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Deep Earth heat surprise

Washington, D.C—The key to understanding Earth’s evolution is to look at how heat is conducted in the deep lower mantle—a region some 400 to 1,800 miles (660 to 2,900 kilometers) below the surface. Researchers at the Carnegie Institution, with colleagues at the University of Illinois, have for the first time been able to experimentally simulate the pressure conditions in this region to measure thermal conductivity using a new measurement technique developed by the collaborators and implemented by the Carnegie team on the mantle material magnesium oxide (MgO).

They found that heat transfer is lower than other predictions, with total heat flow across the Earth of about 10.4 terawatts, which is about 60 % of the power used today by civilization. They also found that conductivity has less dependence on pressure conditions than predicted. The research is published in the August 9, online Scientific Reports.

Lead author of the study Douglas Dalton explains: “The lower mantle sits on top of the core where pressures range from 230,000 to 1.3 million times the pressure at sea level. Temperatures are like an inferno—from about 2,800°F to 6,700 °F. The major constituents are oxides of magnesium, silicon and calcium. Heat transfer occurs at a higher rate across materials of high thermal conductivity than across materials of low thermal conductivity, thus these low thermal conductivity oxides are insulating.”

The atoms of the major mantle materials are solid solutions and are in a disordered arrangement, which affects the way they conduct heat. Until now, the effect of this disorder on the way heat was conducted could only be estimated with experiments at low pressures. The pressure dependence on thermal conductivity has not been addressed in disordered materials before.

“We squeezed the samples between two diamond tips in an anvil cell and measured the thermal conductivity of the samples, debuting a technique called time-domain thermoreflectance,” remarked co-author Alexander Goncharov. “We went up to 600,000 times atmospheric pressure at room temperature. This technique allows us to measure the thermal properties of the material from the change in the reflectance of the material’s surface, thus avoiding the need of contacting the material of interest as required by conventional techniques. We then compared the results to theoretical models.”

The scientists also showed that there is less dependence of thermal conductivity on pressure than had been predicted. Calculations showed that at the core-mantle boundary there is an estimated total heat flow of 10.4 terawatts across the Earth.

“The results provide important bounds on the degree to which heat is transferred by convection as opposed to conduction in the lower mantle,” said Russell J. Hemley, director of Carnegie’s Geophysical Laboratory. “The next step will be to examine effects of different mineral components on the thermal conductivity and to better understand the atomic scale basis of convective motion of these materials within the broader context of mantle dynamics.”

“The results suggest that this technique could really advance other high pressure and temperature studies of the deep Earth and provide a better understanding of how Earth is evolving and how materials act under the intense conditions,” concluded Goncharov.

This research was supported by the National Science Foundation, The Carnegie DOE Alliance Center (CDAC), and Energy Frontier Research in Extreme Environments Center ( EFree).

Note : The above story is based on materials provided by Carnegie Institution for Science

Carbon Under Pressure Exhibits Interesting Traits

Jun Wu and Peter Buseck’s experiments demonstrate a new way of studying materials at high pressure and temperature within an electron microscope. (Credit: Image courtesy of Arizona State University)

High pressures and temperatures cause materials to exhibit unusual properties, some of which can be special. Understanding such new properties is important for developing new materials for desired industrial uses and also for understanding the interior of Earth, where everything is hot and squeezed.

 

A paper in Nature Geoscience highlights a new technique in which small amounts of a sample can be studied while being hot and squeezed within an electron microscope. Use of such a microscopy method permits determination of details down to the scale of a few atoms, including the detection of unexpected atom types or atoms in unexpected places, as within a mineral.

Jun Wu and Peter Buseck, the paper’s authors, both at Arizona State University, conducted the research on campus at the J.M. Cowley Center for High Resolution Electron Microscopy of the LeRoy Eyring Center for Solid State Science. The researchers used tiny containers of carbon, less than one-thousandth the width of a human hair and therefore small enough to fit within high-resolution electron microscopes, to enclose materials similar to those deep within Earth. They then used the electron beam to shrink and thereby squeeze these minuscule capsules. When combined with heating of the samples, new features were observed in the enclosed materials.

“Under such high pressures and temperatures, the materials inside the capsules developed faults that concentrated carbon along them,” explains Buseck, Regents’ Professor in the Department of Chemistry and Biochemistry and the School of Earth and Space Exploration.

The Nature Geoscience paper describes the use of this new method to address the important problem of how and where carbon is located within Earth’s interior. Carbon is an essential building block for all forms of life and it also has important effects on climate and climate change through greenhouses gases such as carbon dioxide and carbon tetrahydride, also known as natural gas or methane.

The largest single reservoir for carbon is within Earth’s interior. However, the known hosts for this carbon are believed to be insufficient to explain the amounts present.

Because Earth’s interior (as well as the interiors of other planets) contains vast amounts of materials like those used in the experiments, the scientists conclude that such faults, and the carbon they concentrate, provide a solution to the problem of explaining where large amounts of carbon reside in Earth’s interior.

Wu and Buseck’s experiments also demonstrate a new way of studying materials at high pressure and temperature within an electron microscope, thereby significantly extending the tools available to scientists for examining materials under extreme conditions.

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

International Research Discovers New Mineral “Qingsongite”

Geologists at the University of California, Riverside have discovered a new mineral, cubic boron nitride, which they have named “qingsongite.”

The discovery, made in 2009, was officially approved this week by the International Mineralogical Association.

The UC Riverside geologists, Larissa Dobrzhinetskaya and Harry Green in the Department of Earth Sciences, were joined by scientists at the Lawrence Livermore National Laboratory, the University of Maine and from institutions in China and Germany in making the discovery.

“The uniqueness of qingsongite is that it is the first boron mineral that was found to be formed at extreme conditions in deep Earth,” Dobrzhinetskaya said.  “All other known boron minerals are found at Earth’s surface.”

The mineral was found in the southern Tibetan mountains of China within chromium-rich rocks of the paleooceanic crust that was subducted to a depth of 190 miles and recrystallized there at a temperature of about 2372 degrees Fahrenheit and pressure of about 118430 atmospheres.

“About 180 million years ago the rocks were returned back to shallow levels of the Earth by plate tectonic processes leading to the closure of the huge Paleo-Thethys ocean — an ancient Paleozoic ocean — and the collision of India with the Asian lithospheric plate,” Dobrzhinetskaya explained.

Until now, cubic boron nitride, created first in the laboratory in 1957, was known as an important technological material.  Because its atomic structure bears resemblance to carbon bonds in diamond, it has high density and could be as hard as diamond.

Over 4,700 species of minerals have been recognized to date, and nowadays at least 100 proposals for new minerals and their names are submitted each year for approval by the Commission on New Minerals, Nomenclature and Classification of the International Mineralogical Association, which was founded in 1958. Commission members, who represent 34 countries including the U.S., vote separately on each new mineral and its name.

Qingsongite was named after Qingsong Fang (1939–2010), a professor at the Institute of Geology, the Chinese Academy of Geological Sciences, who found the first diamond in the Tibetan chromium-rich rocks in the late 1970s, and contributed to the discovery of four new mineral species.

The scientific project that led to the discovery of qingsongite was supported by grants from the University of California Laboratory Fees Research Program and the National Science Foundation.

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

A Waterworld of Volcanoes

At Loki’s Castle in the Arctic Ocean, researchers from the University of Bergen (UiB) have discovered a so far unknown world of volcanic activity underwater. They hope that this can become Norway’s new national park.
In 2008, UiB researchers discovered Loki’s Castle, a field of five active hydrothermal vents on the Mid-Atlantic Ridge between Norway and Greenland at 73°N. The field contains rich metal deposits and a unique wildlife.

New discoveries

This summer a team led by the director of UiB’s Centre for Geobiology, Professor Rolf Birger Pedersen, discovered five new hydrothermal vents in Loki’s Castle. The vents were discovered at depths ranging from 100 to 2,500 metres. In this area, which is the most geological active part of Norway, a new volcanic seabed is formed at a rate of two centimetres a year.

On Thursday 1 August, Professor Pedersen and UiB’s Rector Dag Rune Olsen met with Norway’s Minister of the Environment, Bård Vegar Solhjell, to talk about the research on the world’s last few blank spots and to discuss how Norway can contribute to preserving these wildlife reserves.

“These discoveries are incredibly interesting as they represent a part of the Norwegian nature that is under-explored. They represent a part of nature where conditions are extreme and where we expect to find a lot of new and exciting biology,” Rector Olsen said.

Unique videos

At the meeting Olsen and Pedersen showed new and unique video recordings of Norway’s unknown volcanoes to the minister and other select guests. Minister Solhjell was impressed with the research done and promised action.

“At the Ministry of the Environment will start work to consider more carefully how to take care of these areas in the best way possible. It is an amazing idea that we can create spectacular underwater nature parks, but it may not happen right away as we need more knowledge in how to make this work,” Solhjell said.

