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Icy Greenland’s heated geologic past

Continental plates around Greenland.
This is a visualization of the continental plates around Greenland. Credit: NASA’s Goddard Space Flight Center

By mapping the heat escaping from below the Greenland Ice Sheet, a NASA scientist has sharpened our understanding of the dynamics that dominate and shape terrestrial planets.

Dr. Yasmina M. Martos, a planetary scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, mined publicly available magnetic field, gravity and other geologic information for clues about the amount and distribution of heat beneath the portion of the North American continent that is Greenland.

Her resulting heat map exposed a thermal track beneath Greenland that records the movement of a continent through Earth’s history.

Greenland is thought to have slowly moved over a mantle plume, a source of great heat, which left a diagonal scar of warm, dense rock below the surface as the tectonic plate shifted. Greenland moved from a more southern latitude toward the Arctic over 100 million years, a period when the supercontinent Pangaea was breaking up into the drifting continents of today. Eventually, the plume is thought to have formed Iceland above the surface of the ocean through countless volcanic eruptions — a visible trace of the plume’s existence, in contrast to Greenland’s hidden scar.

“I don’t think there is any other place on Earth where a plume history has been recorded by a piece of continent that hasn’t been affected by it at the surface,” Martos said. “But it’s there, so we can use thermal heat to understand the history of the region.”

Tracking these geodynamics of planets helps scientists understand their evolution. But more immediately, the heat information feeds sea-level-change models on Earth by helping scientists predict the behavior of ice. This is particularly important for the surface of land that, in the case of Greenland, is buried below kilometers of ice and so is hard to get to. More than 80 percent of the Greenland is covered by ice.

Where there’s heat, there might be a plume

In an Aug. 1 Geophysical Research Letters paper, Martos and her team mapped the geothermal heat flux, or rate of heat escape, in Greenland. Their models, surprisingly, showed regional variations, plus a path of heat along a peculiar route from the northwest to the southeast of the island.

“We would expect Greenland to have a more uniform signal of geothermal heat flow in its interior, but that’s not the case,” said Martos, the lead author on the paper.

Other authors include Tom A. Jordan and David G. Vaughan from the British Antarctic Survey; Manuel Catalán from the Royal Institute and Observatory of the Spanish Navy; Thomas M. Jordan from Stanford University and University of Bristol, and Jonathan L. Bamber, also from the University of Bristol.

The team suggests the scar was created as the tectonic plate, which includes Greenland, moved through the millennia over a mantle plume that is active below the lithosphere. The lithosphere is Earth’s outer layer; it includes the crust and upper part of the mantle. This plume is a channel of hot rock that starts hundreds of kilometers below the surface. It rises through the mantle and reaches the bottom of the lithosphere. The heat is then transported up through the lithosphere and alters its chemical composition, which thickens the crust.

Because the northwest region of Greenland moved off the plume earlier it appears in Martos’ models to be significantly cooler than the southeast. Though the southern region is slowly cooling off.

“The nice thing is that the heat is recorded there now, but probably in a hundred million years we’re not going to see that anymore,” Martos said.

A similar plume formed the Hawaiian Islands and is currently fueling the K?lauea volcano eruptions. The Hawaiian chain of islands and seamounts that were created when the Pacific Plate moved over the plume in the middle of the Pacific Ocean is a visible representation of the type of scar that Martos found beneath Greenland.

The heat beneath Earth’s surface

Plumes are one of several geothermal heat-transporting phenomena on Earth; their number is uncertain, but scientists think there could be as many as 20. Otherwise, the inner planet is heated evenly throughout by decaying radioactive elements in Earth’s top layers. There’s also primordial warmth left over from the formation of our planet 4.5 billion years ago, and from the meteorites that pummeled it. The team considered these heat sources, Martos said, but ruled out their role in producing the scar because they would have formed a uniform heat pattern across Greenland.

Another factor that can increase heat in a specific location is tectonic activity. This activity includes rifting — or the breaking apart of continental plates, which creates space for warmer mantle to bubble to the surface — and volcanic eruptions. But these phenomena also didn’t square with the team’s findings, said Martos, given that Greenland is a craton, or an ancient piece of continent with no major tectonic events on record there.

Measuring heat without touching the surface

Because Greenland is covered by an ice sheet that is up to 1.8 miles (3 kilometers) thick in the center, getting physical samples from the ground below the ice is nearly as difficult as getting them from the Moon. Remotely sensed data offers virtually the only window to Greenland’s subsurface dynamics.

Martos’s team decided to look at magnetic field information collected by magnetometers, instruments flown by airplanes that measure the strength of the magnetic field of Earth. The data revealed anomalies in the magnetism of rocks below Greenland.

Magnetism is related to temperature, thus rocks heated to certain temperatures lose their magnetism. This typically happens deep inside Earth. Because magnetite is the most abundant magnetic mineral in the lower part of the crust, the researchers studied that mineral exclusively. Magnetite loses its ferromagnetic properties, or magnetism, when heated to 1,076 degrees Fahrenheit (580 degrees Celsius), a point known as the Curie temperature. Accounting for this temperature’s effect on magnetite allowed the team to find the base of magnetism in the crust of Greenland. From there, they observed the depth variations of the location of the Curie temperature for magnetite to map the heat released all over the island.

Along the plume’s path, the team found that the Curie temperature occurred closer to the surface. This offered evidence that the plume had heated the bottom of the lithosphere, and that the heat was still there.

The team also used gravity data to model the features of the lithosphere and confirm the plume’s effect on crustal thickness.

In the central part of the island, the team estimated geothermal heat flux values around 60 to 70 milliwatts per meter squared, or up to 50 percent higher than the heat escaping parts of the island not affected by the plume. This is a tiny amount; a 100-watt light bulb, by comparison, generates three orders of magnitude — or 1,000 times — more heat.

Still, said Martos and her co-authors, the heat they found can melt ice at the base of the Greenland Ice Sheet. It does not, however, contribute to the accelerated melting of Greenland’s glaciers. Because the geothermal heat declines over such huge periods of time — tens of millions of years — there has likely been no change in heat flux since the ice fully formed on Greenland about 3 million years ago.

Martos’ modeling tools will help scientists better understand the effect of below-surface heat on things like melt or breakage at the base of ice sheets and glaciers on Earth. It will also help them study remote locations on Earth and other rocky bodies in our solar system.

Martos began this research while she was a Marie Curie fellow of the European Union at the British Antarctic Survey.

Reference:
Yasmina M. Martos Tom A. Jordan Manuel Catalan Thomas M. Jordan Jonathan L. Bamber David G. Vaughan. Geothermal heat flux reveals the Iceland hotspot track underneath Greenland. Geophysical Research Letters, 2018 DOI: 10.1029/2018GL078289

Note: The above post is reprinted from materials provided by NASA/Goddard Space Flight Center. Original written by Lonnie Shekhtman.

Urban geophone array offers new look at northern Los Angeles basin

LSU's Patricia Persaud (left) and a Cal Tech undergraduate student mark a newly-buried geophone node in a Los Angeles yard.
LSU’s Patricia Persaud (left) and a Cal Tech undergraduate student mark a newly-buried geophone node in a Los Angeles yard. Credit: Patricia Persaud

Using an array of coffee-can sized geophones deployed for about a month in backyards, golf courses and public parks, researchers collected enough data to allow them to map the depth and shape of the San Gabriel and San Bernardino sedimentary basins of Los Angeles, California.

Seismologists think these sedimentary basins may act a “waveguide” to focus and trap energy from an earthquake on the southern San Andreas Fault, so understanding their structure is important to help predict how well they might channel the energy from such an earthquake into downtown Los Angeles.

The research team, led by Patricia Persaud of Louisiana State University and Robert Clayton from the California Institute of Technology, was able to map the two basins in greater detail than previous studies, showing that the San Gabriel basin is deeper than the San Bernardino basin and that the San Bernardino basin has an irregular shape. Persaud and colleagues also uncovered signs of deep offsets in layers of the earth’s crust that could be related to two faults — the Red Hill and Raymond faults — that have been previously mapped in nearby areas at the surface.

“It is currently too early to say how our results will change how we might think of these basins’ ability to channel seismic energy,” Persaud said. “However, we are collecting more data in the area that will be used to further refine the basin structure.”

Geophones are instruments that convert the velocity of ground motion into voltage which can be used to determine the geometry of structures beneath the earth’s surface. Visualizing the details of sedimentary basin structure requires a large number of seismic stations that are closely spaced in order to capture important changes in structure laterally across the basin. Geophone arrays offer an inexpensive and feasible way to collect this data in a densely-populated urban area, compared to the complications and expense of deploying broadband seismometers, Persaud noted.

Each of the 202 nodes deployed in the study, in three lines spanning the northern basins, are about the size of a coffee can. “They weigh about six pounds and have a data logger, battery and recorder all in one container,” Persaud explained. “To place them in the ground we dig a small hole that will allow the nodes to be covered with about two inches of soil once they are firmly planted. Most Los Angeles area residents tell us to put them wherever we want, some even help us dig the holes; so we choose a site in their yards and in about five minutes we have the node in place and recording.”

