into the mantle. But they are connected to the outer shell that includes the oceanic crust."

"It's like a carpet sliding off the dining room table," Garnero added. "If it is more than half way off, it just goes taking everything with it."

The discovery sheds new light on the processes that drive the movement of Earth's tectonic plates. Earth's outermost layer, its lithosphere, is broken into large, rigid plates composed of the crust and the outer layer of the mantle. New plate material is created at mid-oceanic ridges, where the ocean floor spreads apart, and old plate material is consumed in subduction zones, where one plate dives beneath another. But the fate of subducted lithosphere has been uncertain, at least until this slab was detected.

Garnero said there is an on going debate over whether subducted slabs sink all the way down to the base of the mantle or get trapped in the upper mantle. The new evidence favors the presence of subducted slabs in the deep mantle and, if this is the case, then finding this slab could have significant ramifications for our understanding of the inner workings of Earth.

"It is becoming clear that Earth's interior is rich in complexity," Garnero said. "Earthquakes, volcanoes and large pieces of Earth's outermost layer or 'plates,' slowly move, grinding and shifting. All of these point to a dynamical system within the planet, so this discovery could shed light on large scale circulation of rock in Earth's interior, which in turn shifts the tectonic plates, and the nature of the chemistry of material deep in Earth's interior."

Within the mantle, which extends to a depth of about 1,800 miles (2,900 kilometers), cold rock sinks while hot plumes rise toward the surface, and this slow circulation of mantle rock is thought to drive the movement of Earth's tectonic plates. The base of the mantle absorbs heat from the core. The researchers were able to image the buckling and folding of the subducted oceanic slab at the base of the mantle because of the temperature difference between the relatively cool slab and the hotter mantle rock surrounding it.

The researchers used seismic data from earthquakes in South America that were recorded at seismographic stations in the western United States. The researchers analyzed the data with techniques adapted from oil exploration industry to study complex structures in Earth's crust.

"Alex Hutko employed a method that takes hundreds of recordings that all sample the same volume in the deep mantle, and reconstructs an image of reflective surfaces that give rise to the specific bumps and wiggles on the seismograms in a technique called 'migration,'" Garnero said. "This is the most accurate deep mantle imaging effort to date."

Using the method, the researchers found the subducted slab is composed of essentially the same minerals as the surrounding mantle, but its temperature is about 700 degrees Celsius cooler. This temperature difference affects the location of a "phase transition," where the crystal structure of the mantle rock compresses to a more compact form due to increasing pressure and temperature with depth. Seismic energy reflected by this phase transition revealed an abrupt step in the phase boundary about 60 miles (100 kilometers) high.

The researchers also saw evidence of hot plume-like structures at the edge of the slab, indicating possible upwelling of hot material from the base of the mantle as the spreading slab pushes into it.

"Since there is a conservation of mass in the mantle, something must return as the slab sinks into the Earth," Garnero said. "This return flow can include plumes of hot material that gives rise to volcanism."

"We are very excited about employing our migration approach to other regions in the mantle," Garnero added. "This study is just a starting point for bringing once blurry or obscured structures into sharper focus."

Source: Arizona State University

http://www.physorg.com/news67097315.html

posted in Geology - 1 reply

And The Mountain Moved

bobs — Wed, 17 May 2006 10:07:03 GMT

(Also posted in ""Power and Beauty of nature")

And The Mountain Moved Scientists Study How Heart Mountain Shifted

by Staff Writers
New York NY (SPX) May 17, 2006
"The mountains skipped like rams..."- Psalm 114. "Moving mountains" has come to mean doing the impossible. Yet at least once in the past, one mountain relocated a fair distance away. This feat took place around 50 million years ago, in the area of the present-day border between Montana and Wyoming.
Heart Mountain was part of a larger mountain range when the 100 km (62 mile) long ridge somehow became detached from its position and shifted about 100 km to the southwest. This "migrating mountain" has garnered interest from geologists and geophysicists around the world who have tried to solve the mystery behind the largest known instance of land movement on the face of any continent.

Dr. Einat Aharonov of the Weizmann Institute's Environmental Sciences and Energy Research Department, working in collaboration with Dr. Mark Anders of Columbia University in New York, recently published a paper in the scientific journal Geology that offers an explanation for the phenomenon.

Aharonov and Ander's explanation is based on dikes - vertical cracks in the rock that fill with hot lava boiling up from deep in the earth. In Heart Mountain, these dikes formed a passage for the lava, three kilometers deep, through the limestone aquifer (a porous, water-soaked layer). There, the sizzling lava would have heated the water to extreme temperatures, causing tremendous fluid pressures.

