Diamonds from the deep: Study suggests water may exist in Earth’s lower mantle

March 16, 2018

The molecular structure of ice-VII (upper right) is shown with an artistic rendering of the Earth and a cutaway view of the inner Earth (right). Crystallized water, in the form of ice-VII, was found in diamond samples studied at Berkeley Lab. Its presence suggests liquid water may exist at extreme depths. Credit: Wikimedia Commons

Water on Earth runs deep – very deep. The oceans have been measured to a maximum depth of 7 miles, though water is known to exist well below the oceans. Just how deep this hidden water reaches, and how much of it exists, are the subjects of ongoing research.

Now a new study suggests that water may be more common than expected at extreme depths approaching 400 miles and possibly beyond – within Earth’s lower mantle. The study, which appeared March 8 in the journal Science, explored microscopic pockets of a trapped form of crystallized water molecules in a sampling of diamonds from around the world.

Diamond samples from locations in Africa and China were studied through a variety of techniques, including a method using infrared light at the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab). Researchers used Berkeley Lab’s Advanced Light Source (ALS), and Argonne National Laboratory’s Advanced Photon Source, which are research centers known as synchrotron facilities.

The tiny traces of crystallized water, trapped in spaces called inclusions that measure just a few microns (millionths of a meter) in length, contain the molecular signature of ice VII. This crytallized water likely formed from liquid water existing at very high pressures, according to the study.

The structure and chemical studies helped the scientists to determine the pressures and temperatures at which the diamonds formed. This allowed the scientists to estimate the depths of their formation.

Oliver Tschauner, the study’s lead author and a professor of research in the Department of Geoscience at the University of Nevada, Las Vegas, said it was surprising that so many of the studied diamonds from a random sampling seemed to originate from deep inside the Earth, within and even beyond the so-called transition zone sandwiched between Earth’s upper and lower mantles.

While only about 60 diamonds had previously been confirmed to originate at depths greater than about 190 miles, the latest study added several more to this tally.

“It seems many diamonds come from greater depths,” Tschauner said. “In the past, people had focused more on larger inclusions,” tens of times the size of the ones that were the focus of the latest study. “Some of these small inclusions may have been overlooked before,” he added.

Researchers concluded that some of the inclusions likely were formed from fluid existing at depths of 250 miles to 340 miles beneath Earth’s surface. Others may have formed at depths ranging from 380 miles to 500 miles – possibly within Earth’s “shallow” lower mantle.

“It’s not just a curiosity to have a diamond residing deep in Earth’s mantle – this is direct evidence for aqueous fluid in the deep Earth,” Tschauner said.

The pressures that formed these deeper diamonds are estimated at approximately 24 to 25 gigapascals, which is about 224 times more pressure than exists at the bottom the ocean’s deepest point in its Mariana Trench.

The composition of the fluid that was trapped in the inclusions appears to be complex, with traces of carbonates, oxides, and salt, Tschauner said.

The research team enlisted infrared spectroscopy at the ALS’s Beamline 1.4, which helped them to observe the chemistry of the tiny inclusions.

Hans Bechtel, a research scientist in the Scientific Support Group at the ALS, explained that the infrared technique measures vibrational signatures that detail chemistry at the microscopic level. “With synchrotron light, we can focus down to 2 to 10 microns in the infrared,” he said, “and scan across each sample to create a ‘hyperspectral image’ that reveals the detailed chemical composition.”

It’s not yet possible to estimate how much watery fluid exists in Earth’s transition zone and how it’s distributed, Tschauner said, but more diamond studies should help with the estimates.

Such studies can also help scientists learn about how much water “recycling” goes on in the mantle, and the process by which ocean water reaches into the mantle, for example.

Tschauner said he’s already exploring ways to better prepare diamond samples for future studies – perhaps even using methods enlisted by jewelers – to better understand their microscopic chemistry.

This new thrust of research provides a unique opportunity to “see” inside the inner Earth, Tschauner noted. “It probably will open new avenues in studies.”

The ALS and Advanced Photon Source are DOE Office of Science User Facilities.

Researchers from the University of Chicago, California Institute of Technology, China University of Geosciences, University of Hawaii at Manoa, and Royal Ontario Museum also participated in the study. The work was supported by the U.S. Department of Energy Office of Basic Energy Sciences and the National Science Foundation.

Reference:
Ice-VII inclusions in diamonds: Evidence for aqueous fluid in Earth’s deep mantle. DOI: 10.1126/science.aao3030

Note: The above post is reprinted from materials provided by DOE/Lawrence Berkeley National Laboratory.

The secrets of garnet reveal source of water to fuel powerful volcanoes and earthquakes

March 15, 2018

Among geologists who study powerful earthquakes and volcanoes, there is a mystery: as one of Earth’s tectonic plates slides beneath another in a subduction zone, water is squeezed from certain minerals, lubricating earthquakes and fueling volcanoes in hot spots like the Pacific Ocean “Ring of Fire.” But equations that predict where the forces of subduction wring water from stone consistently point to locations far from the site of actual cataclysms.

By applying a new spectroscopy technique to garnet containing fragments of quartz, metamorphic petrologist Frank Spear of Rensselaer Polytechnic Institute thinks he’s solved the puzzle. His early research shows that the equations are incomplete, lacking the significant variable of “overstepping,” the additional energy needed to initiate a process, in this case, the decomposition of water-bearing minerals.

“The real culprit in powerful volcanoes and earthquakes is water, but scientists have been unable to determine where that water comes from,” said Spear, a professor and head of the Rensselaer Department of Earth and Environmental Sciences. “Conventional thermodynamic equations predict that water is released at too shallow a depth to occur at the known locations of volcanoes and earthquakes. But when you factor in the overstepping we’ve discovered, the locations coincide. The idea of overstepping is an enormous paradigm shift.”

His research is supported by a three-year $419,247 grant from the National Science Foundation.

As one tectonic plate is pushed beneath another in a subduction zone, sediments and minerals are carried deep into the Earth, with pressure and temperature mounting with increasing depth. Early in the process liquid water is squeezed from the pore spaces between rocks, but many minerals – such as micas, serpentines, and chlorites – contain water as part of their mineral structure. Chlorite, for example, contains about 10 percent water by weight. When water-bearing minerals finally succumb to increased temperature and pressure, they release water.

The water acts as a lubricant in the fault zone created between two plates, reducing the strain on the fault and allowing the plates to slide past one another, producing an earthquake. Subduction zones produce some of the world’s biggest and most destructive earthquakes; the largest magnitude earthquake yet recorded – a magnitude 9.5 earthquake in 1960 near Valdivia, Chile – occurred in a subduction zone. The water also acts as a flux on surrounding rock, depressing the melting temperature of rock, which melts into magma that rises to the surface and erupts as a volcano.

At the point at which the water is released, it creates clues Spear tracked back to its origin. New minerals form in the metamorphosing crust, including garnet, which is produced by the breakdown of water-bearing chlorite. The garnet forms under pressure, and sometimes, as it does so, it traps fragments of surrounding minerals in its grip, fragments that retain a record of the pressure under which the garnet formed. Spear found such garnets, which formed around tiny fragments of quartz, on an island in the Greek Cyclades.

In his lab, Spear and his graduate students used Raman spectroscopy – commonly used in chemistry to identify molecular composition of a sample – to examine the quartz embedded in the garnet. In Raman spectroscopy, laser light is shined onto a sample, and the energy of the photons is shifted up or down based on the interactions between the light and the sample. The difference between the frequency of the outgoing and returning light provides a definitive structure signature.

Quartz at ambient pressure produces a well-known signature. But the peak of the signature from the quartz in the Cyclades samples was shifted to a higher value, indicating the pressure on the grain. Because the Raman signal shift of quartz has been carefully calibrated, Spear was able to use it to determine the pressure, and therefore the depth and temperature, at which the garnet crystallized around the quartz.

“What we discovered when we did this is that the garnet forms not at the shallow depth where the thermodynamic calculations predicted, but much deeper down, near the origin of volcanoes and earthquakes,” said Spear.

The finding also indicates that the garnet doesn’t crystalize at equilibrium, as is the basis of thermodynamic calculations predicting that process. That, said Spear, “was a total surprise.” While initiation of most processes requires activation energy – or overstepping – to some extent, researchers always assumed that the activation energy to initiate nucleation of garnet would be trivial. But the results suggest significant overstepping of 50 to 70 degrees Celsius.

The initial research, published in a series of papers beginning in 2014, was based on three samples from a single site on Sifnos. The new funding will support a broader investigation using 10 to 20 samples taken from five separate locations, to determine whether the findings were “a quirk, or a universal truth.” Spear is also working on developing calculations – and a new “maximum driving force method” – that will incorporate observed overstepping to yield more accurate predictions.

Spear’s research fulfills The New Polytechnic, an emerging paradigm for higher education which recognizes that global challenges and opportunities are so great they cannot be adequately addressed by even the most talented person working alone. Rensselaer serves as a crossroads for collaboration—working with partners across disciplines, sectors, and geographic regions—to address complex global challenges, using the most advanced tools and technologies, many of which are developed at Rensselaer. Research at Rensselaer addresses some of the world’s most pressing technological challenges—from energy security and sustainable development to biotechnology and human health. The New Polytechnic is transformative in the global impact of research, in its innovative pedagogy, and in the lives of students at Rensselaer.

Reference:
Adrian E. Castro et al. Reaction overstepping and re-evaluation of peak P‒T conditions of the blueschist unit Sifnos, Greece: implications for the Cyclades subduction zone, International Geology Review (2016). DOI: 10.1080/00206814.2016.1200499

Note: The above post is reprinted from materials provided by Rensselaer Polytechnic Institute.

Scientists capture sounds of volcanic thunder

March 15, 2018

This satellite image shows Bogoslof volcano erupting on May 28, 2017. The eruption began about 18 minutes prior to this image and the cloud rose to an altitude greater than 12 kilometers (40,000 feet) above sea level. Credit: Dave Schneider / Alaska Volcano Observatory & U.S. Geological Survey.

Researchers report in a new study that they’ve documented rumblings of volcanic thunder for the first time, a feat considered nearly impossible by many volcanologists.