In most cases, property owners were “extremely friendly and accommodating” during the current study, said Persaud. “What’s interesting is when we got a positive response it was almost immediate. Los Angeles residents are very much aware of the elevated seismic hazard in this region, and are often curious about our study and the nodes, and they want to find out more. Some offer to spread the word about our study through social media and encourage their friends and neighbors to participate as well.”

The nodes collected data continuously for 35 days. In this time, they detected ground motion from magnitude 6 and greater earthquakes that occurred thousands of kilometers away from Los Angeles. Seismic waveform data from these teleseismic earthquakes can be used with a method called the receiver function technique to map the thickness of the crust and shallow crustal structures below a seismic station. The receiver functions calculated from the nodal arrays are similar to those calculated from broadband data, the researchers concluded, but the nodal array offers a higher-resolution look at crustal structures such as the boundary between the earth’s crust and mantle and the interface between sediments and basement rock across the basins.

This summer, the research team is back in California placing nodes “along new lines that are intended to fill in any areas where there might be a change in basin shape,” said Persaud. “We have just deployed three new profiles and will then compile the results from all of our profiles to produce an updated structural model for the basins.”

Reference:
Guibao Liu, Patricia Persaud, Robert W. Clayton. Structure of the Northern Los Angeles Basins Revealed in Teleseismic Receiver Functions from Short‐Term Nodal Seismic Arrays. Seismological Research Letters, 2018; DOI: 10.1785/0220180071

Note: The above post is reprinted from materials provided by Seismological Society of America.

What makes diamonds blue?

Blue Diamond
A blue, boron-bearing diamond with dark inclusions of a mineral called ferropericlase, which were examined as part of this study. This gem weighs 0.03 carats. Credit: Photo by Evan Smith/GIA.

Blue diamonds — like the world-famous Hope Diamond at the National Museum of Natural History — formed up to four times deeper in the Earth’s mantle than most other diamonds, according to new work published on the cover of Nature.

“These so-called type IIb diamonds are tremendously valuable, making them hard to get access to for scientific research purposes,” explained lead author Evan Smith of the Gemological Institute of America, adding, “and it is very rare to find one that contains inclusions, which are tiny mineral crystals trapped inside the diamond.”

Inclusions are remnants of the minerals from the rock in which the diamond crystallized and can tell scientists about the conditions under which it formed.

Type IIb diamonds owe their blue color to the element boron, an element that is mostly found on the Earth’s surface. But analysis of the trapped mineral grains in 46 blue diamonds examined over two years indicate that they crystallized in rocks that only exist under the extreme pressure and temperature conditions of the Earth’s lower mantle.

The research group — which included Carnegie’s Steven Shirey, Emma Bullock, and Jianhua Wang — determined that blue diamonds form at least as deep as the transition zone between the upper and lower mantle — or between 410 and 660 kilometers below the surface. Several of the samples even showed clear evidence that they came from deeper than 660 kilometers, meaning they originated in the lower mantle. By contrast, most other gem diamonds come up from between 150 and 200 kilometers.

So how did the boron get down there if it is an element known for residing predominately in the shallow crust?

According to the hypothesis put forth by the research group, it came from seafloor that was conveyed down into the Earth’s mantle when one tectonic plate slid beneath another — a process known as subduction.

The new study proposes that boron from the Earth’s surface was incorporated into water-rich minerals like serpentine, which crystallized during geochemical reactions between seawater and the rocks of the oceanic plate. This reaction between rock and water is a process called serpentinization and can extend deep into the seafloor, even into the oceanic plate’s mantle portion.

The group’s discovery reveals that the water-bearing minerals travel far deeper into the mantle than previously thought, which indicates the possibility of a super-deep hydrological cycle.

“Most previous studies of super-deep diamonds had been carried out on diamonds of low quality,” Shirey said. “But between our 2016 finding that the world’s biggest and most-valuable colorless diamonds formed from metallic liquid deep inside Earth’s mantle and this new discovery that blue diamonds also have super-deep origins, we now know that the finest gem-quality diamonds come from the farthest down in our planet.”

Reference:
Evan M. Smith, Steven B. Shirey, Stephen H. Richardson, Fabrizio Nestola, Emma S. Bullock, Jianhua Wang, Wuyi Wang. Blue boron-bearing diamonds from Earth’s lower mantle. Nature, 2018; 560 (7716): 84 DOI: 10.1038/s41586-018-0334-5

Note: The above post is reprinted from materials provided by Carnegie Institution for Science.

New dinosaur found in the wrong place, at the wrong time

Lingwulong shenqi.
Artist’s impression of dinosaur Lingwulong shenqi. Credit: Zhang Zongda

A new dinosaur called Lingwulong shenqi or ‘amazing dragon from Lingwu’ has been discovered by an Anglo-Chinese team involving UCL.

The announcement, published in Nature Communications, reports the surprising discovery of the new dinosaur which roamed the Ningxia Autonomous Region, northwest China, approximately 174 million years ago. This is in a place they were never thought to roam and 15 million years earlier than this type of dinosaur was thought to exist.

Lingwulong is the earliest known example of a type of advanced sauropod dinosaur called a ‘neosauropod’ — one of the long-necked, gigantic herbivores that are the largest land animals known, including famous forms such as Brontosaurus and Diplodocus.

Sauropods originated around 200 million years ago, but they only started to truly dominate terrestrial ecosystems by developing gigantic body size (up to 70 metric tonnes) and numerous new adaptations for obtaining and processing plant food.

These giant neosauropod descendants were thought to originate around 160 million years ago, rapidly diversifying and spreading across the world during a time window perhaps as short as just 5 million years.

“We were surprised to find a close relative of Diplodocus in East Asia 174 million years ago. It’s commonly thought that sauropods did not disperse there until 200 million years ago and many of their giant descendants, reached this region much later, if at all,” explained study co-author Professor Paul Upchurch (UCL Earth Sciences).

“Our discovery of Lingwulong demonstrates that several different types of advanced sauropod must have existed at least 15 million years earlier and spread across the world while the supercontinent Pangaea was still a coherent landmass. This forces a complete re-evaluation of the origins and evolution of these animals.”

The new evidence also reinforces the growing realisation that the Early Jurassic (200-175 million years ago), was a key time in dinosaur evolution, witnessing the origins and diversification of many groups that went on to dominate the later Jurassic and Cretaceous.

“Diplodocus-like neosauropods were thought to have never made it to East Asia because this region was cut-off from the rest of the world by Jurassic seaways, so that China evolved its own distinctive and separate dinosaur fauna. However, Lingwulong shows that these Diplodocus-like sauropods were present after all, and implies that the isolation of East Asia was less profound and short-lived than we realised,” said lead author, Dr Xing Xu (Institute of Vertebrate Paleontology & Paleoanthropology, Chinese Academy of Sciences, Beijing, China).

For the study, palaeontologists analysed the fossilised skeletons of 7-10 individual dinosaurs that were found together in rocks in 2005 and have been dated at approximately 174 million years old. Funding secured in 2016 by National Geographic Research enabled the formation of this Anglo-Chinese project to study the specimens in detail.

The team conclude that finding such a dinosaur ‘in the wrong place, at the wrong time’, emphasises the gaps in our knowledge of the fossil record and suggests that there are many surprises still to come.

Reference:
Xing Xu, Paul Upchurch, Philip D. Mannion, Paul M. Barrett, Omar R. Regalado-Fernandez, Jinyou Mo, Jinfu Ma, Hongan Liu. A new Middle Jurassic diplodocoid suggests an earlier dispersal and diversification of sauropod dinosaurs. Nature Communications, 2018; 9 (1) DOI: 10.1038/s41467-018-05128-1

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

160-year-old mystery about the origin of skeletons solved

A fossil heterostracan, Errivaspis waynensis, from the early Devonian
A fossil heterostracan, Errivaspis waynensis, from the early Devonian (approximately 419 million years ago) of Herefordshire, UK. Credit: Image from Keating et al. 2018

Scientists at The University of Manchester and the University of Bristol have used powerful X-rays to peer inside the skeletons of some of our oldest vertebrate relatives, solving a 160-year-old mystery about the origin of our skeletons.

Living vertebrates have skeletons built from four different tissue types: bone and cartilage (the main tissues that human skeletons are made from), and dentine and enamel (the tissues from which our teeth are constructed). These tissues are unique because they become mineralised as they develop, giving the skeleton strength and rigidity.

Evidence for the early evolution of our skeletons can be found in a group of fossil fishes called heterostracans, which lived over 400 million years ago. These fishes include some of the oldest vertebrates with a mineralised skeleton that have ever been discovered. Exactly what tissue heterostracan skeletons were made from has long puzzled scientists.

Now a team of researchers from the University of Manchester, the University of Bristol and the Paul Scherrer Institute in Switzerland have taken a detailed look inside heterostracan skeletons using Synchrotron Tomography: a special type of CT scanning using very high energy X-rays produced by a particle accelerator. Using this technique, the team have identified this mystery tissue.