The scientists developed a mathematical model (based on the number of dikes in the mountain and their structure) that allowed them to calculate the temperatures and pressures that would have been created deep within the base of the mountain. The results showed that the infiltrating hot lava would have turned the water in the aquifer layer into a sort of giant pressure cooker, releasing enough force to move Heart Mountain from its original spot to its present site.

Related Links
http://www.acwis.org/

http://www.terradaily.com/reports/And_The_Mountain_Moved_Scientists_Study_How_Heart_Mountain_Shifted.html

posted in Geology - 1 reply

Good web sites;

bobs — Wed, 17 May 2006 14:56:36 GMT

The natural history museum ( London) Earth lab

http://internt.nhm.ac.uk/jdsml/nature-online/earthlab//

posted in Geology - 0 replies

Water Witches

Mon, 08 Nov 2004 20:39:39 GMT

any one have a comment, thought, know one, are one, believe in it?

Just curious.

posted in Geology - 40 replies

New Orleans sliding into the sea?

Mon, 17 Apr 2006 15:40:23 GMT

http://dsc.discovery.com/news/briefs/20060327/neworleans_pla.html

New Orleans is at the top end of what looks like a gigantic, slow-moving landslide, according to geologists who have been carefully studying the ground movements in the area.

Amid news that rebuilding the city's levees will cost substantially more than projected, the discovery of a much wider, older cause for the area's rapid subsidence flies in the face of years of policies that have pinned the blame on human activities for most of the area's gradual sinking below sea level.

The pumping of groundwater, levee building, and oil and gas extraction have carried the blame so far, but what's being called "tectonic" subsidence appears to account for 73 percent of all sinking from 1969 to 1971 and 50 percent from 1971 to 1977.

"Not only is southern Louisiana sinking, it's sliding," said geologist Roy Dokka of Louisiana State University.

Like a smaller landslide on the side of a hill, the huge Southern Louisiana landslide has a "headwall" where the slide is breaking away and a "toe" out in the Gulf where the debris from the slide is piling up, Dokka explained. The only difference from a traditional landslide is that this one is far, far larger and it's buried under lots of wet sediments, so it requires very accurate survey measurements to detect it.

Dokka obtained that data by re-examining decades of geodetic survey data from the National Oceanic and Atmospheric Administration (NOAA) in the area and calibrated it with the more stable Global Positioning System.

With that he was able to detect movements in the ground that were not visible to surveyors who used less reliable benchmarks like the more changeable sea level. He also used data from some very deep wells to see how much the land has been compacting from the removal of water and petroleum â€“ a common cause of subsidence.

His conclusion was that while there are certainly local subsidence effects from the over-pumping of groundwater and the river levees keeping sediments from reaching wetlands, these things are sitting atop a much larger block of earth that's been sliding into the Gulf of Mexico for eons. Dokka published a paper on his work in the April issue of Geology.

"Here it's subsidence that's occurring deep in the Earth," said Dokka.

As a result, there are faults along which the motion is taking place. One such fault, the Michoud Fault, runs right through New Orleans and is essentially the place where the sliding section of earth is breaking away.

The huge downward slide of the Mississippi Delta is pretty much what current geological theories would predict, said geologist Art Berman, who writes about such matters for the Houston Geological Society and works as a petroleum geologist in the Gulf of Mexico.

"We're at the margin of an active basin," said Berman. "There's 50,000 feet of sediment in the Gulf of Mexico that's pretty young."

All that sediment has weighed down the crust of the Earth there and caused it to sink.

"This is probably pretty common in areas like this worldwide," Dokka said.

posted in Geology - 0 replies

Anyone Passionate about chronometric dating? Specifically K/Ar dating....

Tue, 28 Feb 2006 05:48:53 GMT

I would love to talk with you because I am struggling with it. I am writing a paper on chronometric dating and it seems sooooo dry.... Anyone out there love this stuff?

I love neuroscience - start talkin about potassium ion channels and I am all ears - but that doesnt help me with my paper :-(

Inspire me with you passion....... please

posted in Geology - 2 replies

Sediment Could Be Major Factor In Big Subduction Zone Earthquakes

bobs — Tue, 31 Jan 2006 17:17:18 GMT

Also posted in 'Power and beauty of nature'

by Staff Writers
Seattle WA (SPX) Jan 31, 2006
The most powerful earthquakes – such as those that shook Indonesia in 2004, Alaska in 1964, Chile in 1960 and the Pacific Northwest in 1700 – occur in subduction zones, areas of the sea floor just offshore where two tectonic plates meet and one dives beneath the other.
But not all subduction zones are created equal, and University of Washington researchers believe they have found a key to determine which subduction zones – or which specific areas within a subduction zone – might produce the most severe shaking when they rupture.