Norway is a volcanic country on par with Iceland. The difference being that whereas Iceland’s volcanoes are onshore, Norway’s volcano landscape is in the deep sea. Norway’s volcanoes are lined up underwater in large active earthquake zones, and there are hydrothermal vents churning out hot water — at 320 degrees Celsius — which gives rise to unique ecosystems and metal deposits on the seabed.

UiB’s Centre for Geobiology is Norway’s leading deep-ocean research environment. For the past ten years, researchers and students from the centre have explored this volcanic underwater world. Through their summer expeditions to the area, they have discovered new Norwegian nature every year.

In this period they have surveyed hundreds of undersea volcanoes and a number of hydrothermal vents. Loki’s Castle (Lokeslottet), Soria Moria and Trollveggen are the names given to the hydrothermal vents discovered by the UiB researchers in 2005 and 2008.

National park on the seabed

The researchers believe that Loki’s Castle could become a Norwegian national park on the seabed, not unlike Yellowstone in the United States or Iceland’s geysers.

The UiB researchers see that there could be future conflicts of interest if such a national park is to be established. They have found significant metal deposits that are formed around the hydrothermal vents in Loki’s Castle. The material value of these deposits remains unknown, but the mining industry is already showing a growing interest in exploiting these resources on the seabed. Deep-ocean mining could become a reality in the not too distant future. The distinctive wildlife in the deep seas, with the hydrothermal vents as oases of a unique genetic life, means that any industrial activity must be weighed against environmental concerns.

Based on their knowledge, the UiB researchers are thus proposing that deep-marine nature parks should be established as soon as possible. This is of particular importance for Norway, with vast deep-sea areas to manage. This management must be based on scientific knowledge.

“It is our opinion that this area is so unique that it should be preserved. We are talking about very vulnerable environments,” Professor Pedersen said and pointed out that research also needs to create more knowledge about the wildlife in the area.

“It would represent a new way of preservation thinking if a national park was to be linked to Loki’s Castle,” Rector Olsen said. “Given the University of Bergen’s marine research profile, we definitely want to take responsibility for further exploration of these fields so as to give the Norwegian government a good scientific basis when they make a decision.”

Note : The above story is based on materials provided by University of Bergen. The original article was written by Walter Wehus and Sverre Ole Drønen. 

‘Highway from Hell’ Fueled Costa Rican Volcano

Volcán Irazú (Costa Rica). If some volcanoes operate on geologic timescales, Costa Rica’s Irazú had something of a short fuse. (Credit: © xevibp / Fotolia)

If some volcanoes operate on geologic timescales, Costa Rica’s Irazú had something of a short fuse. In a new study in the journal Nature, scientists suggest that the 1960s eruption of Costa Rica’s largest stratovolcano was triggered by magma rising from the mantle over a few short months, rather than thousands of years or more, as many scientists have thought. The study is the latest to suggest that deep, hot magma can set off an eruption fairly quickly, potentially providing an extra tool for detecting an oncoming volcanic disaster.

“If we had had seismic instruments in the area at the time we could have seen these deep magmas coming,” said the study’s lead author, Philipp Ruprecht, a volcanologist at Columbia University’s Lamont-Doherty Earth Observatory. “We could have had an early warning of months, instead of days or weeks.”

Towering more than 10,000 feet and covering almost 200 square miles, Irazú erupts about every 20 years or less, with varying degrees of damage. When it awakened in 1963, it erupted for two years, killing at least 20 people and burying hundreds of homes in mud and ash. Its last eruption, in 1994, did little damage.

Irazú sits on the Pacific Ring of Fire, where oceanic crust is slowly sinking beneath the continents, producing some of earth’s most spectacular fireworks. Conventional wisdom holds that the mantle magma feeding those eruptions rises and lingers for long periods of time in a mixing chamber several miles below the volcano. But ash from Irazú’s prolonged explosion is the latest to suggest that some magma may travel directly from the upper mantle, covering more than 20 miles in a few months.

“There has to be a conduit from the mantle to the magma chamber,” said study co-author Terry Plank, a geochemist at Lamont-Doherty. “We like to call it the highway from hell.”

Their evidence comes from crystals of the mineral olivine separated from the ashes of Irazú’s 1963-1965 eruption, collected on a 2010 expedition to the volcano. As magma rising from the mantle cools, it forms crystals that preserve the conditions in which they formed. Unexpectedly, Irazú’s crystals revealed spikes of nickel, a trace element found in the mantle. The spikes told the researchers that some of Irazú’s erupted magma was so fresh the nickel had not had a chance to diffuse.

“The study provides one more piece of evidence that it’s possible to get magma from the mantle to the surface in very short order,” said John Pallister, who heads the U.S. Geological Survey (USGS) Volcano Disaster Assistance Program in Vancouver, Wash. “It tells us there’s a potentially shorter time span we need to worry about.”

Deep, fast-rising magma has been linked to other big events. In 1991, Mount Pinatubo in the Philippines spewed so much gas and ash into the atmosphere that it cooled Earth’s climate. In the weeks before the eruption, seismographs recorded hundreds of deep earthquakes that USGS geologist Randall White later attributed to magma rising from the mantle-crust boundary. In 2010, a chain of eruptions at Iceland’s Eyjafjallajökull volcano that caused widespread flight cancellations also indicated that some magma was coming from down deep. Small earthquakes set off by the eruptions suggested that the magma in Eyjafjallajökull’s last two explosions originated 12 miles and 15 miles below the surface, according to a 2012 study by University of Cambridge researcher Jon Tarasewicz in Geophysical Research Letters.

Volcanoes give off many warning signs before a blow-up. Their cones bulge with magma. They vent carbon dioxide and sulfur into the air, and throw off enough heat that satellites can detect their changing temperature. Below ground, tremors and other rumblings can be detected by seismographs. When Indonesia’s Mount Merapi roared to life in late October 2010, officials led a mass evacuation later credited with saving as many as 20,000 lives.

Still, the forecasting of volcanic eruptions is not an exact science. Even if more seismographs could be placed along the flanks of volcanoes to detect deep earthquakes, it is unclear if scientists would be able to translate the rumblings into a projected eruption date. Most problematically, many apparent warning signs do not lead to an eruption, putting officials in a bind over whether to evacuate nearby residents.

“[Several months] leaves a lot of room for error,” said Erik Klemetti, a volcanologist at Denison University. “In volcanic hazards you have very few shots to get people to leave.”

Scientists may be able to narrow the window by continuing to look for patterns between eruptions and the earthquakes that precede them. The Nature study also provides a real-world constraint for modeling how fast magma travels to the surface. “If this interpretation is correct, you start having a speed limit that your models of magma transport have to catch,” said Tom Sisson, a USGS volcanologist based at Menlo Park, Calif.

Olivine minerals with nickel spikes similar to Irazú’s have been found in the ashes of arc volcanoes in Mexico, Siberia and the Cascades of the U.S. Pacific Northwest, said Lamont geochemist Susanne Straub, whose ideas inspired the study. “It’s clearly not a local phenomenon,” she said. The researchers are currently analyzing crystals from past volcanic eruptions in Alaska’s Aleutian Islands, Chile and Tonga, but are unsure how many will bear Irazú’s fast-rising magma signature. “Some may be capable of producing highways from hell and some may not,” said Ruprecht.

How Did Earth’s Primitive Chemistry Get Kick Started?

This image from the floor of the Atlantic Ocean shows a collection of limestone towers known as the “Lost City.” Alkaline hydrothermal vents of this type are suggested to be the birthplace of the first living organisms on the ancient Earth. Scientists are interested in understanding early life on Earth because if we ever hope to find life on other worlds – especially icy worlds with subsurface oceans such as Jupiter’s moon Europa and Saturn’s Enceladus – we need to know what chemical signatures to look for. (Credit: Image courtesy D. Kelley and M. Elend/University of Washington)

How did life on Earth get started? Three new papers co-authored by Mike Russell, a research scientist at NASA’s Jet Propulsion Laboratory, Pasadena, Calif., strengthen the case that Earth’s first life began at alkaline hydrothermal vents at the bottom of oceans. Scientists are interested in understanding early life on Earth because if we ever hope to find life on other worlds — especially icy worlds with subsurface oceans such as Jupiter’s moon Europa and Saturn’s Enceladus — we need to know what chemical signatures to look for.

Two papers published recently in the journal Philosophical Transactions of the Royal Society B provide more detail on the chemical and precursor metabolic reactions that have to take place to pave the pathway for life. Russell and his co-authors describe how the interactions between the earliest oceans and alkaline hydrothermal fluids likely produced acetate (comparable to vinegar). The acetate is a product of methane and hydrogen from the alkaline hydrothermal vents and carbon dioxide dissolved in the surrounding ocean. Once this early chemical pathway was forged, acetate could become the basis of other biological molecules. They also describe how two kinds of “nano-engines” that create organic carbon and polymers — energy currency of the first cells — could have been assembled from inorganic minerals.

