Geophysicists find reason for sudden tectonic plate movements

Yale-led research may have solved one of the biggest mysteries in geology — namely, why do tectonic plates beneath the Earth’s surface, which normally shift over the course of tens to hundreds of millions of years, sometimes move abruptly?

A new study published Jan. 19 in the journal Proceedings of the National Academy of Sciences says the answer comes down to two things: thick crustal plugs and weakened mineral grains. Those effects, acting together, may explain a range of relatively speedy moves among tectonic plates around the world, from Hawaii to East Timor.

Of course, in this case “speedy” still means a million years or longer.

“Our planet is probably most distinctly marked by the fact that it has plate tectonics,” said Yale geophysicist David Bercovici, lead author of the research. “Our work here looks at the evolution of plate tectonics. How and why do plates change directions over time?”

Traditionally, scientists believed that all tectonic plates are pulled by subducting slabs — which result from the colder, top boundary layer of the Earth’s rocky surface becoming heavy and sinking slowly into the deeper mantle. Yet that process does not account for sudden plate shifts. Such abrupt movement requires that slabs detach from their plates, but doing this quickly is difficult since the slabs should be too cold and stiff to detach.

Yale-led research may have solved one of the biggest mysteries in geology -- namely, why do tectonic plates beneath the Earth's surface, which normally shift over the course of tens to hundreds of millions of years, sometimes move abruptly? Credit: © Mopic / Fotolia

Yale-led research may have solved one of the biggest mysteries in geology — namely, why do tectonic plates beneath the Earth’s surface, which normally shift over the course of tens to hundreds of millions of years, sometimes move abruptly?
Credit: © Mopic / Fotolia

According to the Yale study, there are additional factors at work. Thick crust from continents or oceanic plateaux is swept into the subduction zone, plugging it up and prompting the slab to break off. The detachment process is then accelerated when mineral grains in the necking slab start to shrink, causing the slab to weaken rapidly.

The result is tectonic plates that abruptly shift horizontally, or continents suddenly bobbing up.

“Understanding this helps us understand how the tectonic plates change through the Earth’s history,” Bercovici said. “It adds to our knowledge of the evolution of our planet, including its climate and biosphere.”

The study’s co-authors are Gerald Schubert of the University of California-Los Angeles and Yanick Ricard of the Université de Lyon in France.

Dino-killing asteroid generated global firestorm ?

Pioneering new research has debunked the theory that the asteroid that is thought to have led to the extinction of dinosaurs also caused vast global firestorms that ravaged planet Earth.

A team of researchers from the University of Exeter, University of Edinburgh and Imperial College London recreated the immense energy released from an extra-terrestrial collision with Earth that occurred around the time that dinosaurs became extinct. They found that the intense but short-lived heat near the impact site could not have ignited live plants, challenging the idea that the impact led to global firestorms.

These firestorms have previously been considered a major contender in the puzzle to find out what caused the mass extinction of life on Earth 65 million years ago.

The researchers found that close to the impact site, a 200 km wide crater in Mexico, the heat pulse — that would have lasted for less than a minute — was too short to ignite live plant material. However they discovered that the effects of the impact would have been felt as far away as New Zealand where the heat would have been less intense but longer lasting — heating the ground for about seven minutes — long enough to ignite live plant matter.

This is the fire propagation apparatus recreating the impact induced thermal pulse at the Cretaceous-Palaeogene (K-Pg) boundary. Halogen lamps are delivering the thermal radiation. Credit: University of Exeter

This is the fire propagation apparatus recreating the impact induced thermal pulse at the Cretaceous-Palaeogene (K-Pg) boundary. Halogen lamps are delivering the thermal radiation.
Credit: University of Exeter

The experiments were carried out in the laboratory and showed that dry plant matter could ignite, but live plants including green pine branches, typically do not.

Dr Claire Belcher from the Earth System Science group in Geography at the University of Exeter said: “By combining computer simulations of the impact with methods from engineering we have been able to recreate the enormous heat of the impact in the laboratory. This has shown us that the heat was more likely to severely affect ecosystems a long distance away, such that forests in New Zealand would have had more chance of suffering major wildfires than forests in North America that were close to the impact. This flips our understanding of the effects of the impact on its head and means that palaeontologists may need to look for new clues from fossils found a long way from the impact to better understand the mass extinction event.”