Microphones set out to detect volcanic eruptions in Alaska’s Aleutian Islands recorded sounds of Bogoslof volcano erupting over eight months from December 2016 to August 2017. Researchers analyzing the recordings identified several cracking sounds from eruptions on March 8 and June 10 as volcanic thunder, a phenomenon the study authors said has never before been captured in audio recordings.

Observers have described hearing volcanic thunder in the past, but scientists have been unable to disentangle the booms of thunder caused by volcanic lightning from the cacophony of bellows and blasts that accompany an explosive eruption. In the new study, researchers used microphones on a nearby island and maps of volcanic lightning strokes to identify the sounds of thunder.

“It’s something that people who’ve been at eruptions have certainly seen and heard before, but this is the first time we’ve definitively caught it and identified it in scientific data,” said Matt Haney, a seismologist at the Alaska Volcano Observatory in Anchorage and lead author of the new study accepted for publication in Geophysical Research Letters, a journal of the American Geophysical Union.

Analyzing volcanic thunder offers scientists a new way of detecting volcanic lightning and potentially a way to estimate the size of an ash plume, according to Jeff Johnson, a geophysicist at Boise State University who was not connected to the new study.

Haney and his team found the intensity of the thunder matched the intensity of the lightning, meaning researchers might be able to use thunder as a proxy for volcanic lightning, Johnson said. The intensity of lightning in a volcanic plume can tell scientists how big the plume is and how hazardous it might be.

“Understanding where lightning is occurring in the plume tells us about how much ash has been erupted, and that’s something that’s notoriously difficult to measure,” Johnson said. “So if you’re locating thunder over a long area, you could potentially say something about how extensive the plume is.”

Table of Contents

Monitoring impending eruptions

Volcanic eruptions are inherently noisy – explosions of smoke, ash and magma shake the ground and create loud bangs and rumbles that reverberate for miles. Lightning is common in volcanic plumes because particles of ash and ice scrape and collide with each other and become electrified. Researchers assumed volcanic lightning is followed by thunder, as it is during thunderstorms, but they had not yet been able to tease out thunderclaps from the noises of the eruption itself, and many scientists considered it impossible, according to Haney.

In the new study, scientists detected thunder at Bogoslof volcano in Alaska’s Aleutian Islands, a chain of more than 50 volcanic islands in the northern Pacific Ocean.

Researchers constantly monitor the islands from afar for signs of impending eruptions. They use seismic sensors to pick up ground movement before or during an eruption, arrays of microphones to detect sounds of ash exploding skyward and a global network of lightning sensors to detect lightning strokes within an ash plume. Thunderstorms are rare in the Aleutian Islands, so when sensors detect lightning, it most likely means there’s an ongoing eruption, Haney said.

Bogoslof started erupting in December 2016 and erupted more than 60 times through August 2017. Many of the eruptions produced towering clouds of ash more than six kilometers (20,000 feet) high that disrupted air travel throughout the region.

Isolating thunderclaps

Bogoslof’s eruptions on March 8 and June 10 created ideal conditions for observing volcanic thunder, Haney said. Both eruptions generated immense ash plumes that persisted for several hours after the eruptions ceased. Without the din of an eruption in the background, researchers had a better chance of hearing cracks of thunder caused by lightning in the plume.

Worldwide lightning sensors detected lightning strokes in the ash plumes for several minutes after each eruption ended. In the new study, Haney and his colleagues compared the timing and location of the lightning strokes to sounds recorded by a microphone array on a nearby island.

They found the timing and volume of the sounds the microphones picked up matched the lightning data in a way only thunder could.

On March 8, the microphones recorded at least six distinct bursts of sound that occurred three minutes after lightning activity in the plume peaked. The timing of the bursts means they were almost certainly thunderclaps caused by the lightning: The microphones were 60 kilometers (40 miles) away from the volcano, so it would have taken sound three minutes to reach the microphones. That the thunder was picked up so far away also means it was quite loud, Haney said.

On June 10, the microphones picked up bursts of sound coming from a slightly different direction than sounds from the eruption. The location of the bursts corresponded to areas of peak lightning activity, according to the study.

“If people had been observing the eruption in person, they would have heard this thunder,” Haney said. “I expect that going forward, other researchers are going to be excited and motivated to look in their datasets to see if they can pick up the thunder signal.”

Reference:
Volcanic thunder from explosive eruptions at Bogoslof volcano, Alaska. Geophysical Research Letters. DOI: 10.1002/2017GL076911

Note: The above post is reprinted from materials provided by American Geophysical Union.

Scientists find seismic imaging is blind to water

March 15, 2018

seismic waves are essentially blind to a very common substance found throughout the Earth's interior: water. — Researchers at MIT and the Australian National University have found that seismic waves are essentially blind to a very common substance found throughout the Earth’s interior: water. Credit: Christine Daniloff/MIT

When an earthquake strikes, nearby seismometers pick up its vibrations in the form of seismic waves. In addition to revealing the epicenter of a quake, seismic waves can give scientists a way to map the interior structures of the Earth, much like a CT scan images the body.

By measuring the velocity at which seismic waves travel at various depths, scientists can determine the types of rocks and other materials that lie beneath the Earth’s surface. The accuracy of such seismic maps depends on scientists’ understanding of how various materials affect seismic waves’ speeds.

Now researchers at MIT and the Australian National University have found that seismic waves are essentially blind to a very common substance found throughout the Earth’s interior: water.

Their findings, published today in the journal Nature, go against a general assumption that seismic imaging can pick up signs of water deep within the Earth’s upper mantle. In fact, the team found that even trace amounts of water have no effect on the speed at which seismic waves travel.

The results may help scientists reinterpret seismic maps of the Earth’s interior. For instance, in places such as midocean ridges, magma from deep within the Earth erupts through massive cracks in the seafloor, spreading away from the ridge and eventually solidifying as new oceanic crust.

The process of melting at tens of kilometers below the surface removes tiny amounts of water that are found in rocks at greater depth. Scientists have thought that seismic images showed this “wet-dry” transition, corresponding to the transition from rigid tectonic plates to deformable mantle beneath. However, the team’s findings suggest that seismic imaging may be picking up signs of not water, but rather, melt – tiny pockets of molten rock.

“If we see very strong variations [in seismic velocities], it’s more likely that they’re due to melt,” says Ulrich Faul, a research scientist in MIT’s Department of Earth, Atmospheric, and Planetary Sciences. “Water, based on these experiments, is no longer a major player in that sense. This will shift how we interpret images of the interior of the Earth.”

Faul’s co-authors are lead author Christopher Cline, along with Emmanuel David, Andrew Berry, and Ian Jackson, of the Australian National University.

Table of Contents

A seismic twist

Faul, Cline, and their colleagues originally set out to determine exactly how water affects seismic wave speeds. They assumed, as most researchers have, that seismic imaging can “see” water, in the form of hydroxyl groups within individual mineral grains in rocks, and as molecular-scale pockets of water trapped between these grains. Water, even in tiny amounts, has been known to weaken rocks deep in the Earth’s interior.

“It was known that water has a strong effect in very small quantities on the properties of rocks,” Faul says. “From there, the inference was that water also affects seismic wave speeds substantially.”

To measure the extent to which water affects seismic wave speeds, the team produced different samples of olivine – a mineral that constitutes the majority of Earth’s upper mantle and determines its properties. They trapped various amounts of water within each sample, and then placed the samples one at a time in a machine engineered to slowly twist a rock, similar to twisting a rubber band. The experiments were done in a furnace at high pressures and temperatures, in order to simulate conditions deep within the Earth.

“We twist the sample at one end and measure the magnitude and time delay of the resulting strain at the other end,” Faul says. “This simulates propagation of seismic waves through the Earth. The magnitude of this strain is similar to the width of a thin human hair – not very easy to measure at a pressure of 2,000 times atmospheric pressure and a temperature that approaches the melting temperature of steel.”

The team expected to find a correlation between the amount of water in a given sample and the speed at which seismic waves would propagate through that sample. When the initial samples did not show the anticipated behavior, the researchers modified the composition and measured again, but they kept getting the same negative result. Eventually it became inescapable that the original hypothesis was incorrect.

“From our [twisting] measurements, the rocks behaved as if they were dry, even though we could clearly analyze the water in there,” Faul says. “At that point, we knew water makes no difference.”

A rock, encased

Another unexpected outcome of the experiments was that seismic wave velocity appeared to depend on a rock’s oxidation state. All rocks on Earth contain certain amounts of iron, at various states of oxidation, just as metallic iron on a car can rust when exposed to a certain amount of oxygen. The researchers found, almost unintentionally, that the oxidation of iron in olivine affects the way seismic waves travel through the rock.

Cline and Faul came to this conclusion after having to reconfigure their experimental setup. To carry out their experiments, the team typically encases each rock sample in a cylinder made from nickel and iron. However, in measuring each sample’s water content in this cylinder, they found that hydrogen atoms in water tended to escape out of the rock, through the metal casing. To contain hydrogen, they switched their casing to one made from platinum.

To their surprise they found that the type of metal surrounding the samples affected their seismic properties. Separate experiments showed that what in fact changed was the amount of Fe3+ in olivine. Normally the oxidation state of iron in olivine is 2+. As it turns out, the presence of Fe3+ produces imperfections which affect seismic wave speeds.

Faul says that the group’s findings suggest that seismic waves may be used to map levels of oxidation, such as at subduction zones – regions in the Earth where oceanic plates sink down into the mantle. Based on their results, however, seismic imaging cannot be used to image the distribution of water in the Earth’s interior. What some scientists interpreted as water may in fact be melt – an insight that may change our understanding of how the Earth shifts its tectonic plates over time.

“An underlying question is what lubricates tectonic plates on Earth,” Faul says. “Our work points toward the importance of small amounts of melt at the base of tectonic plates, rather than a wet mantle beneath dry plates. Overall these results may help to illuminate volatile cycling between the interior and the surface of the Earth.”

Reference:
Redox-influenced seismic properties of upper-mantle olivine, Nature (2018). DOI:10.1038/nature25764

Note: The above post is reprinted from materials provided by Massachusetts Institute of Technology.

Are palaeontologists naming too many species?