Lead researcher Dr Joseph Keating, from Manchester’s School of Earth of Environmental Scientists, explained: “Heterostracan skeletons are made of a really strange tissue called ‘aspidin’. It is crisscrossed by tiny tubes and does not closely resemble any of the tissues found in vertebrates today. For a 160 years, scientists have wondered if aspidin is a transitional stage in the evolution of mineralised tissues.”

The results of this study, published in Nature Ecology and Evolution, show that the tiny tubes are voids that originally housed fibre-bundles of collagen, a type of protein found in your skin and bones.

These findings enabled Dr Keating to rule out all but one hypothesis for the tissue’s identity: aspidin is the earliest evidence of bone in the fossil record.

Co-author, Professor Phil Donoghue from the University of Bristol concludes: “These findings change our view on the evolution of the skeleton. Aspidin was once thought to be the precursor of vertebrate mineralised tissues. We show that it is, in fact, a type of bone, and that all these tissues must have evolved millions of years earlier.”

Reference:
Joseph N. Keating, Chloe L. Marquart, Federica Marone, Philip C. J. Donoghue. The nature of aspidin and the evolutionary origin of bone. Nature Ecology & Evolution, 2018; DOI: 10.1038/s41559-018-0624-1

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

The end-Cretaceous extinction unleashed modern shark diversity

This is PhD student Mohamad Bazzi with a fossil lamniform shark tooth
This is PhD student Mohamad Bazzi with a fossil lamniform shark tooth. Credit: Jordi Estefa

A study that examined the shape of hundreds of fossilized shark teeth suggests that modern shark biodiversity was triggered by the end-Cretaceous mass extinction event, about 66 million years ago.

This finding is reported this week in Current Biology.

As part of a larger scientific endeavour aiming to understand the diversity of fossil sharks, a group of researchers from Uppsala University, Sweden, and the University of New England, Australia, have explored how certain groups of sharks responded to the mass extinction that killed-off non-bird dinosaurs and marked the end of the Cretaceous period and the Mesozoic era.

Much like several other vertebrate groups during the Cretaceous (142-66 million years ago), shark diversity looked very different from today. Ground sharks (Carcharhiniformes) are the most diverse shark group living today, with over 200 different species. However, while dinosaurs dominated terrestrial environments during the Cretaceous, Mackerel sharks (Lamniformes) were the dominant shark forms of the sea.

“Our study found that the shift from lamniform- to carcharhiniform-dominated assemblages may well have been the result of the end-Cretaceous mass extinction,” said project leader and Uppsala doctoral student Mohamad Bazzi.

Sharks are one of the major groups that survived the Cretaceous-Palaeogene mass extinction and, today, carcharhiniforms are typified by forms such as the Tiger, Hammerhead, and Blacktip Reef sharks and lamniforms by the Great White and Mako sharks.

“Unlike other vertebrates, the cartilaginous skeletons of sharks do not easily fossilize and so our knowledge of these fishes is largely limited to the thousands of isolated teeth they shed throughout their lives,” says Mr. Bazzi. “Fortunately, shark teeth can tell us a lot about their biology, including information about diet, which can shed light on the mechanisms behind their extinction and survival.”

The team used “cutting-edge” analytical techniques to explore the variation of tooth shape in carcharhiniforms and lamniforms and measured diversity by calculating the range of morphological variation, also called disparity.

“Going into this study, we knew that sharks underwent important losses in species richness across the extinction.” said Dr. Nicolás Campione at the University of New England, who co-devised the project. “But to our surprise, we found virtually no change in disparity across this major transition. This suggests to us that species richness and disparity may have been decoupled across this interval.”

Despite this seemingly stable pattern, the study found that extinction and survival patterns were substantially more complex. Morphologically, there were differential responses to extinction between lamniform and carcharhiniform sharks, with evidence for a selective extinction of lamniforms and a subsequent proliferation of carcharhiniforms (the largest order of living sharks today) in the immediate aftermath of the extinction.

“Carcharhiniforms are the most common shark group today and it would seem that the initial steps towards this dominance started approximately 66 million years ago,” said Mr. Bazzi, who remarks that further research is still needed to understand the diversity patterns of other shark groups, along with the relationship between diet and tooth morphology.

Although the mechanisms that triggered such a shift in sharks can be difficult to interpret. The team hypothesises that changes in food availability may have played an important role. The end-Cretaceous extinction saw to major losses in marine reptiles and cephalopods (e.g. squids) and the post-extinction world saw the rise of bony fishes. In addition, it is likely that the loss of apex predators (such as lamniforms and marine reptiles) benefited mid-trophic sharks, a role fulfilled by many carcharhiniforms.

“By studying their teeth, we are able to get a glimpse at the lives of extinct sharks,” said Dr. Campione, “and by understanding the mechanisms that have shaped their evolution in the past, perhaps we can provide some insights into how to mitigate further losses in current ecosystems.”

Approximately 50% of the shark species in the IUCN are considered to be either endangered, threatened, or near-threatened.

Reference:
Mohamad Bazzi, Benjamin P. Kear, Henning Blom, Per E. Ahlberg, Nicolás E. Campione. Static Dental Disparity and Morphological Turnover in Sharks across the End-Cretaceous Mass Extinction. Current Biology, 2018; DOI: 10.1016/j.cub.2018.05.093

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

Earthquakes can systematically trigger other ones on opposite side of Earth

Earthquake mangled track
Earthquake mangled track

New research shows that a big earthquake can not only cause other quakes, but large ones, and on the opposite side of the Earth.

The findings, published today in Scientific Reports, are an important step toward improved short-term earthquake forecasting and risk assessment.

Scientists at Oregon State University looked at 44 years of seismic data and found clear evidence that tremblors of magnitude 6.5 or larger trigger other quakes of magnitude 5.0 or larger.

It had been thought that aftershocks — smaller magnitude quakes that occur in the same region as the initial quake as the surrounding crust adjusts after the fault perturbation — were the only seismic activity an earthquake could lead to.

But the OSU analysis of seismic data from 1973 through 2016 — an analysis that excluded data from aftershock zones — provided the first discernible evidence that in the three days following one large quake, other earthquakes were more likely to occur.

Each test case in the study represented a single three-day window “injected” with a large-magnitude (6.5 or greater) earthquake suspected of inducing other quakes, and accompanying each case was a control group of 5,355 three-day periods that didn’t have the quake injection.

“The test cases showed a clearly detectable increase over background rates,” said the study’s corresponding author, Robert O’Malley, a researcher in the OSU College of Agricultural Sciences. “Earthquakes are part of a cycle of tectonic stress buildup and release. As fault zones near the end of this seismic cycle, tipping points may be reached and triggering can occur.”

The higher the magnitude, the more likely a quake is to trigger another quake. Higher-magnitude quakes, which have been happening with more frequency in recent years, also seem to be triggered more often than lower-magnitude ones.

A tremblor is most likely to induce another quake within 30 degrees of the original quake’s antipode — the point directly opposite it on the other side of the globe.

“The understanding of the mechanics of how one earthquake could initiate another while being widely separated in distance and time is still largely speculative,” O’Malley said. “But irrespective of the specific mechanics involved, evidence shows that triggering does take place, followed by a period of quiescence and recharge.”

Earthquake magnitude is measured on a logarithmic 1-10 scale — each whole number represents a 10-fold increase in measured amplitude, and a 31-fold increase in released energy.

The largest recorded earthquake was a 1960 temblor in Chile that measured 9.5. The 2011 quake that ravaged the Fukushima nuclear power plant in Japan measured 6.6.

In 1700, an approximate magnitude 9.0 earthquake hit the Cascadia Subduction Zone — a fault that stretches along the West Coast of North American from British Columbia to California.

Collaborating with O’Malley were Michael Behrenfeld of the College of Agricultural Sciences, Debashis Mondal of the College of Science and Chris Goldfinger of the College of Earth, Ocean and Atmospheric Sciences.

Reference:
Robert T. O’Malley, Debashis Mondal, Chris Goldfinger, Michael J. Behrenfeld. Evidence of Systematic Triggering at Teleseismic Distances Following Large Earthquakes. Scientific Reports, 2018; 8 (1) DOI: 10.1038/s41598-018-30019-2

Note: The above post is reprinted from materials provided by Oregon State University. Original written by Steve Lundeberg.

Paleontologists discover largest dinosaur foot ever

Brachiosaur foot bones below a tail of a Camarasaurus.
Photograph from the excavations in 1998, with the brachiosaur foot bones below a tail of a Camarasaurus. University of Kansas expedition crew member as a scale. Credit: Photo courtesy of the KUVP archives

The Black Hills region of the United States is famous today for tourist attractions like Deadwood and Mount Rushmore, but around 150 million years ago it was home to one of the largest dinosaurs known. This dinosaur was a member of the sauropod family with long necks and tails. These giant plant-eating dinosaurs like Brontosaurus and Diplodocus were the largest land animals that ever lived on this planet.

The foot described in a new scientific paper recently published in the open-access journal PeerJ — the Journal of Life and Environmental Sciences was excavated in 1998 by an expedition from the University of Kansas, with Anthony Maltese, lead author of the study, as member of the crew. As he writes, it was immediately apparent that the foot, nearly a meter wide, was from an extremely large animal — so the specimen was nicknamed “Bigfoot.”

