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Counting calories in the fossil record

Professor Jonathan Payne holds up fossil brachiopods that are more than 400 million years old. Credit: John Todd

Starting about 250 million years ago, at the end of the Permian period, brachiopod groups disappeared in large numbers, along with 90 percent of the planet’s species. Today, only a few groups, or genera, of brachiopods remain. “Most people won’t be familiar with brachiopods. They’re pretty rare in the modern ocean,” said Jonathan Payne, a paleobiologist at Stanford University.

Meanwhile, bivalves flourished, diversifying into a staggering variety of shapes and sizes, and spread from marine to freshwater habitats. “After the end-Permian mass extinction, we find far fewer brachiopods and a lot more bivalves,” said Payne, who is an associate professor in the Department of Geological & Environmental Sciences.

Why one group of shelled animals thrived while the other barely survived is one of the great mysteries in paleontology. A popular theory, based on diversity and abundance data from the fossil record for the two groups, is that bivalves simply outcompeted brachiopods. But a new study by Payne and other researchers that looks at the issue from an energy standpoint paints a different picture. Their findings, published online on March 26 in the journal Proceedings of the Royal Society B, show that, despite being fewer in number, ancient bivalves were already consuming as much food as brachiopods, and that modern bivalves consume vastly more.

“Brachiopods and bivalves used about same amount of food during Paleozoic, but bivalve food intake has increased by a factor of 100 since then,” Payne said. “There’s no way that increase is the result of bivalves simply displacing brachiopods. Even if bivalves had entirely supplanted brachiopods, their metabolism would have only doubled.”

Payne and his collaborators reached their conclusions after conducting a comprehensive search of scientific literature and recording the body sizes of more than 6,000 ancient and modern genera of bivalves and brachiopods. Some of the fossils dated back to the Cambrian era, more than 500 million years ago. Five undergraduate students and high school interns spent an entire summer on the task.

Fossil records like the one used in the current study can also provide clues about how the biological makeup of the modern ocean evolved, Payne said. “If scientists want to know how evolution works, one of the best ways is to study changes in animal shape over Earth’s history,” he added. “By moving from form to function as we have done in this study, fossils give us a very direct way of comparing how ancient ecosystems worked compared to their modern counterparts.”

From body size to metabolic rate

Once the body sizes of the different genera were known, the team was ready to estimate each one’s metabolic rate. To do this, they used available data about the ratio between shell size and living, or “soft,” tissue in modern bivalves and brachiopods to calculate the soft tissue amounts, and by extension the metabolic rates, of the extinct genera.The results of their study showed that like their modern descendants, ancient brachiopods possessed relatively little soft tissue and would have had low metabolic rates compared to ancient bivalves. “It turns out that even though brachiopod and bivalve shells are about the same size, if you open up a brachiopod shell, there’s a lot less meat inside,” Payne said. “That’s one reason that we eat bivalves, and not brachiopods. There also aren’t there many brachiopods around, and some of them may be toxic to humans.”

The new finding indicates that, from a metabolic standpoint at least, brachiopods didn’t dominate the Paleozoic. At best, they split their ocean kingdom with bivalves. “Our study is unique in that it provides a deep time perspective of how life arose, and in this case declined as well, because of how these two group differentially use energy,” said study coauthor Craig McClain, an oceanographer at the National Evolutionary Synthesis Center (NESCent) in Durham, NC. “Today’s ocean reflects these evolutionary stories of the past. We can look at the modern oceans and see the end of the story-lots of bivalves and few brachiopods-but now we know more about the introduction and climax of the narrative.”

Unlucky brachiopods

So if bivalves weren’t responsible for the brachiopods fall from glory, then what was? It’s likely, Payne said, that brachiopods were just unlucky. The evolutionary strategies that made them successful for hundreds of millions of years simply no longer worked or were even detrimental in the face of the environmental changes wrought by the End Permian extinction. “We think that about 250 million years ago, a series of large volcanic eruptions in Siberia ejected something on the order of 6 million kilometers of basalt rock. That’s enough to cover all of Western Europe in a quarter-mile deep layer of basalt,” Payne said.When the scalding volcanic rock rained back to surface and penetrated the Earth’s upper crust, it heated other rocks, causing them to release large amounts of gas, including the greenhouse gas carbon dioxide. This catastrophic chain reaction would have altered the chemistry of the oceans, increasing their acidity. Brachiopods would have been particularly hard hit by the change, Payne said. “Bivalves have gills and an active circulatory system, while brachiopods don’t. That means that in general, bivalves are more effective at regulating their internal chemistries relative to the external environment.”

Bivalves would have also been in a better position to take advantage of the new food sources that became available as life recovered from the mass extinction event. More creatures were becoming mobile, and brachiopods, which are largely stationary and filter feed on floating organic debris, would have been less able to capitalize on this shift. Meanwhile, bivalves such as clams were becoming more proficient at moving around by quickly opening and closing their shells or using their muscular foot to burrow. Increased mobility gave bivalves an edge not only over brachiopods, but likely other organisms as well, such as microbes. “What we see is that more mobile organisms tend to be better in the post-Paleozoic,” Payne said.

The new findings cast the fate of the two groups in a new light: Bivalves didn’t outcompete brachiopods by getting better at obtaining the food sources that the two groups shared. Rather, their physiological differences enabled them to branch out and take advantage of other food resources in ways that brachiopods simply couldn’t follow.

Note : The above story is based on materials provided by Stanford University. 

Ancient whodunit may be solved: Methane-producing microbes did it!

An outburst of methane produced effects similar to those predicted by current models of global climate change: a sudden, extreme rise in temperatures, combined with acidification of the oceans. In the case of the end-Permian extinction, virtually all shell-forming marine organisms were wiped out — consistent with the observation that such shells cannot form in acidic waters. Credit: © ryooota / Fotolia

Evidence left at the crime scene is abundant and global: Fossil remains show that sometime around 252 million years ago, about 90 percent of all species on Earth were suddenly wiped out — by far the largest of this planet’s five known mass extinctions. But pinpointing the culprit has been difficult, and controversial.

Now, a team of MIT researchers may have found enough evidence to convict the guilty parties — but you’ll need a microscope to see the killers.

The perpetrators, this new work suggests, were not asteroids, volcanoes, or raging coal fires, all of which have been implicated previously. Rather, they were a form of microbes — specifically, methane-producing archaea called Methanosarcina — that suddenly bloomed explosively in the oceans, spewing prodigious amounts of methane into the atmosphere and dramatically changing the climate and the chemistry of the oceans.

Volcanoes are not entirely off the hook, according to this new scenario; they have simply been demoted to accessories to the crime. The reason for the sudden, explosive growth of the microbes, new evidence shows, may have been their novel ability to use a rich source of organic carbon, aided by a sudden influx of a nutrient required for their growth: the element nickel, emitted by massive volcanism at just that time.

The new solution to this mystery is published this week in the Proceedings of the National Academy of Sciences by MIT professor of geophysics Daniel Rothman, postdoc Gregory Fournier, and five other researchers at MIT and in China.

The researchers’ case builds upon three independent sets of evidence. First, geochemical evidence shows an exponential (or even faster) increase of carbon dioxide in the oceans at the time of the so-called end-Permian extinction. Second, genetic evidence shows a change in Methanosarcina at that time, allowing it to become a major producer of methane from an accumulation of carbon dioxide in the water. Finally, sediments show a sudden increase in the amount of nickel deposited at exactly this time.

The carbon deposits show that something caused a significant uptick in the amount of carbon-containing gases — carbon dioxide or methane — produced at the time of the mass extinction. Some researchers have suggested that these gases might have been spewed out by the volcanic eruptions that produced the Siberian traps, a vast formation of volcanic rock produced by the most extensive eruptions in Earth’s geological record. But calculations by the MIT team showed that these eruptions were not nearly sufficient to account for the carbon seen in the sediments. Even more significantly, the observed changes in the amount of carbon over time don’t fit the volcanic model.

“A rapid initial injection of carbon dioxide from a volcano would be followed by a gradual decrease,” Fournier says. “Instead, we see the opposite: a rapid, continuing increase.”

“That suggests a microbial expansion,” he adds: The growth of microbial populations is among the few phenomena capable of increasing carbon production exponentially, or even faster.

But if living organisms belched out all that methane, what organisms were they, and why did they choose to do so at that time?

That’s where genomic analysis can help: It turns out that Methanosarcina had acquired a particularly fast means of making methane, through gene transfer from another microbe — and the team’s detailed mapping of the organism’s history now shows that this transfer happened at about the time of the end-Permian extinction. (Previous studies had only placed this event sometime in the last 400 million years.) Given the right conditions, this genetic acquisition set the stage for the microbe to undergo a dramatic growth spurt, rapidly consuming a vast reserve of organic carbon in the ocean sediments.

But there is one final piece to the puzzle: Those organisms wouldn’t have been able to proliferate so prodigiously if they didn’t have enough of the right mineral nutrients to support them. For this particular microbe, the limiting nutrient is nickel — which, new analysis of sediments in China showed, increased dramatically following the Siberian eruptions (which were already known to have produced some of the world’s largest deposits of nickel). That provided the fuel for Methanosarcina’s explosive growth.