March 15, 2018

Ichthyosaur skeleton Niedersächsisches Landesmuseum Lower Saxony State Museum Germany

A comprehensive new study looking at variations in Ichthyosaurus, a common British Jurassic ichthyosaur (sea-going reptile) also known as ‘Sea Dragons’, has provided important information into recognizing new fossil species.

Professor Judy Massare (SUNY College at Brockport, NY, USA) and Dean Lomax (The University of Manchester) have studied hundreds of specimens of Ichthyosaurus. After their latest research project the pair urge caution in naming new fossil species on the basis of just a few fragmentary or isolated remains.

For their research Prof Massare and Lomax focused on one particular part of the Ichthyosaurus skeleton, the hindfin (or back paddle). The purpose was to evaluate the different forms among the six-known species of Ichthyosaurus. They examined 99 specimens which could provide useful information.

Early in their research, they found different types of hindfin that initially appeared to represent different species. However, the more specimens they examined the more ‘variation’ they uncovered, such as differences in the size and number of bones. They determined that a single hindfin alone could not be used to distinguish among species of Ichthyosaurus, but that a particular variation was more common in certain species.

Lomax explains: “As we have such a large, complete sample size, which is relatively unique among such fossil vertebrates, our study can help illustrate the limitations that palaeontologists face when dealing with few or even just one specimen.”

Their findings show that with only a few specimens, features can be found that differ substantially from one specimen to the next and thus appear as if there are several species. Whereas, in reality, with a much larger sample size the gaps in the ‘unique’ variations are filled in, showing that differences are simply the result of individual variation and a lack of the full picture.

Prof Massare said: “We described a few hindfins, which might have been called a new species if they were found in isolation. Instead, we had enough specimens to determine that it was just an extreme variation of a common form.”

Palaeontologists fall into one of two camps when it comes to naming species, ‘lumpers’ and ‘splitters’. The former ‘lump’ groups of similar specimens together, whereas the latter opt to split-up specimens and distinguish new species. However, in this new study, if the team opted to split-up the specimens based on the variation found, it would suggest a huge number of species.

“If we considered the variation as unique, it would mean we would be naming about 30 new species. This would be similar to what was done in the 19th Century when any new fossil find, from a new location or horizon, was named as a new species if it differed slightly from previously known specimens.

“As lots of new fossil species are named every year, in some cases, such as with fragmentary or limited remains, the decision to name a new species should be considered very carefully.” Added Lomax.

References:

Judy A. Massare, Dean R. Lomax. Hindfins of Ichthyosaurus: effects of large sample size on ‘distinct’ morphological characters. Geological Magazine, 2018; 1 DOI: 10.1017/S0016756818000146
Dean R. Lomax, Mark Evans, Simon Carpenter. An ichthyosaur from the UK Triassic-Jurassic boundary: A second specimen of the leptonectid ichthyosaur Wahlisaurus massarae Lomax 2016. Geological Journal, 2018; DOI: 10.1002/gj.3155

Note: The above post is reprinted from materials provided by University of Manchester.

Scientists discover evidence of early human innovation, pushing back evolutionary timeline

March 15, 2018

The first evidence of human life in the Olorgesailie Basin comes from about 1.2 million years ago. For hundreds of the thousands of years, people living there made and used large stone-cutting tools called handaxes (left). According to three new studies published in Science, early humans in East Africa had–by about 320,000 years ago–begun using color pigments and manufacturing more sophisticated tools (right) than those of the Early Stone Age handaxes, tens of thousands of years earlier than previous evidence has shown in eastern Africa. The sophisticated tools (right) were carefully crafted and more specialized than the large, all-purpose handaxes (left). Many were points designed to be attached to a shaft and potentially used as projectile weapons, while others were shaped as scrapers or awls. The National Museums of Kenya loaned the artifacts pictured above to conduct the analyses published in Science. Credit: Human Origins Program, Smithsonian

Anthropologists at the Smithsonian’s National Museum of Natural History and an international team of collaborators have discovered that early humans in East Africa had — by about 320,000 years ago — begun trading with distant groups, using color pigments and manufacturing more sophisticated tools than those of the Early Stone Age. These newly discovered activities approximately date to the oldest known fossil record of Homo sapiens and occur tens of thousands of years earlier than previous evidence has shown in eastern Africa. These behaviors, which are characteristic of humans who lived during the Middle Stone Age, replaced technologies and ways of life that had been in place for hundreds of thousands of years.

Evidence for these milestones in humans’ evolutionary past comes from the Olorgesailie Basin in southern Kenya, which holds an archeological record of early human life spanning more than a million years. The new discoveries, reported in three studies published March 15 in the journal Science, indicate that these behaviors emerged during a period of tremendous environmental variability in the region. As earthquakes remodeled the landscape and climate fluctuated between wet and dry conditions, technological innovation, social exchange networks and early symbolic communication would have helped early humans survive and obtain the resources they needed despite unpredictable conditions, the scientists say.

“This change to a very sophisticated set of behaviors that involved greater mental abilities and more complex social lives may have been the leading edge that distinguished our lineage from other early humans,” said Rick Potts, director of the National Museum of Natural History’s Human Origins Program.

Potts has been leading the Human Origin Program’s research in Olorgesailie for more than 30 years in collaboration with the National Museums of Kenya. He is the lead author on one of the three Science publications that describe the adaptive challenges that early humans faced during this phase of evolution. Alison Brooks, a professor of anthropology at George Washington University’s Center for the Advanced Study of Human Paleobiology and an associate of the museum’s Human Origins Program, is lead author on the paper that focuses on the evidence of early resource exchange and use of coloring materials in the Olorgesailie Basin. A third paper, by Alan Deino at the Berkeley Geochronology Center and colleagues, details the chronology of the Middle Stone Age discoveries.

The first evidence of human life in the Olorgesailie Basin comes from about 1.2 million years ago. For hundreds of the thousands of years, people living there made and used large stone-cutting tools called handaxes. Beginning in 2002, Potts, Brooks and their team discovered a variety of smaller, more carefully shaped tools in the Olorgesailie Basin. Isotopic dating by Deino and collaborators revealed that the tools were surprisingly old — made between 320,000 and 305,000 years ago. These tools were carefully crafted and more specialized than the large, all-purpose handaxes. Many were points designed to be attached to a shaft and potentially used as projectile weapons, while others were shaped as scrapers or awls.

While the handaxes of the earlier era were manufactured using local stones, the Smithsonian team found small stone points made of non-local obsidian at their Middle Stone Age sites. The team also found larger, unshaped pieces of the sharp-edged volcanic stone at Olorgesailie, which has no obsidian source of its own. The diverse chemical composition of the artifacts matches that of a wide range of obsidian sources in multiple directions 15 to 55 miles away, suggesting exchange networks were in place to move the valuable stone across the ancient landscape.

The team also discovered black and red rocks — manganese and ocher — at the sites, along with evidence that the rocks had been processed for use as coloring material. “We don’t know what the coloring was used on, but coloring is often taken by archeologists as the root of complex symbolic communication,” Potts said. “Just as color is used today in clothing or flags to express identity, these pigments may have helped people communicate membership in alliances and maintain ties with distant groups.”

Hoping to understand what might have driven such fundamental changes in human behavior, the research team integrated data from a variety of sources to assess and reconstruct the ancient environment in which the users of these artifacts lived. Their findings suggest that the period when these behaviors emerged was one of changing landscapes and climate, in which the availability of resources would have been unreliable.

Geological, geochemical, paleobotanical and faunal evidence indicates that an extended period of climate instability affected the region beginning around 360,000 years ago, at the same time earthquakes were continually altering the landscape. Although some researchers have proposed that early humans evolved gradually in response to an arid environment, Potts says his team’s findings support an alternative idea. Environmental fluctuations would have presented significant challenges to inhabitants of the Olorgesailie Basin, prompting changes in technology and social structures that improved the likelihood of securing resources during times of scarcity.

The research teams for the three studies published in Science include collaborators from the following institutions: the Smithsonian Institution, the National Museums of Kenya, George Washington University, the Berkeley Geochronology Center, the National Science Foundation, the University of Illinois at Urbana-Champaign, the University of Missouri, the University of Bordeaux (Centre National de la Recherche Scientifique), the University of Utah, Harvard University, Santa Monica College, the University of Michigan, the University of Connecticut, Emory University, the University of Bergen, Hong Kong Baptist University and the University of Saskatchewan.

Funding for this research was provided by the Smithsonian, the National Science Foundation and George Washington University.

Reference:
Richard Potts, Anna K. Behrensmeyer, J. Tyler Faith, Christian A. Tryon, Alison S. Brooks, John E. Yellen, Alan L. Deino, Rahab Kinyanjui, Jennifer B. Clark, Catherine Haradon, Naomi E. Levin, Hanneke J. M. Meijer, Elizabeth G. Veatch, R. Bernhart Owen, Robin W. Renaut. Environmental dynamics during the onset of the Middle Stone Age in eastern Africa. Science, 2018 DOI: 10.1126/science.aao2200

Note: The above post is reprinted from materials provided by Smithsonian.

60-year-old paleontological mystery of a ‘phantom’ dicynodont

March 14, 2018

Skeleton of the dicynodont Placerias — This is a skeleton of the dicynodont Placerias, a close relative of the newly-discovered Pentasaurus, with dicynodont trackways (Pentasauropus). Credit: Christian Kammerer

A new study has re-discovered fossil collections from a 19th century hermit that validate ‘phantom’ fossil footprints collected in the 1950s showing dicynodonts coexisting with dinosaurs.

Before the dinosaurs, around 260 million years ago, a group of early mammal relatives called dicynodonts were the most abundant vertebrate land animals. These bizarre plant-eaters with tusks and turtle-like beaks were thought to have gone extinct by the Late Triassic Period, 210 million years ago, when dinosaurs first started to proliferate. However, in the 1950s, suspiciously dicynodont-like footprints were found alongside dinosaur prints in southern Africa, suggesting the presence of a late-surviving phantom dicynodont unknown in the skeletal record. These “phantom” prints were so out-of-place that they were disregarded as evidence for dicynodont survival by paleontologists. A new study has re-discovered fossil collections from a 19th century hermit that validate these “phantom” prints and show that dicynodonts coexisted with early plant-eating dinosaurs. While this research enhances our knowledge of ancient ecosystems, it also emphasizes the often-overlooked importance of trace fossils, like footprints, and the work of amateur scientists.