As the subducting plate slides beneath the upper plate, stress begins to build where the plates meet and the upper plate can deform to create a large structure called a forearc basin. The basin, a sort of a bowl-shaped depression, fills with sediment from nearby rivers that empty into the ocean. Over millions of years, the sediment typically piles to great depths, from a half-mile to nearly 2 miles, and in rare cases might reach 3 miles deep, said Christopher Fuller, a University of Washington doctoral student in Earth and space sciences.

"In many of them, the sediment will stop the deformation of the upper plate," Fuller said. "The simplest way to think of it is that the increased weight of the sediment stops the deformation from occurring."

It appears the most severe subduction zone earthquakes occur in areas where such sediment-filled basins are found, but the reasons aren't exactly clear. Fuller and his colleagues conducted computer simulations of force experienced during plate subduction to determine how sediment buildup influences major earthquakes. They found that the weight of the sediment strengthens the edge of the plate directly above where the earthquakes happen. The stronger edge is deformed far less by subduction than nearby areas without such basins, he said, and that increases the likelihood that large earthquakes will occur in regions with basins.

Fuller is the lead author of a paper explaining the modeling research, published in the February edition of the journal Geology. Co-authors are Sean Willett, a UW associate professor of Earth and space sciences, and Mark Brandon, a professor of geology and geophysics at Yale University. The work was supported by grants from the National Science Foundation.

The Cascadia subduction zone off the coasts of Washington, Oregon and northern California has forearc basins in several areas, Fuller said. As it moves to the east at 2 inches a year, the Juan de Fuca tectonic plate slides beneath the North American plate that contains the landmass of the Pacific Northwest. In the process, sediment as deep as 1½ miles is scraped off the top of the Juan de Fuca plate and is deformed into surface depressions on the North American plate, forming the basins where sediment from coastal rivers is deposited. The probability of large earthquakes is greatest in these areas.

The modeling could have implications in figuring out where, within a subduction zone such as Cascadia, great earthquakes are the most likely to occur, Fuller said. But the work is not applicable to every subduction zone because each has different characteristics. For instance, forearc basins do not play the same role in the subduction zone off the Indonesian island of Sumatra, where the massive 2004 earthquake triggered tsunamis that killed hundreds of thousands of people.

"You have to understand the nature of basins and how they work in each area before you can use them as an interpretive tool," Fuller said. "You can't just apply these correlations everywhere."

Related Links
University of Washington

http://www.terradaily.com/reports/Sediment_Could_Be_Major_Factor_In_Big_Subduction_Zone_Earthquakes.html

posted in Geology - 0 replies

Mountain Ranges Rise Dramatically Faster Than Expected

bobs — Fri, 27 Jan 2006 10:00:46 GMT

(Also posted in "Power and beauty of nature")

by Staff Writers
Rochester NY (SPX) Jan 27, 2006
Two new studies by a University of Rochester researcher show that mountain ranges rise to their height in as little as two million years - several times faster than geologists have always thought. Each of the findings came from two pioneering methods of measuring ancient mountain elevations, and the results are in tight agreement.
The research papers, appearing in today's issue of Science and next week's issue of Earth and Planetary Science Letters, mean scientists will have to re-evaluate tectonic processes that build high elevation plateaus, such as those in Tibet and the central Andes.

"These results really change the paradigm of understanding of how mountain belts grow," says Carmala Garzione, assistant professor of earth and environmental sciences and co-author of both papers. "We've always assumed that the folding and faulting in the upper crust produced high elevation mountains. Now we have data on ancient mountain elevation that shows something else is responsible for the mountains' uplift."

Garzione took a new approach to paleoaltimetry, the tricky science of measuring mountain height from the distant past. As mountains lift, weather erodes them, complicating the estimation of how high they might be at any given time. Until Garzione's research, geologists estimated surface uplift by examining leaf fossils to determine at what elevation the plants lived, or by dating when certain minerals began moving rapidly to the surface.

Unfortunately, plant characteristics can change radically over millions of years, and changes in climate can also cause erosion, throwing a significant question mark into the equation.

Garzione instead focused on the products of that erosion. As mountains are eroded, their sediment is carried down the slope in streams and collected at the base of the forming mountain range. As a mountain range rises, it experiences different atmospheric conditions simply due to its change in height.