The resulting outburst of methane produced effects similar to those predicted by current models of global climate change: a sudden, extreme rise in temperatures, combined with acidification of the oceans. In the case of the end-Permian extinction, virtually all shell-forming marine organisms were wiped out — consistent with the observation that such shells cannot form in acidic waters.

“A lot of this rests on the carbon isotope analysis,” Rothman says, which is exceptionally strong and clear in this part of the geological record. “If it wasn’t such an unusual signal, it would be harder to eliminate other possibilities.”

While no single line of evidence can prove exactly what happened in this ancient die-off, says Rothman, who is also director of MIT’s Lorenz Center, “the cumulative impact of all these things is much more powerful than any one individually.” While it doesn’t conclusively prove that the microbes did it, it does rule out some alternative theories, and makes a strong and consistent case, he says.

Note : The above story is based on materials provided by Massachusetts Institute of Technology.

The Atlantic Ocean dances with the Sun and volcanoes

Ocean temperature has been regularly measured since 1870, which makes it possible to calculate a mean temperature at each point for the period 1870 to the present day. Ocean temperature varies throughout the year and there are significant variations due to weather systems and over longer timescales. These illustrations show how the average temperatures over 20-year intervals have varied between cold (blue) and warm (red) periods. This variation is called the Atlantic Multidecadal Oscillation, abbreviated to AMO. Credit: Illustration by Bo Holm Jacobsen, Aarhus Universitet

Natural fluctuations in the ocean temperature in the North Atlantic have a significant impact on the climate in the northern hemisphere. These fluctuations are the result of a complex dance between the forces of nature, but researchers at Aarhus University can now show that solar activity and the impact of volcanic eruptions have led this dance during the last two centuries.

Imagine a ballroom in which two dancers apparently keep in time to their own individual rhythm. The two partners suddenly find themselves moving to the same rhythm and, after a closer look, it is clear to see which one is leading.

It was an image like this that researchers at Aarhus University were able to see when they compared studies of solar energy release and volcanic activity during the last 450 years, with reconstructions of ocean temperature fluctuations during the same period.

The results actually showed that during the last approximately 250 years — since the period known as the Little Ice Age — a clear correlation can be seen where the external forces, i.e. the Sun’s energy cycle and the impact of volcanic eruptions, are accompanied by a corresponding temperature fluctuation with a time lag of about five years.

In the previous two centuries, i.e. during the Little Ice Age, the link was not as strong, and the temperature of the Atlantic Ocean appears to have followed its own rhythm to a greater extent.

The results were recently published in the scientific journal Nature Communications.

In addition to filling in yet another piece of the puzzle associated with understanding the complex interaction of the natural forces that control the climate, the Danish researchers paved the way for linking the two competing interpretations of the origin of the oscillation phenomenon.

Temperature fluctuations discovered around the turn of the millennium

The climate is defined on the basis of data including mean temperature values recorded over a period of thirty years. Northern Europe thus has a warm and humid climate compared with other regions on the same latitudes. This is due to the North Atlantic Drift (often referred to as the Gulf Stream), an ocean current that transports relatively warm water from the south-west part of the North Atlantic to the sea off the coast of Northern Europe.Around the turn of the millennium, however, climate researchers became aware that the average temperature of the Atlantic Ocean was not entirely stable, but actually fluctuated at the same rate throughout the North Atlantic. This phenomenon is called the Atlantic Multidecadal Oscillation (AMO), which consists of relatively warm periods lasting thirty to forty years being replaced by cool periods of the same duration. The researchers were able to read small systematic variations in the water temperature in the North Atlantic in measurements taken by ships during the last 140 years.

Although the temperature fluctuations are small — less than 1°C — there is a general consensus among climate researchers that the AMO phenomenon has had a major impact on the climate in the area around the North Atlantic for thousands of years, but until now there has been doubt about what could cause this slow rhythm in the temperature of the Atlantic Ocean. One model explains the phenomenon as internal variability in the ocean circulation — somewhat like a bathtub sloshing water around in its own rhythm. Another model explains the AMO as being driven by fluctuations in the amount of solar energy received by the Earth, and as being affected by small changes in the energy radiated by the Sun itself and the after-effects of volcanic eruptions. Both these factors are also known as ‘external forces’ that have an impact on the Earth’s radiation balance.

However, there has been considerable scepticism towards the idea that a phenomenon such as an AMO could be driven by external forces at all — a scepticism that the Aarhus researchers now demonstrate as unfounded

“Our new investigations clearly show that, since the Little Ice Age, there has been a correlation between the known external forces and the temperature fluctuations in the ocean that help control our climate. At the same time, however, the results also show that this can’t be the only driving force behind the AMO, and the explanation must therefore be found in a complex interaction between a number of mechanisms. It should also be pointed out that these fluctuations occur on the basis of evenly increasing ocean temperatures during the last approximately fifty years — an increase connected with global warming,” says Associate Professor Mads Faurschou Knudsen, Department of Geoscience, Aarhus University, who is the main author of the article.

Convincing data from the Earth’s own archives

Researchers have attempted to make computer simulations of the phenomenon ever since the discovery of the AMO, partly to enable a better understanding of the underlying mechanism. However, it is difficult for the computer models to reproduce the actual AMO signal that can be read in the temperature data from the last 140 years.Associate Professor Knudsen and his colleagues instead combined all available data from the Earth’s own archives, i.e. previous studies of items such as radioactive isotopes and volcanic ash in ice cores. This provides information about solar energy release and volcanic activity during the last 450 years, and the researchers compared the data with reconstructions of the AMO’s temperature rhythm during the same period.

“We’ve only got direct measurements of the Atlantic Ocean temperature for the last 140 years, where it was measured by ships. But how do you measure the water temperature further back in time? Studies of growth rings in trees from the entire North Atlantic region come into the picture here, where ‘good’ and ‘bad’ growth conditions are calibrated to the actual measurements, and the growth rings from trees along the coasts further back in time can therefore act as reserve thermometers,” explains Associate Professor Knudsen.

The results provide a new and very important perspective on the AMO phenomenon because they are based on data and not computer models, which are inherently incomplete. The problem is that the models do not completely describe all the physical correlations and feedbacks in the system, partly because these are not fully understood. And when the models are thus unable to reproduce the actual AMO signal, it is hard to know whether they have captured the essence of the AMO phenomenon.

Impact of the sun and volcanoes

An attempt to simply explain how external forces such as the Sun and volcanoes can control the climate could sound like this: a stronger Sun heats up the ocean, while the ash from volcanic eruptions shields the Sun and cools down the ocean. However, it is hardly as simple as that.”Fluctuations in ocean temperature have a time lag of about five years in relation to the peaks we can read in the external forces. However, the direct effect of major volcanic eruptions is clearly seen as early as the same year in the mean global atmospheric temperature, i.e. a much shorter delay. The effect we studied is more complex, and it takes time for this effect to spread to the ocean currents,” explains Associate Professor Knudsen.

“An interesting new theory among solar researchers and meteorologists is that the Sun can control climate variations via the very large variations in UV radiation, which are partly seen in connection with changes in sunspot activity during the Sun’s eleven-year cycle. UV radiation heats the stratosphere in particular via increased production of ozone, which can have an impact on wind systems and thereby indirectly on the global ocean currents as well,” says Associate Professor Knudsen. However, he emphasises that researchers have not yet completely understood how a development in the stratosphere can affect the ocean currents on Earth.

Towards a better understanding of the climate

“In our previous study of the climate in the North Atlantic region during the last 8,000 years, we were able to show that the temperature of the Atlantic Ocean was presumably not controlled by the Sun’s activity. Here the temperature fluctuated in its own rhythm for long intervals, with warm and cold periods lasting 25-35 years. The prevailing pattern was that this climate fluctuation in the ocean was approximately 30-40% faster than the fluctuation we’d previously observed in solar activity, which lasted about ninety years. What we can now see is that the Atlantic Ocean would like to — or possibly even prefer to — dance alone. However, under certain circumstances, the external forces interrupt the ocean’s own rhythm and take over the lead, which has been the case during the last 250 years,” says Associate Professor Bo Holm Jacobsen, Department of Geoscience, Aarhus University, who is the co-author of the article.”It’ll be interesting to see how long the Atlantic Ocean allows itself to be led in this dance. The scientific challenge partly lies in understanding the overall conditions under which the AMO phenomenon is sensitive to fluctuations in solar activity and volcanic eruptions,” he continues.

“During the last century, the AMO has had a strong bearing on significant weather phenomena such as hurricane frequency and droughts — with considerable economic and human consequences. A better understanding of this phenomenon is therefore an important step for efforts to deal with and mitigate the impact of climate variations,” Associate Professor Knudsen concludes.

Note : The above story is based on materials provided by Aarhus University. The original article was written by Christina Troelsen. 

Gersdorffite

Gersdorffite Bou Azzer District, Tazenakht, Ouarzazate Province, Souss-Massa-Draa Region, Morocco Size: 6.0 x 4.5 x 3.5 cm (miniature) © danweinrich

Chemical Formula: NiAsS
Locality: Zinkwand, Schladming, Styria, Austria.
Name Origin: Named after Herr von Gersdorff, owner of Schladming Mine, Austria.