Now, after detailed preparation and study, Maltese and his international team of researchers from the USA, Switzerland, and Germany identified it as belonging to an animal very closely related to Brachiosaurus, famous for its appearance in the 1993 film Jurassic Park.

Anthony Maltese, Emanuel Tschopp, Femke Holwerda, and David Burnham used 3D scanning and detailed measurements to compare Bigfoot to sauropod feet from numerous species. Their research confirmed that this foot was unusually large. According to Holwerda, a Dutch PhD student at the Ludwig Maximilians University of Munich, Germany, comparisons with other sauropod feet showed that Bigfoot was clearly the largest dinosaur foot discovered to date.

It also confirmed that brachiosaurs inhabited a huge area from eastern Utah to northwestern Wyoming, 150 million years ago. “This is surprising,” says Tschopp, a Swiss paleontologist working at the American Museum of Natural History in New York, “many other sauropod dinosaurs seem to have inhabited smaller areas during that time.”

According to Maltese, who was part of the original University of Kansas team in 1998 but is now at the Rocky Mountain Dinosaur Resource Center in Woodland Park, Colorado, the rock outcrops that produced this fossil hold many more “fantastic dinosaur skeletons,” and the research team hopes to continue their studies on fossils from there.

Reference:
Anthony Maltese, Emanuel Tschopp, Femke Holwerda, David Burnham. The real Bigfoot: a pes from Wyoming, USA is the largest sauropod pes ever reported and the northern-most occurrence of brachiosaurids in the Upper Jurassic Morrison Formation. PeerJ, 2018; 6: e5250 DOI: 10.7717/peerj.5250

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

First fossilized snake embryo ever discovered rewrites history of ancient snakes

Skeletal remains from the Xiaophis myanmarensis snake hatchling trapped in Burmese amber.
Overview of skeletal remains from the Xiaophis myanmarensis snake hatchling trapped in Burmese amber. Photo credit: Ming Bai, Chinese Academy of Sciences

The first-ever discovery of an ancient snake embryo, preserved in 105-million-year-old amber, provides important new information on the evolution of modern snakes, according to a new study led by University of Alberta paleontologists.

“This snake is linked to ancient snakes from Argentina, Africa, India and Australia,” explained paleontologist Michael Caldwell, lead author and professor in the Department of Biological Sciences. “It is an important—and until now, missing—component of understanding snake evolution from southern continents, that is Gondwana, in the mid-Mesozoic.”

Caldwell and his international team, including collaborators from Australia, China and the United States, have tracked the migration of these ancient Gondwanan snakes beginning 180 million years ago when they were carried by tectonic movements of continents and parts of continents, from Australia and India, to Madagascar and Africa, and finally to Asia, in modern-day India and Myanmar.

The amber fragment in which the specimen was found also provided important clues about its environment.

“It is clear that this little snake was living in a forested environment with numerous insects and plants, as these are preserved in the clast,” explained Caldwell. “Not only do we have the first baby snake, we also have the first definitive evidence of a fossil snake living in a forest.”

Using CT scans, the scientific team studied the ancient snake and compared it with the young of modern snakes. Their results yielded unexpected insight into the development and embryology of the ancient specimen, including the formation of the vertebrae and notochord.

“All of these data refine our understanding of early snake evolution, as 100-million year-old snakes are known from only 20 or so relatively complete fossil snake species,” said Caldwell. “There is a great deal of new information preserved in this new fossilized baby snake.”

The paper, “A Mid-Cretaceous Embryonic-to-Neonate Snake in Amber From Myanmar,” was published in Science Advances.

Reference:
Lida Xing et al. A mid-Cretaceous embryonic-to-neonate snake in amber from Myanmar, Science Advances (2018). DOI: 10.1126/sciadv.aat5042

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

Yellowstone super-volcano has a different history than previously thought

This is the location of the Yellowstone's hotspot track. The triangles indicate general locations of the Yellowstone and Snake River Plain age-progressive volcanoes with ages shown in millions of years, plotted on a topography map of the Western United States.
This is the location of the Yellowstone’s hotspot track. The triangles indicate general locations of the Yellowstone and Snake River Plain age-progressive volcanoes with ages shown in millions of years, plotted on a topography map of the Western United States. Credit: Virginia Tech

The long-dormant Yellowstone super-volcano in the American West has a different history than previously thought, according to a new study by a Virginia Tech geoscientist.

Scientists have long thought that Yellowstone Caldera, part of the Rocky Mountains and located mostly in Wyoming, is powered by heat from the Earth’s core, similar to most volcanoes such as the recently active Kilauea volcano in Hawaii. However, new research published in Nature Geoscience by Ying Zhou, an associate professor with the Virginia Tech College of Science’s Department of Geosciences, shows a different past.

“In this research, there was no evidence of heat coming directly up from the Earth’s core to power the surface volcano at Yellowstone,” Zhou said. “Instead, the underground images we captured suggest that Yellowstone volcanoes were produced by a gigantic ancient oceanic plate that dove under the Western United States about 30 million years ago. This ancient oceanic plate broke into pieces, resulting in perturbations of unusual rocks in the mantle which led to volcanic eruptions in the past 16 million years.”

The eruptions were very explosive, Zhou added. A theoretical seismologist, Zhou created X-ray-like images of the Earth’s deep interior from USArray — part of the Earthscope project funded by the National Science Foundation — and discovered an anomalous underground structure at a depth of about 250 to 400 miles right beneath the line of volcanoes.

“This evidence was in direct contradiction to the plume model,” Zhou said.

In her study, Zhou found the new images of the Earth’s deep interior showed that the oceanic Farallon plate, which used to be where the Pacific Ocean is now, wedged itself beneath the present-day Western United States. The ancient oceanic plate was broken into pieces just like the seafloor in the Pacific today. A section of the subducted oceanic plate started tearing off and sinking down to the deep earth.

The sinking section of oceanic plate slowly pushed hot materials upward to form the volcanoes that now make up Yellowstone. Further, the series of volcanoes that make up Yellowstone have been slowly moving, achingly so, ever since. “The process started at the Oregon-Idaho border about 16 million years ago and propagated northwestward, forming a line of volcanoes that are progressively younger as they stretched northwest to present-day Wyoming,” Zhou added.

The previously-held plume model was used to explain the unique Yellowstone hotspot track — the line of volcanoes in Oregon, Idaho, and Wyoming that dots part of the Midwest. “If the North American plate was moving slowly over a position-fixed plume at Yellowstone, it will displace older volcanoes towards the Oregon-Idaho border and form a line of volcanoes, but such a deep plume has not been found.” Zhou said. So, what caused the track? Zhou intends to find out.

“It has always been a problem there, and scientists have tried to come up with different ways to explain the cause of Yellowstone volcanoes, but it has been unsuccessful,” she said, adding that hotspot tracks are more popular in oceans, such as the Hawaii islands. The frequent Geyser eruptions at Yellowstone are of course not volcanic eruptions with magna, but due to super-heated water. The last Yellowstone super eruption was about 630,000 years ago, according to experts. Zhou has no predictions on when or if Yellowstone could erupt again.

The use of the X-ray-like images for this study is unique in itself. Just as humans can see objects in a room when a light is on, Zhou said seismometers can see structures deep within the earth when an earthquake occurs. The vibrations spread out and create waves when they hit rocks. The waves are detected by seismometers and used in what is known as diffraction tomography.

“This is the first time the new imaging theory has been applied to this type of seismic data, which allowed us to see anomalous structures in the Earth’s mantle that would otherwise not be resolvable using traditional methods,” Zhou said.

Zhou will continue her study of Yellowstone. “The next step will be to increase the resolution of the X-ray-like images of the underground rock,” she added.

“More detailed images of the unusual rocks in the deep earth will allow us to use computer simulation to recreate the fragmentation of the gigantic oceanic plate and test different scenarios of how rock melting and magma feeding system work for the Yellowstone volcanoes.”

Reference:
Ying Zhou. Anomalous mantle transition zone beneath the Yellowstone hotspot track. Nature Geoscience, 2018; 11 (6): 449 DOI: 10.1038/s41561-018-0126-4

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

New sources of melanin pigment shake up ideas about fossil animals’ colour

10 million-year-old frog from Libros, Spain
10 million-year-old frog from Libros, Spain, showing dark internal melanosomes in the chest cavity and legs. Credit: Museo Nacional de Ciencias Naturales, Madrid, Spain

A team of palaeontologists, led by University College Cork (UCC) and including the University of Bristol, have discovered new sources of the pigment melanin, calling for a rethink of how scientists reconstruct the colour of fossil birds, reptiles and dinosaurs.

Many recent studies of fossil colour have assumed that fossilized granules of melanin – melanosomes – come from the skin. But new evidence shows that other tissues – such as the liver, lungs, and spleen – can also contain melanosomes, suggesting that fossil melanosomes may not provide information on fossil colour.

The study, published today in the journal Nature Communications, is led by UCC’s Dr. Maria McNamara in collaboration with her Ph.D. student Valentina Rossi, Dr. Paddy Orr from University College Dublin and an international team of palaeontologists from the UK and Japan.