Plants and animals are generally resistant to localised fire events — animals can hide or hibernate and plants can re-colonise from other areas, implying that wildfires are unlikely to be directly capable of leading to the extinctions. If however some animal communities, particularly large animals, were unable to shelter from the heat, they may have suffered serious losses. It is unclear whether these would have been sufficient to lead to the extinction of species.

Dr Rory Hadden from the University of Edinburgh said: “This is a truly exciting piece of inter-disciplinary research. By working together engineers and geoscientists have tackled a complex, long-standing problem in a novel way. This has allowed a step forward in the debate surrounding the end Cretaceous impact and will help Geoscientists interpret the fossil record and evaluate potential future impacts. In addition, the methods we developed in the laboratory for this research have driven new developments in our current understanding of how materials behave in fires particularly at the wildland-urban-interface, meaning that we have been able to answer questions relating to both ancient mass extinctions at the same time as developing understanding of the impact of wildfires in urban areas today.”

The results of the study are published in the Journal of the Geological Society.

Courtesy: University of Exeter. “Doubt cast on global firestorm generated by dino-killing asteroid.” ScienceDaily. ScienceDaily, 22 January 2015. <www.sciencedaily.com/releases/2015/01/150122084849.htm>.

Nundasuchus: A reptiles lived before dinosaurs

Finding a new species of dinosaur is pretty rare. Getting a hand in the discovery and naming of one — that’s rarer still.

Or it would be for anyone other than 32-year-old Sterling Nesbitt, an assistant professor of geological sciences in the College of Science and the newest addition to Virginia Tech’s paleontology team. Nesbitt has been responsible for naming more than half a dozen reptiles (including dinosaurs) in his young career.His latest addition to the paleontological vernacular is Nundasuchus, (noon-dah-suh-kis) a 9-foot-long carnivorous reptile with steak knifelike teeth, bony plates on the back, and legs that lie under the body.

Here is a representation of paleontologist Sterling Nesbitt's latest addition to the paleontological vernacular: Nundasuchus, a 9-foot-long carnivorous reptile with steak knife-like teeth and bony plates on the back. Credit: Virginia Tech

Here is a representation of paleontologist Sterling Nesbitt’s latest addition to the paleontological vernacular: Nundasuchus, a 9-foot-long carnivorous reptile with steak knife-like teeth and bony plates on the back.
Credit: Virginia Tech

Nundasuchus is not a dinosaur, but one of the large reptiles that lived before dinosaurs took over the world.

“The full name is actually Nundasuchus songeaensis,” Nesbitt explained. “It’s Swahili mixed with Greek.”

The basic meaning of Nundasuchus, is “predator crocodile,” “Nunda” meaning predator in Swahili, and “suchus” a reference to a crocodile in Greek.

“The ‘songeaensis’ comes from the town, Songea, near where we found the bones,” Nesbitt said. “The reptile itself was heavy-bodied with limbs under its body like a dinosaur, or bird, but with bony plates on its back like a crocodilian.”

The new, albeit ancient, reptile, is featured online in the Journal of Vertebrate Paleontology.

“We discovered the partial skeleton in 2007 when I was a graduate student, but it took some years to piece the bones together as they were in thousands of pieces,” Nesbitt said.

Although a large number of skeleton bones were found, most of the skull was not recovered despite three trips to the site and more than 1,000 hours spent painstakingly piecing the bones back together and cleaning them. Nundasuchus was found in southwestern Tanzania, while Nesbitt and a team of researchers were looking for prehistoric relatives of birds and crocodiles, but not really expecting to find something entirely new.

“There’s such a huge gap in our understanding around the time when the the common ancestor of birds and crocodilians was alive — there isn’t a lot out there in the fossil record from that part of the reptile family tree,” Nesbitt said. “This helps us fill in some gaps in reptile family tree, but we’re still studying it and figuring out the implications.”

The find itself was a bit of a “eureka moment” for the team. Nesbitt said he realized very quickly what he had found.

“Sometimes you know instantly if it’s new and within about 30 seconds of picking up this bone I knew it was a new species,” he said. “I had hoped to find a leg bone to identify it, and I thought, This is exactly why we’re here’ and I looked down and there were bones everywhere. It turns out I was standing on bones that had been weathering out of the rock for hundreds of years — and it was all one individual of a new species.”

