This is the Cotopaxi volcano, Andes Mountain region of Ecuador. Credit: B. Bernard, courtesy of IG
Researchers from the University of Miami (UM) Rosenstiel School of Marine and Atmospheric Science, the Italian Space Agency (ASI), and the Instituto Geofisico — Escuela Politecnica Nacional (IGEPN) of Ecuador, showed an increasing volcanic danger on Cotopaxi in Ecuador using a powerful technique known as Interferometric Synthetic Aperture Radar (InSAR).
The Andes region in which Cotopaxi volcano is located is known to contain some of the world’s most serious volcanic hazard. A mid- to large-size eruption has the potential to instantaneously melt the summit glacier, resulting in devastating mudflows that would intersect with several towns in the Inter-Andean valley — one of the most densely populated regions of Ecuador.
In August 2015, after four months of increasing seismic tremors and gas emissions, Cotopaxi began to erupt.
“Using the InSAR technique, we were able to detect three centimeters of ground inflation along one flank of the volcano during the pre-eruption period,” said Anieri Morales-Rivera, a UM Rosenstiel School graduate student and lead author of the study.
Ground inflation occurs when new magma moves closer to the surface.
The results of the study are supported by ground-based GPS instruments operated around the volcano by the IGEPN, the Ecuadorian agency responsible for monitoring Cotopaxi.
“From our instruments, we knew there was serious activity within Cotopaxi,” said Patricia Mothes, a chief volcanologist at the IGEPN and coauthor of the study. “The satellite data allowed us to pinpoint where the uplift took place, which in turn helped us better understand how the magma ascended prior to the eruption.”
ASI begun acquiring the SAR imagery in this region half a year before Cotopaxi’s unrest started. Although ASI did not know the eruption was imminent, they were aware of the high risks related to Cotopaxi because of their involvement with Geohazard Supersites and Natural Laboratories (GSNL), a recently formed international initiative between space agencies, volcano monitoring agencies and researchers. The objective of the initiative is to better utilize advanced satellite resources for the monitoring of geological activity and to mitigate the development of a crisis.
“Our work would not have been possible without the many images that ASI had acquired,” said Falk Amelung, a UM Rosenstiel School professor in the Department of Marine Geosciences and a coauthor of the study.
Amelung also noted that the accuracy of the InSAR technique improves with the increased availability of SAR images.
“This satellite data will play an increasingly important role for the monitoring and the study of Ecuadorian volcanoes, said Mothes. “Since it is not possible for us to place dense measurement networks on all potentially active sites in Ecuador — since there are about 40 potentially active volcanoes.”
Future eruptions of the Cotopaxi volcano are expected to be preceded by similar or greater ground inflation. With the GSNL framework in place, Cotopaxi continues to be monitored from space, making it easier to prepare for the next eruption.
Reference:
Anieri M. Morales Rivera, Falk Amelung, Patricia Mothes, Sang-Hoon Hong, Jean-Mathieu Nocquet, Paul Jarrin. Ground deformation before the 2015 eruptions of Cotopaxi volcano detected by InSAR. Geophysical Research Letters, 2017; 44 (13): 6607 DOI: 10.1002/2017GL073720
An illustration of the 110-million-year-old Borealopelta markmitchelli discovered in Alberta, Canada. Credit: Royal Tyrrell Museum of Palaeontology, Drumheller, Canada
Researchers reporting in Current Biology on August 3 have named a new genus and species of armored dinosaur. The 110-million-year-old Borealopelta markmitchelli discovered in Alberta, Canada, on view at the Royal Tyrrell Museum of Palaeontology, belongs to the nodosaur family. Now, an analysis of the 18-foot-long (5.5 m) specimen’s exquisitely well-preserved form, complete with fully armored skin, suggests that the nodosaur had predators, despite the fact that it was the “dinosaur equivalent of a tank,” weighing in at more than 2,800 pounds (1,300 kg).
The researchers came to that conclusion based on studies of the dinosaur’s skin, showing that Borealopelta exhibited countershading, a common form of camouflage in which an animal’s underside is lighter than its back. The scientists say the discovery suggests that the nodosaur faced predation stress from meat-eating dinosaurs.
“Strong predation on a massive, heavily-armored dinosaur illustrates just how dangerous the dinosaur predators of the Cretaceous must have been,” says Caleb Brown, a scientist at the Royal Tyrrell Museum.
The specimen was found by accident on March 21, 2011, by mining machine operator Shawn Funk at the Suncor Millennium Mine in Alberta. He noticed that there was something unusual about some of the rock formations. The Royal Tyrrell Museum was notified and sent a crew, including Curator of Dinosaurs Donald Henderson, to take a look. They soon realized that the rocks contained an armored dinosaur.
“Finding the remains of an armored dinosaur that was washed far out to sea was huge surprise,” Henderson says. “The fact that it was so well preserved was an even bigger surprise.”
The real work began when the specimen arrived back at the museum. Over the last five and a half years, museum technician Mark Mitchell spent more than 7,000 hours slowly and gently removing rock from around the specimen to reveal the exceptional, fossilized dinosaur inside. The new species is named in Mitchell’s honor.
The specimen now represents the best-preserved armored dinosaur ever found, and one of the best dinosaur specimens in the world, the researchers say.
“This nodosaur is truly remarkable in that it is completely covered in preserved scaly skin, yet is also preserved in three dimensions, retaining the original shape of the animal,” says Brown. “The result is that the animal looks almost the same today as it did back in the Early Cretaceous. You don’t need to use much imagination to reconstruct it; if you just squint your eyes a bit, you could almost believe it was sleeping… It will go down in science history as one of the most beautiful and best preserved dinosaur specimens — the Mona Lisa of dinosaurs.”
The condition of the specimen made it possible for Brown, Henderson, and an international team of colleagues to document the pattern and shape of scales and armor across the body. They also used chemical analysis of organic compounds in the scales to infer the dinosaur’s pigmentation pattern.
Those studies revealed that the dinosaur had reddish-brown-pigmented skin with countershading across its the body. Although countershading is common, the findings come as surprise because Borealopelta’s size far exceeds that of countershaded animals alive today. It suggests the dinosaur was under enough pressure from predators to select for concealment.
The remarkable specimen is sure to inspire many more studies by Brown’s team and others. For instance, researchers are examining the dinosaur’s preserved gut contents to find out the nature of its last meal, and working to characterize the body armor in even greater detail.
“This remarkable specimen illustrates just how unique and important the fossil record of Alberta is, and highlights the mandate of the Museum in the research, preservation, and education of these amazing resources,” said Andrew Neuman, executive director at the Royal Tyrrell Museum.
Reference:
Brown et al. An Exceptionally Preserved Three-Dimensional Armored Dinosaur Reveals Insights into Coloration and Cretaceous Predator-Prey Dynamics. Current Biology, 2017 DOI: 10.1016/j.cub.2017.06.071
Note: The above post is reprinted from materials provided by Cell Press.
In this illustration by Marianne Collins/Royal Ontario Museum shows a Capinatator praetermissus. Long before dinosaurs roamed the Earth, a bizarre creature swam the seas, a miniaturized prequel of “Jaws.” The Capinatator didn’t even have a face. Instead 50 curved rigid spines jutted out of its head. And when some unsuspecting critter came too close, those jaw-like spines snapped together and dinner was served. Credit: Marianne Collins/Royal Ontario Museum via AP
Long before dinosaurs roamed the Earth, a bizarre creature with a Venus flytrap-like head swam the seas.
Scientists have uncovered fossils of a tiny faceless prehistoric sea worm with 50 spines jutting out of its head. When some unsuspecting critter came too close, its jaw-like spines snapped together and dinner was served.
The discovery reported in Thursday’s journal Current Biology offers a glimpse into the Cambrian explosion of life on Earth about 541 million years ago.
The new creature dubbed Capinatator praetermissus is so different that scientists said the fossils represent not only a new species, but a new genus—a larger grouping of life—as well.
It was only 4 inches long and its spines were about one-third of an inch long. It feasted on smaller plankton and shrimp-like creatures.
It is an ancestor of a group of marine arrow worms called chaetognatha that are abundant in the world’s oceans. The prehistoric version was larger and with far more spines in its facial armory but without the specialized teeth of its descendants, said Derek Briggs of Yale University who led a team that discovered the trove of fossils in two national parks in British Columbia, Canada.
“The spines are like miniature hooks, although more gently curved. They were stiff rather than flexible,” Briggs said in an email. “It’s hard to say why there are so many spines in the fossil example—but presumably thus armed it was a successful predator.”
Capinatator—whose name translates to grasping swimmer—lived 500 million years ago at a time when creatures started getting bigger and more diverse. It’s difficult to find complete fossils belonging to the chaetognatha family because they decayed easily, said Briggs. This latest find, however, was so good that even soft tissue was saved, giving scientists a good idea about what Capinatator looked like.