“Although we tend to think of paleontological discoveries coming from new field work, many of our most important conclusions come from specimens already in museums,” says Dr. Christian Kammerer, Research Curator of Paleontology at the North Carolina Museum of Natural Sciences and author of the new study.

The re-discovered fossils that solved this mystery were originally collected in South Africa in the 1870s by Alfred “Gogga” Brown. Brown was an amateur paleontologist and hermit who spent years trying, with little success, to interest European researchers in his discoveries. Brown had shipped these specimens to the Natural History Museum in Vienna in 1876, where they were deposited in the museum’s collection but never described.

“I knew the Brown collections in Vienna were largely unstudied, but there was general agreement that his Late Triassic collections were made up only of dinosaur fossils. To my great surprise, I immediately noticed clear dicynodont jaw and arm bones among these supposed ‘dinosaur’ fossils,” says Kammerer. “As I went through this collection I found more and more bones matching a dicynodont instead of a dinosaur, representing parts of the skull, limbs, and spinal column.” This was exciting — despite over a century of extensive collection, no skeletal evidence of a dicynodont had ever been recognized in the Late Triassic of South Africa.

Before this point, the only evidence of dicynodonts in the southern African Late Triassic was from questionable footprints: a short-toed, five-fingered track named Pentasauropus incredibilis (meaning the “incredible five-toed lizard foot”). In recognition of the importance of these tracks for suggesting the existence of Late Triassic dicynodonts and the contributions of “Gogga” Brown in collecting the actual fossil bones, the re-discovered and newly described dicynodont has been named Pentasaurus goggai (“Gogga’s five-[toed] lizard”).

“The case of Pentasaurus illustrates the importance of various underappreciated sources of data in understanding prehistory,” says Kammerer. “You have the contributions of amateur researchers like ‘Gogga’ Brown, who was largely ignored in his 19th century heyday, the evidence from footprints, which some paleontologists disbelieved because they conflicted with the skeletal evidence, and of course the importance of well-curated museum collections that provide scientists today an opportunity to study specimens collected 140 years ago.”

Reference:
Christian F. Kammerer. The first skeletal evidence of a dicynodont from the lower Elliot Formation of South Africa. Palaeontologia Africana, 2018

Note: The above post is reprinted from materials provided by North Carolina Museum of Natural Sciences.

Scientists helping to improve understanding of plate tectonics

March 14, 2018

Volcanic Eruption — Plate tectonics is responsible for diverse geological phenomena including continental drift, mountain building and the occurrence of volcanoes and earthquakes. Image credit: Walter Lim, Flickr

Scientists at The Australian National University (ANU) are helping to improve understanding of how rocks in Earth’s hot, deep interior enable the motions of tectonic plates, which regulate the water cycle that is critical for a habitable planet.

Research team leader Professor Ian Jackson said tectonic plates were continuously created at mid-ocean ridges and destroyed when they sink back into the Earth’s mantle.

“Plate tectonics is responsible for diverse geological phenomena including continental drift, mountain building and the occurrence of volcanoes and earthquakes,” said Professor Jackson from the ANU Research School of Earth Sciences.

The stirring of the Earth’s interior, which is responsible for the plate motions at the surface, has resulted in the Earth’s gradual cooling over its 4.5 billion-year life.

He said defects allowed the normally strong and hard minerals of the Earth’s deep interior to change their shape and flow like viscous fluid on geological timescales.

“We have found that flaws in the regular atomic packing in the dominant upper-mantle mineral, called olivine, that become more prevalent under oxidising conditions, substantially reduce the speeds of seismic waves,” Professor Jackson said.

Seismic waves, caused by earthquakes, are used to image the Earth’s deep interior in a manner similar to medical CAT scanning.

“Our new findings challenge a long-held theory that defects involving water absorption in these normally dry rocks could control both their viscosity and seismic properties,” Professor Jackson said.

ANU Research School of Earth Sciences (RSES) PhD scholar Chris Cline is the lead author of the study undertaken in collaboration with RSES colleagues and Professor Ulrich Faul at the Massachusetts Institute of Technology in the United States.

The team used specialised equipment in a laboratory at ANU to make synthetic specimens similar to upper mantle rocks and measured their rigidity, which controls seismic wave speeds, under conditions simulating those of the Earth’s mantle.

Professor Jackson said the research was particularly relevant to environments where old, cold, and oxidised tectonic plates sink into the Earth’s hot interior.

“We have the potential to help map the extent of oxidised regions of the Earth’s mantle that play such an important role in the chemical evolution of Earth,” he said.

Reference:
C. J. Cline II, U. H. Faul, E. C. David, A. J. Berry & I. Jackson. Redox-influenced seismic properties of upper-mantle olivine. Nature, 2018 DOI: 10.1038/nature25764

Note: The above post is reprinted from materials provided by Australian National University.

Underwater volcano behavior captured by timely scientific expedition

March 14, 2018

Underwater bathymetric view with gas venting captured in April 2017. Credit: Imperial College London

Researchers got a rare opportunity to study an underwater volcano in the Caribbean when it erupted while they were surveying the area.

The research, published today in the journal Geochemistry, Geophysics, Geosystems, provides new insight into the little-studied world of underwater volcanoes. It investigated a volcano named Kick-’em-Jenny (KeJ), which is thought to be named after the turbulent waters nearby.

The team from Imperial College London, Southampton and Liverpool universities, in collaboration with The University of the West Indies Seismic Research Centre (SRC), were collecting ocean-bottom seismometers aboard the NERC research ship R.R.S. James Cook as part of a larger experiment when they were alerted to the volcano erupting.

Direct observation of submarine eruptions are very rare, but having the ship nearby allowed them to get to the volcano in time to record the immediate aftermath of the eruption.

Using ship-based imaging technology, the team was able to survey the volcano, observing gas coming from the central cone. The data was then combined with previous surveys going back more than 30 years to reveal the long-term pattern of activity.

Kick-’em-Jenny is one of the Caribbean’s most active volcanoes. It sits eight kilometres off the northern coast of the island of Grenada, and was first discovered in 1939 when a 300-metre column of ash and dust was spotted rising from the ocean.

However, volcanic activity at KeJ is usually detected by accompanying seismic activity picked up on land-based seismometers. These recordings show that the volcano is active on a decadal timescale.

Lead author PhD student Robert Allen, from the Department of Earth Science & Engineering at Imperial, said: “There are surveys of the Kick-’em-Jenny area going back 30 years, but our survey in April 2017 is unique in that it immediately followed an eruption. This gave us unprecedented data on what this volcanic activity actually looks like, rather than relying on interpreting seismic signals.”

The team found that the volcano has frequent cycles of lava ‘dome’ growth followed by collapse through landslides. Similar cycles have been recently witnessed on the nearby volcanic island of Montserrat.

Co-author Dr Jenny Collier, from the Department of Earth Science & Engineering at Imperial, said: “Kick-’em-Jenny is a very active volcano but because it is submarine is less well studied than other volcanoes in the Caribbean. Our research shows that whilst it has quite regular cycles, it is on a relatively small scale, which will help inform future monitoring strategies.”

SRC Director Professor Richard Robertson said: “This study has confirmed very useful recent insights on the activity and evolution of Kick-’em-Jenny volcano. For us, the agency with responsibility for monitoring this volcano, the results of this collaborative research project enable us to better quantify our existing model of this volcano and help in developing strategies for managing future eruptions.”

Any volcano on land which was as lively as KeJ would be constantly monitored by satellites and an array of local instruments looking for the slightest change in behaviour that could precede a major volcanic eruption.

Under the ocean this job is much more difficult, as the electromagnetic energy emitted by satellites cannot penetrate the sea surface and instruments are much more difficult to set up on the volcano itself. Scientists therefore know comparatively little about the growth and long-term behaviour of a fully submerged volcanic cone like KeJ.

The most famous submarine volcanoes are those that lead to the formation of new islands, such as the eruption of Surtsey in Iceland in the 1960s. However, rather than a growing cone, the surveys show significant mass loss from KeJ due to frequent landslides in recent decades.

Comparison with recent studies elsewhere has shown that similar, frequent, small volume landslides may be a fundamental mechanism in the long-term evolution of active submarine volcanoes.

Reference:
R. W. Allen, C. Berry, T. J. Henstock, J. S. Collier, F. J-Y. Dondin, A. Rietbrock, J. L. Latchman, R. E. A. Robertson. 30 Years in the Life of an Active Submarine Volcano: A Time-Lapse Bathymetry Study of the Kick-‘em-Jenny Volcano, Lesser Antilles. Geochemistry, Geophysics, Geosystems, 2018; DOI: 10.1002/2017GC007270

Note: The above post is reprinted from materials provided by Imperial College London. Original written by Hayley Dunning.

The early bird got to fly: Archaeopteryx was an active flyer

March 13, 2018

The Munich specimen of the transitional bird Archaeopteryx. It preserves a partial skull (top left), shoulder girdle and both wings slightly raised up (most left to center left), the ribcage (center), and the pelvic girdle and both legs in a 'cycling' posture (right); all connected by the vertebral column from the neck (top left, under the skull) to the tip of the tail (most right). Imprints of its wing feathers are visible radiating from below the shoulder and vague imprints of the tail plumage can be recognized extending from the tip of the tail. — The Munich specimen of the transitional bird Archaeopteryx. It preserves a partial skull (top left), shoulder girdle and both wings slightly raised up (most left to center left), the ribcage (center), and the pelvic girdle and both legs in a ‘cycling’ posture (right); all connected by the vertebral column from the neck (top left, under the skull) to the tip of the tail (most right). Imprints of its wing feathers are visible radiating from below the shoulder and vague imprints of the tail plumage can be recognized extending from the tip of the tail. Credit: ESRF/Pascal Goetgheluck

The question of whether the Late Jurassic dino-bird Archaeopteryx was an elaborately feathered ground dweller, a glider, or an active flyer has fascinated palaeontologists for decades. Valuable new information obtained with state-of-the-art synchrotron microtomography at the ESRF, the European Synchrotron (Grenoble, France), allowed an international team of scientists to answer this question in Nature Communications. The wing bones of Archaeopteryx were shaped for incidental active flight, but not for the advanced style of flying mastered by today’s birds.