Nesbitt says he has been very lucky to put himself in the right position for finding bones, but it also takes a lot of work doing research on what has been found in various locations through previous research; what type of animals were known to inhabit certain areas; and research into the geological maps of areas to determine the most likely places to find fossils.

Nesbitt has been involved in naming 17 different reptiles, dinosaurs, and dinosaur relatives in the last 10 years, including seven of which he discovered.

Citation: Virginia Tech. “Paleontologist names a carnivorous reptile that preceded dinosaurs.” ScienceDaily. ScienceDaily, 20 January 2015. <www.sciencedaily.com/releases/2015/01/150120085619.htm>.

Purgatorius, an early primate

Earth’s earliest primates have taken a step up in the world, now that researchers have gotten a good look at their ankles.

 A new study has found that Purgatorius, a small mammal that lived on a diet of fruit and insects, was a tree dweller. Paleontologists made the discovery by analyzing 65-million-year-old ankle bones collected from sites in northeastern Montana.

Purgatorius, part of an extinct group of primates called plesiadapiforms, first appears in the fossil record shortly after the extinction of non-avian dinosaurs. Some researchers have speculated over the years that primitive plesiadapiforms were terrestrial, and that primates moved into the tree canopy later. These ideas can still be found in some textbooks today.

“The textbook that I am currently using in my biological anthropology courses still has an illustration of Purgatorius walking on the ground. Hopefully this study will change what students are learning about earliest primate evolution and will place Purgatorius in the trees where it rightfully belongs,” said Stephen Chester, the paper’s lead author. Chester, who conducted much of the research while at Yale University studying for his Ph.D., is an assistant professor at Brooklyn College, City University of New York. Chester is also a curatorial affiliate at the Yale Peabody Museum of Natural History.

Fossil ankles show that Purgatorius, an early primate, lived in trees. Credit: Patrick Lynch/Yale University

Fossil ankles show that Purgatorius, an early primate, lived in trees.
Credit: Patrick Lynch/Yale University

Until now, paleontologists had only the animal’s teeth and jaws to examine, which left much of its appearance and behavior a mystery. The identification of Purgatorius ankle bones, found in the same area as the teeth, gave researchers a better sense of how it lived.

“The ankle bones have diagnostic features for mobility that are only present in those of primates and their close relatives today,” Chester said. “These unique features would have allowed an animal such as Purgatorius to rotate and adjust its feet accordingly to grab branches while moving through trees. In contrast, ground-dwelling mammals lack these features and are better suited for propelling themselves forward in a more restricted, fore-and-aft motion.”

The research provides the oldest fossil evidence to date that arboreality played a key role in primate evolution. In essence, said the researchers, it implies that the divergence of primates from other mammals was not a dramatic event. Rather, primates developed subtle changes that made for easier navigation and better access to food in the trees.

The research appears in the Jan. 19 online edition of the Proceedings of the National Academy of Sciences.

Ancient fossils reveal rise in parasitic infections due to climate change

When seeking clues about the future effects of possible climate change, sometimes scientists look to the past. Now, a paleobiologist from the University of Missouri has found indications of a greater risk of parasitic infection due to climate change in ancient mollusk fossils. His study of clams from the Holocene Epoch (that began 11,700 years ago) indicates that current sea level rise may mimic the same conditions that led to an upsurge in parasitic trematodes, or flatworms, he found from that time. He cautions that an outbreak in human infections from a related group of parasitic worms could occur and advises that communities use the information to prepare for possible human health risks.

Trematodes are internal parasites that affect mollusks and other invertebrates inhabiting estuarine environments, which are the coastal bodies of brackish water that connect rivers and the open sea. John Huntley, assistant professor of geological sciences in the College of Arts and Science at MU, studied prehistoric clam shells collected from the Pearl River Delta in China for clues about how the clams were affected by changes caused from global warming and the resulting surge in parasites.

“Because they have soft bodies, trematodes do not leave body fossils,” Huntley said. “However, infected clam shells develop oval-shaped pits where the clam grew around the parasite in order to keep it out; the prevalence of these pits and their makeup provide clues to how the clams adapted to fight trematodes. When compared to documented rises in sea level more than 9,300 years ago, we found that we currently are creating conditions for an increase in trematodes in present-day estuarine environments. This could have harmful implications for both animal and human health, including many of the world’s fisheries.”