Gersdorffite is a nickel arsenic sulfide mineral with formula NiAsS. It crystallizes in the isometric system showing diploidal symmetry. It occurs as euhedral to massive opaque, metallic grey-black to silver white forms. Gersdorffite belongs to a solid solution series with cobaltite, CoAsS. Antimony freely substitutes also leading to ullmannite, NiSbS. It has a Mohs hardness of 5.5 and a specific gravity of 5.9 to 6.33.

Gersdorffite has three crystallisation forms: Gersdorffite-P213 (NiAsS), Gersdorffite-Pa3 (Ni(As,S)2) and Gersdorffite-Pca21 (NiAsS). Gersdorffite occurs as a hydrothermal vein mineral along with other nickel sulfides. Associated minerals include nickeline, nickel-skutterudite, cobaltite, ullmannite, maucherite, löllingite, platinum-group minerals, millerite, pyrite, marcasite, and chalcopyrite.

Gersdorffite was first described in 1843 and named for Johann von Gersdorff (1781–1849), owner of the nickel mine at Schladming, Austria the type locality.

Physical Properties

Cleavage: {100} Good, {010} Good, {001} Good
Color: Gray, Grayish black, Silver white, Tin white.
Density: 5.9 – 6.33, Average = 6.11
Diaphaneity: Opaque
Fracture: Brittle – Generally displayed by glasses and most non-metallic minerals.
Hardness: 5.5 – Knife Blade
Luminescence: Non-fluorescent.
Luster: Metallic
Magnetism: Nonmagnetic
Streak: grayish black

Photos :

Gersdorffite with Calcite Aït Ahmane, Bou Azzer area, Tazenakht, Ouarzazate  Morocco (11/2012) Specimen size: 7.3 × 5 × 2.3 cm = 2.9” × 2.0” × 0.9” Main crystal size: 1.2 × 0.8 cm = 0.5” × 0.3” © Fabre Minerals
Gersdorffite Aït Ahmane – Bou Azer distr. – Tazenakht – Ouarzazate prov. – Souss-Massa-Draâ Region – Morocco Crystal size:mm. 8 Overall size: 50mm x 42 mm x 52 mm © minservice
Gersdorffite Aït Ahmane, Souss-Massa-Draâ Region, Morocco Crystal size:10 mm Overall size: 42mm x 58 mm x 30 mm © minservice
Aït Ahmane, Bou Azer District (Bou Azzer District), Tazenakht, Ouarzazate Province, Souss-Massa-Draâ Region, Morocco © fabreminerals

Germanite

Schaurteite and Germanite Tsumeb Mine, Tsumeb, Otjikoto Region, Namibia, Africa Size: 5.3 x 3 x 3 cm (Small Cabinet) Owner: Kristalle and Crystal Classics
Chemical Formula: Cu26Fe4Ge4S32
Locality: Tsumeb mine (Tsumcorp mine), Tsumeb, Otavi, Namibia
Name Origin: Named after its content of the element Germanium.Germanite is a rare copper iron germanium sulfide mineral, Cu26Fe4Ge4S32. It was first discovered in 1922, and named for its germanium content. It is only a minor source of this important semiconductor element, which is mainly derived from the processing of the zinc sulfide mineral sphalerite.

Germanite contains gallium, zinc, molybdenum, arsenic, and vanadium as impurities.Its type locality is the Tsumeb Mine in Namibia where it occurs in a hydrothermal polymetallic ore deposit in dolostone in association with renierite, pyrite, tennantite, enargite, galena, sphalerite, digenite, bornite and chalcopyrite. It has also been reported from Argentina, Armenia, Bulgaria, Cuba, Democratic Republic of Congo (Zaire), Finland, France, Greece, Japan, Republic of Congo (Brazzaville), Russia and the United States.

Physical Properties

Cleavage: None
Color: Brown, Red gray.
Density: 4.4 – 4.6, Average = 4.5
Diaphaneity: Opaque
Fracture: Brittle – Generally displayed by glasses and most non-metallic minerals.
Hardness: 3 – Calcite
Luster: Metallic
Streak: dark gray

Photos :

GERMANITE Tsumeb Mine, Tsumeb, Otjikoto Region, Namibia, Africa Size: 5.5 x 4 x 2.5 cm (Small Cabinet) Owner: Kristalle and Crystal Classics
Tsumeb Mine (Tsumcorp Mine), Tsumeb, Otjikoto Region (Oshikoto), Namibia © 2002 Thames Valley Minerals

Five-tonne dinosaur species discovered

An artist’s impression of a Torvosaurus gurneyi. Photograph: Sergey Krasovskiy/PA

Fossilised remains of what scientists believe was the largest terrestrial predator ever to have roamed Europe have been found in Portugal.

The dinosaur, a new species named Torvosaurus gurneyi, was up to 10m (33ft) long and weighed between four and five tonnes.

Its head measured 1.15m from front to back and was filled with blade-shaped teeth up to 10cm (4in) long, suggesting it may have been near the top of the food chain and eaten other large dinosaurs.

Scientists found the bones north of Portugal’s capital, Lisbon, and originally thought they belonged to a species from North America, Torvosaurus tanneri.

But comparisons of the shin bone, upper jawbone, teeth, and partial tail vertebrae suggested it was a new species, making it one of the largest carnivorous dinosaurs of the Jurassic period found in this area, living around 150 million years ago.

The new dinosaur is the second species of Torvosaurus to be named, and scientists believe recently-discovered embryos from Portugal also belong to it. The number of teeth, as well as the size and shape of the mouth, are though to differentiate the European and the American Torvosaurus.

The fossil of the upper jaw of Torvosaurus tanneri has 11 or more teeth, while Torvosaurus gurneyi has fewer than 11, and the mouth bones have a different shape and structure. Fossilised remains of other closely related dinosaurs suggest Torvosaurus gurneyi may have been covered with “protofeathers” – the precursors of bird feathers.

The findings were published in the online journal PLOS ONE. Report co-author Christophe Hendrickx said: “This is not the largest predatory dinosaur we know. Tyrannosaurus, Carcharodontosaurus, and Giganotosaurus from the Cretaceous were bigger animals.

“With a skull of 115cm, Torvosaurus gurneyi was however one of the largest terrestrial carnivores at this epoch, and an active predator that hunted other large dinosaurs, as evidenced by blade-shape teeth up to 10cm.”

• This article was amended on 6 March 2014. The original suggested the newly discovered species was the largest of any terrestrial dinosaur found in Europe. This has been corrected.

Note : The above story is based on materials provided by Press Association

Rough diamond hints at vast quantities of water inside Earth

The diamond is pitted from its violent journey, which ended with the stone shooting up through the Earth’s crust at around 70km/h. Photograph: University of Alberta

A small, battered diamond found in the gravel strewn along a shallow riverbed in Brazil has provided evidence of a vast “wet zone” deep inside the Earth that could hold as much water as all the world’s oceans put together.

The water is not sloshing around inside the planet, but is held fast within minerals in what is known as the Earth’s transition zone, which stretches from 410 to 660km (250-400 miles) beneath the surface.

“It’s not a Jules Verne-style ocean you can sail a boat on,” said Graham Pearson, a geologist who studied the stone at the University of Alberta. The water-rich zone could transform scientists’ understanding of how some of the Earth’s geological features arose.

Tests on the diamond revealed that it contained a water-rich mineral formed in the zone. Researchers believe that the gemstone, which is oblong and about 5mm long, was blasted to the surface from a depth of about 500km by a volcanic eruption of molten rock called kimberlite.

The battle-scarred gem has a delicate metallic sheen, but is pitted and etched from its violent journey, which probably took several days and ended with the stone shooting up through the Earth’s crust at a speed of about 70km/h (40mph).

“It’s a fairly ugly diamond. It looks like it’s been to hell and back,” said Pearson, adding that the gem was worth about $20 at most. The stone was found in 2008 by artisan miners working the Juína riverbeds in Mato Grosso in western Brazil.

Credit: Guardian graphics

Most diamonds used in jewellery form at much shallower depths, about 150km down. Those that form in the transition zone are called super-deep diamonds and are distinguished by their battered appearance and low nitrogen content.

Pearson and his team were testing the diamond to find minerals they could use to work out its age. But by chance they discovered a speck of mineral called ringwoodite, a type of olivine that forms under extremely high pressures. The mineral inclusion was too small to see with the eye.

Without the diamond – and the water-rich mineral inside it – scientists had no hope of confirming the make-up of material so deep inside the Earth’s interior. “No one is ever going to run a geological field trip to the transition zone 500km beneath the Earth’s surface, and no one is ever going to drill down to the transition zone,” said Pearson. “It was a total piece of luck that we found this.”

For decades, scientists have suspected that ringwoodite made up much of the deep Earth, because olivine is so widespread underground. But no one had ever found any ringwoodite from the Earth’s interior that proved the idea beyond doubt. In the transition zone where the diamond and its ringwoodite was formed, the pressure reaches 200,000 atmospheres.

Tests on the mineral found that about 1.5% of its weight is water. “That doesn’t sound like much, but when you calculate the vast volumes of ringwoodite thought to exist in the deep Earth, the amount of water might be as high as that contained in all the world’s oceans,” Pearson told the Guardian. That amounts to more than one billion billion tonnes of water.