The team studied internal tissues in modern frogs with powerful microscopes and chemical techniques to show that internal melanosomes are highly abundant.

Dr. McNamara said: “This means that these internal melanosomes could make up the majority of the melanosomes preserved in some fossils.”

The team also used decay experiments and analysed fossils to show that the internal melanosomes can leak into other body parts during the fossilization process—like snowflakes inside a snow globe, according to Dr. Orr.

There is a way, however, to tell the difference between melanosomes from internal organs and the skin.

Dr. McNamara added: “The size and shape of skin melanosomes is usually distinct from those in internal organs.

“This will allow us to produce more accurate reconstructions of the original colours of ancient vertebrates.”

Reference:
Maria E. McNamara et al. Non-integumentary melanosomes can bias reconstructions of the colours of fossil vertebrates, Nature Communications (2018). DOI: 10.1038/s41467-018-05148-x

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

Scientists use satellites to measure vital underground water resources

Groundwater well levels dropped several meters at most of the 1600 observation wells across the Central Valley, from 2007-2010.
Groundwater well levels dropped several meters at most of the 1600 observation wells across the Central Valley, from 2007-2010. These observations are strongly associated with groundwater extraction during the drought. Credit: ASU

The availability of water from underground aquifers is vital to the basic needs of more than 1.5 billion people worldwide, including those of us who live in the western United States. In recent decades, however, the over-pumping of groundwater, combined with drought, has caused some aquifers to permanently lose essential storage capacity.

With the hope of providing water resource managers with better tools to help keep aquifers healthy, a team of scientists from ASU and the Jet Propulsion Laboratory (JPL) are using the latest space technology to look underneath Earth’s surface to measure this precious natural resource.

They’ve focused their efforts on one of the world’s largest aquifer systems, located in California’s Central Valley, measuring both its groundwater volume and its storage capacity. The results of their most recent findings in this ground breaking study have been recently published in Water Resources Research.

Measuring underground from space

California’s Central Valley is a major agricultural hub covering an area of about 20,000 square miles. It produces more than 25 percent of U.S. agriculture, at an estimated value of $17 billion per year.

Beyond agricultural crops, the Central Valley aquifer system provides necessary water for people and wetlands, supplying about 20 percent of the overall U.S. groundwater demand. With a combination of population increases and drought, this aquifer is ranked one of the most stressed aquifer systems in the world.

While past studies on water resources and drought have focused mainly on low-resolution or local scale measurements of groundwater dynamics, the research team for this study, which includes ASU School of Earth and Space Exploration scientists Chandrakanta Ojha, Manoochehr Shirzaei, and Susanna Werth, with Donald Argus and Thomas Farr from JPL, went an even more high-tech route.

They used the data collection features of several satellite-based Earth remote sensing techniques to get a more consistent and higher resolution view of California’s Central Valley aquifer system than has ever been done before.

“Ironically,” says co-author Werth, who also has a joint appointment at the ASU School of Geographical Sciences and Urban Planning, “we had to go several hundreds of miles up into space to see what was going on under the surface of our planet.”

Using these high-tech remote sensing techniques, the team analyzed data from the 2007 to 2010 drought period and began to map the entire California Central Valley.

“It’s great when we can use our high-tech Earth-orbiting satellites to help solve real-world problems in California,” adds co-author Farr of the Jet Propulsion Laboratory.

They measured land subsidence (when land above and around an aquifer shifts downward) using space-borne Interferometric Synthetic Aperture Radar (InSAR) and added that to data on groundwater levels sampled at thousands of wells across the Central Valley.

“It’s this combination of literally terabytes of data that helps us get the best picture of what is happening below the surface,” says lead author Ojha.

A bell weather for aquifers around the world

From this analysis, the team found that between 2007 and 2010, there was a significant drop in ground levels in the southern area of the Central Valley. In fact, in a three-year period, there was a drop of nearly 32 inches, a decline that should normally take decades.

“Groundwater overdraft in some parts of the Central Valley has permanently altered clay layers, causing rapid ground sinking that can be measured by radar satellites from space,” says co-author Shirzaei.

The most startling result of this study, however, is the permanent loss of water storage capacity in the aquifer system. During the 2007 to 2010 drought, up to two percent of storage capacity was lost entirely when the water level declined and the clay layers in the system were permanently compacted.

“That storage capacity cannot be recovered through natural recharge,” says Ojha. “This means that during the wet season, when the Central Valley gets rain, there is less space to store it, making groundwater supplies scarcer during future droughts.”

New satellites to measure the effects of drought

The next steps for this team will be to focus on the period of drought in California from 2012 to 2016, which was even more detrimental to the Central Valley aquifer than the 2007 to 2010 drought period.

“Periods of drought have long-term effects on groundwater supplies and create major challenges for groundwater management,” says Maggie Benoit, a program director in the National Science Foundation’s Division of Earth Sciences, which provided funding for the research. “Now researchers are developing new methods for monitoring groundwater levels using satellite-based measurements of Earth’s surface, providing a more comprehensive picture of the health of our nation’s groundwater.”

The researchers plan to integrate radar measurements with additional data from the newly launched NASA/GFZ GRACE Follow-On (GRACE-FO) satellites. The GRACE FO mission, which launched on May 22, consists of two nearly identical satellites that follow one another along the same orbit. The satellites continually measure the distance between them, which changes depending on the gravity field over which they are orbiting. Since oscillations of groundwater change the gravity field, scientists can use the data to map underground water location and volume change.

And the work will not end there. The research team hopes to extend the research they are doing in California to Arizona and other areas of the arid southwest.

“The whole region is affected by a long-term drought,” states Werth, “with differences in severity, climate conditions, groundwater geology and water management approaches. Our hope is that these studies will enable authorities and decision makers to accurately manage water resources and plan for future water allocations. Water managers need to know about the irreversible processes taking place and how to act to prevent a future crisis.”

Reference:
Chandrakanta Ojha, Manoochehr Shirzaei, Susanna Werth, Donald F. Argus, Tom G. Farr. Sustained Groundwater Loss in California’s Central Valley Exacerbated by Intense Drought Periods. Water Resources Research, 2018; DOI: 10.1029/2017WR022250

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

Geologist leads effort to update Earth’s geologic time scale

Earth
Earth. Credit: CC0 Public Domain

It’s official. More than 8,000 years ago, a vast amount of water from melting glaciers flooded North America and caused havoc with the currents and atmosphere of the North Atlantic.

That significant event, during the Middle Holocene Northgrippian Age, was followed by droughts and cold temperatures in various parts of the globe that wiped out several civilizations during the Late Holocene Meghalayan Age more than 4,000 years ago.

Scientists have long known about this history. What’s now official are the geological time periods in which these events occurred.

Late last month, the International Union of Geological Sciences officially approved three ages of the Holocene epoch: Early Holocene Greenlandian Age; Middle Holocene Northgrippian Age; and Late Holocene Meghalayan Age.

Laying the groundwork for this sub-division was the International Subcommission on Quaternary Stratigraphy—Quaternary referring to the period under which the Holocene epoch falls.

Brock University Professor of Earth Sciences Martin Head chairs the subcommission, made up of geologists around the globe. He is also co-author of the academic article that reports these changes to the time scale along with lead author Professor Mike Walker of the University of Wales.

Head says his group debated a proposal by international Earth experts to sub-divide the Holocene into three ages and determine where to place the so-called “golden spike” at those points where these three sub-divisions occur.

The golden spike—technically known as the Global Boundary Stratotype Section and Point, or GSSP—is an internationally agreed upon reference point that determines the lower part of a stage, which are rock layers laid down in a single age.

Now, the Early Holocene Greenlandian Age; Middle Holocene Northgrippian Age; and Late Holocene Meghalayan Age have their own individual golden spikes.

“The terms early, middle and late Holocene have long been in use, but they’ve never been formally defined,” says Head, adding that a lack of formal definition created some confusion among experts.

“This is the job of the subcommission, to provide order where none existed before,” he says.

The Holocene Epoch stretches back to about 11,700 years ago in Earth’s history. It is characterized by events of both warming and cooling temperatures and the resulting changes to sea levels and land masses.

Rock layers in the Holocene contain sediments from ancient sea floors, lake bottoms, glacial ice and a mineral called calcite, giving researchers many clues as to the occurrence of climate-change related events during the Holocene’s three sub-divisions.

Head says his subcommission’s formalizing of the three ages solidifies scientists’ knowledge of the Holocene and explains in particular the fall of several civilizations some 4,200 years ago.

“This event brings together the convergence of global climatic change, archaeological evidence, historical records and societal evolution,” he says. “We’re bringing all this together to form a coherent story that is now reflected in formal geological time. We’re revealing the whole picture here.”

Head says the Geological Time Scale not only “reflects a narrative of how we understand Earth history,” but also illuminates “the history of humans, and so their story also becomes entwined with the geological record and geological time, and that’s very exciting.”