The discovery expands scientists’ knowledge of a “pretty enigmatic” group of animals from the Cambrian era, said Smithsonian paleobiologist Doug Erwin, who had no role in the research.
Note: The above post is reprinted from materials provided by The Associated Press.
Senckenberg scientists have studied the diet of anatomically modern humans. With their recent study, published in the journal Scientific Reports, they were able to refute the theory that the diet of early representatives of Homo sapiens was more flexible than that of Neanderthals. Just like the Neanderthals, our ancestors had mainly mammoth and plants on their plates — the researchers were unable to document fish as part of their diet. Therefore, the international team assumes that the displacement of the Neanderthals was the result of direct competition.
The first representatives of Homo sapiens colonized Europe around 43,000 years ago, replacing the Neanderthals there approximately 3,000 years later. “Many studies examine the question of what led to this displacement — one hypothesis postulates that the diet of the anatomically modern humans was more diverse and flexible and often included fish,” explains Prof. Dr. Hervé Bocherens of the Senckenberg Center for Human Evolution and Palaeoenvironment (HEP) at the University of Tübingen
Together with his colleague, Dr. Dorothée Drucker, the biogeologist from Tübingen now set out to get to the bottom of this hypothesis. In conjunction with an international team, he studied the dietary habits of early modern man on the basis of the oldest know fossils from the Buran Kaya caves on the Crimean Peninsula in the Ukraine. “In the course of this study, we examined the finds of early humans in the context of the local fauna,” explains Drucker, and she continues, “Until now, all analyses of the diet of early modern humans were based on isolated discoveries; therefore, they are very difficult to interpret.”
In order to reconstruct our ancestor’s menu — despite the lack of a fossil dietary record — the team around the scientists from Tübingen measured the percentage of stable carbon and nitrogen isotopes in the bones of the early humans and the locally present potential prey animals such as Saiga, horses, and deer. In addition, they also analyzed the nitrogen-15 content of individual amino acids, making it possible to not only determine the origin, but also the proportion of the nitrogen. “Our results reveal a very high proportion of the nitrogen isotope 15N in early modern humans,” adds Bocherens, and he continues, “However, contrary to our previous assumptions, these do not originate from the consumption of fish products, but primarily from mammoths.”
And yet another result came as a surprise for the scientists: The proportion of plants in the diet of the anatomically modern humans was significantly higher than in comparable Neanderthal finds — mammoths, on the other hand, appear to have been one of the primary sources of meat in both species.
“According to our results, Neanderthals and the early modern humans were in direct competition in regard to their diet, as well — and it appears that the Neanderthals drew the short straw in this contest,” adds Drucker in conclusion.
Reference:
Dorothée G. Drucker, Yuichi I. Naito, Stéphane Péan, Sandrine Prat, Laurent Crépin, Yoshito Chikaraishi, Naohiko Ohkouchi, Simon Puaud, Martina Lázničková-Galetová, Marylène Patou-Mathis, Aleksandr Yanevich, Hervé Bocherens. Isotopic analyses suggest mammoth and plant in the diet of the oldest anatomically modern humans from far southeast Europe. Scientific Reports, 2017; 7 (1) DOI: 10.1038/s41598-017-07065-3
“Broken Hill Skull” from Kabwe, Zambia. ype specimen of Homo rhodesiensis, renamed as Homo erectus, also sometimes named Homo heidelbergensis or “archaic Homo sapiens”. Credit: Gerbil/Wikipedia
An often cited claim that humans, who are smarter and more technologically advanced than their ancestors, originated in response to climate change is challenged in a new report by a Center for the Advanced Study of Human Paleobiology researcher at George Washington University.
Many scientists have argued that an influx, described as a “pulse,” of new animal species appear in the African fossil record between 2.8 and 2.5 million years ago, including our own genus Homo. Experts believe it takes a broad-scale event like global climate change to spark the origination of so many diverse new species. However, W. Andrew Barr, a visiting assistant professor of anthropology, published a report that says it’s possible the pulse of new species could have occurred by chance and might not be directly related to climate change.
It is generally accepted that when major environmental changes occur, some species will go extinct and others will originate, which can create a cluster or pulse of new species in the fossil record. However, there is not a set definition of what is considered a pulse, so experts have disagreed about which clusters constitute meaningful events and which can be explained as random fluctuations.
Dr. Barr used computer simulation to model what the fossil record might look like over time in the absence of any climate change and found clusters of species originations that were of similar magnitude to the clusters observed in the fossil record. This means random patterns are likely under-credited for their role in speciation fluctuation, he said.
Dr. Barr’s findings mean scientists may need to rethink widely-accepted ideas about why human ancestors became smarter and more sophisticated.
“The idea that our genus originated more than 2.5 million years ago as part of a turnover pulse in direct response to climate change has a deep history in paleonthropology,” Dr. Barr said. “My study shows that the magnitude of that pulse could be caused by random fluctuations in speciation rates. One implication is that we may need to broaden our search for why our genus arose at that time and place.”
He compared the pattern to flipping a coin. If you flip a coin 100 times, you would expect to record 50 heads and 50 tails. However, if you are only looking at 10 coin flips, you could see a greater imbalance, instead recording seven heads and only three tails. This would even out over time, but in the short-run, you could see clusters of these independent coin flips, he said.
Similarly, fluctuations in turnover in Dr. Barr’s model are pronounced, but are caused purely by random processes.
“The idea the the origin of Homo is part of a climate-caused turnover pulse doesn’t really bear out when you carefully look at the evidence and compare it against other possible explanations,” Dr. Barr said.
This research challenges scientists to be careful about the stories they tell about the history of human adaption, Dr. Barr said. Traits that make humans different from our ancestors, like larger brains and greater technological sophistication, could have arisen for a variety of reasons, he said.
“We can sit in the present and tell stories of the past that make sense of our modern day adaptations,” he said. “But these could have evolved for reasons we don’t know.”
The report, “Signal or noise? A null model method for evaluating the significance of turnover pulses,” was published July 31.
Reference:
W. Andrew Barr. Signal or noise? A null model method for evaluating the significance of turnover pulses. Paleobiology, 2017; 1 DOI: 10.1017/pab.2017.21
The ancestral flower was bisexual with multiple whorls (concentric cycles) of petal-like organs, in sets of threes. Credit: Copyright Hervé Sauquet/Jürg Schönenberger
Flowering plants with at least 300,000 species are by far the most diverse group of plants on Earth. They include almost all the species used by people for food, medicine, and many other purposes. However, flowering plants arose only about 140 million years ago, quite late in the evolution of plants, toward the end of the age of the dinosaurs, but since then have diversified spectacularly. No one knows exactly how this happened, and the origin and early evolution of flowering plants and especially their flowers still remains one of the biggest enigmas in biology, almost 140 years after Charles Darwin called their rapid rise in the Cretaceous “an abominable mystery.”
This new study, the “eFLOWER project,” is an unprecedented international effort to combine information on the structure of flowers with the latest information on the evolutionary tree of flowering plants based on DNA. The results shed new light on the early evolution of flowers as well as major patterns in floral evolution across all living flowering plants.
Among the most surprising results is a new model of the original ancestral flower that does not match any of the ideas proposed previously. “When we finally got the full results, I was quite startled until I realized that they actually made good sense,” said Hervé Sauquet, the leader of the study and an Associate Professor at Université Paris-Sud in France. “No one has really been thinking about the early evolution of flowers in this way, yet so much is easily explained by the new scenario that emerges from our models.”
According to the new study, the ancestral flower was bisexual, with both female (carpels) and male (stamens) parts, and with multiple whorls (concentric cycles) of petal-like organs, in sets of threes. About 20% of flowers today have such “trimerous” whorls, but typically fewer: lilies have two, magnolias have three. “These results call into question much of what has been thought and taught previously about floral evolution!,” said Juerg Schoenenberger, a Professor at the University of Vienna, who coordinated the study together with Hervé Sauquet. It has long been assumed that the ancestral flower had all organs arranged in a spiral.
The researchers also reconstructed what flowers looked like at all the key divergences in the flowering plant evolutionary tree, including the early evolution of monocots (e.g., orchids, lilies, and grasses) and eudicots (e.g., poppies, roses, and sunflowers), the two largest groups of flowering plants. “The results are really exciting!” said Maria von Balthazar, a Senior Scientist and specialist of floral morphology and development at the University of Vienna. “This is the first time that we have a clear vision for the early evolution of flowers across all angiosperms.”