At the very least, the scientists say, there must be local wet spots or “oases” in the Earth’s interior. “The beauty of this diamond is that it gives us a real sample from those depths,” Pearson said. The diamond is described in the latest issue of the journal Nature.

A huge water store in the Earth’s mantle might help geologists explain some oddities seen on the planet’s surface. Water in the transition zone could dissolve in molten magma and reach the undersides of continental plates, where it would weaken the huge slabs of rock. That could create weak spots prone to volcanoes, and even cause “uplift”, where the land rises up.

Hans Keppler, at the University of Bayreuth in Germany, said: “Until now, nobody had ever seen ringwoodite from the Earth’s mantle, although geophysicists were sure that it must exist. Most people, including me, never expected to see such a sample.”

Note : The above story is based on materials provided by Ian Sample, science correspondent For The Guardian

Earth’s Dynamic Interior

Graduate student Mingming Li in collaboration with ASU professors Allen McNamara and Ed Garnero developed new simulations that depict the dynamics of deep Earth. Here, Li stands in front of the massive computer clusters required for running the calculations. Credit: Allen McNamara

Graduate student Mingming Li in collaboration with ASU professors Allen McNamara and Ed Garnero developed new simulations that depict the dynamics of deep Earth. Here, Li stands in front of the massive computer clusters required for running the calculations. Credit: Allen McNamara

Seeking to better understand the composition of the lowermost part of Earth’s mantle, located nearly 2,900 kilometers (1,800 miles) below the surface, a team of Arizona State University researchers has developed new simulations that depict the dynamics of deep Earth. A paper published March 30 in Nature Geoscience reports the team’s findings, which could be used to explain the complex geochemistry of lava from hotspots such as Hawaii.

Mantle convection is the driving force behind continental drift and causes earthquakes and volcanoes on the surface. Through mantle convection, material from the lowermost part of Earth’s mantle could be carried up to the surface, which offers insight into the composition of the deep Earth. The Earth’s core is very hot (~4000 K) and rocks at the core mantle boundary are heated and expand to have a lower density. These hot rocks (also called mantle plumes) could migrate to the surface because of buoyancy.

Observations, modeling and predictions have indicated that the deepest mantle is compositionally complex and continuously churning and changing.

“The complex chemical signatures of hotspot basalts provide evidence that the composition of the lowermost part of Earth’s mantle is different from other parts. The main question driving this research is how mantle plumes and different compositional components in Earth’s mantle interact with each other, and how that interaction leads to the complex chemistry of hotspot basalts. The answer to this question is very important for us to understand the nature of mantle convection,” explains lead author Mingming Li, who is pursuing his Ph.D. in geological sciences.

“Obviously, we cannot go inside of the Earth to see what is happening there. However, the process of mantle convection should comply with fundamental physics laws, such as conservation of mass, momentum and energy. What we have done is to simulate the process of mantle convection by solving the equations which controls the process of mantle convection,” says Li.

It has long been suggested that the Earth’s mantle contains several different compositional reservoirs, including an ancient more-primitive reservoir at the lowermost mantle, recycled oceanic crust and depleted background mantle. The complex geochemistry of lava found at hotspots such as Hawaii are evidence of this. The various compositional components in hotspot lava may be derived from these different mantle reservoirs. The components could become embedded in and carried to the surface by mantle plumes, but it is unclear how individual plumes could successively sample each of these reservoirs.

Joined by his advisor Allen McNamara, geodynamicist and associate professor in Arizona State University’s School of Earth and Space Exploration, and seismologist and SESE professor Ed Garnero, Li and his collaborators’ numerical experiments show that plumes can indeed carry a combination of different materials from several reservoirs.

According to the simulations, some subducted oceanic crust is entrained directly into mantle plumes, but a significant fraction of the crust—up to 10%—enters the more primitive reservoirs. As a result, mantle plumes entrain a variable combination of relatively young oceanic crust directly from the subducting slab, older oceanic crust that has been stirred with ancient more primitive material and background, depleted mantle. Cycling of oceanic crust through mantle reservoirs can therefore explain observations of different recycled oceanic crustal ages and explain the chemical complexity of hotspot lavas.

“Our calculations take a long time – more than one month for one calculation – but the results are worth it,” says Li.


Note : The above story is based on materials provided by Arizona State University College of Liberal Arts and Sciences.

Garnet

GARNET “Pillar” with ALBITE Gilgit District, Northern Areas, Pakistan, Asia Size: 3.9 x 2.3 x 1.6 cm (Miniature) Owner: Crystal Classics

Garnets are a group of silicate minerals that have been used since the Bronze Age as gemstones and abrasives.

All species of garnets possess similar physical properties and crystal forms, but differ in chemical composition. The different species are pyrope, almandine, spessartine, grossular (varieties of which are hessonite or cinnamon-stone and tsavorite), uvarovite and andradite. The garnets make up two solid solution series: pyrope-almandine-spessartine and uvarovite-grossular-andradite.

Physical properties

Properties

Garnet species are found in many colors including red, orange, yellow, green, purple, brown, blue, black, pink and colorless. The rarest of these is the blue garnet, discovered in the late 1990s in Bekily, Madagascar. It is also found in parts of the United States, Russia, Kenya, Tanzania, and Turkey. It changes color from blue-green in the daylight to purple in incandescent light, as a result of the relatively high amounts of vanadium (about 1 wt.% V2O3). Other varieties of color-changing garnets exist. In daylight, their color ranges from shades of green, beige, brown, gray, and blue, but in incandescent light, they appear a reddish or purplish/pink color. Because of their color-changing quality, this kind of garnet is often mistaken for Alexandrite.

Garnet species’ light transmission properties can range from the gemstone-quality transparent specimens to the opaque varieties used for industrial purposes as abrasives. The mineral’s luster is categorized as vitreous (glass-like) or resinous (amber-like).

Crystal structure

Garnets are nesosilicates having the general formula X3Y2(Si O4)3. The X site is usually occupied by divalent cations (Ca, Mg, Fe, Mn)2+ and the Y site by trivalent cations (Al, Fe, Cr)3+ in an octahedral/tetrahedral framework with[SiO4]4− occupying the tetrahedra. Garnets are most often found in the dodecahedral crystal habit, but are also commonly found in the trapezohedron habit. (Note: the word “trapezohedron” as used here and in most mineral texts refers to the shape called a Deltoidal icositetrahedron in solid geometry.) They crystallize in the cubic system, having three axes that are all of equal length and perpendicular to each other. Garnets do not show cleavage, so when they fracture under stress, sharp irregular pieces are formed (conchoidal).

Hardness

Because the chemical composition of garnet varies, the atomic bonds in some species are stronger than in others. As a result, this mineral group shows a range of hardness on the Mohs scale of about 6.5 to 7.5. The harder species like almandine are often used for abrasive purposes.

Photos :

GROSSULAR GARNET var “HESSONITE” Saint-Marcel, Valle d’Aosta, Italy, Europe Size: 3 x 2.8 x 1.7 cm (Miniature) Owner: Crystal Classics
GARNET var ANDRADITE Serifos Island, Aegean Islands, Greece, Europe Size: 4.3 x 3 x 2.6 cm (Small Cabinet) Owner: Kristalle and Crystal Classics
GARNET and CALCITE Valle d’Aosta, Italy, Europe Size: 4.5 x 3 x 2 cm (Small Cabinet) Owner: Kristalle and Crystal Classics
Andradite Marki Khel, Spin Ghar range (Speen Ghar range), Khogyani District, Nangarhar Province (Ningarhar Province), Afghanistan © 2001 John H. Betts

Pennsylvanian Period

The Pennsylvanian is, in the ICS geologic timescale, the younger of two subperiods (or upper of two subsystems) of the Carboniferous Period. It lasted from roughly 323.2 ± 1.3 to 298.9 ± 0.8 Ma (million years ago). As with most other geochronologic units, the rock beds that define the Pennsylvanian are well identified, but the exact date of the start and end are uncertain by a few million years. The Pennsylvanian is named after the U.S.A. state of Pennsylvania, where the coal-productive beds of this age are widespread.

The division between Pennsylvanian and Mississippian comes from North American stratigraphy. In North America, where the early Carboniferous beds are primarily marine limestones, the Pennsylvanian was in the past treated as a full fledged geologic period between the Mississippian and the Permian. In Europe, the Mississippian and Pennsylvanian are one more-or-less continuous sequence of lowland continental deposits and are grouped together as the Carboniferous Period. The current internationally used geologic timescale of the ICS gives the Mississippian and Pennsylvanian the rank of subperiods, subdivisions of the Carboniferous Period.

Life

Fungi

All modern classes of fungi were later in the Pennsylvanian.

Vertebrates

Amphibians were diverse and common; some were several meters long as adults. The collapse of the rainforest ecology in the mid Pennsylvanian (between the Moscovian and the Kasimovian) removed many amphibian species that did not survive as well in the cooler, drier conditions. Reptiles, however, prospered due to specific key adaptations. One of the greatest evolutionary innovations of the Carboniferous was the amniote egg, which allowed for the further exploitation of the land by certain tetrapods. These included the earliest sauropsid reptiles (Hylonomus), and the earliest known synapsid (Archaeothyris). These small lizard-like animals quickly gave rise to many descendants. Reptiles underwent a major evolutionary radiation, in response to the drier climate that followed the rainforest collapse.

