From rocks in Colorado, evidence of a ‘chaotic solar system’

February 22, 2017

The layer cake of sedimentary rock near Big Bend, Texas, shows the alternating layers of shale and limestone characteristic of the rock laid down at the bottom of a shallow ocean during the late Cretaceous period. The rock holds the 87 million-year-old signature of a ‘resonance transition’ in the orbits of Mars and Earth, definitive geologic evidence that the orbits of the planets in our solar system behave differently than prevailing theory, which held that the planets orbit like clockwork in a quasiperiodic manner. Credit: Bradley Sageman, Northwestern University

Plumbing a 90 million-year-old layer cake of sedimentary rock in Colorado, a team of scientists from the University of Wisconsin-Madison and Northwestern University has found evidence confirming a critical theory of how the planets in our solar system behave in their orbits around the sun.

The finding, published Feb. 23, 2017 in the journal Nature, is important because it provides the first hard proof for what scientists call the “chaotic solar system,” a theory proposed in 1989 to account for small variations in the present conditions of the solar system. The variations, playing out over many millions of years, produce big changes in our planet’s climate — changes that can be reflected in the rocks that record Earth’s history.

The discovery promises not only a better understanding of the mechanics of the solar system, but also a more precise measuring stick for geologic time. Moreover, it offers a better understanding of the link between orbital variations and climate change over geologic time scales.

Using evidence from alternating layers of limestone and shale laid down over millions of years in a shallow North American seaway at the time dinosaurs held sway on Earth, the team led by UW-Madison Professor of Geoscience Stephen Meyers and Northwestern University Professor of Earth and Planetary Sciences Brad Sageman discovered the 87 million-year-old signature of a “resonance transition” between Mars and Earth. A resonance transition is the consequence of the “butterfly effect” in chaos theory. It plays on the idea that small changes in the initial conditions of a nonlinear system can have large effects over time.

In the context of the solar system, the phenomenon occurs when two orbiting bodies periodically tug at one another, as occurs when a planet in its track around the sun passes in relative proximity to another planet in its own orbit. These small but regular ticks in a planet’s orbit can exert big changes on the location and orientation of a planet on its axis relative to the sun and, accordingly, change the amount of solar radiation a planet receives over a given area. Where and how much solar radiation a planet gets is a key driver of climate.

“The impact of astronomical cycles on climate can be quite large,” explains Meyers, noting as an example the pacing of Earth’s ice ages, which have been reliably matched to periodic changes in the shape of Earth’s orbit, and the tilt of our planet on its axis. “Astronomical theory permits a very detailed evaluation of past climate events that may provide an analog for future climate.”

To find the signature of a resonance transition, Meyers, Sageman and UW-Madison graduate student Chao Ma, whose dissertation work this comprises, looked to the geologic record in what is known as the Niobrara Formation in Colorado. The formation was laid down layer by layer over tens of millions of years as sediment was deposited on the bottom of a vast seaway known as the Cretaceous Western Interior Seaway. The shallow ocean stretched from what is now the Arctic Ocean to the Gulf of Mexico, separating the eastern and western portions of North America.

“The Niobrara Formation exhibits pronounced rhythmic rock layering due to changes in the relative abundance of clay and calcium carbonate,” notes Meyers, an authority on astrochronology, which utilizes astronomical cycles to measure geologic time. “The source of the clay (laid down as shale) is from weathering of the land surface and the influx of clay to the seaway via rivers. The source of the calcium carbonate (limestone) is the shells of organisms, mostly microscopic, that lived in the water column.”

Meyers explains that while the link between climate change and sedimentation can be complex, the basic idea is simple: “Climate change influences the relative delivery of clay versus calcium carbonate, recording the astronomical signal in the process. For example, imagine a very warm and wet climate state that pumps clay into the seaway via rivers, producing a clay-rich rock or shale, alternating with a drier and cooler climate state which pumps less clay into the seaway and produces a calcium carbonate-rich rock or limestone.”

The new study was supported by grants from the National Science Foundation. It builds on a meticulous stratigraphic record and important astrochronologic studies of the Niobrara Formation, the latter conducted in the dissertation work of Robert Locklair, a former student of Sageman’s at Northwestern.

Dating of the Mars-Earth resonance transition found by Ma, Meyers and Sageman was confirmed by radioisotopic dating, a method for dating the absolute ages of rocks using known rates of radioactive decay of elements in the rocks. In recent years, major advances in the accuracy and precision of radioisotopic dating, devised by UW-Madison geoscience Professor Bradley Singer and others, have been introduced and contribute to the dating of the resonance transition.