Was Archaeopteryx capable of flying, and if so, how? Although it is common knowledge that modern-day birds descended from extinct dinosaurs, many questions on their early evolution and the development of avian flight remain unanswered. Traditional research methods have thus far been unable to answer the question whether Archaeopteryx flew or not. Using synchrotron microtomography at the ESRF’s beamline ID19 to probe inside Archaeopteryx fossils, an international team of scientists from the ESRF, Palacký University, Czech Republic, CNRS and Sorbonne University, France, Uppsala University, Sweden, and Bürgermeister-Müller-Museum Solnhofen, Germany, shed new light on this earliest of birds.

Reconstructing extinct behaviour poses substantial challenges for palaeontologists, especially when it comes to enigmatic animals such as the famous Archaeopteryx from the Late Jurassic sediments of southeastern Germany that is considered the oldest potentially free-flying dinosaur. This well-preserved fossil taxon shows a mosaic anatomy that illustrates the close family relations between extinct raptorial dinosaurs and living dinosaurs: the birds. Most modern bird skeletons are highly specialised for powered flight, yet many of their characteristic adaptations in particularly the shoulder are absent in the Bavarian fossils of Archaeopteryx. Although its feathered wings resemble those of modern birds flying overhead every day, the primitive shoulder structure is incompatible with the modern avian wing beat cycle.

“The cross-sectional architecture of limb bones is strongly influenced by evolutionary adaptation towards optimal strength at minimal mass, and functional adaptation to the forces experienced during life,” explains Prof. Jorge Cubo of the Sorbonne University in Paris. “By statistically comparing the bones of living animals that engage in observable habits with those of cryptic fossils, it is possible to bring new information into an old discussion,” says senior author Dr. Sophie Sanchez from Uppsala University, Sweden

Archaeopteryx skeletons are preserved in and on limestone slabs that reveal only part of their morphology. Since these fossils are among the most valuable in the world, invasive probing to reveal obscured or internal structures is therefore highly discouraged. “Fortunately, today it is no longer necessary to damage precious fossils,” states Dr. Paul Tafforeau, beamline scientist at the ESRF. “The exceptional sensitivity of X-ray imaging techniques for investigating large specimens that is available at the ESRF offers harmless microscopic insight into fossil bones and allows virtual 3D reconstructions of extraordinary quality. Exciting upgrades are underway, including a substantial improvement of the properties of our synchrotron source and a brand new beamline designated for tomography. These developments promise to give even better results on much larger specimens in the future.”

Scanning data unexpectedly revealed that the wing bones of Archaeopteryx, contrary to its shoulder girdle, shared important adaptations with those of modern flying birds. “We focused on the middle part of the arm bones because we knew those sections contain clear flight-related signals in birds,” says Dr. Emmanuel de Margerie, CNRS, France. “We immediately noticed that the bone walls of Archaeopteryx were much thinner than those of earthbound dinosaurs but looked a lot like conventional bird bones,” continues lead author Dennis Voeten of the ESRF. “Data analysis furthermore demonstrated that the bones of Archaeopteryx plot closest to those of birds like pheasants that occasionally use active flight to cross barriers or dodge predators, but not to those of gliding and soaring forms such as many birds of prey and some seabirds that are optimised for enduring flight.”

“We know that the region around Solnhofen in southeastern Germany was a tropical archipelago, and such an environment appears highly suitable for island hopping or escape flight,” remarks Dr. Martin Röper, Archaeopteryx curator and co-author of the report. “Archaeopteryx shared the Jurassic skies with primitive pterosaurs that would ultimately evolve into the gigantic pterosaurs of the Cretaceous. We found similar differences in wing bone geometry between primitive and advanced pterosaurs as those between actively flying and soaring birds,” adds Vincent Beyrand of the ESRF.

Since Archaeopteryx represents the oldest known flying member of the avialan lineage that also includes modern birds, these findings not only illustrate aspects of the lifestyle of Archaeopteryx but also provide insight into the early evolution of dinosaurian flight. “Indeed, we now know that Archaeopteryx was already actively flying around 150 million years ago, which implies that active dinosaurian flight had evolved even earlier!” says Prof. Stanislav Bureš of Palacký University in Olomouc. “However, because Archaeopteryx lacked the pectoral adaptations to fly like modern birds, the way it achieved powered flight must also have been different. We will need to return to the fossils to answer the question on exactly how this Bavarian icon of evolution used its wings,” concludes Voeten.

It is now clear that Archaeopteryx is a representative of the first wave of dinosaurian flight strategies that eventually went extinct, leaving only the modern avian flight stroke directly observable today.

Reference:
Dennis F. A. E. Voeten, Jorge Cubo, Emmanuel de Margerie, Martin Röper, Vincent Beyrand, Stanislav Bureš, Paul Tafforeau, Sophie Sanchez. Wing bone geometry reveals active flight in Archaeopteryx. Nature Communications, 2018; 9 (1) DOI: 10.1038/s41467-018-03296-8

Note: The above post is reprinted from materials provided by European Synchrotron Radiation Facility.

Pterosaurs went out with a bang, not a whimper

March 13, 2018

Some of the Moroccan pterosaur fossils from the study. Top: the mandible (lower jaw) of Alcione elainus, a small pterosaur newly described in this paper. Bottom: part of the ulna (forearm bone) from a giant pterosaur, tentatively identified as Arambourgiania. Note the different scales – the mandible is less than 20 cm long, while the ulna is more than 40 cm long; Arambourgiania would have had a wingspan more than three times that of Alcione. Credit: pbio.2001663

Fossils of six new species of pterosaurs – giant flying reptiles that flew over the heads of the dinosaurs – have been discovered by a research team led by the Milner Centre for Evolution at the University of Bath, revealing that this lineage was killed off in its prime. An analysis of the fossils, publishing 13 March in the open access journal PLOS Biology shows that, contrary to previous studies, there was still remarkable diversity among pterosaurs up to the point of their extinction.

Pterosaurs – prehistoric reptiles popularly known as pterodactyls – were flying cousins of the dinosaurs. Soaring on skin wings supported by a single huge finger, they were the largest animals ever to take wing.

The pterosaurs were previously thought to be declining before the mass extinction at the end of the Cretaceous period, which was caused by an asteroid impact 66 million years ago. However, hundreds of new fossils from the end of the Cretaceous, discovered at sites in northern Morocco, show that the region supported seven species of pterosaur from three different families. It was thought that the rarity of pterosaur fossils from the end of the dinosaur era meant that they were slowly going extinct. But the new study shows that the data had been misleadingly skewed by the dearth of fossils and that the pterosaurs at this time were actually far more diverse than thought.

The new pterosaurs ranged in wingspan from a little over two meters to almost ten meters (from 6 to 30 feet) – almost three times bigger than the largest living bird – and weighed up to 200 kg (440 pounds). The fossils date to just over 66 million years ago, the very end of the Cretaceous period, making these pterosaurs among the last of their kind on Earth. As well as the diversity in size, the authors were also able to show that the species differed significantly in the shape and size of parts of their bodies (such as beak shape, neck length, and wing proportions), suggesting that they occupied distinct ecological niches.

Dr Nick Longrich, from the Milner Centre for Evolution and the Department of Biology & Biochemistry at the University of Bath, and the study’s lead author, said: “To grow so large and still be able to fly, pterosaurs evolved incredibly lightweight skeletons, with the bones reduced to thin-walled, hollow tubes like the frame of a carbon-fiber racing bike.

“But unfortunately, that means these bones are fragile, and so almost none survive as fossils.”

Longrich said he had always found pterosaurs fascinating, and as a university student had dreamed of studying them. Years later in Morocco, he would stumble across a single, small bone mixed in with fossil fish dug up from a phosphate mine. “It was like a light went off,” he said. “I remembered back to the Illustrated Encyclopedia of Pterosaurs, a book I’d practically memorized as an undergraduate. And I thought ‘that’s a nyctosaur.'”

Nyctosaurs, a family of small pterosaurs, hadn’t been proven to survive to the end of the Cretaceous. On a hunch, he looked for more pterosaurs, and found more species – including Tethydraco, a member of the pteranodontids, a family that had been thought to disappear fifteen million years earlier. In addition to the single species previously found in the area, six additional species turned up. “I believe there are many more species to find,” he said.

Co-author of the study, Professor David Martill from the University of Portsmouth said: “Exciting discoveries are being made all the time, and sometimes, just the smallest of bones can radically change our perception of the history of life on Earth.”

Dr Brian Andres, Research Associate at The University of Texas at Austin, also a co-author of the study, added: “The Moroccan fossils tell the last chapter of the pterosaurs’ story – and they tell us pterosaurs dominated the skies over the land and sea, as they had for the previous 150 million years.”

Moroccan paleontologist Professor Nour-Eddine Jalil from the Muséum national d’Histoire naturelle, France commented: “This is a fabulous discovery of pterosaurs from Morocco – they tell us their amazing diversity while we thought them in decline. “The Moroccan phosphates are an open window on a key moment in the history of the Earth, one that shortly preceded the global crisis that swept away, among others, dinosaurs and marine reptiles.”

Reference:
Longrich NR, Martill DM, Andres B (2018) Late Maastrichtian pterosaurs from North Africa and mass extinction of Pterosauria at the Cretaceous-Paleogene boundary. PLoS Biol 16(3): e2001663. DOI: 10.1371/journal.pbio.2001663

Note: The above post is reprinted from materials provided by Public Library of Science.

Ancient giant shark tooth goes missing in Australia

March 13, 2018

The well-preserved tooth is an estimated 2-2.5 million years old and belonged to a Megalodon, regarded as one of the largest and most powerful fish to have ever lived. Credit: Department of Biodiversity, Conservation and Attractions/AFP / Handout

A giant fossilised tooth from a prehistoric shark has gone missing from a supposedly secret location at a remote Australian World Heritage site, and wildlife officials want it back.