Those atmospheric changes, such as temperature and the amount and composition of rainfall are recorded in minerals that grow near the surface at different altitudes on the mountainside. Garzione wrote her doctoral dissertation on the possibility of retrieving that atmospheric information from the ancient sediment, dating it, and forming a record of a mountain belt's uplift history.

Garzione's recent work concentrated on the Bolivian Altiplano, which is a large, high elevation basin in the Andes Mountains in South America. There she took samples of sedimentary rock that had accumulated between 12 million and 5 million years ago from erosion of the surrounding ranges. One type of mineral, carbonate, precipitates from surface water, so the composition of the carbonate is a good indicator of the composition of rainfall.

The composition of rainwater changes with altitude. More than 99 percent of the oxygen in water is made up of oxygen-16 and less than 1 percent of oxygen-18. As vapor rises to higher altitudes in the form of clouds, oxygen-18 is removed from the cloud in rainfall, leaving the cloud more and more depleted in the isotope. This change locks into the minerals that formed at the surface from rainwater. These minerals accumulated in sedimentary basins in Bolivia over millions of years to become the rock strata Garzione sampled.

The second method looked at the same Bolivian sediment, but focused on the temperature at which the surface-forming carbonates were created. Atmosphere once again played a key role since air temperature decreases with altitude, meaning a temperature-based recording of the rocks' original altitude should be preserved. Garzione, along with Prosenjit Ghosh and John M. Eiler of the California Institute of Technology, employed a technique developed at CalTech that looks at the abundance of oxygen-18 and carbon-13 that are bonded together.

At high temperatures, such as the warm climate at low elevations in the Andes, individual atoms will vibrate vigorously and their bonds to other atoms will break more easily. Because heavy isotope bonds are stronger, at lower temperatures and lower vibrational frequencies, the light isotope bonds are more likely to be broken. Using the CalTech measuring method, Garzione and the CalTech team gauged the temperature at which the carbonates formed--from the hot Amazonian jungle climate to the freezing peaks of the Andes.

Both studies yielded the same results: between 10 million and 7 million years ago, the Andes shot up.

"When I first showed this data to others, they had a hard time believing that mountains could pop up so quickly," says Garzione. "With supporting data from the new paleotemperature technique, we have more confidence in the uplift history and can determine processes that caused the mountains to rise."

If the Andes rose a dramatic kilometer per million years as the studies suggest, scientists can now assign a very specific--and very controversial--process to their uplift.

"Deblobbing" may not sound like a very scientific word, but it's the term given to a dense root beneath the Earth's crust--a blob--that becomes unstable and begins to flow downward into the earth's mantle under the force of its own mass, until it detaches. When two tectonic plates collide, such as the Nazca oceanic plate in the southeastern Pacific colliding with the South American continental plate, the continental plate usually begins to buckle. Floating on a liquid mantle, the plates press together and the buckling creates the first swell of a mountain range.

Below the crust, however, there also is a kind of buckling going on in the solid portion of the upper mantle. This dense mantle root clings to the underside of the crust, growing in step with the burgeoning mountains above. This dense root acts like an anchor, weighing down the whole range and preventing it from rising, much like a fishing weight on a small bobber holds the bobber low in the water.

In the case of the Andes, they swelled to a height of about one kilometer before the mantle root beneath them disconnected and sunk into the liquid mantle. The effect was like cutting the line to the fishing weight--the mountains suddenly "bobbed" high above the surrounding crust, and in less than 3 million years, they had lifted from one kilometer to roughly four.

This process had been proposed since the early 1980s, but it has never stood up to scrutiny because these techniques to estimate surface elevation have only been recently developed.

"People have largely ignored the role of the mantle lithosphere because it is difficult to look 50 to 200 kilometers into the earth; whereas we can easily see the deformation on the surface." says Garzione. "Some geologists have guessed that the mantle lithosphere is removed continuously and evenly during mountain building. Our data argue that the mantle just accumulates down there until some critical moment when it becomes unstable and drops off."

Scientists can use earthquakes to measure the way that seismic waves travel through the Earth, turning a quake into a kind of planetary-scale ultrasound imager. Using this method, geologists believe there may be sizeable blobs of mantle lithosphere sinking beneath the Sierra Nevada mountains, though it could take millions of years for them to detach.