The new study sheds new light on the earliest phases in the evolution of flowers and offers for the first time a simple, plausible scenario to explain the spectacular diversity of floral forms. Nevertheless, many questions remain. The fossil record of flowering plants is still very incomplete, and scientists have not yet found fossil flowers as old as the group itself. “This study is a very important step toward developing a new and increasingly sophisticated understanding of the major patterns in the evolution of flowers,” said Peter Crane, President of the Oak Spring Garden Foundation and a colleague familiar with the results of the study. “It reflects great progress and the results on the earliest flowers are especially intriguing.”
Reference:
Hervé Sauquet, Maria von Balthazar, Susana Magallón, James A. Doyle, Peter K. Endress, Emily J. Bailes, Erica Barroso de Morais, Kester Bull-Hereñu, Laetitia Carrive, Marion Chartier, Guillaume Chomicki, Mario Coiro, Raphaël Cornette, Juliana H. L. El Ottra, Cyril Epicoco, Charles S. P. Foster, Florian Jabbour, Agathe Haevermans, Thomas Haevermans, Rebeca Hernández, Stefan A. Little, Stefan Löfstrand, Javier A. Luna, Julien Massoni, Sophie Nadot, Susanne Pamperl, Charlotte Prieu, Elisabeth Reyes, Patrícia dos Santos, Kristel M. Schoonderwoerd, Susanne Sontag, Anaëlle Soulebeau, Yannick Staedler, Georg F. Tschan, Amy Wing-Sze Leung, Jürg Schönenberger. The ancestral flower of angiosperms and its early diversification. Nature Communications, 2017; 8: 16047 DOI: 10.1038/NCOMMS16047
Locations of earthquakes analyzed in the study led by U-M seismologist Yihe Huang. Image credit: Huang, Ellsworth, Beroza, Science Advances 2017
The stresses released by human-induced and naturally occurring earthquakes in the central United States are in many cases indistinguishable, meaning that existing tools to predict shaking damage can be applied to both types.
That’s the main conclusion of a study by a University of Michigan seismologist and two Stanford University colleagues, scheduled for online publication Aug. 2 in the journal Science Advances.
“Our study shows that induced earthquakes and natural earthquakes in the central U.S. are inherently similar, and we can predict the damaging effects of induced earthquakes using the same framework as natural earthquakes,” said Yihe Huang, first author of the Science Advances paper and an assistant professor in the U-M Department of Earth and Environmental Sciences.
“Our finding simplifies the task of hazard assessment because we don’t have to treat the shaking from these two kinds of earthquakes differently,” said co-author Gregory Beroza, co-director of Stanford’s Center for Induced and Triggered Seismicity.
Within the central and eastern U.S., the number of earthquakes has increased dramatically over the past few years. Wastewater disposal in deep wells, often associated with oil and natural gas extraction, is the primary cause of the recent increase in the central U.S., according to the U.S. Geological Survey.
In March, USGS concluded that about 3.5 million people live and work in areas of the central and eastern U.S. with significant potential for damaging shaking from human-caused earthquakes in 2017. Most of them live in Oklahoma and southern Kansas.
A key question is whether these so-called induced earthquakes excite ground motions that are substantially different than those of naturally occurring earthquakes. If that’s the case, then human-induced earthquakes could result in different levels and types of damage to buildings and infrastructure.
But if the ground motions in induced and natural earthquakes are largely the same, then equations used to predict damage from natural earthquakes can also be applied to human-induced quakes.
To answer this question, Huang and her colleagues used available instrumental recordings to estimate the stress drop—the difference between the stress across a fault before and after an earthquake—of 39 moderate-magnitude induced and natural earthquakes in the central U.S and in eastern North America.
They found that the stress drops of induced and natural earthquakes in the central U.S. are “indistinguishable” once the faulting mechanism and the depth of the quakes are accounted for. The finding suggests that ground motion prediction equations, known as GMPEs, used to predict damage from naturally occurring earthquakes can also be applied to induced quakes.
The results are also consistent with the idea that both naturally occurring and induced earthquakes are driven by stresses along geologic faults and that the injection of fluids in deep disposal wells advances the timing of induced earthquakes, triggering them.
The researchers analyzed natural and induced earthquakes with magnitudes between 3.8 and 5.8 in the central U.S. and eastern North America, comprising three populations.
They looked at naturally occurring earthquakes in and around the New Madrid and Wabash Valley seismic zones in the central U.S., as well as induced earthquakes occurring further to the west but east of the Rocky Mountains, mainly in Oklahoma and southern Kansas.
In the central U.S., more than half of the induced earthquakes were shallower than 5 kilometers (3.1 miles), while all of the naturally occurring earthquakes were deeper than 5 kilometers.
In eastern North America, they studied naturally occurring U.S. and Canadian earthquakes around and to the east of the Appalachian Mountains.
“We found that naturally occurring earthquakes in the east may lead to stronger shaking than natural earthquakes in the central U.S., differences that may be due in part to fault type,” said co-author William Ellsworth, co-director of Stanford’s Center for Induced and Triggered Seismicity.
Most eastern earthquakes occur on reverse faults, while most central U.S. induced and natural earthquakes occur on strike-slip faults. Reverse-faulting earthquakes typically have stronger shaking than strike-slip earthquakes.
Between 1980 and 2000, Oklahoma averaged about two earthquakes greater than or equal to magnitude 2.7 per year, according to the U.S. Geological Survey. That number jumped to about 2,500 in 2014 and 4,000 in 2015, then dropped to 2,500 in 2016, according to USGS. On Sept. 3, 2016, a magnitude-5.8 earthquake struck Oklahoma, the state’s largest earthquake to date.
According to USGS, many earthquakes in Oklahoma and other parts of the central U.S. have been triggered by wastewater fluid injection associated with oil and gas operations. In some cases, wastewater disposal in deep wells is associated with hydraulic fracturing sites. However, studies suggest that the fracking process itself is rarely the direct cause of these earthquakes.
Reference:
“Stress drops of induced and tectonic earthquakes in the central United States are indistinguishable” Science Advances (2017). DOI: 10.1126/sciadv.1700772
Aerial image of Tarim Basin in northwest China, where rock samples for the study were obtained. Credit: Photo by NASA Landsat, via Wikimedia Commons (public domain).
Measuring unobservable forces of nature is not an easy feat, but it can make the difference between life and death in the context of an earthquake, or the collapse of a coal mine or tunnel.
To manage the risk of such events, researchers often rely on estimating a quantity called rock stress.
“Rock stress—the amount of pressure experienced by underground layers of rock—can only be measured indirectly because you can’t see the forces that cause it,” explains Hiroki Sone, an assistant professor of civil and environmental engineering and geological engineering at the University of Wisconsin-Madison. “But instruments for estimating rock stress are difficult to use at great depths, where the temperature and pressure increase tremendously.”
Addressing this challenge, Sone and his colleagues in China and Japan have now pushed the limits of rock stress measurements that don’t require temperature-sensitive instruments to new depths, from a previous maximum of 4.5 kilometers (2.8 miles) to a whopping 7 kilometers (4.3 miles).
In a study published in July 2017 in Scientific Reports, the researchers used rocks sampled from a well bore of that depth to show that stress estimates obtained by the so-called anelastic strain recovery method were consistent with a visual analysis of borehole wall images, a reliable but often infeasible approach that requires a specialized scanner.
The scientists conducted their proof-of-principle study in the Tarim Basin in northwest China, an area almost two-thirds the size of Alaska that is surrounded by K2, the world’s second highest mountain after Mount Everest, and several other mountain ranges. The region is well known to historians because of its association with the Silk Road, an ancient trade route between China and the Mediterranean.
Today, in addition to historians and mountain climbers, petroleum companies have taken an interest in Tarim Basin, as it contains some of the largest oil and gas resources in Central Asia. These companies want to understand the region’s geology to assess whether drilling may trigger seismic activity, given that many smaller earthquakes have occurred in the surrounding mountains.
For Sone and his colleagues, this presented a unique opportunity to advance the methodology for measuring rock stress.
“We wanted to test the reliability of the anelastic strain recovery method at up to 7 kilometers depth because its main advantage is that you only need to sample and analyze the rock itself,” Sone says. “It estimates stress indirectly by measuring how much the rock sample expands in different directions after it has been recovered.”
With that kind of depth, the recovery process—pulling a large enough rock sample out of a borehole—can take a few days, which is why the researchers were excited to prove that the method still worked.
For the first time, they measured rock stress even when sensors weren’t attached to the sample until 65 hours after coring and found that the results matched a conventional image analysis of the borehole wall, obtained with a resistivity scanner. While the visual method also worked in this case, it can be infeasible at such great depths because of the scanner’s temperature limitations.
In addition to proving the easier method’s validity at greatly increased depth, the study resolved a longstanding geological puzzle in the Tarim Basin: The rock stress in Earth’s outer shell—which consists of many large pieces of cooler rock (tectonic plates) floating on a very thick layer of hot magma—differs between the Basin’s periphery and its interior.
Other scientists had found evidence for this difference before, but the current study confirmed it.