The well-preserved tooth, which could be valuable to collectors, is an estimated 2-2.5 million years old and belonged to a Megalodon, regarded as one of the largest and most powerful fish to have ever lived.

“It had quite defined features on it, so you could see the serrated edge of the shark’s tooth, it was probably one of the better specimens we knew of,” said Arvid Hogstrom from Parks and Wildlife in Western Australia.

One of just a few Megalodon specimens in the Ningaloo Coast World Heritage Area, “very few people” knew of its location, he added, without elaborating on exactly how many.

“It is not something someone would have stumbled across and they have been required to put a bit of effort in to get it out of the rock as well,” he said.

“We presume… an amateur collector (has taken it) or someone that just wants to have a fossil sitting on their mantelpiece.”

Hogstrom said that his team had been working on protecting the fossil, which is some 10 centimetres long (3.93 inches), by concealing it with rocks while considering a range of options for its longer-term perseveration.

“But unfortunately someone has beaten us to it,” he said.

“It is in such a remote location and we just don’t check the site every day, we are not exactly sure when it disappeared but we got a report on Friday.”

Megalodon, which can grow up to 15 metres long, are believed to have become extinct 1.6 million years ago.

Note: The above post is reprinted from materials provided by AFP.

Ash from dinosaur-era volcanoes linked with shale oil, gas

March 13, 2018

The eruption of Alaska’s Pavlof Volcano as seen from the International Space Station May 18, 2013. The volcano’s ash cloud rose to 20,000 feet and extended over hundreds of miles of the northern Pacific Ocean. Credit: Photo courtesy of NASA/ISS Crew Earth Observations experiment and Image Science and Analysis Laboratory, Johnson Space Center

Nutrient-rich ash from an enormous flare-up of volcanic eruptions toward the end of the dinosaurs’ reign kicked off a chain of events that led to the formation of shale gas and oil fields from Texas to Montana.

That’s the conclusion of a new study by Rice University geologists that appears this week in Nature Publishing’s online journal Scientific Reports.

“One of the things about these shale deposits is they occur in certain periods in Earth’s history, and one of those is the Cretaceous time, which is around the time of the dinosaurs,” said study lead author Cin-Ty Lee, professor and chair of Rice’s Department of Earth, Environmental and Planetary Sciences. “This was about 90 million to 100 million years ago, which is about the same time as a massive flare-up of arc volcanoes along what is today the Pacific rim of the Western United States.”

Advances in horizontal drilling and hydraulic fracturing over the past 20 years led to a U.S. energy boom in “unconventionals,” a category that includes the shale gas and “tight” oil found in shale fields like the Cretaceous Eagle Ford and Mowry and older ones like the Barnett and Bakken.

“These types of natural gas and oil are in tiny, tiny pores that range from a few millionths of a meter in diameter to a few thousandths of a meter,” Lee said. “The deposits are in narrow bands that can only be accessed with horizontal drilling, and the oil and gas are locked in these little pockets and are only available with techniques like hydraulic fracturing.”

Lee said that there have always been hints of a connection between ancient volcanic eruptions and unconventional shale hydrocarbons. During field trips out to West Texas, he and Rice students noticed hundreds of ash layers in exposed rock that dated to the Cretaceous period when much of western North America lay beneath a shallow ocean.

One of these trips happened in 2014 while Lee and Rice colleagues also were studying how a flare-up of Cretaceous-era arc volcanoes along the U.S. Pacific rim had impacted Earth’s climate through enhanced volcanic production of carbon dioxide.

“We had seen ash layers before, but at this site we could see there were a lot of them, and that got us thinking,” Lee said. Lee, graduate student Hehe Jiang and Rice undergraduates Elli Ronay, Jackson Stiles and Matthew Neal decided to investigate the ash beds in collaboration with Daniel Minisini, a colleague at Shell Oil who had been doing extensive work on quantifying the exact number of ash beds.

“It’s almost continuous,” Lee said. “There’s an ash layer at least every 10,000 years.”

Lee said the team determined that ash had come from hundreds of eruptions that spanned some 10 million years. The layers had been transported several hundred miles east of their volcanic source in California. The ash was deposited on the seafloor after being blown through plumes that rose miles into the atmosphere and drifted over the ocean. Lee and students analyzed samples of the ash beds in the geochemical facilities at Rice.

“Their chemical composition didn’t look anything like it would have when they left the volcano,” he said. “Most of the original phosphorus, iron and silica were missing.”

That brought to mind the oceanic “dead zones” that often form today near the mouths of rivers. Overfertilization of farms pumps large volumes of phosphorus down these rivers. When that hits the ocean, phytoplankton gobble up the nutrients and multiply so quickly they draw all the available oxygen from the water, leaving a “dead” region void of fish and other organisms.

Lee suspected the Cretaceous ash plumes might have caused a similar effect. To nail down whether the ash could have supplied enough nutrients, Lee and his team used trace elements like zirconium and titanium to match ash layers to their volcanic sources. By comparing rock samples from those sources with the depleted ash, the team was able to calculate how much phosphorus, iron and silica were missing.

“Normally, you don’t get any deposition of organic matter at the bottom of the water column because other living things will eat it before it sinks to the bottom,” Lee said. “We found the amount of phosphorus entering the ocean from this volcanic ash was about 10 times more than all the phosphorus entering all the world’s oceans today. That would have been enough to feed an oxygen-depleted dead zone where carbon could be exported all the way down to the sediment.”

The combination of the ashfall and oceanic dead zone concentrated enough carbon to form hydrocarbons.

“To generate a hydrocarbon deposit of economic value, you have to concentrate it,” Lee said. “In this case, it got concentrated because the ashes drove that biological productivity, and that’s where the organic carbon got funneled in.”

Lee said shale gas and tight oil deposits are not found in the ash layers but appear to be associated with them. Because the layers are so thin, they don’t show up on seismic scans that energy companies use to look for unconventionals. The discovery that hundreds of closely spaced ash layers could be a tell-tale sign of unconventionals might allow industry geologists to look for bulk properties of ash layers that would show up on scans, Lee said.

“There also are implications for the nature of marine environments,” he said. “Today, phosphorus is also a limiting nutrient for the oceans, but the input of the phosphorus and iron into the ocean from these volcanoes has major paleoenvironmental and ecological consequences.”

While the published study looked specifically at the Cretaceous and North America, Lee said arc volcano flare-ups at other times and locations on Earth may also be responsible for other hydrocarbon-rich shale deposits.

“I suspect they could,” he said. “The Vaca Muerta field in Argentina is the same age and was behind the same arc as what we were studying. The rock record gets more incomplete as you go further back in time, but in terms of other U.S. shales, the Marcellus in Pennsylvania was laid down more than 400 million years ago in the Ordovician, and it’s also associated with ashes.”

Reference:
Cin-Ty A. Lee, Hehe Jiang, Elli Ronay, Daniel Minisini, Jackson Stiles, Matthew Neal. Volcanic ash as a driver of enhanced organic carbon burial in the Cretaceous. Scientific Reports, 2018; 8 (1) DOI: 10.1038/s41598-018-22576-3

Note: The above post is reprinted from materials provided by Rice University. Original written by Jade Boyd.

Mexico’s 2017 earthquake emerged from a growing risk zone

March 12, 2018

Map shows earthquake epicenters (surrounded in light red) offshore where the Cocos and North American tectonic plates meet. The newer fault zone is inland, the black lines mark the changing trajectories of abyssal hills atop the descending Cocos Plate. Blue-shaded areas in this zone are where subduction angles remain steep. The pink area, below Mexico City, is a transition zone where another earthquake could occur. The 2017, 1999 and 1980 quake epicenters are in a red-shaded zone to the southeast that is considered to be at most risk for quakes. Credit: Diego Melgar

Under Mexico, where the Cocos Plate from the Pacific Ocean slides under the North American Plate, a bending line of hills, created when the seafloor first formed, sits atop a flattened area of subduction.

That newly recognized combination, scientists report, has created a fault that likely explains last September’s Puebla earthquake, scientists report.

On Sept. 19, a 7.1 magnitude quake struck 55 kilometers (34 miles) south of Puebla and 100 kilometers (62 miles) from Mexico City. It caused damage from the capital southeast through the states of Puebla and Morelos. In Mexico City alone, there were 228 deaths and more than 40 buildings collapsed.

“The 2017 earthquake was peculiar but not all that uncommon,” said University of Oregon seismologist Diego Melgar, lead author of a newly published paper. “The question became could earthquakes like this one occur closer to Mexico City? The answer is uncertain but it seems like it is unlikely.”

In a geometry-heavy analysis published online ahead of print in the journal Geophysical Research Letters, a seven-member research team of U.S. and Mexican scientists mapped a zone of high earthquake risks in a line going southeast of Mexico City that includes Puebla City, Oaxaca and Tehuacan.

Mexico City is in a hazy area, Melgar said. The map has a spot directly south where a quake conceivably could occur. Similar earthquakes in 1980 and 1999 in less populated areas to the southeast also occurred within the map. The research is part on an on-going effort to better understand Mexico’s earthquake risks.

“This 2017 earthquake was a test for the national capabilities on rapidly reporting an event in a region with a relatively good station coverage, said study co-author Xyoli Pérez-Campos, chief of Mexico’s National Seismological Service. “It also posed new scientific and social questions, of particular significance was how plausible it is to have a similar event closer to Mexico City.”

Inland earthquakes are known to happen, Melgar said, but there has been insufficient information for hazard maps that guide building codes and readiness plans.

“We find that earthquakes like the Puebla earthquake in 2017 are not always prioritized in Mexico when we think about the earthquakes that can happen,” Melgar said. “We need to prepare for these kinds of earthquakes, as well, not just for the earthquakes like 1985 that strike far away along the coast.”

The research focused on the fabric of the seafloor, particularly slightly raised fault lines called abyssal hills. They appear like lines of waves occurring repeatedly outward as mid-ocean ridges spread apart in pulses. The lines can read much like tree rings.

“They record the rates at which the seafloor is being formed,” Melgar said. “By looking at them we can tell if seafloor is being made quickly or slowly.”