Related Links
http://www.rochester.edu/

http://www.terradaily.com/reports/Mountain_Ranges_Rise_Dramatically_Faster_Than_Expected.html

posted in Geology - 2 replies

amateur fossil dork

buddyboy76 — Wed, 11 Jan 2006 15:53:05 GMT

hey there. a really sexy girl turned me on to hunting for fossils. now i'm hooked.

but i don't really know anyting about it.
can anyone recommend a field guide that would have info on how to find fossils (nothing like complex excavations), how to identify them, and a little bit of historical information about different types?

thanks guys

posted in Geology - 6 replies

Tattoo

lunataylor — Tue, 12 Jul 2005 23:04:29 GMT

Check out my new trilobite tattoo:

http://people.tribe.net/lunataylor

posted in Geology - 9 replies

polishing opals

MickD — Mon, 28 Nov 2005 05:01:09 GMT

I have some interesting opal specimens from (presumably) Australia. I'd like to get them polished to bring out the richness of color, without harming the strata which holds them. Can anyone recommend how to do this? Perhaps there are polishers here in Georgia I can commission for the job?

posted in Geology - 2 replies

Blue Clay deposits w/o pebbles

JustaGuy — Fri, 23 Sep 2005 19:29:31 GMT

I've got a map from the Eighth Annual Report of the USGS on my office wall. Think it's from 1887…It's a plate of the Quaternary deposits on Mt. Desert Island in Maine and I just noticed for the first time that the legend depicts areas described as:

Areas where blue clay without pebbles have been observed

Obviously glacial deposits dominate the Quaternary geology of the island...so not being well versed in glacial geology, anybody have an idea of the significance of separating out such areas?
In my experience, blue clays signify reducing conditions, probably lacustrine. No pebbles indicate quiet water deposition. Beyond that, I’m clueless
Any ideas?

posted in Geology - 3 replies

K-feldspar megacrysts in volcanic rocks

bobs — Thu, 17 Nov 2005 16:02:06 GMT

From: Allen Glazner <afglazne@email.unc.edu>

I am interested in occurrences of large K-feldspar phenocrysts in
volcanic rocks and would like to compile a bibliography. I am aware
of some occurrences with crystals up to 5 cm in length, but would
like to find more. If anyone could send me examples I would
appreciate it. I will gladly email the resulting list to interested
people.

Thanks,

Allen Glazner
Dept. of Geological Sciences, CB# 3315
University of North Carolina
Chapel Hill, NC 27599-3315
919-962-0689, fax 919-966-4519
http://www.geosci.unc.edu/faculty/glazner/glazner.html

posted in Geology - 0 replies

Carbon Dioxide?

Jim — Sat, 17 Sep 2005 00:26:49 GMT

Does anyone know of any geological sources of carbon dioxide? This could either be the gas or carbonated water.

posted in Geology - 5 replies

Help! I need to organize my rock collection.

morleyroarly — Thu, 31 Mar 2005 21:14:10 GMT

My rock collection is growing large and unwieldy, and I'm afraid I'm forgetting where they all came from. I'm looking for cheap plentiful sample boxes - the open top kind. Like you used to see in mineralogy class!

Does anyone know where to get these, cheap? Used is fine. Local to the bay area is even better!

posted in Geology - 7 replies

rocks to bring back from Brazil

alfonso — Tue, 18 Oct 2005 22:09:09 GMT

Does anyone know what type of rocks, gems, ect, ect, are worth bringing back from Brazil? I m interested in making some money on the side, while spending some time here. I m not interested in rocks that cause any form of geological/environmental degradation. Maybe I m asking for to much...

posted in Geology - 1 reply

'Popping rocks' gases key to Earth's gases

bobs — Mon, 17 Oct 2005 20:18:05 GMT

(Also posted in 'The power & beauty of nature')

Scientists aboard the Scripps research vessel Roger Revelle solved a 45-year-old geological mystery concerning the rocks, which spontaneously explode with a sharp snapping sound when brought to the surface.

A team of U.S. and Mexican geologists and student researchers explored the region, including the area now known as Popcorn Ridge, to find the source of the popping rocks.

The researchers hit the jackpot with the area labeled "D-11," located along the flank of what the scientists are calling Krause Volcano -- after Scripps oceanographer Dale Krause, who discovered the deep-sea volcanic rocks in 1960.

"As soon as we took the rocks out of the water we could hear them popping, much like a firecracker," said Barry Eakins.

The rocks are important because the volcanic gases trapped in the bubbles did not escape during eruption. That could give researchers more information about the inventory of gases within Earth, but also help them better understand the origin and history of Earth's atmosphere.

http://www.physorg.com/news7270.html

posted in Geology - 3 replies