The past also sheds light on present trends. Head says the massive flooding that took place 8,200 years ago at the start of the Middle Holocene Northgrippian Age serves as a “warning shot” of how contemporary human-induced climate change can exacerbate melting of ice in the high northern latitudes, causing ocean currents to shift and extreme weather to result.

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

Newly discovered armored dinosaur from Utah reveals intriguing family history

Akainacephalus johnsoni
Representative Image: Akainacephalus johnsoni. Credit: Andrey Atuchin/DMNS

Fossils of a new genus and species of an ankylosaurid dinosaur — Akainacephalus johnsoni — have been unearthed in the Kaiparowits Formation of Grand Staircase-Escalante National Monument (GSENM), in Kane County, southern Utah, U.S.A., and are revealing new details about the diversity and evolution of this group of armored dinosaurs. Expected to look like other North American Late Cretaceous ankylosaurid dinosaurs with smooth bony armor on the skull, the new research suggests just the opposite and indicates that the defining features of Akainacephalus, specifically the spiky bony armor covering the skull and snout, align more closely with Asian ankylosaurids, who also have more pronounced spikes covering their skulls.

Akainacephalus was announced today in the open-access scientific journal PeerJ and unveiled on exhibit in the Past Worlds Gallery of the Natural History Museum of Utah at the Rio Tinto Center in Salt Lake City, Utah. The genus name is derived from the Greek words akaina, which means ‘thorn’ or ‘spike’, and cephalus, meaning ‘head.’ The species epithet johnsoni honors Randy Johnson, a dedicated museum volunteer who skillfully prepared its skull. Other talented volunteers helped to prepare the rest of the specimen.

“I’m a retired chemist, but I’ve always been interested in most of the science disciplines. I never thought that I would have the opportunity to actually work on fossils that could be important for paleontologists,” said Randy Johnson. “Now that I’m a museum volunteer, I’m getting the opportunity to work on a large variety of fossils and consult with top paleontologists — it’s like a dream second career. I couldn’t believe it when they told me they are naming the ankylosaur after me, a once in a lifetime honor,” said Johnson.

Ankylosaurids are a group of four-legged herbivorous armored dinosaurs with imposing bony tail clubs. Though ankylosaurids originated in Asia between 125 — 100 million years ago, they do not appear in the western North American fossil record until ~77 million years ago. The new species Akainacephalus lived 76 million years ago during the Late Cretaceous Period and offers the most complete skeleton of an ankylosaurid dinosaur found in the southwestern US. It includes a complete skull, much of the vertebral column, including a complete tail club, several fore and hind limbs elements, and bony body armor that includes two neck rings and spiked armor plates.

The unique arrangement of bony armor in the shape of small cones and pyramids covering the snout and head is the key research finding indicating that Akainacephalus is closely related to the New Mexican ankylosaurid Nodocephalosaurus kirtlandensis. Surprisingly, Akainacephalus and Nodocephalosaurus are more closely related to Asian ankylosaurids such as Saichania and Tarchia than to other Late Cretaceous North American ankylosaurids, including Ankylosaurus and Euoplocephalus. Both of the latter taxa possess flat skull armor.

“A reasonable hypothesis would be that ankylosaurids from Utah are related to those found elsewhere in western North America, so we were really surprised to discover that Akainacephalus was so closely related to species from Asia,” remarked Randall Irmis, co-author of the study.

Though ankylosaurids originated in Asia between 125 — 100 million years ago, they do not appear in the North American fossil record until around 77 million years ago. Akainacephalus once roamed the southern part of Laramidia, a landmass on the western coast of a shallow sea that flooded the central region, splitting the continent of North America in two. This caused isolation along western and eastern portions of the North American continent during the Late Cretaceous Period, between 95-70 million years ago.

Lead author Jelle Wiersma suggests that the geographic distribution of Late Cretaceous ankylosaurids throughout the Western Interior was the result of several geologically brief intervals of lowered sea level that allowed Asian ankylosaurid dinosaurs to immigrate to North America several times during the Late Cretaceous, resulting in the presence of two separate groups of ankylosaurid dinosaurs. This lowering of sea levels exposed the Beringian land bridge, allowing dinosaurs and other animals to move between Asia and North America.

“It is always exciting to name a new fossil taxon, but it is equally exciting if that taxon also provides additional insights into the bigger picture of its life, such as its diet or aspects of its behavior, and the environment it lived in,” said Wiersma. “Such is exactly the case with Akainacephalus johnsoni; not only is this the first described and named Late Cretaceous ankylosaurid dinosaur from Utah, but this unique animal also strengthens the evidence that distinct northern and southern provincialism existed during the late Campanian stage in Laramidia, because to date, we don’t see this type of ankylosaurid dinosaurs in the fossil record of northern Laramidia,” he said.

Wiersma explained that additionally, together with its close relative Nodocephalosaurus from New Mexico, Akainacephalus looks very different compared to other North American ankylosaurids such as Ankylosaurus, but instead, look much more like Asian ankylosaurids including Saichania and Tarchia. From these observations we can conclude that at least two immigration events took place during Late Cretaceous times when lowered sea levels exposed the Beringian land bridge, connecting Asia with western North America.

Ankylosaurid dinosaurs, among many other groups of animals, eventually crossed this land bridge, emigrating from Asia into western North America, resulting into two different types of Late Cretaceous ankylosaurid dinosaurs: ones that evolved flatter skull armor like Ankylosaurus and Euoplocephalus, and ones possessing very spiky skull armor such as Akainacephalus and Nodocephalosaurus.

“It is extremely fascinating and important for the science of paleontology that we can read so much information from the fossil record, allowing us to better understand extinct organisms and the ecosystems they were a part of,” concluded Wiersma.

These new findings are part of a study funded in large part by the Bureau of Land Management, as well as the Geological Society of America, and a University of Utah Department of Geology & Geophysics Graduate Student Grant. The project was led by University of Utah M.Sc. student Jelle Wiersma, now a Ph.D. student in the Dept. of Geosciences at James Cook University, Queensland, Australia. Wiersma was advised by co-author Dr. Randall Irmis, chief curator and curator of paleontology at the Natural History Museum of Utah, and associate professor in the Dept. of Geology and Geophysics, University of Utah.

Anklysaurid Dinosaurs on the Lost Continent of Southern Laramidia

Akainacephalus johnsoni was discovered in Grand Staircase-Escalante National Monument (GSENM) which encompasses a large area of high desert terrain in south-central Utah. This vast and rugged region, part of the National Landscape Conservation System administered by the Bureau of Land Management (BLM), was the last major area in the lower 48 states to be formally mapped by cartographers.

During the Late Cretaceous, GSENM was in the southern portion of Laramidia, which stretched from the Arctic Circle to the Gulf of Mexico. Akainacephalus is part of a growing number of new dinosaur discoveries over the past 15 years demonstrating the incredible diversity of animals and plants living on Laramidia between 80-75 million years ago. One of the most exciting conclusions from this work is that nearly every species of dinosaur discovered in GSENM is new to science, and Akainacephalus is no exception. Other recently discovered species include large and small meat-eating dinosaurs (e.g., tyrannosaurs), horned dinosaurs, and duck-billed dinosaurs. “A major long-term goal of our work in southern Utah is to try and understand why the species in GSENM differ from relatives of the same geologic age found in other parts of Laramidia,” said Wiersma. Hypotheses for the differences include changes in sea level, climate differences across latitude, and physical barriers to animal movement such as mountains and large rivers.

Fact Sheet: Major Points of the Paper

(1) Akainacephalus is a remarkable new species of ankylosaurid dinosaur from the upper Campanian Kaiparowits Formation in Grand Staircase-Escalante National Monument in Kane County, southern Utah.

(2) Akainacephalus is the most complete Late Cretaceous ankylosaurid dinosaur discovered from Utah and the southwestern U.S., and is distinguished by a number of unique features, including spikes and cones of the bony exterior covering the head and snout.

(3) The spikes and cones of bony armor on the skull of Akainacephalus are similar to those found on the New Mexican ankylosaurid Nodocephelausaurus kirtlandensis but distinct from all other known Late Cretaceous Laramidian ankylosaurids such as Ankylosaurus, Euoplocephalus, and Ziapelta, indicating these two species are more closely related to some Asian ankylosaurids.

(4) The new ankylosaurid Akainacephalus suggests multiple ankylosaurid emigration events from Asia to Laramidia during the Late Cretaceous.

(5) Together with some anklylosaurid dinosaurs from northern Laramidia, including Dyoplosaurus acutossquameus and Scolosaurus cutleri (both ~ 77 Ma), Akainacephalus represents one of the oldest known ankylosaurid dinosaurs from the Late Cretaceous of western North America (~76 Ma).

New Dinosaur Name: Akainacephalus johnsoni

  • The first part of the name, Akaina, is a Greek word that can be translated to spike or thorn. The second part of the name cephalus means head, and the epithet johnsoni honors Randy Johnson, a dedicated paleontology volunteer at the Natural History Museum of Utah who prepared the specimen’s skull.

Size

  • Akainacephalus, is a medium-sized dinosaur, and was 13-16 feet long (4-5 meters) and was 3 ½ feet tall (1 — 1.5 meters) at the hips.