Earthquakes in Mexico normally are generated offshore where the two plates converge like those in the Cascadia Subduction Zone from northern California to British Columbia, Canada.

The 8.1 magnitude Mexico City earthquake on Sept. 19, 1985, was a typical one. Centered in the ocean 250 miles west, it killed 10,000 people and destroyed 3,000 buildings. The capital’s susceptibility to earthquake damage is the result of the soft soil of an ancient lake on which the city was built.

“The smaller, inland 2017 earthquake comes along, but it was much closer to the city,” Melgar said. “It also impacted the city because of the lake bed that allows shaking to occur for longer periods than an earthquake on solid bedrock. We wanted to know why the 2017 earthquake happened at that particular location.”

The team showed that the lines of abyssal hills initially occurred at regularly occurring intervals as the Cocos Plate descended under the Mexico. However, that alignment eventually changed dramatically as the depth of areas of subduction shifted under the nation’s surface.

Where the subduction continued at deep angles, hills atop the diving plate shifted to a northeasterly direction. Beginning just south of Mexico City, the alignment of hills shifted, reflecting a zone where plate subduction flattened.

The 2017 earthquake likely was the result of “bending stresses occurring at the transition from flat-slab subduction to steeply dipping subduction,” the researchers concluded. “It’s like the grain on a plank of wood,” Melgar said. “If you bend with the grain or across the grain you might get some resistance. When you go too far, you get a snap.”

Where subduction stays deep, offshore earthquakes will continue to pose the most risk. The shallower subduction zone is at risk for land-based earthquakes.

An 8.2 earthquake near Chiapas that occurred two weeks before Sept. 19 Puebla event also may be related to the misalignment pattern, Melgar said.

Similar flat-slab subduction zones where such misalignment occurs, he said, may be common southward through Guatemala, El Salvador and Nicaragua, and again in Peru and northern Chile.

Reference:
Diego Melgar, Xyoli Pérez-Campos, Leonardo Ramirez-Guzman, Zack Spica, Victor Hugo Espíndola, William C. Hammond, Enrique Cabral-Cano. Bend Faulting at the Edge of a Flat Slab: The 2017 M w7.1 Puebla-Morelos, Mexico Earthquake. Geophysical Research Letters, 2018; DOI: 10.1002/2017GL076895

Note: The above post is reprinted from materials provided by University of Oregon.

Digging up the Precambrian: Fossil burrows show early origins of animal behavior

March 12, 2018

Reconstruction of the late Ediacaran (ca. 550 million years ago) sea floor with burrows of a worm-like animal.This was the first discovery of such deeply penetrating burrows. Credit: Nagoya University

Researchers led by Nagoya University discover penetrative trace fossils from the late Ediacaran of western Mongolia, revealing earlier onset of the “agronomic revolution”.

In the history of life on Earth, a dramatic and revolutionary change in the nature of the sea floor occurred in the early Cambrian (541–485 million years ago): the “agronomic revolution.” This phenomenon was coupled with the diversification of marine animals that could burrow into seafloor sediments. Previously, the sea floor was covered by hard microbial mats, and animals were limited to standing on, resting on, or moving horizontally along those mats. In the agronomic revolution, part of the so-called Cambrian Explosion of animal diversity and complexity, vertical burrowers began to churn up the underlying sediments, which softened and oxygenated the subsurface, created new ecological niches, and thus radically transformed the marine ecosystem into one more like that observed today.

This event has long been considered to have occurred in the early Cambrian Period. However, new evidence obtained from western Mongolia shows that the agronomic revolution began in the late Ediacaran, the final period of the Precambrian, at least locally.

A team of researchers, primarily based in Japan, surveyed Bayan Gol Valley, western Mongolia, and found late Ediacaran trace fossils in marine carbonate rocks. They identified U-shaped, penetrative trace fossils, called Arenicolites, from 11 beds located more than 130 meters below the lowermost occurrence of Treptichnus pedum, widely recognized as the marker of the Ediacaran–Cambrian boundary. The researchers confirmed the late Ediacaran age of the rocks, estimated to be between 555 and 541 million years old, based on the stable carbon isotope record.

“It is impossible to identify the kind of animal that produced the Arenicolites traces,” lead author Tatsuo Oji says. “However, they were certainly bilaterian animals based on the complexity of the traces, and were probably worm-like in nature. These fossils are the earliest evidence for animals making semi-permanent domiciles in sediment. The evolution of macrophagous predation was probably the selective pressure for these trace makers to build such semi-permanent infaunal structures, as they would have provided safety from many predators.”

These Arenicolites also reached unusually large sizes, greater than one centimeter in diameter. The discovery of these large-sized, penetrative trace fossils contradicts the conclusions of previous studies that small-sized penetrative traces emerged only in the earliest Cambrian.

“These trace fossils indicate that the agronomic revolution actually began in the latest Ediacaran in at least one setting,” co-author Stephen Dornbos explains. “Thus, this revolution did not proceed in a uniform pattern across all depositional environments during the Cambrian radiation, but rather in a patchwork of varying bioturbation levels across marine seafloors that lasted well into the early Paleozoic.”

Reference:
Tatsuo Oji, Stephen Q. Dornbos, Keigo Yada, Hitoshi Hasegawa, Sersmaa Gonchigdorj, Takafumi Mochizuki, Hideko Takayanagi, Yasufumi Iryu. Penetrative trace fossils from the late Ediacaran of Mongolia: early onset of the agronomic revolution. Royal Society Open Science, 2018; 5 (2): 172250 DOI: 10.1098/rsos.172250

Note: The above post is reprinted from materials provided by Nagoya University.

Unique diamond impurities indicate water deep in Earth’s mantle

March 11, 2018

Diamond crystal on kimberlite from South Africa. Credit: Shutterstock

A UNLV scientist has discovered the first direct evidence that fluid water pockets may exist as far as 500 miles deep into the Earth’s mantle.

Groundbreaking research by UNLV geoscientist Oliver Tschauner and colleagues found diamonds pushed up from the Earth’s interior had traces of unique crystallized water called Ice-VII.

The study, “Ice-VII inclusions in Diamonds: Evidence for aqueous fluid in Earth’s deep Mantle,” was published Thursday in the journal Science.

In the jewelry business, diamonds with impurities hold less value. But for Tschauner and other scientists, those impurities, known as inclusions have infinite value, as they may hold the key to understanding the inner workings of our planet.

For his study, Tschauner used diamonds found in China, the Republic of South Africa, and Botswana that surged up from inside Earth. “This shows that this is a global phenomenon,” the professor said.

Scientists theorize the diamonds used in the study were born in the mantle under temperatures reaching more than 1,000-degrees Fahrenheit.

The mantle – which makes up more than 80 percent of the Earth’s volume – is made of silicate minerals containing iron, aluminum, and calcium among others.

And now we can add water to the list.

The discovery of Ice-VII in the diamonds is the first known natural occurrence of the aqueous fluid from the deep mantle. Ice-VII had been found in prior lab testing of materials under intense pressure. Tschauner also found that while under the confines of hardened diamonds found on the surface of the planet, Ice-VII is solid. But in the mantle, it is liquid.

“These discoveries are important in understanding that water-rich regions in the Earth’s interior can play a role in the global water budget and the movement of heat-generating radioactive elements,” Tschauner said.

This discovery can help scientists create new, more accurate models of what’s going on inside the Earth, specifically how and where heat is generated under the Earth’s crust.

In other words: “It’s another piece of the puzzle in understanding how our planet works,” Tschauner said.

Of course, as it often goes with discoveries, this one was found by accident, explained Tschauner.

“We were looking for carbon dioxide,” he said. “We’re still looking for it, actually,”

The study was co-authored by UNLV geoscience professor Shichun Huang, along with colleagues from the University of Chicago, the California Institute of Technology, China University of Geosciences, the University of Hawaii at Manoa, and the Royal Ontario Museum, Toronto.

Reference:
O. Tschauner, S. Huang, E. Greenberg, V. B. Prakapenka, C. Ma, G. R. Rossman, A. H. Shen, D. Zhang, M. Newville, A. Lanzirotti, K. Tait. Ice-VII inclusions in diamonds: Evidence for aqueous fluid in Earth’s deep mantle. Science, 2018; 359 (6380): 1136 DOI: 10.1126/science.aao3030

Note: The above post is reprinted from materials provided by University of Nevada, Las Vegas. Original written by Francis McCabe.

International ocean drilling expedition obtains unique record of plate tectonic rifting and changing climate in Greece

March 9, 2018

IODP Expedition 381 collected 1.6 kilometers of sediment core from the Corinth Rift in Greece. Credit: University of Southampton

Core samples taken during an international ocean drilling expedition are yielding the most high-resolution, extended record of continental rifting ever obtained.

A team of researchers from around the world, working as part of the Corinth Active Rift Development expedition, collected 1.6 kilometers (one mile) of sediment core and data from boreholes at three different locations in the Gulf of Corinth in Central Greece. The samples provide a continuous, high resolution record of complex changes in past environment and rift-faulting rates over at least the last one million years.

The Corinth Rift is one of the most seismically active areas in Europe where one of the Earth’s tectonic plates is being ripped apart causing geological hazards including earthquakes, tsunamis and landslides. This rifting process is the focus of the International Ocean Discovery Program (IODP) Expedition 381 led by Co-Chief Scientists Professor Lisa McNeill from the University of Southampton and Professor Donna Shillington of the Lamont-Doherty Earth Observatory of Columbia University in the USA.

The Expedition team collected the core samples whilst aboard the drilling vessel Fugro Synergy between October and December 2017. The cores were then opened, analysed and sampled by the scientific team in February 2018 during a month of intensive work at the University of Bremen in Germany.

Analysis of the cores recovered from deep below the seafloor reveals a series of very complex changes in the chemical and biological conditions within the waters of the basin over the last approximately 0.5 million years. These changes are driven by the global growth and shrinkage of the Earth’s ice sheets, which in turn control the height of global sea level.

Fluctuations in sea level cause the Gulf of Corinth basin to switch between a normal marine environment, when the Gulf was connected to the world’s oceans, and a wide range of more complex conditions when sea level is low. The rift’s sediments show that an unusual range of organisms lived within the basin under these complex conditions.