In the interior of Tarim Basin, tectonic plates are relatively stable, even though they crash and fold up against each other in the periphery, explaining the observed seismic activity. This translates to a lower risk of earthquakes in the interior and informs a petroleum company’s decisions about the depth at which boreholes should be stabilized to minimize the risk of structural collapse.
For earth scientists, the new study is an important validation of a more practical method for estimating rock stress. “These new results give us confidence that we can use the anelastic strain recovery method at greater depths than we thought possible,” Sone says. “As long as the rock deforms the same amount in vertical and horizontal directions, this method is much easier to apply when very high temperatures and pressures in the Earth’s crust challenge the other options in our toolbox.”
Reference:
Dongsheng Sun et al. Stress state measured at ~7 km depth in the Tarim Basin, NW China, Scientific Reports (2017). DOI: 10.1038/s41598-017-04516-9
In the Fountain of Apollo stone (shown in the image) and the four fountains facing the Museo del Prado, the Trochactaeon lamarcki fossils, a species of gastropod which lived around 85 million years ago, are easily seen. Credit: D.M. Freire-Lista /IGEO
The fountains standing next to the Museo del Prado are built using a sedimentary rock full of gastropod shells from the time of the dinosaurs. These fossils have revealed the origin of the stone: forgotten quarries in Redueña, in the province of Madrid, where the building material for the Fountain of Apollo and the Palacio de las Cortes also came from.
The tourists who visit the Museo del Prado can take the opportunity to see fossils of snails that lived alongside dinosaurs millions of years ago. They are embedded in the stone of four small fountains designed by the architect Ventura Rodríguez in the 18th century, which stand next to the art gallery.
Now, researchers from the Institute of Geosciences (IGEO, a CSIC-UCM joint centre) have discovered the old quarries where the rock was extracted in order to sculpt these fountains and other monuments in Madrid. The study was published in the journal AIMS Geosciences.
“These quarries, lost over a century ago, are located in Redueña in the province of Madrid,” says co-author David M. Freire-Lista. “Here the geological formation of the dolomite (a sedimentary rock similar to limestone) known as Castrojimeno presents characteristic features, such as a layer containing fossils that do not appear in other areas.”
Specifically, numerous Trochactaeon lamarcki fossils (measuring up to 2.5 cm), which lived in the Upper Cretaceous approximately 85 million years ago, were identified in the fountain stone, which has proven key for dating and tracing the origin of the rocks.
Through historical documents and direct observation, the researchers confirmed that they are the same quarries that supplied the stone used to construct the jambs, lintels and mantelpieces in the Palacio de las Cortes, the site of the Spanish Parliament.
The same material was also used to build the Fountain of Apollo, located in the Paseo del Prado between the most famous fountains, Neptune and Cybele, whose terrazzo stone was also from Redueña, according to the original plans drawn up by Ventura Rodríguez, although over time, it was replaced by stone from another source.
“The dolomite from Redueña containing gastropods was frequently used in monuments dating back to the 18th century due to its light colour, ease of carving, and the proximity to Madrid,” says Freire-Lista. “Its petrographic and petrophysical properties, most notably its low solubility and porosity, lend it high durability for use in places where water is present, such as these fountains,” he says.
Nevertheless, the researchers warn that the passage of time affects even the most resistant stone, and it is necessary to conduct petrophysical studies using non-destructive techniques to determine the degree of deterioration and to take measures for their successful conservation.
200 million years of geological history in the Trinitarians
In another study published in the journal Ge-conservación, the same authors analysed the material used to construct the Convento de las Trinitarias Descalzas de San Ildefonso in Madrid, where the remains of Miguel de Cervantes lie, finding Cretaceous dolomite (in this instance Tamajón-Redueña stone, without gastropods) in the coats of arms and low reliefs on the church’s façade.
“This convent is constructed using the four traditional building stones most representative of the capital: flint, granite, Cretaceous dolomite and Miocene limestone, and the presence of these four on its façade makes it a showcase of the last 200 million years of geological history of the region of Madrid,” concludes the researcher.
Reference:
David M. Freire-Lista et al. Historical Quarries, Decay and Petrophysical Properties of Carbonate Stones Used in the Historical Center of Madrid (Spain), AIMS Geosciences (2017). DOI: 10.3934/geosci.2017.2.284
Note: The above post is reprinted from materials provided by Plataforma SINC.
Tiny regions of compositionally distinct rock (red material, known as ultra-low velocity zones), collect at Earth’s core-mantle boundary (tan surface), nearly halfway to the center of our planet. Small accumulations of this distinct rock collect near the margins of large thermochemical piles (green) that reside at the base of Earth’s mantle. Credit: Edward Garnero/ASU
A team led by geoscientists from Arizona State University and Michigan State University has used computer modeling to explain how pockets of mushy rock accumulate at the boundary between Earth’s core and mantle.
These pockets, lying roughly 2,900 kilometers (1,800 miles) below the surface, have been known for many years, but previously lacked an explanation of how they formed.
The relatively small rock bodies are termed “ultra-low velocity zones” because seismic waves greatly slow down as they pass through them. Geoscientists have thought the zones are partially molten, yet the pockets are puzzling because many are observed in cooler regions of the deep mantle.
“These small regions have been assumed to be a partially molten version of the rock that surrounds them,” says Mingming Li, lead author of the study, which was published August 2, 2017, in the journal Nature Communications. “But their global distribution and large variations of density, shape, and size suggest that they have a composition different from the mantle.”
Li joined ASU’s School of Earth and Space Exploration (SESE) this month as an assistant professor. He was a graduate student of former SESE associate professor Allen McNamara, also a coauthor on the paper; McNamara is now at Michigan State’s Department of Earth and Environmental Sciences. The additional coauthors are SESE professor Edward Garnero and his PhD student Shule Yu.
“We don’t know what ultra-low velocity zones are,” says McNamara. “They are either hot, partially-molten portions of otherwise normal mantle, or they are something else entirely, some other composition.”
Because seismic evidence allows both possibilities, he says, “We decided to model mantle convection by computer to investigate whether their shapes and positions can answer the question.”
Do pockets relate to blobs?
About year ago, Garnero, McNamara, and SESE associate professor Dan Shim reported that two gigantic structures of rock deep in the Earth are likely made of something different from the rest of the mantle. They called the large structures “thermochemical piles,” or more simply, blobs.
“While the origin and composition of these blobs are unknown,” Garnero said at the time, “we suspect they hold important clues as to how the Earth was formed and how it works today.”
What the big blobs are made of and how they formed still remain unknown, says Garnero. “But the new computer modeling explains how these ultra-low velocity zones are associated with the much bigger blobs.”
Li says, “The ultra-low velocity zones are generally around tens of kilometers tall, and hundreds of kilometers wide or less. They are mostly located near the edges of the much larger blobs, but some of them are detected both inside the blobs and well away from them.”
The outcome of the computer modeling showed that most of these ultra-low velocity zones are different in composition from the surrounding mantle, Li says. What’s more, the modeling showed that pockets of rock with different compositions will migrate from anywhere on the core-mantle boundary towards the margins of the large blobs.
“The margins of the thermochemical piles are where mantle flow patterns converge,” McNamara says, “and therefore these areas provide a ‘collection depot’ for denser types of rock.”
Gathered by heat
The force driving this movement is heat, which powers convection in the mantle.
Earth’s mantle is made of hot rock, but it behaves more like fudge simmering slowly on a stove. In the mantle, heat comes both from radioactivity within the mantle rock and from the planet’s core, the center of which is about as hot as Sun’s surface. Mantle rock responds to this heat with a slow churning—convective—motion.
“The details are not completely clear,” says Li. But the modeling shows that rocks of different composition respond to the convection in a way that gathers compositionally similar materials together. This moves the small pockets of chemically distinct rocks to the edges of the hotter blobs above the core-mantle boundary.
“We ran 3D high-resolution computer modeling and we developed a method to track the movement of both the small pockets of ultra-low velocity zones and the much larger thermochemical piles.” Li explains, “This allowed us to study how the small pockets move around and how their locations can be related to their origin.”
McNamara says, “What was new about our approach—and also computationally challenging—was that the modeling simultaneously took into account vastly different scales of motion.” These ranged from global mantle-scale convection patterns, to the large thermochemical piles in the lower mantle, and down to the very small-scale pockets of ultra-low velocity zone at the bottom.
“What we ultimately found,” he says, “is that if ultra-low velocity zones are caused by melting of otherwise normal mantle, they should be located well inside of the thermochemical piles, where mantle temperatures are the hottest.”
But he adds, “If the ultra-low velocity pockets of rock have a composition different from the ordinary mantle rock, then mantle convection would continually carry them to the edges of piles where they collect.
“This is consistent with what we see in the seismic observations.”
Rocks diving deep?