This image shows the following: (A) Whole specimen from sample 154 with shallow pits; (B) Partial specimen from sample 154 with deep pits; (C) Partial specimen from sample 157 displaying pits on multiple growth layers; and (D) Incipient steinkern from sample 162 displaying pits preserved as positive relief on lower half of specimen. Credit: John Warren Huntley

This image shows the following: (A) Whole specimen from sample 154 with shallow pits; (B) Partial specimen from sample 154 with deep pits; (C) Partial specimen from sample 157 displaying pits on multiple growth layers; and (D) Incipient steinkern from sample 162 displaying pits preserved as positive relief on lower half of specimen.
Credit: John Warren Huntley

Modern-day trematodes will first infest mollusks like clams and snails, which are eaten by shore birds and mammals including humans. Symptoms of infection in humans range from liver and gall bladder inflammation to chest pain, fever, and brain inflammation. The infections can be fatal. At least 56 million people globally suffer from one or more foodborne trematode infections, according to the World Health Organization.

Huntley and his team compared these findings to those from his previous study on clams found in the Adriatic Sea. Using data that includes highly detailed descriptions of climate change and radiocarbon dating Huntley noticed a rising prevalence of pits in the clam shells, indicating a higher prevalence of the parasites during times of sea level rise in both the fossils from China and Italy.

“By comparing the results we have from the Adriatic and our new study in China, we’re able to determine that it perhaps might not be a coincidence, but rather a general phenomenon,” Huntley said. “While predicting the future is a difficult game, we think we can use the correspondence between the parasitic prevalence and past climate change to give us a good road map for the changes we need to make.”

Source: Science daily : John Warren Huntley, Franz T. Fürsich, Matthias Alberti, Manja Hethke, Chunlian Liu. A complete Holocene record of trematode–bivalve infection and implications for the response of parasitism to climate change. Proceedings of the National Academy of Sciences, 2014; 111 (51): 18150 DOI: 10.1073/pnas.1416747111

Fossil found by boy fills gap in reptile evolution

A fossil of a lizard-like creature found by a boy on a Prince Edward Island beach is a new species and the only reptile in the world ever found from its time, 300 million years ago, a new study shows.

The fossilized species has been named Erpetonyx arsenaultorum after the family of Michael Arsenault of Prince County, P.E.I., who found the fossil at Cape Egmont, said a study published this week in the Proceedings of Royal Society B: Biological Sciences.

“Our animal is the only reptile known from this time period called the Gzhelian,” said Sean Modesto, a paleontologist at Cape Breton University who was the lead author of the new paper about the fossil, now in the collection of the Royal Ontario Museum in Toronto. He collaborated with researchers at the ROM, University of Toronto at Mississauga, and the Smithsonian Institution.

The new ancient reptile has been named Erpetonyx arsenaultorum after the family of Michael Arsenault of Prince County, P.E.I., who found the fossil on a beach when he was a young boy. (Courtesy Sean Modesto/Cape Breton University)

The new ancient reptile has been named Erpetonyx arsenaultorum after the family of Michael Arsenault of Prince County, P.E.I., who found the fossil on a beach when he was a young boy. (Courtesy Sean Modesto/Cape Breton University)

‘They built a box and Michael kept it under his bed for many years. He knew it was very valuable.’— Bette Sheen, family friend of Michael Arsenault

The Gzhelian Age was a five-million-year span that started about 304 million years ago, just 10 million years after the first reptiles appeared.

Erpetonyx helps fill a big gap in the fossil record, revealing that there were nearly twice as many kinds of reptiles living around that time as scientists previously believed, Modesto said.

At the time that Erpetonyx lived, P.E.I. was located on the equator and its home was likely a tropical forest.

The animal was about 25 centimetres long — about the size of a chameleon — and would have looked like an average modern-day lizard, even though it isn’t closely related to them. Its sharp, peg-like teeth showed it likely ate insects and small amphibians rather than plants.

“Anything that it could catch or stuff down its throat it probably ate,” said Modesto.

Source:Article By By Emily Chung, CBC News

WFS Archive : Only second Jurassic dinosaur ever found in Antarctica

A new genus and species of dinosaur from the Early Jurassic has been discovered in Antarctica. The massive plant-eating primitive sauropodomorph is called Glacialisaurus hammeri and lived about 190 million years ago.