Subdivisions

The Pennsylvanian has been variously subdivided. The international timescale of the ICS follows the Russian subdivision into four stages:

  • Bashkirian (oldest)
  • Moscovian
  • Kasimovian
  • Gzhelian (youngest)
North American subdivision is into five stages, but not precisely the same, with additional (older) Appalachian series names following:
  • Morrowan stage, corresponding with the middle and lower part of the Pottsville Group (oldest)
  • Atokan stage, corresponding with the upper part of the Pottsville group
  • Desmoinesian stage, corresponding with the Allegheny Group
  • Missourian stage, corresponding with the Conemaugh Group
  • Virgilian stage, corresponding with the Monongahela Group (youngest)

The Virgilian or Conemaugh corresponds to the Gzhelian plus the uppermost Kasimovian. The Missourian or Monongahela corresponds to the rest of the Kasimovian. The Desmoinesian or Allegheny corresponds to the upper half of the Moscovian. The Atokan or upper Pottsville corresponds to the lower half of the Moscovian. The Morrowan corresponds to the Bashkirian.

In the European subdivision, the Carboniferous is divided into two epochs: Dinantian (early) and Silesian (late). The Silesian starts earlier than the Pennsylvanian and is divided in three ages:

  • Namurian (corresponding to Serpukhovian and early Bashkirian)
  • Westphalian (corresponding to late Bashkirian, Moskovian and Kasimovian)
  • Stephanian (corresponding to Gzelian).
Note : The above story is based on materials provided by Wikipedia

Great earthquakes, water under pressure, high risk

Earthquake history of Chile. Credit: Manuela Dziggel, GFZ

The largest earthquakes occur where oceanic plates move beneath continents. Obviously, water trapped in the boundary between both plates has a dominant influence on the earthquake rupture process. Analyzing the great Chile earthquake of February, 27th, 2010, a group of scientists from the GFZ German Research Centre for Geosciences and from Liverpool University found that the water pressure in the pores of the rocks making up the plate boundary zone takes the key role.

The stress build-up before an earthquake and the magnitude of subsequent seismic energy release are substantially controlled by the mechanical coupling between both plates. Studies of recent great earthquakes have revealed that the lateral extent of the rupture and magnitude of these events are fundamentally controlled by the stress build-up along the subduction plate interface. Stress build-up and its lateral distribution in turn are dependent on the distribution and pressure of fluids along the plate interface.

“We combined observations of several geoscience disciplines — geodesy, seismology, petrology. In addition, we have a unique opportunity in Chile that our natural observatory there provides us with long time series of data,” says Onno Oncken, director of the GFZ-Department “Geodynamics and Geomaterials.” Earth observation (Geodesy) using GPS technology and radar interferometry today allows a detailed mapping of mechanical coupling at the plate boundary from the Earth’s surface. A complementary image of the rock properties at depth is provided by seismology. Earthquake data yield a high resolution three-dimensional image of seismic wave speeds and their variations in the plate interface region. Data on fluid pressure and rock properties, on the other hand, are available from laboratory measurements. All these data had been acquired shortly before the great Chile earthquake of February 2010 struck with a magnitude of 8.8.

“For the first time, our results allow us to map the spatial distribution of the fluid pressure with unprecedented resolution showing how they control mechanical locking and subsequent seismic energy release,” explains Professor Oncken. “Zones of changed seismic wave speeds reflect zones of reduced mechanical coupling between plates.” This state supports creep along the plate interface. In turn, high mechanical locking is promoted in lower pore fluid pressure domains. It is these locked domains that subsequently ruptured during the Chile earthquake releasing most seismic energy causing destruction at Earth’s surface and tsunami waves. The authors suggest the spatial pore fluid pressure variations to be related to oceanic water accumulated in an altered oceanic fracture zone within the Pacific oceanic plate. Upon subduction of the latter beneath South America the fluid volumes are released and trapped along the overlying plate interface, leading to increasing pore fluid pressures. This study provides a powerful tool to monitor the physical state of a plate interface and to forecast its seismic potential.

Note : The above story is based on materials provided by Helmholtz Centre Potsdam – GFZ German Research Centre for Geosciences.

Giant catfish and a legacy of disaster in one of the world’s most seismically active regions

Gregory Smits

Greg Smits’ interest in earthquakes began with a catfish. A book full of catfish, to be precise.Back in 2002, Smits, then an assistant professor of history at Penn State, was poking around a used book store in Tokyo, looking for titles relating to his specialty, the intellectual history of Japan, when a large and colorful volume caught his eye.
It was a comprehensive, illustrated treatment of namazu-e, the brash, fantastic, often satirical prints depicting namazu—mythical giant catfish—that proliferated in the aftermath of the great Ansei Edo earthquake of 1855. Its price had been marked down drastically, and the bargain was too good to resist.

“I bought the book and took it home, and it sat on a shelf for years,” Smits recalls. “I finally got around to reading it, and thought as long as I’ve plowed through this I should write something about it.”

At the time, Smits had posted on his professional web page a series of self-written textbooks for use by students in his classes on Japanese history. By the miracle of Google, the chapter he posted on namazu-e found its way to Ruth Ludwin, a University of Washington seismologist who was researching the native earthquake lore of the Pacific Northwest.

“Ruth contacted me with a bunch of questions,” Smits remembers. “We eventually wrote an article together, and by the time it was finished I was hooked. I’ve been working on the history of Japanese earthquakes ever since.”

That work has now culminated in two books released in rapid succession, the first a close look at the pivotal Ansei Edo earthquake and its enduring legacy, and the second tracing the broader history of Japanese earthquakes since the 17th century. Both volumes provide important context for the massive disaster that struck the country in March 2011, and whose impacts are still unfolding.

An Earth-shaking Event

The Ansei Edo earthquake, estimated at 7.0 magnitude, shook the capital of Edo (now Tokyo) at about 10 p.m. on November 11, 1855, killing at least 7,000 people and destroying key areas of the city. It was the third of three major seismic events to hit Japan in just over a year, and only one of dozens that have struck the region since records were kept. Yet this earthquake, Smits says, is arguably the most important of the pre-modern era. For one thing, according to the prevailing wisdom at the time, it never should have happened.”The theory on what causes earthquakes involved the idea of yin and yang, the two fundamental energy types that govern the physical world,” Smits explains. Yang energy, in this conception, would be hot and dry: the power of Sun and wind. Yin would be dark and moist, the realm under the Earth’s crust. “The theory was that an earthquake happens when yang energy gets trapped underground in a yin environment. It builds up to the point where there’s an explosive event.”

According to this thinking, Edo was safe from earthquakes, since the city’s plentiful water wells provided a means of relieving underground pressure. “So when this earthquake struck, one of the things it shook up was scientific thought,” Smits says.

The disaster also exacerbated discontent between different groups in society, especially with respect to disparities in wealth. That’s where the pictures of catfish come in. Catfish, Smits explains, had long been regarded as a symbol for earthquakes. “There’s this whole elaborate mythology, where catfish symbolize the unruly forces under the earth.”

In November of 1855, they became something else. “Two days after the initial earthquake, hastily printed, anonymous broadsheets and images began to appear for sale around the city,” Smits wrote in the Journal of Social History. Over 400 varieties of these namazu-e were soon spilling out everywhere, most of them featuring giant, anthropomorphized catfish.

Some of these prints show angry citizens attacking the local deities who allowed namazu to run rampant. In others, remorseful catfish apologize for their destructive behavior. In still others, gods shower coins on happy tradesmen who would profit from rebuilding, embodying a popular idea that the earthquake had set the world to rights by correcting an imbalance of wealth.

“Namazu-e were a coded mechanism for making statements about politics or society,” Smits says. “Among other things, they tended to show the bakufu, this powerful military government, as helpless vis-a-vis the forces of nature. The invincibility of this military organization was suddenly brought into question.”

Sensing the potential import of the catfish prints, the bakufu moved within a month to suppress them. By 1867, the bakufu government would fall, and a new government would form around the emperor. “The earthquake didn’t cause this collapse,” Smits says, “but it set the stage and presaged it in the realm of rhetoric.”

Ongoing Aftershocks

Beyond its immediate impacts, the Ansei Edo revived a tantalizing and tenacious idea: that earthquakes can be reliably predicted from natural phenomena—if only we know what to look for.Electromagnetic disturbances, for example. “One of the stories that came out of the earthquake was of a huge magnetic stone in a shop, a curiosity—people would throw pieces of metal toward it and the metal would stick to it,” Smits says. “Two hours before the earthquake happened, this stone reportedly lost its magnetic properties and all these things fell to the floor.”

Another supposed signal of impending doom was unusual activity observed in—you guessed it—catfish. Instead of their usual bottom-dwelling torpor, these fish, pre-earthquake, would be seen swimming on the surface of the water. Cue disaster.

In fact, Smits notes, the idea that catfish can predict earthquakes still survives in Japan. Government-funded experiments observing catfish in aquariums continued as recently as 1993, and newspaper speculation on the connection between fish and earthquakes popped up repeatedly after the March 2011 disaster.