A paper published in the journal Biochimica et Biophysica Acta analyzes the structural similarity between the most ancient enzymes of life and minerals precipitated at these alkaline vents, an indication that the first life didn’t have to invent its first catalysts and engines.

“Our work on alkaline hot springs on the ocean floor makes what we believe is the most plausible case for the origin of the life’s building blocks and its energy supply,” Russell said. “Our hypothesis is testable, has the right assortment of ingredients and obeys the laws of thermodynamics.”

Russell’s work was funded by the NASA Astrobiology Institute through the Icy Worlds team based at JPL, a division of the California Institute of Technology, Pasadena. The NASA Astrobiology Institute, based at NASA’s Ames Research Center, Moffett Field, Calif., is a partnership among NASA, 15 U.S. teams and 13 international consortia. The Institute is part of NASA’s astrobiology program, which supports research into the origin, evolution, distribution and future of life on Earth and the potential for life elsewhere.

Note : The above story is based on materials provided by NASA/Jet Propulsion Laboratory. 

Ice-free Arctic winters could explain amplified warming during Pliocene

Year-round ice-free conditions across the surface of the Arctic Ocean could explain why Earth was substantially warmer during the Pliocene Epoch than it is today, despite similar concentrations of carbon dioxide in the atmosphere. (Credit: © Jan Schuler / Fotolia)

Year-round ice-free conditions across the surface of the Arctic Ocean could explain why the Earth was substantially warmer during the Pliocene Epoch than it is today, despite similar concentrations of carbon dioxide in the atmosphere, according to new research carried out at the University of Colorado Boulder.

In early May, instruments at the Mauna Loa Observatory in Hawaii marked a new record: The concentration of carbon dioxide climbed to 400 parts per million for the first time in modern history.

The last time researchers believe the carbon dioxide concentration in the atmosphere reached 400 ppm—between 3 and 5 million years ago during the Pliocene—the Earth was about 3.5 to 9 degrees Fahrenheit warmer (2 to 5 degrees Celsius) than it is today. During that time period, trees overtook the tundra, sprouting right to the edges of the Arctic Ocean, and the seas swelled, pushing ocean levels 65 to 80 feet higher.

Scientists’ understanding of the climate during the Pliocene has largely been pieced together from fossil records preserved in sediments deposited beneath lakes and on the ocean floor.

“When we put 400 ppm carbon dioxide into a model, we don’t get as warm a planet as we see when we look at paleorecords from the Pliocene,” said Jim White, director of CU-Boulder’s Institute of Arctic and Alpine Research and co-author of the new study published online in the journal Palaeogeography, Paleoclimatology, Palaeoecology. “That tells us that there may be something missing in the climate models.”

Scientists have proposed several hypotheses in the past to explain the warmer Pliocene climate. One idea, for example, was that the formation of the Isthmus of Panama, the narrow strip of land linking North and South America, could have altered ocean circulations during the Pliocene, forcing warmer waters toward the Arctic. But many of those hypotheses, including the Panama possibility, have not proved viable.

For the new study, led by Ashley Ballantyne, a former CU-Boulder doctoral student who is now an assistant professor of bioclimatology at the University of Montana, the research team decided to see what would happen if they forced the model to assume that the Arctic was free of ice in the winter as well as the summer during the Pliocene. Without these additional parameters, climate models set to emulate atmospheric conditions during the Pliocene show ice-free summers followed by a layer of ice reforming during the sunless winters.

“We tried a simple experiment in which we said, ‘We don’t know why sea ice might be gone all year round, but let’s just make it go away,’ ” said White, who also is a professor of geological sciences. “And what we found was that we got the right kind of temperature change and we got a dampened seasonal cycle, both of which are things we think we see in the Pliocene.”

In the model simulation, year-round ice-free conditions caused warmer conditions in the Arctic because the open water surface allowed for evaporation. Evaporation requires energy, and the water vapor then stored that energy as heat in the atmosphere. The water vapor also created clouds, which trapped heat near the planet’s surface.

“Basically, when you take away the sea ice, the Arctic Ocean responds by creating a blanket of water vapor and clouds that keeps the Arctic warmer,” White said.

White and his colleagues are now trying to understand what types of conditions could bridge the standard model simulations with the simulations in which ice-free conditions in the Arctic are imposed. If they’re successful, computer models would be able to model the transition between a time when ice reformed in the winter to a time when the ocean remained devoid of ice throughout the year.

Such a model also would offer insight into what could happen in our future. Currently, about 70 percent of sea ice disappears during the summertime before reforming in the winter.

“We’re trying to understand what happened in the past but with a very keen eye to the future and the present,” White said. “The piece that we’re looking at in the future is what is going to happen as the Arctic Ocean warms up and becomes more ice-free in the summertime.

“Will we continue to return to an ice-covered Arctic in the wintertime? Or will we start to see some of the feedbacks that now aren’t very well represented in our climate models? If we do, that’s a big game changer.”

Note : The above story is based on materials provided by University of Colorado at Boulder.

Head-to-head record suggests dinosaurs were headbangers

Skull of a pachycephalosaurian dinosaur – did they use their bony domes to fight with one another? Photograph: Dave Hone

Working out the functions of various features of long extinct animals can be fraught with difficulty. For every case where it is really rather obvious (pterosaurs could fly with their wings, and the teeth of tyrannosaurs were not used for opening coconuts) there are those that are contentious, or just plain baffling. One of the more controversial has been the huge domes on the heads of many pachycephalosaurian dinosaurs.

That mouthful of a name roughly translates as “thick-headed reptiles” and this time at least it’s a fair comment. The largest forms had the best part of 10 inches (25 cm) of solid bone on the top of their skull, giving them a unique appearance and indeed unique structure. In some this was elaborated with a frill of spikes at the back of the head and various knobs and bumps across the main dome. On animals that are otherwise quite lightly built and apparently fast and agile bipeds, it is quite a feature.

This certainly looks like some form of battering ram. The idea that these animals faced off and charged in, head lowered, to butt at one another’s heads or flanks gained in popularity and there are plenty of dramatic images of pachycephalosaurs charging into one another in the manner of buffalo or bighorn sheep, and the idea of the Cretaceous echoing to the cracks of impacting dinosaur skulls is certainly an evocative one.

Section through a pachycephalosaur skull to show the brain (in white) buried deep within the solid mass of the bony dome. Photograph: Dave Hone

However, more recently a number of analyses and suggestions have made the area much more contentions. Various studies have concluded that the heads of these animals either would, or would not, shield the brain from serious injury in case of impacts and it has even been suggested that the heads were purely for display. To complicate matters a little further, a number of specimens don’t seem to have the thick domes, but more of a flat head (though sometimes with various knobs and spikes still being present) and it is not clear if these were different species, or juveniles or females of known species. Into this debate steps a new paper with a totally new line of evidence.

Pachycephalosaur remains are actually rather rare, but the one thing that does survive well are the domes themselves since they are very tough chunks of solid bone. Researchers examined over 100 preserved skulls and isolated domes (also called skull-caps) and found a pretty consistent pattern – they very often suffered from damage and modifications to the cap consistent with injuries. Now injuries in wild animals are quite common. Over a lifetime, most animals will suffer the odd accident or disease that will leave its mark on the skeleton and can be seen. However, the damage observed is collectively far more than just odd incidences of trauma.

For a start, they are pretty much all on the top of the dome – where a head-down strike would most likely impact – and not randomly distributed across the skulls, which would be expected from general accidents. Second, the number of incidences is high (22% of animals, a little lower than in sheep and higher than in bison), and much more than would be expected from normal accidents or chance, implying some kind of behaviour that repeatedly leads to cranial injuries. Furthermore, injuries of this kind appear to be absent in the specimens of pachycephalosaurs that don’t have thick skull-caps, meaning that rates of damage are obviously still more common in the domed animals, and also that damage seems to correlate with having the dome.

Charge! A pachycephalosaur butts into the flanks of its opponent. This may have been a favoured method of attack over a pure head-on-head impact. Photograph: Dave Hone

In short, there is good reason to think that these animals really were impacting with their heads: the giant dome of bone was both weapon and crash helmet. It isn’t clear if this was true head-to-head impacts, or more generalised butting of whatever bits of their opponents they could hit, but they were clearly hitting things, and hard. That they were doesn’t rule out that the domes might also have been used to signal dominance, but clearly they had a major role in combat and individuals were clearly facing off and fighting.

It seem we can use these impressive animals’, in some cases, rather nasty skull trauma injuries to show what they got up to around a hundred million years ago. With the largest individuals weighing close to half a tonne, the clashes would presumably have been spectacular.

Peterson, J E, Dischler, C, Longrich, N R, 2013. Distributions of cranial pathologies provide evidence for head-butting in dome-headed dinosaurs (Pachycephalosauridae). PLoS ONE 8(7): e68620.