The recently published description of the new dinosaur is based on partial foot, leg and ankle bones found on Mt. Kirkpatrick near the Beardmore Glacier in Antarctica at an elevation of more than 13,000 feet.

“The fossils were painstakingly removed from the ice and rock using jackhammers, rock saws and chisels under extremely difficult conditions over the course of two field seasons,” said Nathan Smith, a graduate student at The Field Museum. “They are important because they help to establish that primitive sauropodomorph dinosaurs were more broadly distributed than previously thought, and that they coexisted with their cousins, the true sauropods.”

The findings were published online Dec. 5 in the Acta Palaeontologica Poloncica. Diego Pol, a paleontologist at the Museo Paleontológico Egidio Feruglio in Chubut, Argentina, is the other co-author of the research.

Sauropodomorph dinosaurs were the largest animals to ever walk the earth. They were long-necked herbivores and include Diplodocus and Apatosaurus. Their sister group is the theropods, which include Tyrannosaurus, Velociraptor, and modern birds.

Glacialisaurus hammeri was about 20-25 feet long and weighed about 4-6 tons . It was named after Dr. William Hammer, a professor at Augustana College who led the two field trips to Antarctica that uncovered the fossils. Glacialisaurus belongs to the sauropodomorph family Massopsondylidae, which may represent a secondary radiation of basal sauropodomorphs during the Early Jurassic.

Currently, the development and evolutionary relationships of the sauropodomorph dinosaurs are hotly debated by paleontologists. This discovery, however, helps to resolve some of this debate by establishing two things. First, it shows that sauropodomorphs were widely distributed in the Early Jurassic-not only in China, South Africa, South America and North America, but also in Antarctica.

“This was probably due to the fact that major connections between the continents still existed at that time, and because climates were more equitable across latitudes than they are today,” Smith said.

Second, the discovery of Glacialisaurus hammeri shows that primitive sauropodomorphs probably coexisted with true sauropods for an extended period of time. The recent discovery of a possible sauropod at roughly the same location in Antarctica lends additional evidence to the theory that the earliest sauropods coexisted with their basal sauropodomorph cousins, including Glacialisaurus hammeri, during the Late Triassic and Early Jurassic, Smith and Pol conclude in their research findings.

Note: This story has been adapted from a news release issued by the Field Museum 2007

WFS Dinosaur Diary: “Eotyrannus”

Eotyrannus (meaning “dawn tyrant”) was a genus of tyrannosauroid theropod dinosaur hailing from the Early Cretaceous Wessex Formation beds, included in Wealden Group, located in the southwest coast of the Isle of Wight, United Kingdom. The remains (MIWG1997.550), consisting of assorted skull, axial skeleton and appendicular skeleton elements, from a juvenile or subadult, found in a plant debris clay bed, were described by Hutt et al. in early 2001. The etymology of the generic name refers to the animals classification as an early tyrannosaur or “tyrant lizard”, while the specific name honors the discoverer of the fossil.

Eotyrannus

Eotyrannus

Eotyrannus has the following tyrannosauroid characters: serrated premaxillary teeth with a D cross section, proportionally elongate tibiae and metatarsals. Primitive characters for Tyrannosauroidea are the elongate neck vertebrae and the long, well-developed arms forelimbs along with the undecorated dorsal surface of the skull, unlike the more advanced tyrannosaurids. However this animal, proportionally, has one of the longest hands among non-avialan theropods known to date. This theropod would be a probable predator of such herbivorous dinosaurs as Hypsilophodon.

FACT SHEET

Meaning – Eotyrannus means “dawn tyrant” or “early tyrant”
Pronounced – e-o-tie-RAN-us
Named By – Hutt, Naish, Martill, Barker and Newbery
When Named – 2001

DIET: Carnivore (meat-eater)
SIZE: Length – 15 ft (4.5 m) long
Weight – ?
WHEN IT LIVED: Middle Cretaceous period, about 120 to 125 million years ago
WHERE IT LIVED: Fossils have been found in the Wessex Formation, Isle of Wight, off the coast of Great Britain, Europe.

FOSSILS:

What was Found – A 40-percent complete fossil was found in 1997 (including the front half of the skull).
Who Found the Fossils – Eotyrannus was found by a team headed by Darren Naish (Univ. of Portsmouth).