Relationships

  • Akainacephalus belongs to a group of herbivorous armored dinosaurs called anklosaurids that lived in Asia and western North America during the Late Cretaceous Period (100-66 million years ago). One of the unique features of ankylosaurid dinosaurs is the presence of a characteristic bony tail club.

Anatomy

  • Akainacephalus walked on four legs, which were positioned directly underneath his body.
  • Akainacephalus was covered in bony armor from head to tail, with various sized and shaped bony plates, called osteoderms, which are thought to provide protection.
  • Akainacephalus is characterized by its elaborate covering of spikes and horns on the skull, as well a large bony club at the end of its tail.
  • Akainacephalus presumably had small, leaf-shaped teeth for eating plants. These fell out of the jaw after death, but before the skeleton was buried by sediment.

Age and Geography

  • Akainacephalus lived during the upper Campanian stage of the Late Cretaceous Period, which spanned from approximately 84 million to 72 million years ago. This animal lived about 76 million years ago.
  • Akainacephalus was discovered in 76 Ma old rocks of the Kaiparowits Formation, a geological/stratigraphic unit exposed in southern Utah consisting of sedimentary rocks deposited by rivers and streams.

Discovery & Excavation

  • Akainacephalus was first discovered in 2008 during a museum-led paleontological expedition in a remote area of BLM-administered Grand Staircase-Escalante National Monument (GSENM) in Kane County, southern Utah, USA. The site was discovered by BLM employee Scott Richardson.
  • The bones of Akainacephalus that were discovered include a complete skull, bony armor that includes neck rings and spiked plates, many vertebrae, forelimb and hindlimb bones, and a near complete tail with tail club.
  • Akainacephalus was found together with skeletons of several other animals at the same site, including a duck-bill dinosaur (Gryposaurus), a recently-described species of turtle (Arvinachelys), and a yet unnamed relative of alligators and caimans).
  • Akainacephalus is permanently housed in the collections of the Natural History Museum of Utah at the Rio Tinto Center in Salt Lake City and on public display at the museum’s Past Worlds exhibit.
  • These discoveries are the result of an ongoing collaboration between the Natural History Museum of Utah and the Bureau of Land Management.

Preparation

  • It required almost four years to fully prepare all of the bones of Akainacephalus.
  • Preparation of the skull was done by museum volunteer Randy Johnson, who is honored in the new name, Akainacephalus johnsoni

Reference:
Jelle P. Wiersma, Randall B. Irmis. A new southern Laramidian ankylosaurid, Akainacephalus johnsoni gen. et sp. nov., from the upper Campanian Kaiparowits Formation of southern Utah, USA. PeerJ, 2018; 6: e5016 DOI: 10.7717/peerj.5016

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

Giant’s Causeway, Ireland

Giant’s Causeway

The Giant’s Causeway is an area of about 40,000 interlocking basalt columns, the result of an ancient volcanic eruption. It is also known as Clochán an Aifir or Clochán na bhFomhórach in Irish and tha Giant’s Causey in Ulster-Scots.

It is located in County Antrim on the northeast coast of Northern Ireland, about three miles (4.8 km) northeast of the town of Bushmills. It was declared a World Heritage Site by UNESCO in 1986, and a national nature reserve in 1987 by the Department of the Environment for Northern Ireland.

In a 2005 poll of Radio Times readers, the Giant’s Causeway was named as the fourth greatest natural wonder in the United Kingdom. The tops of the columns form stepping stones that lead from the cliff foot and disappear under the sea. Most of the columns are hexagonal, although there are also some with four, five, seven or eight sides. The tallest are about 12 metres (39 ft) high, and the solidified lava in the cliffs is 28 metres (92 ft) thick in places.

Much of the Giant’s Causeway and Causeway Coast World Heritage Site is today owned and managed by the National Trust and it is one of the most popular tourist attractions in Northern Ireland. The remainder of the site is owned by the Crown Estate and a number of private landowners.

Sound waves reveal enormous diamond cache deep in Earth’s interior

Representative Image: Deep Earth

There may be more than a quadrillion tons of diamond hidden in the Earth’s interior, according to a new study from MIT and other universities. But the new results are unlikely to set off a diamond rush. The scientists estimate the precious minerals are buried more than 100 miles below the surface, far deeper than any drilling expedition has ever reached.

The ultradeep cache may be scattered within cratonic roots — the oldest and most immovable sections of rock that lie beneath the center of most continental tectonic plates. Shaped like inverted mountains, cratons can stretch as deep as 200 miles through the Earth’s crust and into its mantle; geologists refer to their deepest sections as “roots.”

In the new study, scientists estimate that cratonic roots may contain 1 to 2 percent diamond. Considering the total volume of cratonic roots in the Earth, the team figures that about a quadrillion (1016) tons of diamond are scattered within these ancient rocks, 90 to 150 miles below the surface.

“This shows that diamond is not perhaps this exotic mineral, but on the [geological] scale of things, it’s relatively common,” says Ulrich Faul, a research scientist in MIT’s Department of Earth, Atmospheric, and Planetary Sciences. “We can’t get at them, but still, there is much more diamond there than we have ever thought before.”

Faul’s co-authors include scientists from the University of California at Santa Barbara, the Institut de Physique du Globe de Paris, the University of California at Berkeley, Ecole Polytechnique, the Carnegie Institution of Washington, Harvard University, the University of Science and Technology of China, the University of Bayreuth, the University of Melbourne, and University College London.

A sound glitch

Faul and his colleagues came to their conclusion after puzzling over an anomaly in seismic data. For the past few decades, agencies such as the United States Geological Survey have kept global records of seismic activity — essentially, sound waves traveling through the Earth that are triggered by earthquakes, tsunamis, explosions, and other ground-shaking sources. Seismic receivers around the world pick up sound waves from such sources, at various speeds and intensities, which seismologists can use to determine where, for example, an earthquake originated.

Scientists can also use this seismic data to construct an image of what the Earth’s interior might look like. Sound waves move at various speeds through the Earth, depending on the temperature, density, and composition of the rocks through which they travel. Scientists have used this relationship between seismic velocity and rock composition to estimate the types of rocks that make up the Earth’s crust and parts of the upper mantle, also known as the lithosphere.

However, in using seismic data to map the Earth’s interior, scientists have been unable to explain a curious anomaly: Sound waves tend to speed up significantly when passing through the roots of ancient cratons. Cratons are known to be colder and less dense than the surrounding mantle, which would in turn yield slightly faster sound waves, but not quite as fast as what has been measured.

“The velocities that are measured are faster than what we think we can reproduce with reasonable assumptions about what is there,” Faul says. “Then we have to say, ‘There is a problem.’ That’s how this project started.”

Diamonds in the deep

The team aimed to identify the composition of cratonic roots that might explain the spikes in seismic speeds. To do this, seismologists on the team first used seismic data from the USGS and other sources to generate a three-dimensional model of the velocities of seismic waves traveling through the Earth’s major cratons.

Next, Faul and others, who in the past have measured sound speeds through many different types of minerals in the laboratory, used this knowledge to assemble virtual rocks, made from various combinations of minerals. Then the team calculated how fast sound waves would travel through each virtual rock, and found only one type of rock that produced the same velocities as what the seismologists measured: one that contains 1 to 2 percent diamond, in addition to peridotite (the predominant rock type of the Earth’s upper mantle) and minor amounts of eclogite (representing subducted oceanic crust). This scenario represents at least 1,000 times more diamond than people had previously expected.

“Diamond in many ways is special,” Faul says. “One of its special properties is, the sound velocity in diamond is more than twice as fast as in the dominant mineral in upper mantle rocks, olivine.”

The researchers found that a rock composition of 1 to 2 percent diamond would be just enough to produce the higher sound velocities that the seismologists measured. This small fraction of diamond would also not change the overall density of a craton, which is naturally less dense than the surrounding mantle.

“They are like pieces of wood, floating on water,” Faul says. “Cratons are a tiny bit less dense than their surroundings, so they don’t get subducted back into the Earth but stay floating on the surface. This is how they preserve the oldest rocks. So we found that you just need 1 to 2 percent diamond for cratons to be stable and not sink.”

In a way, Faul says cratonic roots made partly of diamond makes sense. Diamonds are forged in the high-pressure, high-temperature environment of the deep Earth and only make it close to the surface through volcanic eruptions that occur every few tens of millions of years. These eruptions carve out geologic “pipes” made of a type of rock called kimberlite (named after the town of Kimberley, South Africa, where the first diamonds in this type of rock were found). Diamond, along with magma from deep in the Earth, can spew out through kimberlite pipes, onto the surface of the Earth.

For the most part, kimberlite pipes have been found at the edges of cratonic roots, such as in certain parts of Canada, Siberia, Australia, and South Africa. It would make sense, then, that cratonic roots should contain some diamond in their makeup.

“It’s circumstantial evidence, but we’ve pieced it all together,” Faul says. “We went through all the different possibilities, from every angle, and this is the only one that’s left as a reasonable explanation.”

This research was supported, in part, by the National Science Foundation.