Note : The above story is reprinted from materials provided byhttp://guardian.co.uk. The original article was written by Dr Dave Hone.

Rocks Can Restore Our Climate … After 300,000 Years

A study of a global warming event that happened 93 million years ago suggests that the Earth can recover from high carbon dioxide emissions faster than thought, but that this process takes around 300,000 years after emissions decline.Scientists from Oxford University studied rocks from locations including Beachy Head, near Eastbourne, and South Ferriby, North Lincolnshire, to investigate how chemical weathering of rocks ‘rebalanced’ the climate after vast amounts of carbon dioxide (CO2) were emitted during more than 10,000 years of volcanic eruptions.
In chemical weathering CO2 from the atmosphere dissolved in rainwater reacts with rocks such as basalt or granite, dissolving them so that this atmospheric carbon then flows into the oceans, where a large proportion is ‘trapped’ in the bodies of marine organisms.

The team tested the idea that, as CO2 warms the planet, the reactions involved in chemical weathering speed up, causing more CO2 to be ‘locked away’, until, if CO2 emissions decline, the climate begins to cool again. The Oxford team looked at evidence from the ‘Ocean Anoxic Event 2’ in the Late Cretaceous when volcanic activity spewed around 10 gigatonnes of CO2 into the atmosphere every year for over 10,000 years. The researchers found that during this period chemical weathering increased, locking away more CO2 as the world warmed and enabling the Earth to stabilise to a cooler climate within 300,000 years, up to four times faster than previously thought.

A report of the research is published in Nature Geoscience.

‘Looking at this event is rather like imagining what the Earth would be like if humans disappeared tomorrow,’ said Dr Philip Pogge von Strandmann of Oxford University’s Department of Earth Sciences, who led the research. ‘Volcanic CO2 emissions in this period are similar to, if slightly slower than, current manmade emissions so that we can imagine a scenario in which, after human CO2 emissions ceased, the planet’s climate would start to recover and cool down. The bad news is that it’s likely this would take around 300,000 years.’

Reconstructing a record of past chemical weathering is challenging because of how plants and animals take carbon out of the environment. To get around this the team used a recently-developed technique involving studying lithium isotopes in marine limestone (this lithium could only come from weathering and is not changed by biological organisms).

The Ocean Anoxic Event 2 is believed to have been caused by a massive increase in volcanic activity in one of three regions: the Caribbean, Madagascar, or the Solomon Islands. The event saw the temperature of seawater around the equator warm by about 3 degrees Celsius. It is thought that this warming caused around 53% of marine species to go extinct. Animals like turtles, fish, and ammonites were amongst those severely affected.

‘Everyone remembers the mass extinction of land animals caused by the K-T meteorite impact 30 million years later, thought to be responsible for the demise of the dinosaurs, but in many ways this was just as devastating for marine life,’ said Dr Pogge von Strandmann. ‘Whilst nutrients from weathering caused a population boom of some species near the surface of the oceans, it also led to a loss of oxygen to the deeper ocean, killing off over half of all marine species and creating a ‘dead zone’ of decaying animals and plants. It’s a scenario we wouldn’t want to see repeated today.

‘Our research is good news, showing that the Earth can recover up to four times faster than we thought from CO2 emissions, but even if we stopped all emissions today this recovery would still take hundreds of thousands of years. We have to start doing something soon to remove CO2 from the atmosphere if we don’t want to see a repeat of the kind of mass extinctions that global warming has triggered in the past.’

The research was supported by the UK’s Natural Environment Research Council.

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

Dinosaur tail found in Mexico

A team of palaeontologists has discovered the fossilised remains of a 72m-year-old dinosaur tail in a desert in northern Mexico, according to the country’s National Institute for Anthropology and History (INAH).

Unusually well preserved, the five-metre (16ft) tail (above) was the first ever found in Mexico, said Francisco Aguilar, INAH’s director in the border state of Coahuila.
The team, made up of palaeontologists and students from INAH and the National Autonomous University of Mexico, identified the fossil as a hadrosaur, or duck-billed dinosaur. The tail, found near the small town of General Cepeda, probably made up half the dinosaur’s length, Aguilar said.

Palaeontologists found the 50 vertebrae of the tail completely intact after spending 20 days in the desert slowly lifting a sedimentary rock covering the creature’s bones.

Strewn around the tail were other fossilised bones, including one of the dinosaur’s hips, INAH said.

Dinosaur tail finds are relatively rare, according to INAH. The new discovery could improve understanding of the hadrosaur family and aid research on diseases that afflicted dinosaur bones, which resembled those of humans, Aguilar said.

Scientists have already determined that dinosaurs suffered from tumours and arthritis, for example.

Dinosaur remains have been found in many parts of the state of Coahuila, in addition to Mexico’s other northern desert states.

“We have a very rich history of paleontology,” Aguilar said.

He noted that during the Cretaceous period, which ended about 65m years ago, much of what is now central northern Mexico was on the coast. This has enabled researchers to unearth remains of both marine and land-based dinosaurs.

The presence of the remains was reported to INAH by locals in June 2012. After initial inspections, excavation began earlier this month. The remains of the tail will be transferred to General Cepeda for cleaning and further investigation.

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Note : The above story is based on materials provided by Reuters

Western-led ‘international beam team’ solves Martian meteorite age puzzle

NWA 5298 © Royal Ontario Museum

By directing energy beams at tiny crystals found in a Martian meteorite, a Western University-led team of geologists has proved that the most common group of meteorites from Mars is almost 4 billion years younger than many scientists had believed – resolving a long-standing puzzle in Martian science and painting a much clearer picture of the Red Planet’s evolution that can now be compared to that of habitable Earth.

In a paper published today in the journal Nature, lead author Desmond Moser, an Earth Sciences professor from Western’s Faculty of Science, Kim Tait, Curator, Mineralogy, Royal Ontario Museum, and a team of Canadian, U.S., and British collaborators show that a representative meteorite from the Royal Ontario Museum (ROM)’s growing Martian meteorite collection, started as a 200 million-year-old lava flow on Mars, and contains an ancient chemical signature indicating a hidden layer deep beneath the surface that is almost as old as the solar system.

The team, comprised of scientists from ROM, the University of Wyoming, UCLA, and the University of Portsmouth, also discovered crystals that grew while the meteorite was launched from Mars towards Earth, allowing them to narrow down the timing to less than 20 million years ago while also identifying possible launch locations on the flanks of the supervolcanoes at the Martian equator.

More details can be found in their paper titled, “Solving the Martian meteorite age conundrum using micro-baddeleyite and launch-generated zircon.”

Moser and his group at Western’s Zircon & Accessory Phase Laboratory (ZAPLab), one of the few electron nanobeam dating facilities in the world, determined the growth history of crystals on a polished surface of the meteorite. The researchers combined a long-established dating method (measuring radioactive uranium/lead isotopes) with a recently developed gently-destructive, mineral grain-scale technique at UCLA that liberates atoms from the crystal surface using a focused beam of oxygen ions.

Moser estimates that there are roughly 60 Mars rocks dislodged by meteorite impacts that are now on Earth and available for study, and that his group’s approach can be used on these and a much wider range of heavenly bodies.

“Basically, the inner solar system is our oyster. We have hundreds of meteorites that we can apply this technique to, including asteroids from beyond Mars to samples from the Moon,” says Moser, who credits the generosity of the collectors that identify this material and make it available for public research.

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Note : The above story is based on materials provided by University of Western Ontario

Devastating Long-Distance Impact of Earthquakes

Seismograph. (Credit: © huebi71 / Fotolia)

In 2006 the island of Java, Indonesia was struck by a devastating earthquake followed by the onset of a mud eruption to the east, flooding villages over several square kilometers and that continues to erupt today. Until now, researchers believed the earthquake was too far from the mud volcano to trigger the eruption. Geophysicists at the University of Bonn, Germany and ETH Zurich, Switzerland use computer-based simulations to show that such triggering is possible over long distances. The results have been published in Nature Geoscience.

On May 27, 2006 the ground of the Indonesian island Java was shaking with a magnitude 6.3 earthquake. The epicenter was located 25 km southwest of the city of Yogyakarta and initiated at a depth of 12 km. The earthquake took thousands of lives, injured ten thousand and destroyed buildings and homes. 47 hours later, about 250 km from the earthquake hypocenter, a mud volcano formed that came to be known as “Lusi,” short for “Lumpur Sidoarjo.” Hot mud erupted in the vicinity of an oil drilling-well, shooting mud up to 50 m into the sky and flooding the area. Scientists expect the mud volcano to be active for many more years.

Eruption of mud volcano has natural cause

Was the eruption of the mud triggered by natural events or was it human-made by the nearby exploration-well? Geophysicists at the University of Bonn, Germany and at ETH Zürich, Switzerland investigated this question with numerical wave-propagation experiments. “Many researchers believed that the earthquake epicenter was too far from Lusi to have activated the mud volcano,” says Prof. Dr. Stephen A. Miller from the department of Geodynamics at the University of Bonn. However, using their computer simulations that include the geological features of the Lusi subsurface, the team of Stephen Miller concluded that the earthquake was the trigger, despite the long distance.