CLASSIFICATION:
• Kingdom Animalia (animals)
• Phylum Chordata (having a hollow nerve chord ending in a brain)
• Class Archosauria (diapsids with socket-set teeth, etc.)
• Order Saurischia – lizard-hipped dinosaurs
• Suborder Theropoda – bipedal carnivores
• Tetanura – advanced theropods
• Infraorder Coelurosauria – lightly-built fast-running predators with hollow bones and large brains
• Superfamily Maniraptoriformes – advanced coelurosaurs with a fused wrist bone
• Family Tyrannosauroidea – huge predators with small arms and two-fingered hands (the third finger was very tiny). Tyrannosaurids include T. rex, Albertosaurus, Alectrosaurus, Alioramus, Chingkankousaurus, Daspletosaurus, Gorgosaurus, Nanotyrannus, Prodeinodon, Tarbosaurus, etc.
• Genus Eotyrannus
• Species E. lengi (type species named by Hutt, Naish, Martill, Barker & Newbery, 2001), named to honor Gavin Leng, who found the first fossil on the Isle of Wight.

Earth grow a new layer under an Icelandic volcano

 

New research into an Icelandic eruption has shed light on how the Earth’s crust forms, according to a paper published today in Nature.

When the Bárðarbunga volcano, which is buried beneath Iceland’s Vatnajökull ice cap, reawakened in August 2014, scientists had a rare opportunity to monitor how the magma flowed through cracks in the rock away from the volcano. The molten rock forms vertical sheet-like features known as dykes, which force the surrounding rock apart.

Study co-author Professor Andy Hooper from the Centre for Observation and Modelling of Earthquakes, volcanoes and Tectonics (COMET) at the University of Leeds explained: “New crust forms where two tectonic plates are moving away from each other. Mostly this happens beneath the oceans, where it is difficult to observe.

“However, in Iceland this happens beneath dry land. The events leading to the eruption in August 2014 are the first time that such a rifting episode has occurred there and been observed with modern tools, like GPS and satellite radar.”

Although it has a long history of eruptions, Bárðarbunga has been increasingly restless since 2005. There was a particularly dynamic period in August and September this year, when more than 22,000 earthquakes were recorded in or around the volcano in just four weeks, due to stress being released as magma forced its way through the rock.

Using GPS and satellite measurements, the team were able to track the path of the magma for over 45km before it reached a point where it began to erupt, and continues to do so to this day. The rate of dyke propagation was variable and slowed as the magma reached natural barriers, which were overcome by the build-up of pressure, creating a new segment.

The dyke grows in segments, breaking through from one to the next by the build up of pressure. This explains how focused upwelling of magma under central volcanoes is effectively redistributed over large distances to create new upper crust at divergent plate boundaries, the authors conclude.

As well as the dyke, the team found ‘ice cauldrons’ – shallow depressions in the ice with circular crevasses, where the base of the glacier had been melted by magma. In addition, radar measurements showed that the ice inside Bárðarbunga’s crater had sunk by 16m, as the volcano floor collapsed.

Artist's conception illustrating the three-dimensional geometry of the plumbing (left) and timing of events (right column) at Eyjafjallajökull volcano in Iceland. The complicated plumbing inside the volcano consists of inter--connected conduits, sills, and dikes that allow magma to rise from deep within the Earth. The first three panels in the time series show distinct episodes of magmatic intrusions that caused measurable deformation and seismic events in 1994, 1999, and in the first several months of 2010. No eruptive activity occurred during this period of unrest. Each intrusive episode inflated a different section of the plumbing, drawn and modeled as sills at approximately 5 km depth. The fourth panel illustrates the first eruption, between 20 March and 12 April 2010, when basaltic magma (orange) erupted onto the Earth's surface on the flank of the mountain. The fifth panel shows the second eruption, between 14 April and 22 May, when a different type of magma (trachyandesite, shown in red), erupted explosively at the ice-capped summit (1600 m elevation). The interaction of magma and ice initially increased the explosive activity, generating a plume of particles that rose as high as the 30,000-foot flight level and disrupted air traffic across Europe for weeks. [show less] Credit: Illustration by Zina Deretsky, U.S. National Science Foundation