Where do the different materials in the deep mantle come from in the first place?
“There are several possibilities,” Garnero says. “Some material might be associated with former basaltic oceanic crust that got subducted deeply. Or it might be associated with chemical reactions between the outer core’s iron-rich fluid and the crystalline silicate mantle.”
Garnero says that where the rock in ultra-low velocity zones originally came from is currently unsolved. But the process of collecting this material into small pockets of rock is clear.
“You can have various mechanisms, such as plate tectonics, that push rock of differing chemistries into the deepest mantle anywhere on Earth,” he says.
“But once these different rocks have gone down deep, convection wins and sweeps them to the hot regions, namely, where the continental-sized thermochemical piles reside.”
Reference:
Mingming Li et al, Compositionally-distinct ultra-low velocity zones on Earth’s core-mantle boundary, Nature Communications (2017). DOI: 10.1038/s41467-017-00219-x
Parisite-(La): This new-to-science mineral, predicted by big data analysis, was discovered in Brazil’s northeast state of Bahia. Credit: Luiz Menezes
Applying big data analysis to mineralogy offers a way to predict minerals missing from those known to science, where to find them, and where to find new deposits of valuable minerals such as gold and copper, according to a groundbreaking study.
In a paper published by American Mineralogist, scientists report the first application to mineralogy of network theory (best known for analysis of e.g. the spread of disease, terrorist networks, or Facebook connections).
The results, they say, pioneer a way to reveal mineral diversity and distribution worldwide, mineral evolution through deep time, new trends, and new deposits.
Led by Shaunna Morrison of the Deep Carbon Observatory and DCO Executive Director Robert Hazen (both at the Carnegie Institution for Science in Washington, D.C.), the paper’s 12 authors include DCO colleagues Peter Fox and Ahmed Eleish at the Keck Foundation sponsored Deep-Time Data Infrastructure Data Science Teams at Rensselaer Polytechnic Institute, Troy NY.
“The quest for new mineral deposits is incessant, but until recently mineral discovery has been more a matter of luck than scientific prediction,” says Dr. Morrison. “All that may change thanks to big data.”
Humans have collected a vast amount of information on Earth’s more than 5,200 known mineral species (each of which has a unique combination of chemical composition and atomic structure).
Millions of mineral specimens from hundreds of thousands of localities around the world have been described and catalogued. Databases containing details of where each mineral was discovered, all of its known occurrences, and the ages of those deposits are large and growing by the week.
Databases also record essential information on chemical compositions and a host of physical properties, including hardness, color, atomic structure, and more.
Coupled with data on the surrounding geography, the geological setting, and coexisting minerals, Earth scientists now have access to “big data” resources ripe for analysis.
Until recently, scientists didn’t have the necessary modelling and visualization tools to capitalize on these giant stockpiles of information.
Network analysis offers new insight into minerals, just as complex data sets offer important understanding of social media connections, city traffic patterns, and metabolic pathways, to name a few examples.
“Big data is a big thing,” says Dr. Hazen. “You hear about it in all kinds of fields—medicine, commerce; even the US National Security Agency uses it to analyze phone records—but until recently no one had applied big data methods to mineralogy and petrology.”
“I think this is going to expand the rate of mineral discovery in ways that we can’t even imagine now.”
The network analysis technique enables Earth scientists to represent data from multiple variables on thousands of minerals sampled from hundreds of thousands of locations within a single graph.
These visualizations can reveal patterns of occurrence and distribution that might otherwise be hidden within a spreadsheet.
In other words, big data provides an intimate picture of which minerals coexist with each other, as well as what geological, physical, chemical, and (perhaps most surprising) biological characteristics are necessary for their appearance.
From those insights it’s a relatively simple step to predict what minerals are missing from scientific lists, as well as where to go to find new deposits.
Says Dr. Hazen: “Network analysis can provide visual clues to mineralogists regarding where to go and what to look for. This is a brand new idea in the paper and I think it will open up an entirely new direction in mineralogy.”
Already the technique has been used to predict 145 missing carbon-bearing minerals and where to find them, leading to creation of the Deep Carbon Observatory’s Carbon Mineral Challenge. Ten have been found so far.
The estimate came from a statistical analysis of carbon-bearing minerals known today, then extrapolating how many scientists should be looking for.
Predicted before they were found
“We have used the same kinds of techniques to predict that at least 1,500 minerals of all kinds are ‘missing,’ to predict what some of them are, and where to find them,” Dr. Hazen says.
Says Dr. Morrison: “These new approaches to data-driven discovery allow us to predict both minerals unknown to science today and the location of new deposits.
Additionally, understanding how minerals have changed through geologic time, coupled with our knowledge of biology, is leading to new insights regarding the co-evolution of the geosphere and biosphere. ”
In a test case, the researchers explored minerals containing copper, which plays critical roles in modern society (e.g., pipes, wires), as well as essential roles in biological evolution. The element is extremely sensitive to oxygen, so the nature of copper in a mineral offers a clue to the level of oxygen in the atmosphere at the time the mineral formed.
The investigators also performed an analysis of common minerals in igneous rocks-those formed from a hot molten state. The mineral networks of igneous rocks revealed through big data recreated “Bowen’s reaction series” (based on Norman L. Bowen’s painstaking lab experiments in the early 1900s), which shows how a sequence of characteristic minerals appears as the magma cools.
The analysis showed the exact same sequence of minerals embedded in the mineral networks.
The researchers hope that these techniques will lead to an understanding and appreciation of previously unrecognized mineral relationships in varied mineral deposits.
Mineral networks will also serve as effective visual tools for learning about mineralogy and petrology – the branches of science concerned with the origin, composition, structure, properties, and classification of rocks and minerals.
Network analysis has numerous potential applications in geology, both for research and mineral exploration.
Mining companies could use the technology to predict the locations of unknown mineral deposits based on existing data.
Researchers could use these tools to explain how Earth’s minerals have changed over time and incorporate data from biomarker molecules to show how cells and minerals interact.
And ore geologists hope to use mineral network analysis to lead to valuable new deposits.
Dr. Morrison also hopes to use network analysis to reveal the geologic history of other planets. She is a member of the NASA Mars Curiosity Rover team identifying Martian minerals through X-ray diffraction data sent back to Earth. By applying these tools to analyze sedimentary environments on Earth, she believes scientists may also start answering similar questions about Mars.
“Minerals provide the basis for all our material wealth,” she notes, “not just precious gold and brilliant gemstones, but in the brick and steel of every home and office, in cars and planes, in bottles and cans, and in every high-tech gadget from laptops to iPhones.”
“Minerals form the soils in which we grow our crops, they provide the gravel with which we pave our roads, and they filter the water we drink.”
“This new tool for understanding minerals represents an important advance in a scientific field of vital interest.”
A tsunami can occur as ocean crust (brown area) dives under continental crust (orange), causing the ocean floor to suddenly move. In a region off Alaska, researchers have found a large fault and other evidence indicating that the leading edge of the continental crust has split off, creating a tsunami-prone area where the floor can move more efficiently. Credit: Anne Becel
Scientists probing under the seafloor off Alaska have mapped a geologic structure that they say signals potential for a major tsunami in an area that normally would be considered benign. They say the feature closely resembles one that produced the 2011 Tohoku tsunami off Japan, killing some 20,000 people and melting down three nuclear reactors. Such structures may lurk unrecognized in other areas of the world, say the scientists. The findings appear in the print edition of the journal Nature Geoscience.
The discovery “suggests this part of Alaska is particularly prone to tsunami generation,” said seismologist Anne Bécel of Columbia University’s Lamont-Doherty Earth Observatory, who led the study. “The possibility that such features are widespread is of global significance.” In addition to Alaska, she said, waves could hit more southerly North American coasts, Hawaii and other parts of the Pacific.
Tsunamis can occur as giant plates of ocean crust dive under adjoining continental crust, a process called subduction. Some plates get stuck for decades or centuries and tension builds, until they suddenly slip by each other. This produces a big earthquake, and the ocean floor may jump up or down like a released spring. That motion transfers to the overlying water, creating a surface wave.
The 2011 Japan tsunami was a surprise, because it came partly on a “creeping” segment of seafloor, where the plates move steadily, releasing tension in frequent small quakes that should prevent a big one from building. But researchers are now recognizing it may not always work that way. Off Japan, part of the leading edge of the overriding continental plate had become somewhat detached from the main mass. When a relatively modest quake dislodged this detached wedge, it jumped, unleashing a wave that topped 130 feet in places. The telltale sign of danger, in retrospect: a fault in the seafloor that demarcated the detached section’s boundary landward of the “trench,” the zone where the two plates initially meet. The fault had been known to exist, but no one had understood what it meant.