The overpressured solid mud layer was trapped between layers with different acoustic properties, and this system was shaken from the earthquake and aftershocks like a bottle of champagne. The key, however, is the reflections provided by the dome-shaped geology underneath Lusi that focused the seismic waves of the earthquakes like the echo inside a cave. Prof. Stephen Miller explains: “Our simulations show that the dome-shaped structure with different properties focused seismic energy into the mud layer and could very well have liquified the mud that then injected into nearby faults.”

Previous studies would have underestimated the energy of the seismic waves, as ground motion was only considered at the surface. However, geophysicists at the University of Bonn suspect that those were much less intense than at depth. The dome-like structure “kept” the seismic waves at depth and damped those that reached the surface. “This was actually a lower estimate of the focussing effect because only one wave cycle was input. This effect increases with each wave cycle because of the reducing acoustic impedance of the pressurizing mud layer.” In response to claims that the reported highest velocity layer used in the modeling is a measurement artifact, Miller says „that does not change our conclusions because this effect will occur whenever a layer of low acoustic impedance is sandwiched between high impedance layers, irrespective of the exact values of the impedances. And the source of the Lusi mud was the inside of the sandwich. ”

It has already been proposed that a tectonic fault is connecting Lusi to a 15 km distant volcanic system. Prof. Miller explains “This connection probably supplies the mud volcano with heat and fluids that keep Lusi erupting actively up to today,” explains Miller.

With their publication, scientists from Bonn and Zürich point out, that earthquakes can trigger processes over long distances, and this focusing effect may apply to other hydrothermal and volcanic systems. Stephen Miller concludes: “Being a geological rarity, the mud volcano may contribute to a better understanding of triggering processes and relationships between seismic and volcanic activity.” Miller also adds „maybe this work will settle the long-standing controversy and focus instead on helping those affected.” The island of Java is part of the so called Pacific Ring of Fire, a volcanic belt which surrounds the entire Pacific Ocean. Here, oceanic crust is subducted underneath oceanic and continental tectonic plates, leading to melting of crustal material at depth. The resulting magma uprises and is feeding numerous volcanoes.

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

Geochemical ‘fingerprints’ leave evidence that megafloods eroded steep gorge

U.S. Geological Survey This 2005 image shows a concentration of grains of zircon taken from sand deposits, where it occurs with other heavy minerals such as magnetite and ilmenite

The Yarlung-Tsangpo River in southern Asia drops rapidly through the Himalaya Mountains on its way to the Bay of Bengal, losing about 7,000 feet of elevation through the precipitously steep Tsangpo Gorge.
For the first time, scientists have direct geochemical evidence that the 150-mile long gorge, possibly the world’s deepest, was the conduit by which megafloods from glacial lakes, perhaps half the volume of Lake Erie, drained suddenly and catastrophically through the Himalayas when their ice dams failed at times during the last 2 million years.

“You would expect that if a three-day long flood occurred, there would be some pretty significant impacts downstream,” said Karl Lang, a University of Washington doctoral candidate in Earth and space sciences.

In this case, the water moved rapidly through bedrock gorge, carving away the base of slopes so steep they already were near the failure threshold. Because the riverbed through the Tsangpo Gorge is essentially bedrock and the slope is so steep and narrow, the deep flood waters could build enormous speed and erosive power.

As the base of the slopes eroded, areas higher on the bedrock hillsides tumbled into the channel, freeing microscopic grains of zircon that were carried out of the gorge by the fast-moving water and deposited downstream.

Uranium-bearing zircon grains carry a sort of geochemical signature for the place where they originated, so grains found downstream can be traced back to the rocks from which they eroded. Lang found that normal annual river flow carries about 40 percent of the grains from the Tsangpo Gorge downstream. But grains from the gorge found in prehistoric megaflood deposits make up as much as 80 percent of the total.

He is the lead author of a paper documenting the work published in the September edition of Geology. Co-authors are Katharine Huntington and David Montgomery, both UW faculty members in Earth and space sciences.

The Yarlung-Tsangpo is the highest major river in the world. It begins on the Tibetan Plateau at about 14,500 feet, or more than 2.5 miles, above sea level. It travels more than 1,700 miles, crossing the plateau and plunging through the Himalayas before reaching India’s Assam Valley, where it becomes the Brahmaputra River. From there it continues its course to the Ganges River delta and the Bay of Bengal.

0. Karl Lang/UW During a 2011 field trip, a regional assistant gathers samples from a deposit left by a catastrophic flood on the Yarlang-Tsangpo River in 200

At the head of the Tsangpo Gorge, the river makes a sharp bend around Namche Barwa, a 25,500-foot

Lang matched zircons in the megaflood deposits far downstream with zircons known to come only from Namche Barwa, and those signature zircons turned up in the flood deposits at a much greater proportion than they would in sediments from normal river flows. Finding the zircons in deposits so far downstream is evidence for the prehistoric megafloods and their role in forming the gorge.

Lang noted that a huge landslide in early 2000 created a giant dam on the Yiggong River, a tributary of the main river just upstream from the Gorge. The dam failed catastrophically in June 2000, triggering a flood that caused numerous fatalities and much property damage downstream.

That provided a vivid, though much smaller, illustration of what likely occurred when large ice dams failed millions of years ago, he said. It also shows the potential danger if humans decide to build dams in that area for hydroelectric generation.

“We are interested in it scientifically, but there is certainly a societal element to it,” Lang said. “This takes us a step beyond speculating what those ancient floods did. There is circumstantial evidence that, yes, they did do a lot of damage.”

The process in the Tsangpo Gorge is similar to what happened with Lake Missoula in Western Montana 12,000 to 15,000 years ago. That lake was more than 10,000 feet lower in elevation than lakes associated with the Tsangpo Gorge, though its water discharge was 10 times greater. Evidence suggests that Lake Missoula’s ice dam failed numerous times, unleashing a torrent equal to half the volume of Lake Michigan across eastern Washington, where it carved the Channeled Scablands before continuing down the Columbia River basin.

“This is a geomorphic process that we know shapes the landscape, and we can look to eastern Washington to see that,” Lang said.

The work was funded by the National Science Foundation and the UW Quaternary Research Center.
peak that is the eastern anchor of the Himalayas. Evidence indicates that giant lakes were impounded behind glacial dams farther inland from Namche Barwa at various times during the last 2.5 million years ago.

Note :  The above story is based on materials provided by University of Washington. The original article was written by Vince Stricherz.

Global warming 5 million years ago caused sea levels to rise by 20 meters

Antarctic glacier. (Credit: © Goinyk Volodymyr / Fotolia)

Global warming five million years ago may have caused parts of Antarctica’s large ice sheets to melt and sea levels to rise by approximately 20 metres, scientists report today in the journal Nature Geoscience.

The researchers, from Imperial College London, and their academic partners studied mud samples to learn about ancient melting of the East Antarctic ice sheet. They discovered that melting took place repeatedly between five and three million years ago, during a geological period called Pliocene Epoch, which may have caused sea levels to rise approximately ten metres.

Scientists have previously known that the ice sheets of West Antarctica and Greenland partially melted around the same time. The team say that this may have caused sea levels to rise by a total of 20 metres.

The academics say understanding this glacial melting during the Pliocene Epoch may give us insights into how sea levels could rise as a consequence of current global warming. This is because the Pliocene Epoch had carbon dioxide concentrations similar to now and global temperatures comparable to those predicted for the end of this century.

Dr Tina Van De Flierdt, co-author from the Department of Earth Science and Engineering at Imperial College London, says: “The Pliocene Epoch had temperatures that were two or three degrees higher than today and similar atmospheric carbon dioxide levels to today. Our study underlines that these conditions have led to a large loss of ice and significant rises in global sea level in the past. Scientists predict that global temperatures of a similar level may be reached by the end of this century, so it is very important for us to understand what the possible consequences might be.”

The East Antarctic ice sheet is the largest ice mass on Earth, roughly the size of Australia. The ice sheet has fluctuated in size since its formation 34 million years ago, but scientists have previously assumed that it had stabilised around 14 million years ago.

The team in today’s study were able to determine that the ice sheet had partially melted during this “stable” period by analysing the chemical content of mud in sediments. These were drilled from depths of more than three kilometres below sea level off the coast of Antarctica.

Analysing the mud revealed a chemical fingerprint that enabled the team to trace where it came from on the continent. They discovered that the mud originated from rocks that are currently hidden under the ice sheet. The only way that significant amounts of this mud could have been deposited as sediment in the sea would be if the ice sheet had retreated inland and eroded these rocks, say the team.

The academics suggest that the melting of the ice sheet may have been caused in part by the fact that some of it rests in basins below sea level. This puts the ice in direct contact with seawater and when the ocean warms, as it did during the Pliocene, the ice sheet becomes vulnerable to melting.