The motions of the planets around the sun has been a subject of deep scientific interest since the advent of the heliocentric theory — the idea that Earth and planets revolve around the sun — in the 16th century. From the 18th century, the dominant view of the solar system was that the planets orbited the sun like clockwork, having quasiperiodic and highly predictable orbits. In 1988, however, numerical calculations of the outer planets showed Pluto’s orbit to be “chaotic” and the idea of a chaotic solar system was proposed in 1989 by astronomer Jacques Laskar, now at the Paris Observatory.

Following Laskar’s proposal of a chaotic solar system, scientists have been looking in earnest for definitive evidence that would support the idea, says Meyers.

“Other studies have suggested the presence of chaos based on geologic data,” says Meyers. “But this is the first unambiguous evidence, made possible by the availability of high-quality, radioisotopic dates and the strong astronomical signal preserved in the rocks.”

Reference:
Chao Ma, Stephen R. Meyers, Bradley B. Sageman. Theory of chaotic orbital variations confirmed by Cretaceous geological evidence. Nature, 2017; 542 (7642): 468 DOI: 10.1038/nature21402

Note: The above post is reprinted from materials provided by University of Wisconsin-Madison. Original written by Terry Devitt.

Insight into a physical phenomenon that leads to earthquakes

February 22, 2017

Aerial photo of the San Andreas Fault in the Carrizo Plain, northwest of Los Angeles.
Credit: Wikipedia.

Scientists have gotten better at predicting where earthquakes will occur, but they’re still in the dark about when they will strike and how devastating they will be.

In the search for clues that will help them better understand earthquakes, scientists at the University of Pennsylvania are studying a phenomenon called ageing. In ageing, the longer that materials are in contact with each other, the more force is required to move them. This resistance is called static friction. The longer something, such as a fault, is sitting still, the more static friction builds up and the stronger the fault gets.

Even when the fault remains still, tectonic motion is still occurring; stress builds up in the fault as the plates shift until finally they shift so much that they exceed the static friction force and begin to slide. Because the fault grew stronger with time, the stress can build up to large levels, and a huge amount of energy is then released in the form of a powerful quake.

“This ageing mechanism is critical in underlying the unstable behavior of faults that lead to earthquakes,” said Robert Carpick, the John Henry Towne Professor and chair of the Department of Mechanical Engineering and Applied Mechanics in Penn’s School of Engineering and Applied Science. “If you didn’t have ageing, then the fault would move very easily and so you’d get much smaller earthquakes happening more frequently, or maybe even just smooth motion. Ageing leads to the occurrence of infrequent, large earthquakes that can be devastating.”

Scientists have been studying the movement of faults and ageing in geological materials at the macroscale for decades, producing phenomenological theories and models to describe their experimental results. But there’s a problem when it comes to these models.

“The models are not fundamental, not physically based, which means we cannot derive those models from basic physics,” said Kaiwen Tian, a graduate student in Penn’s School of Arts & Sciences.

But a Penn-based project seeks to understand the friction of rocks from a more physical point of view at the nanoscale.

In their most recent paper, published in Physical Review Letters, the researchers verified the first fundamental theory to describe ageing and explain what happens when load increases.

The research was led by Tian and Carpick. David Goldsby, an associate professor in the Department of Earth and Environmental Science at Penn; Izabela Szlufarska, a professor of materials science and engineering at the University of Wisconsin-Madison; UW alumnus Yun Liu; and Nitya Gosvami, now an assistant professor in the Department of Applied Mechanics at IIT Delhi, also contributed to the study.

Previous work from the group found that static friction is logarithmic with time. That means that if materials are in contact for 10 times longer, then the friction force required to move them doubles. While scientists had seen this behavior of rocks and geological materials at the macroscopic scale, these researchers observed it at the nanoscale.

In this new study, the researchers varied the amount of normal force on the materials to find out how load affects the ageing behavior.

“That’s a very important question because load may have two effects,” Tian said. “If you increase load, you will increase contact area. It may also affect the local pressure.”

To study this, the researchers used an atomic force microscope to investigate bonding strength where two surfaces meet. They used silicon oxide because it is a primary component of many rock materials. Using the small nanoscale tip of the AFM ensures that the interface is composed of a single contact point, making it easier to estimate the stresses and contact area.

They brought a nanoscale tip made from silicon oxide into contact with a silicon oxide sample and held it there. After enough time passed, they slid the tip and measured the force required to initiate sliding. Carpick said this is analogous to putting a block on the floor, letting it sit for a while, and then pushing it and measuring how much force it takes for the block to start moving.