The broader belief that seismic events can be reliably predicted is a topic Smits takes up in his second book. “In every earthquake since 1855, you get these long lists of possible precursors, all of them applied after the fact,” he says. “It’s almost like there’s a religious faith in this idea.”

Today, “Japan spends more money on earthquake prediction than any other developed country, and probably all the rest combined,” Smits adds. “This has produced zero predictive results.”

In addition to being a blind alley, the relentless focus on prediction, he suggests, may feed a troubling gap between what scientists actually know and the public perception of what they know, a gulf that was on dramatic display in the recent much-publicized case of seismologists sentenced to jail for failing to adequately warn people about the 2009 earthquake in L’Aquila, Italy.

“In the ’60s, in Japan, you had this public perception that surely we should be able to predict earthquakes by now,” he says. “This put great pressure on the seismological community to claim that earthquake prediction was possible.” But when the Kobe earthquake hit in 1995, killing 7,500 people, “it was absolutely unpredicted,” Smits says. “They didn’t even know that the fault that caused it existed.

There was a lot of scrambling among earthquake research agencies, and now, instead of ‘predicting,’ they talk about ‘forecasting.’ But the forecasts are so broad as to be of little practical use.”

Lessons from History?

A more hopeful outcome of the Kobe disaster is its validation of advances in anti-seismic engineering. “This effort has paid off tremendously well,” Smits says. “Purely as a function of building code revisions, everything built after 1980 survived the Kobe earthquake. The technology has improved so much that during the [March 2011] quake tall buildings in Tokyo swayed but they didn’t break.”Unfortunately, the so-called “3-11” event spawned a massive tsunami whose giant waves killed 20,000 people and swamped the Fukushima Dai-Ichi nuclear power plant, adding a whole new chapter to the history of earthquake-related disasters in Japan. Ironically, Smits says, officials of the utility company responsible for the plant ignored that history when they argued that no one could have predicted a tsunami of such size. “They claimed the event was ‘unprecedented.’ But that’s been said about every earthquake for the last couple centuries,” he says.

Smits also criticizes the notion of “characteristic earthquakes” that pegged the 2011 disaster as a 1,000-year event, “as though the rupture of faults occurs at regular intervals, and now that this one has happened we can relax for another thousand years.”

That kind of rhetoric, he argues, only aggravates general misperceptions. “Instead, wouldn’t it be good if the government and the scientific community spoke in a unified voice, and said loud and clear, ‘We can’t predict earthquakes’? ‘And ‘There is no place on these islands that is not subject to the possibility of a serious earthquake, but here’s how you can minimize the danger’? I think that would help.”

It would at least reflect the lessons learned from the record of earthquakes past.

Note : The above story is based on materials provided by Pennsylvania State University

Galena

Galena Gidiurska Mine, Madan, Bulgaria Size: 6.7 x 5 x 2.1 cm Photo Copyright © SpiriferMinerals

Chemical Formula: PbS
Locality: Joplin district of Missouri, Kansas, and Oklahoma and other world wide occurrences.
Name Origin: The Roman naturalist, Pliny, used the name galena to describe lead ore.

Galena, also called lead glance, is the natural mineral form of lead(II) sulfide. It is the most important ore of lead and an important source of silver.

Galena is one of the most abundant and widely distributed sulfide minerals. It crystallizes in the cubic crystal system often showing octahedral forms. It is often associated with the minerals sphalerite, calcite and fluorite.

Physical Properties

Cleavage: {001} Perfect, {010} Perfect, {100} Perfect
Color: Light lead gray, Dark lead gray.
Density: 7.2 – 7.6, Average = 7.4
Diaphaneity: Opaque
Fracture: Brittle – Generally displayed by glasses and most non-metallic minerals.
Hardness: 2.5 – Finger Nail
Luminescence: Non-fluorescent.
Luster: Metallic
Magnetism: Nonmagnetic
Streak: grayish black

Photos :

Galena Freiberg District, Erzgebirge, Saxony  Germany Specimen size: 4.7 × 3.7 × 2.4 cm = 1.9” × 1.5” × 0.9” Main crystal size: 2 × 1.7 cm = 0.8” × 0.7”  Photo Copyright © Fabre Minerals
Galena Gonderbach Mine, Fischelbach, Bad Laasphe, North Rhine-Westphalia, Germany Size: 4.5 x 2.5 x 1.8 cm Photo Copyright ©  danweinrich
Galena 11.0×9.5×8.3 cm United Keno Hill Mines, Elsa, Yukon, Canada Copyright © David K. Joyce Minerals
Baxter Springs, Picher Field, Tri-State District, Cherokee Co., Kansas, USA © 2002 John H. Betts

Million suns shed light on fossilized plant

Optical plus X-ray false color composite image (Cu = red, Zn = green, and Ni =blue) montage of a 50 million year old leaf fossil. Credit: P. wyomingensis, specimen BHI-3113

Scientists have used one of the brightest lights in the Universe to expose the biochemical structure of a 50 million-year-old fossil plant to stunning visual effect.

The team of palaeontologists, geochemists and physicists investigated the chemistry of exceptionally preserved fossil leaves from the Eocene-aged ‘Green River Formation’ of the western United States by bombarding the fossils with X-rays brighter than a million suns produced by synchrotron particle accelerators.

Researchers from Britain’s University of Manchester and Diamond Light Source and the Stanford Synchrotron Radiation Lightsource in the US have published their findings, along with amazing images, in Metallomics; one of the images is featured on the cover of the latest edition of the Royal Society of Chemistry journal.

Lead author Dr Nicholas Edwards, a postdoctoral researcher at The University of Manchester, said: “The synchrotron has already shown its potential in teasing new information from fossils, in particular our group’s previous work on pigmentation in fossil animals. With this study, we wanted to use the same techniques to see whether we could extract a similar level of biochemical information from a completely different part of the tree of life.

“To do this we needed to test the chemistry of the fossil plants to see if the fossil material was derived directly from the living organisms or degraded and replaced by the fossilisation process.

“We know that plant chemistry can be preserved over hundreds of millions of years — this preserved chemistry powers our society today in the form of fossil fuels. However, this is just the ‘combustible’ part; until now no one has completed this type of study of the other biochemical components of fossil plants, such as metals.”

By combining the unique capabilities of two synchrotron facilities, the team were able to produce detailed images of where the various elements of the periodic table were located within both living and fossil leaves, as well as being able to show how these elements were combined with other elements.

The work shows that the distribution of copper, zinc and nickel in the fossil leaves was almost identical to that in modern leaves. Each element was concentrated in distinct biological structures, such as the veins and the edges of the leaves, and the way these trace elements and sulphur were attached to other elements was very similar to that seen in modern leaves and plant matter in soils.

Co-author Professor Roy Wogelius, from Manchester’s School of Earth, Atmospheric and Environmental Sciences, said: “This type of chemical mapping and the ability to determine the atomic arrangement of biologically important elements, such as copper and sulphur, can only be accomplished by using a synchrotron particle accelerator.

“In one beautiful specimen, the leaf has been partially eaten by prehistoric caterpillars — just as modern caterpillars feed — and their feeding tubes are preserved on the leaf. The chemistry of these fossil tubes remarkably still matches that of the leaf on which the caterpillars fed.”

The data from a suite of other techniques has led the team to conclude that the chemistry of the fossil leaves is not wholly sourced from the surrounding environment, as has previously been suggested, but represents that of the living leaves. Another modern-day connection suggests a way in which these specimens are so beautifully preserved over millions of years.

Manchester palaeontologist and co-author Dr Phil Manning said: “We think that copper may have aided preservation by acting as a ‘natural’ biocide, slowing down the usual microbial breakdown that would destroy delicate leaf tissues. This property of copper is used today in the same wood preservatives that you paint on your garden fence before winter approaches.”

Note : The above story is based on materials provided by Manchester University.

Paleontologists assemble giant turtle bone from fossil discoveries made centuries apart

The two partial limb fossils from the ancient sea turtle Atlantochelys mortoni fit together perfectly, leaving little room for doubt that they are from the same bone. This discovery surprised paleontologists because the two halves were discovered at least 163 years apart, defying conventional wisdom that most fossils break down after weeks or months of surface exposure. Credit: Jason Poole, Academy of Natural Sciences of Drexel University

“As soon as those two halves came together, like puzzle pieces, you knew it,” said Ted Daeschler, PhD, associate curator of vertebrate zoology and vice president for collections at the Academy of Natural Sciences of Drexel University.

That surprising puzzle assembly occurred in the fall of 2012, when Jason Schein, assistant curator of natural history at the New Jersey State Museum, visited the Academy’s research collections to better identify and describe a recently-unearthed fossil. The discovery linked scientists from both museums to their predecessors from the 19th century, while setting the stage to advance science today.

The partial fossil bone that Schein had brought to the Academy was a recent discovery by amateur paleontologist Gregory Harpel. Harpel thought the bone seemed strange and out of place when he noticed it on a grassy embankment, a bit upstream from his usual fossil-hunting haunt at a brook in Monmouth County, N.J. Visiting the brook to search for fossil shark teeth is a weekend hobby for Harpel, an analytical chemist from Oreland, Pa. “I picked it up and thought it was a rock at first — it was heavy,” Harpel said.