Carys Cook, co-author and research postgraduate from the Grantham Institute for Climate Change at Imperial, adds: “Scientists previously considered the East Antarctic ice sheet to be more stable than the much smaller ice sheets in West Antarctica and Greenland, even though very few studies of East Antarctic ice sheet have been carried out. Our work now shows that the East Antarctic ice sheet has been much more sensitive to climate change in the past than previously realised. This finding is important for our understanding of what may happen to the Earth if we do not tackle the effects of climate change.”

The next step will see the team analysing sediment samples to determine how quickly the East Antarctic ice sheet melted during the Pliocene. This information could be useful in the future for predicting how quickly the ice sheet could melt as a result of global warming.

Note : The above story is based on materials provided by Imperial College London. The original article was written by Colin Smith.

Sinkhole : What are sinkholes? What causes them?

Great Blue Hole, Coast of Belize – a phenomenon of Karst topography. U.S. Geological Survey (USGS)

A sinkhole, also known as a sink-hole, sink, swallow hole, shakehole, swallet or doline, is a natural depression or hole in the Earth’s surface which may have various causes. Some are caused by karst processes—for example, the chemical dissolution of carbonate rocks or suffosion processes in sandstone. Others are formed as a result of the collapse of old mine workings close to the surface.

\Sinkholes may vary in size from 1 to 600 m (3.3 to 2,000 ft) both in diameter and depth, and vary in form from soil-lined bowls to bedrock-edged chasms. Sinkholes may be formed gradually or suddenly, and are found worldwide. The different terms for sinkholes are often used interchangeably.

Formation

Natural processes

Sinkholes may capture surface drainage from running or standing water, but may also form in high and dry

Sinkholes near the Dead Sea, formed when underground salt is dissolved by freshwater intrusion, due to continuing sea level drop.

places in certain locations.

The formation of sinkholes involves natural processes of erosion or gradual removal of slightly soluble bedrock (such as limestone) by percolating water, the collapse of a cave roof, or a lowering of the water table. Sinkholes often form through the process of suffosion. Thus, for example, groundwater may dissolve the carbonate cement holding the sandstone particles together and then carry away the lax particles, gradually forming a void.

Occasionally a sinkhole may exhibit a visible opening into a cave below. In the case of exceptionally large sinkholes, such as the Minyé sinkhole in Papua New Guinea or Cedar Sink at Mammoth Cave National Park in Kentucky, an underground stream or river may be visible across its bottom flowing from one side to the other.

Sinkholes are common where the rock below the land surface is limestone or other carbonate rock, salt beds, or other rocks that can naturally be dissolved by circulating ground water. As the rock dissolves, spaces and caverns develop underground. These sinkholes can be dramatic, because the surface land usually stays intact until there is not enough support. Then, a sudden collapse of the land surface can occur.

Artificial processes

Sinkholes also form from human activity, such as the rare but still occasional collapse of abandoned mines

Sinkhole formed by rainwater leaking through pavement and carrying soil into a ruptured sewer pipe.

and salt cavern storage in salt domes in places like Louisiana, Mississippi and Texas. More commonly, sinkholes occur in urban areas due to water main breaks or sewer collapses when old pipes give way. They can also occur from the overpumping and extraction of groundwater and subsurface fluids.

Sinkholes can also form when natural water-drainage patterns are changed and new water-diversion systems are developed. Some sinkholes form when the land surface is changed, such as when industrial and runoff-storage ponds are created; the substantial weight of the new material can trigger an underground collapse of supporting material, thus causing a sinkhole.

Occurrence

 Sinkholes are frequently linked with karst landscapes. In such regions, there may be hundreds or even thousands of sinkholes in a small area so that the surface as seen from the air looks pock-marked, and there are no surface streams because all drainage occurs subsurface. Examples of karst landscapes dotted with numerous enormous sinkholes are Khammouan Mountains (Laos) and Mamo Plateau (Papua New Guinea). The largest known sinkholes formed in sandstone are Sima Humboldt and Sima Martel in Venezuela.

The most impressive sinkholes form in thick layers of homogenous limestone. Their formation is facilitated by high groundwater flow, often caused by high rainfall; such rainfall causes formation of the giant sinkholes in Nakanaï Mountains, on the New Britain island in Papua New Guinea. On the contact of limestone and insoluble rock below it, powerful underground rivers may form, creating large underground voids.In such conditions the largest known sinkholes of the world have formed, like the 662-metre (2,172 ft) deep Xiaozhai Tiankeng (Chongqing, China), giant sótanos in Querétaro and San Luis Potosí states in Mexico and others.

Unusual processes have formed the enormous sinkholes of Sistema Zacatón in Tamaulipas (Mexico), where more than 20 sinkholes and other karst formations have been shaped by volcanically heated, acidic groundwater. This has produced not only the formation of the deepest water-filled sinkhole in the world—Zacatón—but also unique processes of travertine sedimentation in upper parts of sinkholes, leading to sealing of these sinkholes with travertine lids.The state of Florida in the United States is known for having frequent sinkhole collapses, especially in the central part of the state. The Murge area in southern Italy also has numerous sinkholes. Sinkholes can be formed in retention ponds from large amounts of rain.

Local names of sinkholes

Large and visually unusual sinkholes have been well-known to local people since ancient times. Nowadays sinkholes are grouped and named in site-specific or generic names. Some examples of such names are listed below.
Black holes – This term refers to a group of unique, round, water-filled pits in the Bahamas. These formations seem to be dissolved in carbonate mud from above, by the sea water. The dark color of the water is caused by a layer of phototropic microorganisms concentrated in a dense, purple colored layer at 15 to 20 m (49 to 66 ft) depth; this layer “swallows” the light. Metabolism in the layer of microorganisms causes heating of the water, the only known case in the natural world where microorganisms create significant thermal effects. Most impressive is the Black Hole of Andros.
Blue holes – This name was initially given to the deep underwater sinkholes of the Bahamas but is often used for any deep water-filled pits formed in carbonate rocks. The name originates from the deep blue color of water in these sinkholes, which in turn is created by the high lucidity of water and the great depth of sinkholes; only the deep blue color of the visible spectrum can penetrate such depth and return back after reflection.
Cenotes – This refers to the characteristic water-filled sinkholes in the Yucatán Peninsula, Belize and some other regions. Many cenotes have formed in limestone deposited in shallow seas created by the Chicxulub meteorite’s impact.
Sótanos – This name is given to several giant pits in several states of Mexico.
Tiankengs – These are extremely large sinkholes, typically deeper and wider than 250 m (820 ft), with mostly vertical walls, most often created by the collapse of underground caverns. The term means sky hole in Chinese; many of this largest type of sinkhole are located in China.
Tomo – This term is used in New Zealand karst country to describe pot holes.

 

 Note : The above story is reprinted from materials provided by Wikipedia

Dinosaur teeth reveal feeding habits

Diplodocus’ peg-like teeth were constantly replaced

Teeth from sauropod dinosaurs – the largest land animals that ever lived – reveal the feeding habits of these giants.

Researchers report that Diplodocus’ teeth were replaced as often as once a month throughout the dinosaur’s life.

In contrast, the teeth of Camarasaurus, another sauropod, show less frequent replacement, but bulkier growth.

This suggests that Diplodocus fed off low-lying vegetation while Camarasaurus ate upper-canopy plants.

Michael D’Emic, from Stony Brook University, New York, and co-workers used the daily layers of dentin, laid down as the dinosaur teeth grew, to determine the working lifetime and replacement rates of these massive herbivores’ teeth.

Dr D’Emic explains “A nearly 100-foot-long sauropod would have had a fresh tooth in each position about every one to two months, sometimes less.” These huge plant-eaters ate enormous quantities of vegetation, and their teeth suffered heavy wear.

The results are reported in the journal PLoS ONE.

Dr Emily Rayfield, reader in palaeobiology at the University of Bristol, commented “Diplodocus had peg-like teeth that stuck forward and out from its long narrow jaw, while Camarasaurus had a shorter jaw with a stronger bite. Their teeth wore down as they cropped vegetation.”

Dinosaurs replaced their teeth constantly throughout their life with new tooth crowns sitting deep in the jaw ready to erupt beneath each working tooth. This contrasts with mammals like us, which only replace their teeth once after birth (milk teeth and adult teeth).

The results indicate that Diplodocus and Camarasaurus had different approaches to feeding, allowing them to co-exist in the same ecosystem, with Diplodocus grazing plants at ground level and Camarasaurus taking the higher-lying vegetation.

Was T-Rex predator or scavenger, or both?

T-Rex and the one that got away

Earlier this week, a different dinosaur dental examination was described in the Proceedings of the National Academy of Sciences journal. A tooth of the carnivorous giant, Tyrannosaurus rex, found in the back bone of a duck-billed dinosaur, a type of hadrosaur, has been used to infer the eating habits of T.Rex.