Reference:
Joshua M. Garber, Satish Maurya, Jean-Alexis Hernandez, Megan S. Duncan, Li Zeng, Hongluo L. Zhang, Ulrich Faul, Catherine McCammon, Jean-Paul Montagner, Louis Moresi, Barbara A. Romanowicz, Roberta L. Rudnick, Lars Stixrude. Multidisciplinary Constraints on the Abundance of Diamond and Eclogite in the Cratonic Lithosphere. Geochemistry, Geophysics, Geosystems, 2018; DOI: 10.1029/2018GC007534

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

Study finds deep subterranean connection between two Japan volcanoes

Southern Japan on Feb. 3rd, 2011, showing the active cones of Kirishima (Shinmoedake) and Aira caldera (Sakurajima) volcanoes.
Southern Japan on Feb. 3rd, 2011, showing the active cones of Kirishima (Shinmoedake) and Aira caldera (Sakurajima) volcanoes. While Kirishima is erupting very strongly, Aira’s activity is relatively low. Credit: NASA

Scientists have confirmed for the first time that radical changes of one volcano in southern Japan was the direct result of an erupting volcano 22 kilometers (13.7 miles) away. The observations from the two volcanos—Aira caldera and Kirishima—show that the two were connected through a common subterranean magma source in the months leading up to the 2011 eruption of Kirishima.

The Japanese cities of Kirishima and Kagoshima lie directly on the border of the Aira caldera, one of the most active, hazardous, and closely monitored volcanoes in southern Japan. Identifying how volcanoes interact is critical to determine if and how an eruption can influence the activity of a distant volcano or raise the threat of a new strong explosive event.

The research team from the University of Miami’s (UM) Rosenstiel School of Marine and Atmospheric Science and Florida International University analyzed deformation data from 32 permanent GPS stations in the region to identify the existence of a common magma reservoir that connected the two volcanoes.

Leading up to the eruption of Kirishima, which is located in the densely-populated Kagoshima region, the Aira caldera stopped inflating, which experts took as a sign that the volcano was at rest. The results from this new study, however, indicated that the opposite was happening—the magma chamber inside Aira began to deflate temporarily while Kirishima was erupting and resumed shortly after the activity at Kirishima stopped.

“We observed a radical change in the behavior of Aira before and after the eruption of its neighbor Kirishima,” said Elodie Brothelande, a postdoctoral researcher at the UM Rosenstiel School and lead author of the study. “The only way to explain this interaction is the existence of a connection between the two plumbing systems of the volcanoes at depth.”

Prior to this new study, scientists had geological records of volcanoes erupting or collapsing at the same time, but this is the first example of an unambiguous connection between volcanoes that allowed scientists to study the underlying mechanisms involved. The findings confirm that volcanoes with no distinct connection at the surface can be part of a giant magmatic system at depth.

“To what extend magmatic systems are connected is an important question in terms of the hazards,” said Falk Amelung, professor of geophysics at the UM Rosenstiel School and coauthor of the study. “Is there a lot of magma underground and can one eruption trigger another volcano? Up until now there was little or no evidence of distinct connections.”

“Eruption forecasting is crucial, especially in densely populated volcanic areas,” said Brothelande. “Now, we know that a change in behavior can be the direct consequence of the activity of its neighbor Kirishima.”

The findings also illustrate that large volcanic systems such as Aira caldera can respond to smaller eruptions at nearby volcanoes if fed from a common deep reservoir but not all the time, since magma pathways open and close periodically.

“Now, we have to look whether this connnection is particular for these volcanoes in southeastern Japan or are widespread and occurr around the world,” said Amelung.

The study, titled “Geodetic evidence for interconnectivity between Aira and Kirishima magmatic systems, Japan,” was published June 28 in the journal Scientific Reports.

Reference:
E. Brothelande et al, Geodetic evidence for interconnectivity between Aira and Kirishima magmatic systems, Japan, Scientific Reports (2018). DOI: 10.1038/s41598-018-28026-4

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

Fingal’s Cave

Fingal's Cave
Fingal’s Cave. Credit ©2009 Jim Richardson/National Geographic

Fingal’s Cave is a sea cave on the uninhabited island of Staffa, in the Inner Hebrides of Scotland, known for its natural acoustics. The National Trust for Scotland owns the cave as part of a National Nature Reserve. It became known as Fingal’s Cave after the eponymous hero of an epic poem by 18th-century Scots poet-historian James Macpherson.

Formation

Fingal’s Cave is formed entirely from hexagonally jointed basalt columns within a Paleocene lava flow, similar in structure to the Giant’s Causeway in Northern Ireland and those of nearby Ulva.

In all these cases, cooling on the upper and lower surfaces of the solidified lava resulted in contraction and fracturing, starting in a blocky tetragonal pattern and transitioning to a regular hexagonal fracture pattern with fractures perpendicular to the cooling surfaces. As cooling continued these cracks gradually extended toward the centre of the flow, forming the long hexagonal columns we see in the wave-eroded cross-section today. Similar hexagonal fracture patterns are found in desiccation cracks in mud where contraction is due to loss of water instead of cooling.

Growing a dinosaur’s dinner

Dinosaur
Dinosaur. Credit: CC0 Public Domain

Scientists have measured the nutritional value of herbivore dinosaurs’ diet by growing their food in atmospheric conditions similar to those found roughly 150 million years ago.

Previously, many scientists believed that plants grown in an atmosphere with high carbon dioxide levels had low nutritional value. But a new experimental approach led by Dr. Fiona Gill at the University of Leeds has shown this is not necessarily true.

The team grew dinosaur food plants, such as horsetail and ginkgo, under high levels of carbon dioxide mimicking atmospheric conditions similar to when sauropod dinosaurs, the largest animals ever to roam Earth, would have been widespread.

An artificial fermentation system was used to simulate digestion of the plant leaves in the sauropods’ stomachs, allowing the researchers to determine the leaves’ nutritional value. The findings, published in Palaeontology, showed many of the plants had significantly higher energy and nutrient levels than previously believed.

This suggests that the megaherbivores would have needed to eat much less per day and the ecosystem could potentially have supported a significantly higher dinosaur population density, possibly as much as 20% greater than previously estimated.

Dr. Gill, a palaeontologist and geochemist from the School of Earth and Environment at Leeds, said: “The climate was very different in the Mesozoic era—when the huge brachiosaurus and diplodocus lived—with possibly much higher carbon dioxide levels. There has been the assumption that as plants grow faster and/or bigger under higher CO2 levels, their nutritional value decreases. Our results show this isn’t the case for all plant species.

“The large body size of sauropods at that time would suggest they needed huge quantities of energy to sustain them. When the available food source has higher nutrient and energy levels it means less food needs to be consumed to provide sufficient energy, which in turn can affect population size and density.

“Our research doesn’t give the whole picture of dinosaur diet or cover the breadth of the plants that existed at this time, but a clearer understanding of how the dinosaurs ate can help scientists understand how they lived.”

“The exciting thing about our approach to growing plants in prehistoric atmospheric conditions is that it can used to simulate other ecosystems and diets of other ancient megaherbivores, such as Miocene mammals—the ancestors of many modern mammals.”

Reference:
Fiona L. Gill et al, Diets of giants: the nutritional value of sauropod diet during the Mesozoic, Palaeontology (2018). DOI: 10.1111/pala.12385

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

Scientists discover Earth’s youngest banded iron formation in western China

Earth's youngest banded iron formation in western China.
Earth’s youngest banded iron formation in western China. Credit: Zhiquan Li

The banded iron formation, located in western China, has been conclusively dated as Cambrian in age. Approximately 527 million years old, this formation is young by comparison to the majority of discoveries to date. The deposition of banded iron formations, which began approximately 3.8 billion years ago, had long been thought to terminate before the beginning of the Cambrian Period at 540 million years ago.

“This is critical, as it is the first observation of a Precambrian-like banded iron formation that is Early Cambrian in age. This offers the most conclusive evidence for the presence of widespread iron-rich conditions at a time, confirming what has recently been suggested from geochemical proxies,” said Kurt Konhauser, professor in the Department of Earth and Atmospheric Sciences and co-author. Konhauser supervised the research that was led by Zhiquan Li, a PhD candidate from Beijing while on exchange at UAlberta.

The Early Cambrian is known for the rise of animals, so the level of oxygen in seawater should have been closer to near modern levels. “This is important as the availability of oxygen has long been thought to be a handbrake on the evolution of complex life, and one that should have been alleviated by the Early Cambrian,” says Leslie Robbins, a PhD candidate in Konhauser’s lab and a co-author on the paper.

The researchers compared the geological characteristics and geochemistry to ancient and modern samples to find an analogue for their deposition. The team relied on the use of rare earth element patterns to demonstrate that the deposit formed in, or near, a chemocline in a stratified iron-rich basin.

“Future studies will aim to quantify the full extent of these Cambrian banded iron formations in China and whether similar deposits can be found elsewhere,” says Kurt Konhauser.

Reference:
Zhiquan Li et al. Earth’s youngest banded iron formation implies ferruginous conditions in the Early Cambrian ocean. Scientific Reports, 2018 DOI: 10.103841598-018-28187-2

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

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