The researchers in the new study have now mapped a similar system in the Shumagin Gap, a creeping subduction zone near the end of the Alaska Peninsula some 600 miles from Anchorage. The segment is part of a subduction arc spanning the peninsula and the Aleutian Islands. Sailing on a specially equipped research vessel, the scientists used relatively new technology to penetrate deep into the seafloor with powerful sound pulses. By reading the echoes, they created CAT-scan-like maps of both the surface and what is underneath. The newly mapped fault lies between the trench and the coast, stretching perhaps 90 miles underwater more or less parallel to land. On the seafloor, it is marked by scarps about 15 feet high, indicating that the floor has dropped one side and risen on the other. The fault extends down more than 20 miles, all the way to where the two plates are moving against each other.
The team also analyzed small earthquakes in the region, and found a cluster of seismicity where the newly identified fault meets the plate boundary. This, they say, confirms that the fault may be active. Earthquake patterns also suggest that frictional properties on the seaward side of the fault differ from those on the landward side. These differences may have created the fault, slowly tearing the region off the main mass; or the fault may be the remains of a past sudden movement. Either way, it signals danger, said coauthor Donna Shillington, a Lamont-Doherty seismologist.
“With that big fault there, that outer part of the plate could move independently and make a tsunami a lot more effective,” said Shillington. “You get a lot more vertical motion if the part that moves is close to the seafloor surface.” A rough analogy: imagine snapping off a small piece of a dinner plate, laying the two pieces together on a table and pounding the table from below; the smaller piece will probably jump higher than if the plate were whole, because there is less holding it down.
Other parts of the Aleutian subduction zone are already known to be dangerous. A 1946 quake and tsunami originating further west killed more than 160 people, most in Hawaii. In 1964, an offshore quake killed around 140 people with landslides and tsunamis, mainly in Alaska; 19 people died in Oregon and California, and waves were detected as far off as Papua New Guinea and even Antarctica. In July 2017, an offshore quake near the western tip of the Aleutians triggered a Pacific-wide tsunami warning, but luckily it produced just a six-inch local wave.
As for the Shumagin Gap, in 1788, Russian colonists then living on nearby Unga Island recorded a great quake and tsunami that wiped out coastal structures and killed many native Aleut people. The researchers say it may have originated at the Shumagin Gap, but there is no way to be sure. Rob Witter, a geologist with the U.S. Geological Survey (USGS), has scoured area coastlines for evidence of such a tsunami, but so far evidence has eluded him, he said. The potential danger “remains a puzzle here,” he said. “We know so little about the hazards of subduction zones. Every little bit of new information we can glean about how they work is valuable, including the findings in this new paper.”
The authors say that apart from Japan, such a fault structure has been well documented only off Russia’s Kuril Islands, east of the Aleutians. But, Shillington said, “We don’t have images from many places. If we were to look around the world, we would probably see a lot more.” John Miller, a retired USGS scientist who has studied the Aleutians, said that his own work suggests other segments of the arc have other threatening features that resemble both those in the Shumagin and off Japan. “The dangers of areas like these are just now being widely recognized,” he said.
Lamont seismologists have been studying earthquakes in the Aleutians since the 1960s, but early studies were conducted mainly on land. In the 1980s, the USGS collected the same type of data used in the new study, but seismic equipment now able to produce far more detailed images deep under the sea floor made this latest discovery possible, said Bécel. She and others conducted the imaging survey aboard the Marcus G. Langseth, the United States’ flagship vessel for acoustic research. Owned by the U.S. National Science Foundation, it is operated by Lamont-Doherty on behalf the nation’s universities and other research institutions.
Reference:
Anne Bécel, Donna J. Shillington, Matthias Delescluse, Mladen R. Nedimović, Geoffrey A. Abers, Demian M. Saffer, Spahr C. Webb, Katie M. Keranen, Pierre-Henri Roche, Jiyao Li, Harold Kuehn. Tsunamigenic structures in a creeping section of the Alaska subduction zone. Nature Geoscience, 2017; 10 (8): 609 DOI: 10.1038/ngeo2990
Carbon dioxide released into the atmosphere at a glacial pace. Credit: Paul Quackenbush
Some say the world will end in fire, some in ice. One more reason to hold with those who favor fire: USC scientists have found that rock and soil breakdown in glaciers generates more acidity and releases more carbon than other forms of natural weathering, according to a new study.
Perhaps most interestingly, researchers say, it is the elevated oxidation of pyrite, popularly known as “fool’s gold,” in the glacial breakdown that produces increased acidity and leads to CO2 escaping to the atmosphere from rivers and the oceans.
“CO2 has gone up and down repeatedly over time, and we don’t really know why. Our study suggests that this process may play a meaningful role,” said Joshua West, professor of earth sciences and environmental studies at the USC Dornsife College of Letters, Arts and Sciences and the study’s corresponding author.
This means that, over very long earth cycles, nature is self-regulating against future runaway glaciation.
Graduate researcher Mark Torres of USC Dornsife’s Department of Earth Sciences served as the study’s lead author, which published July 31 in the Proceedings of the National Academy of Sciences.
The fool’s gold standard
As oxidized pyrite slowly makes its way from glaciated water to the ocean, it creates an increase in CO2 in the atmosphere.
“We found glacial rivers are rich in dissolved sulfur, and when they’re rich in sulfur, we have found that this tends to be because of the weathering of pyrite or fool’s gold. When these kinds of rivers flow into the ocean, the sulfur causes the transfer of carbon that was previously stored in rocks and the ocean back into the atmosphere,” Torres said.
To measure the amount of carbon released by glacial weathering, Torres, West and the rest of the team analyzed a large database of 7,700 river glacier drainage samples.
The database was made up of a variety of samples collected from all over the world: Argentina, Canada, Greenland, Nepal, Iceland and the United States, among others. Included in the database were earlier field samples that had been collected by West and study co-author Jens Hartmann of the University of Hamburg.
The glacial river samples consistently demonstrated a lower alkalinity-to-carbon ratio than other river samples, which is indicative of pyrite weathering and carbon dioxide release.
A long time getting to Goldilocks
Earth’s slow geologic cycles have acted as a sort of balanced climate control, releasing and absorbing atmospheric carbon dioxide that helps keep our perfect little Goldilocks planet not too hot and not too cold in supporting the life currently on it.
However, there may have been at least one time in the planet’s history hundreds of millions of years ago when it tilted more closely to Frozen’s Queen Elsa than Goldilocks: a period when the Earth was nearly completely frozen, called “Snowball Earth.”
During this time, the atmosphere contained much less oxygen, which is required to weather pyrite. Less oxygen would potentially limit the amount of carbon released by glaciers.
“There were extensive glaciations with ‘Snowball Earth.’ And the evidence suggests that there was little oxygen in the atmosphere at this time, which is maybe why there was no apparent limit on the amount of glacial cover,” Torres said.
In the last few hundreds of thousands of years, though, there has been substantial change between glacial periods — including the Earth’s last ice age, which was just over 11,000 years ago — and our own warmer, interglacial ones. The team believes that the oxidation of glacial pyrite may hold one of the keys to understanding the rise and fall of CO2 during these relatively shorter cycles as well.
That, in turn, could offer additional insights into how our planet has continued to support life for billions of years, and how other planets somewhere out there might hold the same possibility, even deep into the future.
“The types of carbon cycle feedbacks we discuss in our paper operate really slowly, but they can give us insight into the features we might look for in other planets that might be habitable,” Torres said.
Reference:
Glacial weathering, sulfide oxidation, and global carbon cycle feedbacks. DOI: 10.1073/pnas.1702953114
Theodore Them and field assistant Emma Tulsky doing field work in Alberta, Canada. Credit: Benjamin Gill
There could be some good news on the horizon as scientists try to understand the effects and processes related to climate change.
A team of Florida State University scientists has discovered that chemical weathering, a process in which carbon dioxide breaks down rocks and then gets trapped in sediment, can happen at a much faster rate than scientists previously assumed and could potentially counteract some of the current and future climate change caused by humans.
The findings were published in the journal Scientific Reports.
Scientists have generally thought that this process takes hundreds of thousands to millions of years to occur, helping to alleviate warming trends at an exceptionally slow rate.
Rather than potentially millions of years, FSU researchers now suggest it can take several tens of thousands of years.
It’s not a quick fix though.
“Increased chemical weathering is one of Earth’s natural responses to carbon dioxide increases,” said Theodore Them, the lead researcher on the paper and a postdoctoral researcher at Florida State and the National High Magnetic Field Laboratory. “The good news is that this process can help balance the effects of fossil fuel combustion, deforestation and agricultural practices. The bad news is that it will not begin to counteract the excessive amounts of atmospheric carbon dioxide that humans are emitting for at least several thousand years.”
As atmospheric carbon dioxide concentrations increase, the climate gets warmer. The warmer climate speeds up chemical weathering, which consumes carbon dioxide from the atmosphere and mitigates the greenhouse effect, thus leading to a climate cooling.