When he realized it was indeed a fossil, certainly much larger and possibly a lot more scientifically significant than shark teeth, he took it to the experts at the New Jersey State Museum, to which he ultimately donated his find.

Schein and David Parris, the museum’s curator of natural history, immediately recognized the fossil as a humerus — the large upper arm bone — from a turtle, but its shaft was broken so that only the distal end, or end nearest to the elbow, remained.

Parris also thought the fossil looked extremely familiar. He joked with Schein that perhaps it was the missing half of a different large, partial turtle limb housed in the collections at the Academy of Natural Sciences of Drexel University. That bone also had a broken shaft, but only its proximal end, nearest to the shoulder, remained. The coincidence was striking.

“I didn’t think there was any chance in the world they would actually fit,” Schein said.

3-D scan of the two broken turtle limb fossils from Atlantocheyls mortoni shows a detailed view of their surfaces. Credit: Jesse Pruitt, Idaho Museum of Natural History

That’s because the Academy’s piece of the puzzle was much too old, according to the conventional wisdom of paleontology. Paleontologists expect that fossils found in exposed strata of rock will break down from exposure to the elements if they aren’t collected and preserved, at least within a few years– decades at the most. There was no reason to think a lost half of the same old bone would survive, intact and exposed, in a New Jersey streambed from at least the time of the old bone’s first scientific description in 1849, until Harpel found it in 2012.

The Academy’s older bone was also without a match of any kind, making a perfect match seem even more farfetched: It was originally named and described by famed 19th-century naturalist Louis Agassiz as the first, or type specimen, of its genus and species, Atlantochelys mortoni. In the intervening years, it remained the only known fossil specimen from that genus and species.

It remained so until that fateful day when Schein carried the “new” New Jersey fossil to the Academy in Philadelphia, connecting the two halves. The perfect fit between the fossils left little space for doubt. Stunned by the implications, Schein and Academy paleontology staffers Jason Poole and Ned Gilmore, who had assembled the puzzle together, called Daeschler into the room.

“Sure enough, you have two halves of the same bone, the same individual of this giant sea turtle,” said Daeschler. “One half was collected at least 162 years before the other half.”

Now, the scientists are revising their conventional wisdom to say that, sometimes, exposed fossils can survive longer than previously thought. They report their remarkable discovery in the forthcoming 2014 issue of the Proceedings of the Academy of Natural Sciences of Philadelphia.

“The astounding confluence of events that had to have happened for this to be true is just unbelievable, and probably completely unprecedented in paleontology,” said Schein.

The fully assembled A. mortoni humerus now gives the scientists more information about the massive sea turtle it came from as well. With a complete limb, they have calculated the animal’s overall size — about 10 feet from tip to tail, making it one of the largest sea turtles ever known. The species may have resembled modern loggerhead turtles, but was much larger than any sea turtle species alive today.

The scientists believe that the entire unbroken bone was originally embedded in sediment during the Cretaceous Period, 70 to 75 million years ago, when the turtle lived and died. Then those sediments eroded and the bone fractured millions of years later during the Pleistocene or Holocene, before the bone pieces became embedded in sediments and protected from further deterioration for perhaps a few thousand more years until their discovery.

Video :

The above story is based on materials provided by Drexel University.

Geologists study Yilgarn’s western crust

The Youanmi Terrane – named after the former gold town of Youanmi in the western goldfields – which constitutes the western portion of the Yilgarn Craton. Credit: Matthew Perkins

A group of geologists working for the Geological Survey of Western Australia has confirmed a long-standing belief that most of the Yilgarn Craton has a similar crustal architecture.

Structural geologist Ivan Zibra says they studied the Youanmi Terrane – named after the former gold town of Youanmi in the western goldfields – which constitutes the western portion of the Yilgarn Craton.

He says large shear zones are easily detectable from magnetic geophysical images that have been available for a long time.

“We corroborated the view proposed before,” he says.

“Many of the exposed shear zones transect the crust down to 35km, so they are large-scale structures affecting the whole craton.

“The new view is that we are dealing with a fairly homogenous craton-scale crustal architecture, in the order of 1000km in size.”

The Yilgarn bedrock dates from the Archean eon (4000–2500 million years ago) when molten magma cooled to become the earth’s crust.

Dr Zibra says more magma then deformed the solid crust, cracking and partially melting it as the hot molten material attempted to rise to the surface.

He says while the orogen’s large shear zones have been well documented for about 15 years, detailed studies were rare on a scale larger than individual mining tenements.

He says the group’s methodologies ranged from seismic surveys to the microscopic examinations at a sub-millimetric scale.

Having done his PhD dissertation on the Alps – a geologically young formation that has been studied for centuries – he says the Youanmi Terrane presented particular difficulties.

“Many Archean terranes are not well exposed so there are often limitations in terms of how much we can understand,” he says.

“Moreover, the 4000–2500 million years-old Archean orogens are fundamentally different from any younger one, so we miss a present-day equivalent that could help us understand how geological processes worked in the Archean.

“In the modern earth, geological processes are governed by plate tectonics, but it is currently unclear if this was the case during Archean times.

“We are providing quite a well constrained and detailed view of the interaction between deformation and magmatism.”

Dr Zibra says the Alps are regarded as a “cold” orogen, as opposed to “hot” or “ultra hot” orogens, where the deformation was accompanied by huge magmatic activity.

“This has not been really taken into account, especially here in the Yilgarn Craton,” he says.

“All the deformation processes that occur are fundamentally different if they are associated with magmatic activity.”

The above story is based on materials provided by Science Network WA

Gahnite

Spinel (Gahnite) Amity, New York, USA Thumbnail, 3 x 2.8 x 2.5 cm Photo Copyright © Arkenstone

Chemical Formula: ZnAl2O4
Locality: Falun, Sweden.
Name Origin: Named after the Swedish chemist and mineralogist, J. G. Gahn (1745-1818).

Gahnite, ZnAl2O4, is a rare mineral belonging to the spinel group. It forms octahedral crystals which may be green, blue, yellow, brown or grey. It often forms as an alteration product of sphalerite in altered massive sulphide deposits such as at Broken Hill, Australia. Other occurrences include Falun, Sweden where it is found in pegmatites and skarns, Charlemont, Massachusetts; Spruce Pine, North Carolina; White Picacho district, Arizona; Topsham, Maine; and Franklin, New Jersey in the United States.

It was first described in 1807 for an occurrence in the Falu mine, Falun, Dalarna, Sweden, and named after the Swedish chemist, Johan Gottlieb Gahn (1745–1818), the discoverer of the element manganese. It is sometimes called zinc spinel.

Physical Properties

Cleavage: {111} Indistinct
Color: Bluish green, Grayish green, Deep leek green, Greenish black, Bluish black.
Density: 4 – 4.6, Average = 4.3
Diaphaneity: Subtransparent to opaque
Fracture: Uneven – Flat surfaces (not cleavage) fractured in an uneven pattern.
Hardness: 8 – Topaz
Luminescence: Non-fluorescent.
Luster: Vitreous (Glassy)
Magnetism: Nonmagnetic
Streak: gray

Photos :

Gahnite Davis Pyrite Mine, Charlemont, Franklin Co., Massachusetts, USA Size: 6.5 x 5.0 x 2.5 cm (small cabinet) © danweinrich
GAHNITE Locality: Erik Mattsgruvan Stope, Falu Copper Mine, Falun, Dalana, Sweden Collected before 1900 Specimen Size: 2.5 x 2 cm (thumbnail) Largest crystal: 1.5 cm.  © Mineral Classics
Gahnite with Quartz Mina Victoria, Arres, Val d’Aran, Lleida  Spain (09/2009) Specimen size: 3.8 × 2.1 × 2 cm = 1.5” × 0.8” × 0.8” Main crystal size: 1 × 1 cm = 0.4” × 0.4”  © Fabre Minerals
Franklin Mine, Franklin, Franklin Mining District, Sussex Co., New Jersey, USA © Rob Lavinsky

Yellowstone supervolcano unlikely to erupt for 1 to 2 million years

Ilya Bindeman is an associate professor of geological sciences at the University of Oregon. Credit: Ilya Bindeman, University of Oregon

As with many things in nature, it helps to understand the past when trying to predict the future.

Ilya Bindeman, an associate professor of geological sciences at the University of Oregon, believes this is true of the Yellowstone supervolcano and the likelihood that it will produce an apocalyptic eruption as it has three times over the last the last 2 million years.

“Yellowstone is one of the biggest supervolcanos in the world,” he says. “Sometimes it erupts quietly with lava flow, but once or twice every million years, it erupts very violently, forming large calderas,” which are very large craters measuring tens of kilometers in diameter.

If it happens again, and he says most scientists think that it will, he predicts such an eruption will obliterate the surroundings within a radius of hundreds of kilometers, and cover the rest of the United States and Canada with multiple inches of ash. This, effectively, would shut down agriculture and cause global climate cooling for as long as a decade, or more, he says. A volcanic event of such magnitude “hasn’t happened in modern civilization,” he says.

However, the National Science Foundation (NSF)-funded scientist doesn’t think it’s going to happen anytime soon—at least not for another 1 million to 2 million years.