Artist’s conception illustrating the three-dimensional geometry of the plumbing (left) and timing of events (right column) at Eyjafjallajökull volcano in Iceland. The complicated plumbing inside the volcano consists of inter–connected conduits, sills, and dikes that allow magma to rise from deep within the Earth. The first three panels in the time series show distinct episodes of magmatic intrusions that caused measurable deformation and seismic events in 1994, 1999, and in the first several months of 2010. No eruptive activity occurred during this period of unrest. Each intrusive episode inflated a different section of the plumbing, drawn and modeled as sills at approximately 5 km depth. The fourth panel illustrates the first eruption, between 20 March and 12 April 2010, when basaltic magma (orange) erupted onto the Earth’s surface on the flank of the mountain. The fifth panel shows the second eruption, between 14 April and 22 May, when a different type of magma (trachyandesite, shown in red), erupted explosively at the ice-capped summit (1600 m elevation). The interaction of magma and ice initially increased the explosive activity, generating a plume of particles that rose as high as the 30,000-foot flight level and disrupted air traffic across Europe for weeks.
Credit: Illustration by Zina Deretsky, U.S. National Science Foundation

COMET PhD student Karsten Spaans from the University of Leeds, a co-author of the study, added: “Using radar measurements from space, we can form an image of caldera movement occurring in one day. Usually we expect to see just noise in the image, but we were amazed to see up to 55cm of subsidence.”Like other liquids, magma flows along the path of least resistance, which explains why the dyke at Bárðarbunga changed direction as it progressed.  Magma flow was influenced mostly by the lie of the land to start with, but as it moved away from the steeper slopes, the influence of plate movements became more important.

Summarising the findings, Professor Hooper said: “Our observations of this event showed that the magma injected into the crust took an incredibly roundabout path and proceeded in fits and starts.

“Initially we were surprised at this complexity, but it turns out we can explain all the twists and turns with a relatively simple model, which considers just the pressure of rock and ice above, and the pull exerted by the plates moving apart.”

Source: University of Leeds. “Scientists observe the Earth grow a new layer under an Icelandic volcano.” ScienceDaily. ScienceDaily, 15 December 2014. <www.sciencedaily.com/releases/2014/12/141215114101.htm>.

Shedding new light on diet of extinct animals

A study of tooth enamel in mammals living today in the equatorial forest of Gabon could ultimately shed light on the diet of long extinct animals, according to new research from the University of Bristol.

Reconstructing what extinct organisms fed on can be a real challenge. Scientists use a variety of methods including the structure of an animal’s bones, analysis of its stomach contents and the patterns of wear left on the surface of its teeth. Geochemical methods have also proved useful but can be limited by poor preservation of the animal’s remains.

Dr Jeremy Martin, formerly of Bristol’s School of Earth Sciences and now at the Laboratoire de Géologie de Lyon: terre, planètes et environnement, University of Lyon/ENS de Lyon, and colleagues found that magnesium isotopes are particularly well suited to deciphering the diet of living mammals and, when used in conjunction with other methods such as carbon isotopes, they could open up new perspectives on the study of fossilised animals.

Dr Martin said: “Most chemical elements exist in distinct forms called isotopes which are characterized by different masses. Therefore, all the isotopes of an element will behave differently during a chemical reaction preferentially sorting out heavier ones from lighter ones.”

As noted by Dr Balter, who took part in the study: “Biological processes such as digestion involve important isotopic fractionations of the various elements assimilated through food consumption so the stable isotope composition of an organism tends to reflect its diet — we are what we eat.”

Scientists know that the carbon and nitrogen isotopes preserved in bone collagen can give direct evidence about an animal’s food intake. However, because of the rapid decay of organic matter, these inferences are limited to the recent past.

Dr Martin and colleagues explored the isotopic variability of one of the major elements that compose tooth apatite, the hardest biological structure to retain its pristine signal throughout the fossil record.

Teeth from various mammals living today in the equatorial forest of Gabon were purified for magnesium isotopes. The results show that the isotope ratios of magnesium 26 mg/24 mg increase from herbivore to higher-level consumers (such as carnivores) and, when used in conjunction with other geochemical proxies, serve as a strong basis to infer the diet of mammals.

Dr Martin said: “Many fossil groups do not have living analogues and inferring their diet is far from clear. Applying a new perspective to palaeoecology by using non-traditional isotopes (such as magnesium or calcium in conjunction with traditional approaches) holds great promise for our understanding of how such ancient organisms interacted with each other.”