To conduct the study, the research team determined the rate at which rocks were chemically broken down over a period of rapid warming in the Early Jurassic Epoch called the Toarcian Oceanic Anoxic Event, an interval where a major extinction event occurred about 183 million years ago.
Working with colleagues at Durham University in the United Kingdom and using state-of-the-art analytical instrumentation within the National MagLab’s Geochemistry Group, the researchers processed and measured the trace elements of their rock samples.
“We noticed that, although chemical weathering increased significantly during this time interval, it was not as large as previously hypothesized for this event,” Them said. “What’s really striking, however, is the planet’s ability to respond to these environmental changes on such short timescales.”
This increased chemical weathering process could have another downside.
The researchers’ findings suggest that widespread oxygen-deficient oceans occurred because an excess of nutrients from the breakdown of rocks flowed into the oceans during the Early Jurassic Period.
The researchers predict that future changes in climate and weather patterns due to a warming planet will create more precipitation and increase the amount of river water and nutrients transported to coastal regions. This is expected to increase both the size and duration of future coastal ocean deoxygenation, negatively impacting sea life in those areas.
“Understanding ancient climatic change like this helps us anticipate the timing, implications, and environmental response to better predict future climate scenarios,” said FSU Assistant Professor of Geology Jeremy Owens, a co-author on the paper.
Reference:
Theodore R. Them, Benjamin C. Gill, David Selby, Darren R. Gröcke, Richard M. Friedman, Jeremy D. Owens. Evidence for rapid weathering response to climatic warming during the Toarcian Oceanic Anoxic Event. Scientific Reports, 2017; 7 (1) DOI: 10.1038/s41598-017-05307-y
Weathering of Earth by glaciers may have warmed Earth over eons by aiding the release of carbon dioxide into the atmosphere. A new study shows the cumulative effect may have created negative feedback that prevented runaway glaciation. Credit: Paul Quackenbush
It seems counterintuitive, but over the eons, glaciers may have made Earth warmer, according to a Rice University professor.
Mark Torres, an assistant professor of Earth, environmental and planetary sciences, took a data-driven dive into the mechanics of weathering by glaciation over millions of years to see how glacial cycles affected the oceans and atmosphere and continue to do so.
Torres, who joined the Rice faculty in July, is lead author of a paper in the Proceedings of the National Academy of Sciences. He wanted to know how and when chemicals released by weathering of the land reached the atmosphere and ocean, and what effect they have had.
The study shows that glaciation, through enhanced erosion, probably increased the rate of carbon dioxide released to the environment.
The researchers determined enhanced oxidation of pyrite, an iron sulfide also known as fool’s gold, most likely generated acidity that fed carbon dioxide into the oceans and altered the carbon cycle. The oscillation of glaciers over 10,000 years could have changed atmospheric carbon dioxide by 25 parts per million or more. While this is a significant percentage of the 400 parts per million measured in recent months, present anthropogenic carbon dioxide release is occurring at a much faster rate than it is naturally released by glaciation.
Over long timescales, they found, glaciers’ contribution to the release of carbon dioxide could have acted as a negative feedback loop that may have inhibited runaway glaciation.
“The ocean stores a lot of carbon,” Torres said. “If you change the chemistry of the ocean, you can release some of that stored carbon into the atmosphere as carbon dioxide. This release of carbon dioxide affects Earth’s climate, due to the greenhouse effect.”
Glacial runoff appeared to have an outsize effect on carbon dioxide levels compared with that of rivers in warmer climes. Torres, until recently a postdoctoral researcher at the California Institute of Technology, studied glacier-fed rivers and used existing databases to compare their chemical contents with that of thousands of rivers around the world. The goal was to evaluate the dominant chemical reactions associated with glacial weathering and explore the long-term implications.
“Mainly, we’re thinking about the effect of glaciers and glaciation on the way our planet works,” he said. “In particular, we’re looking at rivers that drain areas of land surface that are covered by glaciers, and whether or not there are any differences in the chemical composition of those rivers.”
The researchers acknowledged that glaciers are equal-opportunity weathering agents, as they also break down silicates in rocks. Silicates release alkalinity that removes carbon from the atmosphere. Still, they believe the net effect of glaciation could be to supply carbon dioxide to the atmosphere rather than to remove it.
The results support a couple of interesting additional theories. One is that billions of years ago in the Archean eon and Paleoproterozoic era, when the atmosphere contained little oxygen, Earth may indeed have been a “snowball” as oxidative weathering in glaciated regions and the subsequent release of carbon would have been less active.
Another is that the growth of a sulfide reservoir in Earth’s crust over time may have helped to stabilize the climate, which is important for maintaining Earth’s habitability over geologic timescales.
Reference:
Mark A. Torres et al. Glacial weathering, sulfide oxidation, and global carbon cycle feedbacks. PNAS, 2017 DOI: 10.1073/pnas.1702953114
Note: The above post is reprinted from materials provided by Rice University. Original written by Mike Williams.
The Siberian Traps lava flows and sills, with the Maymecha River in the background. Credit: Ben Black
A study by a researcher in the Syracuse University College of Arts and Sciences offers new clues to what may have triggered the world’s most catastrophic extinction, nearly 252 million years ago.
James Muirhead, a research associate in the Department of Earth Sciences, is the co-author of an article in Nature Communications (Macmillan Publishers Limited, 2017) titled “Initial Pulse of Siberian Traps Sills as the Trigger of the End-Permian Mass Extinction.”
His research involves Seth Burgess, the article’s lead author and a geologist at the U.S. Geological Survey, and Samuel Bowring, the Robert R. Shock Professor of Geology at the Massachusetts Institute of Technology.
Their findings suggest that the formation of intrusive igneous rock, known as sills, sparked a chain of events that brought the Permian geological period to a close. In the process, more than 95 percent of marine species and 70 percent of land species vanished.
“There have been five major mass extinctions, since life originated on Earth more than 600 million years ago,” says Burgess, who works at the nexus of volcanic and tectonic processes. “Most of these events have been blamed, at various times, on volcanic eruptions and asteroids impacts. By reexamining the timing and connection between magmatism [the movement of magma], climate change and extinction, we’ve created a model that explains what triggered the end-Permian mass extinction.”
Central to their study is a large igneous province (LIP) in Russia called the Siberian Traps. Spanning more than 500,000 square miles, this rocky outpost was the site of nearly a million years of epic volcanic activity. Broad, flat volcanoes likely dispelled significant volumes of lava, ashes and gas, while pushing sulfur dioxide, carbon dioxide and methane to dangerous levels in the environment.
But that’s only part of the story.
“Until recently, the relative timing and duration of mass extinctions and LIP volcanism was obscured by age imprecision,” Muirhead says. “Our model is based on new, high-resolution age data that suggests surface lava flows erupted too early to drive mass extinction. Instead, there was a subinterval of magmatism — a shorter, particular part of the LIP — that triggered a cascade of events causing mass extinction.”
The trigger? Extreme heat given off during the formation of sills.
“Heat from sills exposed untapped, gas-rich sediments to contact metamorphism [the process in which rock minerals and texture are changed by exposure to heat and pressure], thus liberating the massive greenhouse gas volumes needed to drive extinction,” Muirhead says. “Our model links the onset of extinction with the initial pulse of sill emplacement. It represents a critical juncture in the evolution of life on Earth.”
There are two ways that magma forms igneous rock. One way is extrusion, in which magma erupts through volcanic craters and cracks in the Earth’s surface; the other is intrusion, whereby magma forces itself between or through existing formations of rock, without reaching the surface. Common types of intrusion are sills, dykes and batholiths.
Sills in Siberia’s Tunguska Basin, where Muirhead’s team carries out most of its research, likely pushed their way through limestone, coal, clastic rocks and evaporates. The mixture of hot, molten rock and hydrocarbon-bearing coals is thought to have set the stage for massive greenhouse gas release and global-scale climate change.
“Sediment composition and the amount of hydrocarbons [petroleum and natural gas] available within these sediments help us understand whether or not an LIP can trigger a mass extinction,” says Burgess, adding that his team’s model may apply to other extinction events coinciding with LIPs. “Mass extinction can take 10,000 years or less — the blink of an eye, by geological standards — but its effects on the evolutionary trajectory of life are still observable today.”
Reference:
S. D. Burgess, J. D. Muirhead, S. A. Bowring. Initial pulse of Siberian Traps sills as the trigger of the end-Permian mass extinction. Nature Communications, 2017; 8 (1) DOI: 10.1038/s41467-017-00083-9
Note: The above post is reprinted from materials provided by Syracuse University. Original written by Rob Enslin.