The study, led by Dr David Burnham at the University of Kansas, demonstrates that the hadrosaur back bone had re-healed around the embedded T.Rex tooth, showing that it escaped from the T.Rex and continued to live for some time afterwards.

Importantly, this observation feeds into a long-standing debate over whether T.Rex was a scavenger or a predator, with the authors suggesting it supports the picture of T.Rex as a predator, and not simply a carrion scavenger.

It demonstrates once more the methods used by scientists to piece together the behaviour of ancient animals from fossil fragments.

Dr Paul Barrett, dinosaur researcher at the Natural History Museum in London, added “When we look at the ecology of living animals, we see that carnivores generally eat whatever they can get hold of.

“Hyenas, that we think of as specialist scavengers, hunt quite a bit; lions, that we think of as hunters, steal carcasses from other animals.

“There is no reason to think that T.Rex, as a big carnivore, would do anything other than it would need to, to survive at the cheapest possible cost.”

Note : The above story is reprinted from materials provided by BBC News. The original article was written by Simon Redfern

Fossils in Western Australia could hold clues for life on Earth

Hancock Gorge, Karijini national park, Pilbara, home to some of the planet’s most ancient rock formations. Photograph: Anne Montfort/Photononstop/Cor

Scientists analysing Australian rocks have discovered traces of bacteria that lived a record-breaking 3.49bn years ago, a mere 1bn years after Earth formed.

If the find withstands the scrutiny that inevitably faces claims of fossils this old, it could move scientists one step closer to understanding the first chapters of life on Earth. The discovery could also spur the search for ancient life on other planets.
These traces of bacteria “are the oldest fossils ever described. Those are our oldest ancestors,” said Nora Noffke, a biogeochemist at Old Dominion University in Norfolk, Virginia, who was part of the group that made the find and presented it in November at a meeting of the Geological Society of America. Unlike dinosaur bones, the newly identified fossils are not petrified body parts. They’re textures on the surfaces of sandstone thought to be sculpted by once-living organisms.

Today, similar patterns decorate parts of Tunisia’s coast, created by thick mats of bacteria that trap and glue together sand particles. Sand that is stuck to the land beneath the mats and thus protected from erosion can over time turn into rock that can long outlast the living organisms above it.

Finding the earliest remnants of this process required a long, hard look at some of the planet’s oldest rocks, located in Western Australia’s Pilbara region. This ancient landscape was once shoreline. Rocks made from sediment piled up billions of years ago are now exposed and available for examination. Relatively pristine in condition, such outcrops, along with others in South Africa, have long been a popular place to look for traces of life from the Archean eon, which ended 2.5bn years ago.

There are older rocks on Earth, said Maud Walsh, a biogeologist at Louisiana State University in Baton Rouge. “But these are the best-preserved sedimentary rocks we know of, the ones most likely to preserve the really tiny structures and chemicals that provide evidence for life.”

Last year, another team of researchers published the discovery of microscopic fossils in Pilbara’s Strelley Pool Formation, about 3.4bn years old. “It’s not just finding this stuff that’s interesting,” says Alan Decho, a geobiologist at the University of South Carolina’s Arnold School of Public Health. “It’s showing that the life had some organisation to it.” Ridges that crisscross the rocks like strands in a spider web hint that primitive bacteria linked up in sprawling networks. Like their modern counterparts, they may have lived in the equivalent of microbial cities that hosted thousands of kinds of bacteria, each specialised for a different task and communicating with the others via chemical signals.

Many of the textures seen in the Australian rocks had already shown up in 2.9bn-year-old rocks from South Africa, reported on by Noffke and colleagues in 2007.

Still, old Australian rocks have proved deceptive before. As early as 1980, rippling layers within the Strelley Pool were thought to be the handiwork of bacteria. But such stromatolites, which are different from the structures that Noffke studies, can also be the work of natural, non-living processes. For instance, water flowing along a seafloor can create similar structures under the right conditions. So can spraying jets of liquid loaded with particles onto a surface, as scientists at Oxford University demonstrated in laboratory experiments.

That’s why Noffke and her colleagues corroborated their story by measuring the carbon that makes up the textured rocks. About 99% of carbon in non-living stuff is carbon-12, a lighter version of the element than the carbon-13 that accounts for most of the remaining 1%. Microbes that use photosynthesis to make their food contain even more carbon-12 and less carbon-13. That bias, a signature of “organic” carbon that comes from a living being, showed up in the Australian rock.

“It’s always nice to have a number of different lines of evidence, and you definitely want to see organic carbon,” says geomicrobiologist John Stolz of Duquesne University in Pittsburgh.

What wasn’t preserved: any proteins or fats or body fossils that would clinch the case for life and identify what types of bacteria left behind this organic carbon. Most microbial mats today contain lots of photosynthetic cyanobacteria, which make the food that sustains the other bacteria. Named after the blue-green pigment they use for this process, called phycocyanin, cyanobacteria also make oxygen and are given the credit for creating Earth’s atmosphere about 2.4bn years ago.

Cyanobacteria living in microbial mats nearly 3.5bn years ago could shake up the history of the air we all breathe.

“Studying this kind of past life is really about learning how the Earth got to be the way it is today,” says Michael Tice, a geobiologist at Texas A&M University.

Ultimately, the fossils found on Earth could help those looking for the building blocks of life on Mars, where Nasa’s Curiosity rover has recently found evidence for ancient waterways. Remnants of life on the red planet might even be better preserved than they are here on Earth, says Harvard University paleontologist Andrew Knoll. That’s because old terrestrial rocks tend to get banged around by the movement of tectonic plates and cooked by the extreme heat of the planet’s depths. Mars, a planet that’s nearly dead geologically, lacks such tectonic activity.

Though no signs of ancient Martian microbes have been found, fossil hunters may now have something new to start looking for.

• This article was amended on 9 January 2013 to delete a reference to the archaeologically productive Pilbara region: the age of the fossils found would better suit the field of palaeontology. A missing fragment of a quote from geobiologist Alan Decho has also been reinstated.

Note : The above story is reprinted from materials provided by guardian.co.uk. The original article was written by Devin Powell for the Washington Post

A near miss for a Tyrannosaurus rex: evidence of failed predation

CT scans of the hadrosaur bones. A) the two tail bones fused together and B) showing the cross-section of the Tyrannosaurus rex tooth buried in the bone (the white oval at the bottom of the picture). Scale bars are 1 cm. Modified from DePalma et al. 2013.

For too long there has been an apparently unending debate about the basic manner in which Tyrannosaurus and its near relatives obtained their food. Were these animals dedicated predators, hunting down and killing their prey before consuming it, or scavengers, too slow and poorly equipped to catch live prey, but instead limited to taking already dead meals, perhaps using their size to bully smaller carnivores from their meals.

Despite the press this has had and the evocative language that often appears in association with this question (‘deadly’ on the predatory size and inevitably ‘skulking’ on the scavenging one) the truth has been known to scientists for some time – they did both. Certainly tyrannosaurs scavenged when food was available, but they were clearly capable predators (or at least there was no truly strong evidence to suggest they were not) and some tentative evidence pointed towards animals that might have been injured by them.

However, this doesn’t mean that new evidence is not welcome and now a rather exciting and pretty definitive case has come forwards. A pair of bones from the tail of a hadrosaurian dinosaur (more often know as duck-bills) have been found that are fused together and with a huge chunk of amorphous bone joining them. In short, the site of some major injury or infection has caused this unusual growth to occur. However, it is what lies inside that is the real delight – a Tyrannosaurus tooth.

Carnivorous dinosaurs actually shed their teeth quite often – like sharks they continually grew new teeth and the old ones would eventually fall out. So while finding shed teeth in or around carcasses of other dinosaurs is quite common, and in other cases we have found teeth embedded into bones, the question is how do we know this didn’t happen when scavenging a carcass, but was a real strike on a living animal?

In the study by DePalma and colleagues, the tooth is buried deep within the mass of bone and is completely covered by it. The shape and texture of the bone growth is indicative of a major injury occurring to the hadrosaur and the obvious and entirely reasonable interpretation for this is that a bite from a tyrannosaur left the tooth in there.

It’s unlikely that this was an accident: large predators don’t usually bite prey species very hard for no reason (and indeed probably rarely get close enough to do so except when going after them) so it’s entirely justifiable to chalk this up to an attempted attack. “Attempted” is the key word here: the animal survived the incident and lived for many months or even years based on the amount of bone that had built up over the tooth.

This is also not a major surprise, few predators are successful much more than about half the time they try and hunt prey and of course many failed efforts would leave only a slight graze that would not show up on the bones, or be so bad as to kill the animal perhaps a few hours or days later where healing may not show. This doesn’t show that Tyrannosaurus was a poor predator, merely that this hadrosaur got very lucky but lived to honk the tale for some time at least. Perhaps we are luckier still to find such an event marked in the fossil record, but this is hopefully the final, final nail in the ‘scavenging only’ idea and we can move onto some more detailed analysis of the behaviour of these giant carnivores.