“Our research of the pattern of such volcanism in two older, ‘complete’ caldera clusters in the wake of Yellowstone allows a prognosis that Yellowstone is on a dying cycle, rather than on a ramping up cycle,” he says.

By this, he is referring to an ongoing cycle that occurs within the so-called Yellowstone “hot spot,” an upwelling plume of hot mantle beneath the Earth’s surface, when magma chambers, which are large underground pools of liquid rock, reuse rocks, eject lava, melt again and prompt large eruptions many thousands of years later.

It is a complicated process that also involves the position of the North American plate, which is moving at the rate of two to four centimeters a year, and its relationship to the hot spot, as well as the continuing interaction of the Earth’s crust with basalt, a common volcanic rock derived from the mantle.

“Yellowstone is like a conveyer belt of caldera clusters,” he says. “By investigating the patterns of behavior in two previously completed caldera cycles, we can suggest that the current activity of Yellowstone is on the dying cycle.”

Calderas first form due to the hot spot’s interaction with the North American plate, forming new magma after about a two-million-year delay.

“It takes a long time to build magma bodies in the crust,” he says. “We discovered a consistent pattern: subsequent volcanism is a combination of new magma production and the recycling of already erupted material, which includes lava and tuff,” a rock composed of consolidated volcanic ash.

By comparing Yellowstone to previous completed caldera cycles, “we can detect that the Yellowstone hot spot is re-using the already erupted and buried material, rather than producing just new magma, ” he says. “Either the crust under Yellowstone is turning into hard-to-melt basalt, or because the movement of North American plate has changed the magma pluming system away from Yellowstone, or both of these reasons.”

The Yellowstone hot spot has produced multiple clusters of nested volcanic craters, known as calderas, during the last 16 million years. “Caldera cycles go on for maybe several million years, and then it is done,” he adds. “The current magmatic activity in Yellowstone is in the middle of the cycle, or at the end, as three caldera forming eruptions have already happened.”

The three most recent eruptions, which occurred 2 million, 1.3 million, and 640,000 years ago, resulted in a series of nested calderas forming what we know as Yellowstone National Park and its immediate vicinity.

Eventually, the cycle comes to an end for unknown reasons.

“By performing micro-analytical isotopic investigation of tiny minerals in rocks, we are trying to understand when it’s done,” he says. “We know the behavior of the past and we know at what comparative stage Yellowstone is right now. We think Yellowstone is currently on a third cycle, and it’s a dying cycle. We’ve observed a lot of material that represent recycled volcanic rocks, which were once buried inside of calderas and are now getting recycled. Yellowstone has erupted enough of this material already to suggest that the future melting potential of the crust is getting exhausted.”

To be sure, however, he also points out that “everything is possible in geology, and not very precise.”

Bindeman is conducting his research under an NSF Faculty Early Career Development (CAREER) award, which he received in 2009. The award supports junior faculty who exemplify the role of teacher-scholars through outstanding research, excellent education, and the integration of education and research within the context of the mission of their organization. NSF is funding his work with $533,606 over five years.

As part of the grant’s education component, Bindeman is training graduate and undergraduate students using lab-based learning, summer research programs for undergraduates and community college students, and through new courses.

He also has developed exchanges and collaboration among graduate and undergraduate students and scientists in the United States, Switzerland, Russia, France and Iceland.

“International exchange will involve collaborative lab visits, joint fieldwork, excursions for foreign students, and international student and postdoc hiring,” he says. He recently led a two-week Yellowstone field school for graduate students and professors visiting from Switzerland.

Bindeman’s research involves using radioactive dating to determine the age of volcanic materials, such as tuff and lava, “with the goal of understanding its history,” he says. “Knowing the age is important as a context for understanding everything else.”

They analyze oxygen isotope ratios in quartz and zircon, and water- and heat-resistant minerals, from volcanic rocks. Despite re-melting, the zircon crystals have retained their isotope signatures, enabling the scientists to date their cores and rims, and look into the history of the magma assembly.

“We found patterns indicating that material was recycled as older volcanic rocks forming the roofs of magma chambers collapsed and re-melted during eruptions, only to be re-ejected in the next volcanic outburst,” he says.

Specifically he and his team studied the two most recently completed cycles, that is, the cycle that produced the eruption of 2 million years ago, known as Heise, and the one that followed, producing the eruption of 1.3 million years ago, known as Picabo.

The results of those studies enabled them to determine the current state of the supervolcano, and predict that a new catastrophic caldera-forming eruption likely will happen only in 1 million to 2 million years, probably in Montana.

An eruption of power has not occurred in the world for at least 74,000 years. “The last one was in Toba, Indonesia,” he says.

Bindeman also is investigating the potential effects of the next massive eruption on the atmosphere. “Sulfur dioxide gas will be released in large quantities, resulting in global cooling and ozone destruction, but nobody knows yet how cold it’s going to get and what will be the effects of temporary ozone layer destruction,” he says.

To convey the power of the last Yellowstone eruption, and quite possibly the next one, Bindeman cites two recent examples for comparison purposes: The 1980 eruption of Mt. St. Helens in Washington State, which killed 57 people and caused widespread destruction, spewed one cubic kilometer of material into the air, he says. The 1991 eruption of Mt. Pinatubo in the Philippines, which killed hundreds of people and for several years decreased global temperatures, released ten cubic kilometers, he says.

“The last Yellowstone eruption 640,000 years ago was 1,000 kilometers of material,” he says.

Note : The above story is based on materials provided by National Science Foundation

Fossils of earliest stick insect to mimic plants discovered

At left: Cretophasmomima melanogramma at right: Membranifolia admirabilis. Credit: left: O. Béthoux, right: F. Jacques

An ancient stick insect species may have mimicked plant leaves for defense, according to a paper published in the open-access journal PLOS ONE on March 19, 2014 by Maomin Wang, from Capital Normal University, China and colleagues.

Many insects have developed defense mechanisms, including the ability to mimic the surrounding environment. Stick and leaf insects mimic plants from their environment, but scientists know little about the original of this interaction due to little or no previous stick insect fossil records showing this adaptation. The scientists discovered three specimens, one female and two males, belonging to a new fossil stick insect referred to as Cretophasmomima melanogramma, in Inner Mongolia at the Jehol locality, a site from the Cretaceous period (approximately 126 million years ago). The species possessed adaptive features that make it resembling a plant recovered from the same locality.

The insects’ wings have parallel dark lines and when in the resting position, likely produced a tongue-like shape concealing the abdomen. Fossils from a relative of the ginkgo plant have been documented in the area with similar tongue-shaped leaves along with multiple longitudinal lines. The authors suggest the insect used this plant as a model for concealment.

The new fossils indicate that leaf mimicry was a defensive strategy performed by some insects as early as in the Early Cretaceous, but that additional refinements characteristic of recent forms, such as a curved part of the fore legs for hiding the head, were still lacking.

The new fossil suggests that leaf mimicry predated the appearance of twig and bark mimicry in these types of insects. The diversification of small-sized, insect-eating birds and mammals may have triggered the acquisition of such primary defenses.

Note : The above story is based on materials provided by PLOS.

Computer models solve geologic riddle millions of years in the making

Computer model of typical mantle flow patterns. Credit: Courtesy of Louis Moresi/Monash University

An international team of scientists that included USC’s Meghan Miller used computer modeling to reveal, for the first time, how giant swirls form during the collision of tectonic plates — with subduction zones stuttering and recovering after continental fragments slam into them.

The team’s 3D models suggest a likely answer to a question that has long plagued geologists: why do long, curving mountain chains form along some subduction zones — where two tectonic plates collide, pushing one down into the mantle?

Based on the models, the researchers found that parts of the slab that is being subducted sweep around behind the collision, pushing continental material into the mountain belt.

With predictions confirmed by field observations, the 3D models show a characteristic pattern of intense localized heating, volcanic activity and fresh sediments that remained enigmatic until now.

“The new model explains why we see curved mountains near colliding plates, where material that has been scraped off of one plate and accreted on another is dragged into a curved path on the continent,” Miller said.

Miller collaborated with lead author Louis Moresi from Monash University and his colleagues Peter Betts (also from Monash) and R. A. Cayley from the Geological Survey of Victoria in Australia. Their research was published online by Nature on March 23.

Their research specifically looked at the ancient geologic record of Eastern Australia, but is also applicable to the Pacific Northwest of the United States, the Mediterranean, and southeast Asia. Coastal mountain ranges from Northern California up to Alaska were formed by the scraping off of fragment of the ancient Farallon plate as it subducted beneath the North American continent. The geology of the Western Cordillera (wide mountain belts that extend along all of North America) fits the predictions of the computer model.

“The amazing thing about this research is that we can now interpret arcuate-shaped geological structures on the continents in a whole new way,” Miller said. “We no longer need to envision complex motions and geometries to explain the origins of ancient or modern curved mountain belts.”

The new results from this research will help geologists interpret the formation of ancient mountain belts and may prove most useful as a template to interpret regions where preservation of evidence for past collisions is incomplete — a common, and often frustrating, challenge for geologists working in fragmented ancient terrains.

Moresi was funded by the Australian Research Council and Miller was funded by NSF CAREER award.

Note : The above story is based on materials provided by University of Southern California. 

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