Remember the classic flocking scene from Jurassic Park? Alan and the kids are walking over a grassy plain. A flock of ostrich-like dinosaurs appear. Alan is amazed at how similar their movements are to a flock of birds, while the kids are more concerned that they are flocking in their direction…
How dinosaurs move is, of course, fascinating, but also provides vital clues to understanding the biomechanics of locomotion from an evolutionary perspective. A paper published in the July issue of Interface suggests that the movement of birds we see today first began evolving about 50 million years before they first appeared on Earth.
The authors studied fossil footprints left by extinct theropod dinosaurs more than 210 million years ago. Theropods, believed to be the ancestors of modern birds, include all carnivorous species of dinosaurs, like Tyrannosaurus and Velociraptor. They all walked on their two back legs, balancing the front of their body with long tails.
The fossil footprints used in the study all came from one site in Virginia, USA, and are estimated to be about 211 million years old, putting them in the Triassic Period – the early part of dinosaur history. The site is unique because the footprints were made by animals that were actively speeding up or slowing down, which meant that locomotor behaviour could be studied across a range of speeds.
The authors measured step width, or how wide the feet are spaced apart from each other during locomotion, and compared fossil measurements to measurements made from modern bipeds: humans and birds. They found that step width decreased with increasing speed in all groups, which means that as they sped up they tended to place their feet closer to the body midline.
However, whilst step width decreased gradually with speed in the dinosaurs and birds, it changed abruptly (sharp and sudden decreases) as humans switched from walking to running…
In birds and humans this type of pattern has been observed before and paints the same picture: humans have distinct walking and running gaits. In contrast, birds do not; walking smoothly transitions into running as the bird moves faster, going through an intermediate gait of grounded running, where the bird is running, but never having both feet off the ground at the same time.
This research shows that theropods displayed the same continuous locomotor behaviour as today’s birds, suggesting that the unique terrestrial locomotor repertoire of modern birds started to evolve early in dinosaur history.
Lead author Peter Bishop is a self-proclaimed dino-nut:
“I have always wanted to study dinosaurs and other prehistoric animals. But I’ve also had a strong passion for mathematics and physics, and dinosaur biomechanics is where these fields intersect.”
Commenting on future work, he said: “It would be good to find other sites of fossil theropod footprints that show them speeding up or slowing down, so we can measure different parameters to gain further insight. Also, more experimental studies on modern birds moving over different kinds of substrate, firm ground, soft mud, sloppy mud, etc., could provide more clues as to how to interpret dinosaur fossil footprints.”
You’ll never watch Jurassic Park in the same way again.
Reference:
P. J. Bishop et al. Using step width to compare locomotor biomechanics between extinct, non-avian theropod dinosaurs and modern obligate bipeds, Journal of The Royal Society Interface (2017). DOI: 10.1098/rsif.2017.0276
Note: The above post is reprinted from materials provided by The Royal Society.
Lychnothamnus barbatus. Photo Credit: Paul Skawinski, University of Wisconsin Extension
Imagine you’re at work and suddenly, a cheetah pokes its head through your window.
That’s about what Richard McCourt, PhD, and his colleagues dealt with when they came across Lychnothamnus barbatus, a large green alga that was thought to have died in the Western Hemisphere long before the cheetahs here died out.
“This means mainly that we don’t know as much about what’s out there as we could,” said McCourt, associate curator of Botany at the Academy of Natural Sciences of Drexel University and professor in the University’s College of Arts and Sciences. “Lychnothamnus barbatus’ survival isn’t, per se, ecologically earth-shaking, but it changes our view of what the algal flora of North America is composed of and inspires us to keep hunting for more new finds.”
A paper on the find, featuring mapping and analysis by the Academy’s John D. Hall, PhD, and lead-authored by Kenneth Karol, PhD, of the New York Botanical Garden, was published in the American Journal of Botany’s July issue.
Samples of the algae were taken from 14 lakes across Wisconsin — as well as two in Minnesota — between 2012 and 2016. Collectors knew they hadn’t seen it in North America before and, previously, the only record of Lychnothamnus barbatus on the western side of the Atlantic Ocean were Argentinian Cretaceous-era fossils (the same period from which Tyrannosaurus rex fossils are discovered).
“Almost right away we knew we might be dealing with something previously thought to be extinct because it was clearly different from any other species seen in North America,” said McCourt, who helped identify the samples after they were collected. “But we had to look at it closely to confirm the identity and also extract the DNA to confirm.”
Much like cheetahs, Lychnothamnus barbatus is relatively rare in the areas it is currently found. A “stonewort” type of algae, it is known to inhabit areas of Europe and Australasia (the area of Australia, New Zealand and Papua New Guinea).
But this species actually grows relatively tall (one foot) and has a pretty distinct shape to it. So why was it being missed?
“We might not have been missing it — it might be a new invader,” McCourt explained.
Then how could it have made the trip to not just North America, but the Midwest?
“Other species like it have probably been brought in in ballast water on ships and released into the St. Lawrence seaway or other lakes,” McCourt said.
However, the possibility remains that Lychnothamnus barbatus has always been here and we just didn’t know.
“If it went unnoticed, it is probably due to the fact that much of what is in lakes and streams is not thoroughly examined, despite centuries of collecting,” McCourt said. “We need more feet on the ground, hands in the water, collecting.”
And while there were 16 locations in the Midwest that Lychnothamnus barbatus was pulled from, there is the possibility that this dinosaur-era plant may have survived into our era elsewhere in North America.
“We are keeping an eye out, but it’s generally in the kinds of habitats that we collect for the other stonewort species that are known to be in America,” McCourt said. “So if it’s there, we will find out by looking in the right places. The trouble is, we don’t know where the right places are.”
Reference:
First discovery of the charophycean green alga Lychnothamnus barbatus (Charophyceae) extant in the New World. DOI: 10.3732/ajb.1700172
Map showing the Zealandia ‘new continent’, a massive underwater landmass in the South Pacific that has never been properly studied.
Scientists are attempting to unlock the secrets of the “lost continent” of Zealandia, setting sail Friday to investigate the huge underwater landmass east of Australia that has never been properly studied.
Zealandia, which is mostly submerged beneath the South Pacific, was once part of the Gondwana super-continent but broke away some 75 million years ago.
In a paper published in the Geological Society of America’s Journal GSA Today in February, researchers made the case that it should be considered a new continent.
They said it was a distinct geological entity that met all the criteria applied to Earth’s other continents, including elevation above the surrounding area, distinctive geology, a well-defined area and a crust much thicker than that found on the ocean floor.
Covering five million square kilometres (1.9 million square miles), it extends from south of New Zealand northward to New Caledonia and west to the Kenn Plateau off Australia’s east.
Drill ship Joides Resolution will recover sediments and rocks lying deep beneath the sea bed in a bid to discover how the region has behaved over the past tens of millions of years.
The recovered cores will be studied onboard, allowing scientists to address issues such as oceanographic history, extreme climates, sub-seafloor life, plate tectonics and earthquake-generating zones.
Co-chief scientist Jerry Dickens, from Rice University in Texas, said the region was a vital area to study changes in global climate.
“As Australia moved north and the Tasman Sea developed, global circulation patterns changed and water depths over Zealandia fluctuated,” he said.
“This region was important in influencing global changes.”
Australian National University’s Neville Exon said the two-month expedition, setting out Friday from Townsville, would also help better understand major changes in the global tectonic configuration that started about 53 million years ago.
This is around the time that the Pacific “Ring of Fire“, a hotspot for volcanoes and earthquakes, came into existence.
In the February scientific paper, lead author Nick Mortimer said experts had been gathering data to make the case for Zealandia being a continent for more than 20 years.
But their efforts had been frustrated because most of it was hidden beneath the waves.
“If we could pull the plug on the oceans, it would be clear to everybody that we have mountain chains and a big, high-standing continent,” he said at the time.
Note: The above post is reprinted from materials provided by AFP.
International Chronostratigraphic Chart “Version 2017/02”
Click here (PDF or JPG) to download the latest version (v2017/02) of the International Chronostratigraphic Chart.
Translations of the chart: Chinese (v2017/02: PDF or JPG), Finnish (v2017/02: PDF or JPG), American Spanish (v2016/04: PDF or JPG), Spanish (v2015/01: PDF or JPG), Basque (v2015/01: PDF or JPG), Catalan (v2015/01: PDF or JPG), Norwegian (v2015/01: PDF or JPG), Lithuanian (v2015/01: PDF or JPG), Japanese (v2014/02: PDF or JPG), Portuguese (v2013/01: PDF or JPG) and French (v2012).
The old versions can be download at the following links: 2008 (PDF or JPG), 2009 (PDF or JPG), 2010 (PDF or JPG), 2012 (PDF or JPG), 2013/01 (PDF or JPG), 2014/02 (PDF or JPG) , 2014/10 (PDF or JPG), 2015/01 (PDF or JPG)