The data collected will be used to calculate how quickly the active earthquake-generating faults are slipping within the rift. This can be used to assess the earthquake hazard potential of the region, which has a populated coastal zone around the Gulf and the city of Athens nearby that can be impacted by future earthquakes.

“The new cores are revealing exactly what we hoped: The potential to accurately calculate the activity of important faults that regularly generate earthquakes with magnitudes 6 to 7 in the area,” said Professor McNeill. “Researchers have been working in the Corinth Rift region for many decades, examining sediments and active fault traces exposed on land and using marine geophysics to image the basin and its structure below the seafloor. The missing piece of the jigsaw puzzle has been the age of the basin sediments that record the history of rifting. We know now that the core samples will enable us to complete this piece of the puzzle. This in turn can be used to calculate fault earthquake potential, and, on a longer timescale, unravel the sequence of events as the rift has evolved.”

Professor Shillington added: “The new discoveries resulting from this expedition will help us to understand other active and ancient rift zones around the world, including others with high hazard potential. The complex story from the microfossils preserved in the sediments and their implications for the living conditions in the basin was unexpected and will significantly widen the impact of the project. Analysis of these results will take many months and we are excited to see what they reveal.”

Continental rifting is fundamental for the formation of new ocean basins, and active rift zones are dynamic regions of high hazard potential. The Corinth Rift is one such location and serves as a unique laboratory in an area of Europe with some of the highest levels of earthquake activity. Geologically the Corinth Rift is very young (only a few million years old) and provides a unique chance to study the very first stages of the splitting apart of a continent and changing climate in the eastern Mediterranean. Young rift basins fill with eroded sediments that are also sensitive recorders of past changes in climate and sea level and of the chemical and biological conditions of the rift basin.

Note: The above post is reprinted from materials provided by University of Southampton.

Deep-sea observatories to offer new view of seabed earthquakes

March 9, 2018

On its current expedition, the drillship JOIDES Resolution is working off the coast of New Zealand. Credit: IODP

A mission to study New Zealand’s largest fault by lowering two sub-seafloor observatories into the Hikurangi subduction zone is underway this week.

The expedition is led by scientists from The Pennsylvania State University (PennState) and GNS Science in New Zealand, and funded by the National Science Foundation (NSF) and the International Ocean Discovery Program (IODP).

“This expedition will yield information that’s key to understanding why destructive tsunamis happen after shallow earthquakes and after underwater landslides,” says James Allan, a program director in NSF’s Division of Ocean Sciences, which funds IODP.

This is the second of two related expeditions aboard the scientific drilling ship JOIDES Resolution, and is aimed at studying the Hikurangi subduction zone to find out more about New Zealand’s largest earthquake and tsunami hazard.

Table of Contents

Studying an undersea earthquake zone

The Hikurangi subduction zone, off the east coast of the North Island, is part of the Pacific Ring of Fire, where the Pacific tectonic plate dives beneath the Australian plate.

Scientists believe the Hikurangi subduction zone is capable of generating earthquakes greater than magnitude 8. Subduction zone earthquakes can produce major tsunamis because there are large and rapid displacements of the seafloor during these quakes.

The voyage’s international science team will sample and analyze cores from below the seabed to understand the rock properties and conditions where these events occur.

“We don’t yet understand the slow-slip processes that cause faults to behave in this way, and we don’t know very much about their relationship to large subduction zone earthquakes,” says expedition co-leader Demian Saffer of PennState.

Expedition co-leader Laura Wallace of GNS Science adds, “slow-slip earthquakes are similar to other earthquakes in that they involve more rapid than normal movement along a fault. However, during a slow-slip event, it takes weeks to months for this fault movement to occur. That’s very different from an earthquake where fault movement happens in a matter of seconds, suddenly releasing energy.”

Best place for slow-slip quake research

Slow-slip events occur at intervals of 12 to 24 months in the study area, and at a relatively shallow depths beneath the seabed—making this region one of the best places in the world for scientists to study them.

Last year’s Kaikôura earthquake triggered a large slow-slip event off New Zealand’s east coast that covered an area of more than 15,000 square kilometers (5,792 square miles). The event started near the current planned IODP expedition; results from this research should shed new light on why it occurred.

Investigating why and where slow-slip events happen is a key missing link in understanding how faults work. Wallace believes that “slow-slip events have great potential to improve our ability to forecast earthquakes.”

Sub-seafloor observatories offer new view of quakes

A major aim of the voyage is installing two borehole observatories into pre-drilled holes 500 meters (1,641 feet) below the seafloor. This will be the first time such observatories have been installed in New Zealand waters.

They will bring new monitoring capabilities to New Zealand, which may help pave the way for offshore instrumentation needed for earthquake and tsunami early warning systems.

The observatories contain high-tech measuring and monitoring equipment inside their steel casings, and will remain beneath the seafloor for five to 10 years. They will collect data on how rocks are strained during slow-slip events, as well as on changes in temperature and the flow of fluids through fault zones.

The information will give scientists important new insights into the behavior of slow-slip events and their relationship to earthquakes along a subduction plate boundary.

Understanding the links between slow-slip events and devastating earthquakes and tsunamis will allow for better risk modeling, say the researchers, and ultimately, better hazard preparation for coastal communities.

Note: The above post is reprinted from materials provided by National Science Foundation.

Vermilion Cliffs

March 7, 2018

The Vermilion Cliffs are the second “step” up in the five-step Grand Staircase of the Colorado Plateau, in northern Arizona and southern Utah. They extend west from near Page, Arizona, for a considerable distance, in both Arizona and Utah.

112,500 acres (45,500 ha) of the region were designated as the Paria Canyon-Vermilion Cliffs Wilderness in 1984. An even greater area was protected within Vermilion Cliffs National Monument in 2000.

Table of Contents

Geology

The Vermilion Cliffs are made up of deposited silt and desert dunes, cemented by infiltrated carbonates and intensely colored by red iron oxide and other minerals, particularly bluish manganese. They are in the physiographic High Plateaus Section and Canyon Lands Section of the Colorado Plateau Province.

Geography

Reddish or vermilion-colored cliffs are found along U.S. Highway 89A near Navajo Bridge, and may be seen from U.S. Highway 89 close to Bitter Springs. Highway 89A runs alongside the Vermilion Cliffs for most of its route between Jacob Lake and Marble Canyon, and offers a great view of the cliffs.

In the spring, after a good winter rain, the valley between Highway 89 and the Vermilion Cliffs will be covered with a carpet of desert mallow and other spring flowers.

In the image below, Highway 89A is atop the yellow rocks capping the first step of the series, the Chocolate Cliffs, and will turn east (to the right) upon entry to the valley below, ultimately crossing the Colorado River at Marble Canyon via the Navajo Bridge.

Diamond discovery under pressure

March 7, 2018

For the first time, scientists have found Earth’s fourth most abundant mineral—calcium silicate perovskite—at Earth’s surface.

“Nobody has ever managed to keep this mineral stable at the Earth’s surface,” said Graham Pearson, a professor in the University of Alberta’s Department of Earth and Atmospheric Sciences and Canada Excellence Research Chair Laureate. He explained the mineral is found deep inside Earth’s mantle, at 700 kilometres.

“The only possible way of preserving this mineral at the Earth’s surface is when it’s trapped in an unyielding container like a diamond,” he explained. “Based on our findings, there could be as much as zetta tonnes (1021) of this perovskite in deep Earth.”

Pearson and colleagues from UBC found the calcium silicate perovskite within a diamond mined from less than one kilometre beneath Earth’s crust, at South Africa’s famous Cullinan Mine, best known as the source of two of the largest diamonds in the British Crown Jewels. Pearson explained that the diamonds from the mine are among not only the most commercially valuable in the world, but they are also the most scientifically valuable, providing insight into the deepest parts of Earth’s core.

He said the particular diamond in question would have sustained more than 24 billion pascals of pressure, equivalent to 240,000 atmospheres. The diamond originated roughly 700 kilometres below Earth’s surface, whereas most diamonds are formed at 150 to 200 kilometres depth.

“Diamonds are really unique ways of seeing what’s in the Earth,” said Pearson. “And the specific composition of the perovskite inclusion in this particular diamond very clearly indicates the recycling of oceanic crust into Earth’s lower mantle. It provides fundamental proof of what happens to the fate of oceanic plates as they descend into the depths of the Earth.”

He said the discovery once again highlights the uniqueness of diamonds being able to preserve things that we otherwise would never be able to see.

“And it’s a nice illustration of how science works. That you build on theoretical predictions in this case from seismology and that once in a while you’re able to make a clinching observation that really proves that the theory works,” said Pearson.

One of the best known diamond researchers in the world, Pearson was also behind the major 2014 discovery of ringwoodite—Earth’s fifth most abundant mineral—in a diamond that pointed to a vast reservoir of water bound to silicate rocks in Earth’s mantle.

Pearson worked with an international team of researchers including one of the best X-ray crystallographers in the world, Fabrizio Nestola from Padova, Italy, as well as scientists from the Deep Carbon Observatory in Washington, DC.

This research also saw Pearson team up with colleagues from the University of British Columbia who together lead a program—the Diamond Exploration Research and Training School, part of NSERC’s Collaborative Research and Training Experience—to train the next generation of highly qualified diamond explorers.

“CaSiO3 perovskite in diamond indicates the recycling of oceanic crust into the lower mantle,” will be published in the March 8 issue of Nature.

Reference:
F. Nestola et al, CaSiO3 perovskite in diamond indicates the recycling of oceanic crust into the lower mantle, Nature (2018). DOI: 10.1038/nature25972

Note: The above post is reprinted from materials provided by University of Alberta.

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Digging up the Precambrian: Fossil burrows show early origins of animal behavior

Unique diamond impurities indicate water deep in Earth’s mantle

International ocean drilling expedition obtains unique record of plate tectonic rifting and changing climate in Greece

Deep-sea observatories to offer new view of seabed earthquakes

Studying an undersea earthquake zone

Best place for slow-slip quake research

Sub-seafloor observatories offer new view of quakes

Vermilion Cliffs

Geology

Geography

Diamond discovery under pressure

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