R.A. De Palma II, et al., 2013. Physical evidence of predatory behavior in Tyrannosaurus rex. Proceedings of the National Academy of Sciences. doi:10.1073/pnas.1216534110 

Note : The above story is reprinted from materials provided by guardian.co.uk. The original article was written by Dr Dave Hone

Pumping water underground could trigger major earthquake, say scientists

A geothermal plant in California. Water injection may prime cracks, making them vulnerable to triggering by tremors from distant earthquakes. Photograph: Getty

Pumping water underground at geothermal power plants can lead to dangerous earthquakes even in regions not prone to tremors, according to scientists. They say that quake risk should be factored into decisions about where to site geothermal plants and other drilling rigs where water is pumped underground – for example in shale gas fracking.
Prof Emily Brodsky, who led a study of earthquakes at a geothermal power plant in California, said: “For scientists to make themselves useful in this field we need to be able to tell operators how many gallons of water they can pump into the ground in a particular location and how many earthquakes that will produce.”

It is already known that pumping large quantities of water underground can induce minor earthquakes near to geothermal power generation and fracking sites. However, the new evidence reveals the potential for much larger earthquakes, of magnitude 4 or 5, related to the weakening of pre-existing undergrounds faults through increased fluid pressure.

The water injection appears to prime cracks in the rock, making them vulnerable to triggering by tremors from earthquakes thousands of miles away. Nicholas van der Elst, the lead author on one of three studies published on Thursday in the journal Science, said: “These fluids are driving faults to their tipping point.”

Prof Brodsky said they found a clear correlation between the amount of water extracted and injected into the ground, and the number of earthquakes.

The analysis of the Californian site showed that for a net injection of 500m gallons of water into the ground per month, there is an earthquake on average every 11 days.

“The problem is we can only predict how many earthquakes will occur but not their size and so with this knowledge then it has to be decided what is an acceptable size and frequency of earthquakes for a particular area,” said Brodsky.

Because of the increase in the exploitation of geothermal power for renewable energy, and hydraulic fracturing or “fracking” to release natural gas, it is important to understand the chances of a large earthquake occurring at these sites, particularly if they are in densely populated regions.

Another key feature of the research shows that sites experiencing sustained pumping of water into the ground for a period of decades or more are more susceptible to large tremors triggered by earthquakes occurring in other parts of the world.

Large earthquakes in Chile in 2010, Japan in 2011 and Sumatra in 2012 all set off mid-size tremors in the central United States near to sites of water injection, with the largest induced earthquake of magnitude 5.7 destroying 14 homes and injuring two people. Van der Elst said: “The remote triggering by big earthquakes is an indication the area is critically stressed.”

Heather Savage, a co-author on the same study said: “It is already accepted that when we have very large earthquakes seismic waves travel all over the globe, but even though the waves are small when they reach the other side of the world, they still shake faults. This can trigger seismicity in seismically active areas such as volcanoes where there is already a high fluid pressure. But this is the first time the same has been recognised for areas with anthropogenically induced high fluid pressure.”

Scientists map the exact location of faults that occur naturally over most of the Earth’s crust. However, there are many underground faults that do not intersect the Earth’s surface, some of which could be very large. The fear is that one of these previously inactive faults could be triggered. Van der Elst added: “It is an important subject for the future that we understand about the disposal of fluids as they arise from many processes.”

Rather than completely stopping the pumping of wastewater into the ground at geothermal plants, Prof Brodsky suggests that careful observation and analysis at each pumping site may help predict the chances of an earthquake.

Note : The above story is reprinted from materials provided by guardian.co.uk. The original article was written by Natalie Starkey

High Tooth Replacement Rates in Largest Dinosaurs Contributed to Their Evolutionary Success

This is an illustration of a skull of Diploducus alongside the research team’s CT scan-generated images of some teeth in the front of its jaws. Bone is transparent and teeth are yellow. The arrows show the direction of tooth replacement, which is back to front similar to a shark. (Credit: Image courtesy of Stony Brook University)

Rapid tooth replacement by sauropods, the largest dinosaurs in the fossil record, likely contributed to their evolutionary success, according to a research paper by Stony Brook University paleontologist Michael D’Emic, PhD, and colleagues. Published in PLOS ONE, the study also hypothesizes that differences in tooth replacement rates among the giant herbivores likely meant their diets varied, an important factor that allowed multiple species to share the same ecosystems for several million years.

Paleontologists have long wondered how sauropods digested massive amounts of foliage that would have been necessary for their immense sizes. In “Evolution of high tooth replacement rates in sauropod dinosaurs,” the team of paleontologists reveal that their new research into the microscopic structure of sauropod teeth shows the dinosaurs formed and replaced teeth faster than any other type of dinosaurs — more like sharks and crocodiles — and this process kept teeth fresh given the immense amount of wear they underwent from clipping off enormous volumes of food required for them.

“The microscopic structure of teeth and bones records aspects of an animal’s physiology, giving us a window into the biology of long-extinct animals,” said Dr. D’Emic, Research Instructor in the Department of Anatomical Sciences at Stony Brook University School of Medicine. “We determined that for the gigantic sauropods, each tooth took just a few months to form. Effectively, sauropods took a ‘quantity over quality’ approach.”

Dr. D’Emic explained that unlike mammals and some other dinosaurs, sauropods did not chew their food. They snipped food into smaller pieces before swallowing.

“At least twice during their evolution, sauropods evolved small, peg-like teeth that formed and replaced quickly,” said Dr. D’Emic. “This characteristic may have led to the evolutionary success of sauropods.”

The team developed a novel method to estimate sauropod tooth formation and replacement rate without

With computed tomography (CT) scanning and microscopic anatomical methods, they measured tooth formation time, replacement rate, crown volume and enamel thickness in sectioned teeth of Camarasaurus and Diplodocus, two dinosaurs from the Late Jurassic Formation of North America. The technology and method enabled the researchers to count the number of growth lines in each tooth. Growth lines are a fraction of the thickness of a human hair. A tally of the lines gives the formation of each tooth in days.

To find out how fast these teeth were replaced, D’Emic and colleagues subtracted the ages of successive teeth from one another. The results indicated that replacement in these animals was extremely fast.

“A nearly 100-foot-long sauropod would have had a fresh tooth in each position about every one to two months, sometimes less” said Dr. D’Emic.

The tooth replacement rate, size and shape data collected by the team indicates that despite their somewhat stereotyped body plan and large body size, sauropods exhibited varied approaches to feeding. The paper indicates that this variation “represents a potential factor that allowed multiple giant species such as Camarasurus and Diplodocus to partition the same ecosystem.”

Dr. D’Emic added that the research also contributes to a new view of sauropods, which were once thought to be more primitive than other dinosaur groups such as horned and duckbilled dinosaurs.

The paper co-authors include John Whitlock of Mount Aloysius College, Kathlyn Smith of Georgia Southern University, and Jeffrey Wilson and Daniel Fisher of the University of Michigan.

The dinosaur specimens used for the research were loaned to the paleontologists from the Yale Peabody Museum, Utah Museum of Natural History, Staatliches Museum für Naturkunde and the Iziko South African Museum.

This is a sketch of a skull of Diplodocus alongside an actual horse skull. Note the similarity in shape of the skulls. However, the dinosaur has few, puny teeth in the front of its jaw, illustrating the non-chewing eating process in sauropds in comparison to the grinding method of horses and other mammals.

destructively sampling the teeth by making microscopic sections. Using these estimates, the researchers could track the evolution of tooth formation and replacement rates through time in species whose fossil remains are too rare to section.

Sauropod Dinosaur Facts:

1. Sauropod dinosaurs were the largest animals that ever walked the land.

2. Familiar examples of sauropods are Diplodocus, Brachiosaurus, and Apatosaurus. Apatosaurus was formerly called “Brontosaurus.” These are genera (plural of genus) and should be italicized.

3. Sauropods had tiny heads for their bodies — even a 100-foot-long animal would have a head only slightly larger than that of a horse.

4. Along with their tiny heads, sauropods had tiny teeth, ranging from the diameter of a pencil to a wide marker and only a few inches long.

5. Sauropods did not chew their food, but clipped it and swallowed it, where it was broken down in their digestive system.

6. In living animals, daily incremental lines are laid down in teeth. These lines are thinner than a human hair. The total number of lines indicates how long it took for the tooth to form.

7. Most animals have only one or two replacement teeth in a given socket (or tooth position), but sauropods had up to nine.

8. Sauropod teeth formed quickly — in just a few months.

9. Sauropods replaced their teeth more quickly than most animals, including other dinosaurs. A new tooth was replaced in each tooth position every month or so.

10. Sauropods twice evolved small teeth that formed and replaced quickly.

Note : The above story is reprinted from materials provided by Stony Brook University, via Newswise. 

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