They observed what happened when they pushed harder in the normal direction, increasing the load. They found that they doubled the normal force, and then the friction force required also doubled.

Explaining it required looking very carefully the mechanism leading to this increase in friction force.

“The key,” Carpick said, “is we showed in our results how the dependence of the friction force on the holding time and the dependence of the friction force on the load combine. This was consistent with a model that assumes that the friction force is going up because we’re getting chemical bonds forming at the interface, so the number of those bonds increase with time. And, when we push harder, what we’re doing is increasing the area of contact between the tip and the sample, causing friction to go up with normal force.”

Prior to this research, it had been suggested that pushing harder might also cause those bonds to form more easily.

The researchers found that this wasn’t the case: to a good approximation, increasing the normal force simply increases the amount of contact and the number of sites where atoms can react.

Currently, the group is looking at what happens when the tip sits on the sample for very short amounts of time. Previously they had been looking at hold times from one-tenth of a second to as much as 100 seconds. But now they’re looking at timescales even shorter than one-tenth of a second.

By looking at very short timescales, they can gain insights into the details of the energetics of the chemical bonds to see if some bonds can form easily and if others take longer to form. Studying bonds that form easily is important because those are the first bonds to form and might provide insight into what happens at the very beginning of the contact.

In addition to providing a better understanding of earthquakes, this work could lead to more efficient nano-devices. Because many micro- and nano-devices are made from silicon, understanding friction is key to getting those devices to function more smoothly.

But, most important, the researchers hope that somewhere down the line, a better understanding of ageing will enable them to predict when earthquakes will occur.

“Earthquake locations can be predicted fairly well,” Carpick said, “but when an earthquake is going to happen is very difficult to predict, and this is largely because there’s a lack of physical understanding of the frictional mechanisms behind the earthquakes. We have long way to go to connect this work to earthquakes. However, this work gives us more fundamental insights into the mechanism behind this ageing and, in the long term, we think these kinds of insights could help us predict earthquakes and other frictional phenomena better.”

This research was supported by a grant from the Earth Sciences Division of the National Science Foundation.

Reference:
Kaiwen Tian, Nitya N. Gosvami, David L. Goldsby, Yun Liu, Izabela Szlufarska, Robert W. Carpick. Load and Time Dependence of Interfacial Chemical Bond-Induced Friction at the Nanoscale. Physical Review Letters, 2017; 118 (7) DOI: 10.1103/PhysRevLett.118.076103

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

Experiments call origin of Earth’s iron into question

February 21, 2017

This is an infographic describing theories on how the Earth got its iron. Credit: Designed by Laura Martin/The University of Texas at Austin Jackson School of Geosciences. Images 1 and 2 from NASA/JPL-Caltech, Image 3 from X-Science, Earth from NASA/JPL.

New research from The University of Texas at Austin reveals that the Earth’s unique iron composition isn’t linked to the formation of the planet’s core, calling into question a prevailing theory about the events that shaped our planet during its earliest years.

The research, published in Nature Communications on Feb. 20, opens the door for other competing theories about why the Earth, relative to other planets, has higher levels of heavy iron isotopes. Among them: light iron isotopes may have been vaporized into space by a large impact with another planet that formed the moon; the slow churning of the mantle as it makes and recycles the Earth’s crust may preferentially incorporate heavy iron into rock; or, the composition of the raw material that formed the planet in its earliest days may have been enriched with heavy iron.

An isotope is a variety of atom that has a different weight from other atoms of the same element because it has a different numbers of neutrons.

“The Earth’s core formation was probably the biggest event affecting Earth’s history. Materials that make up the whole Earth were melted and differentiated,” said Jung-Fu Lin, a professor at the UT Jackson School of Geosciences and one of the study’s authors. “But in this study, we say that there must be other origins for Earth’s iron isotope anomaly.”

Jin Liu, now a postdoctoral researcher at Stanford University, led the research while earning his Ph.D. at the Jackson School. Collaborators include scientists from The University of Chicago, Sorbonne Universities in France, Argonne National Laboratory, the Center for High Pressure Science and Advanced Technology Research in China, and the University of Illinois at Urbana-Champaign.

Rock samples from other planetary bodies and objects — ranging from the moon, to Mars, to ancient meteorites called chondrites — all share about the same ratio of heavy to light iron isotopes. In comparison to these samples from space, rocks from Earth have about 0.01 percent more heavy iron isotopes than light isotopes.

That might not sound like much, but Lin said it’s significant enough to make the Earth’s iron composition unique among known worlds.

“This 0.01 percent anomaly is very significant compared with, say, chondrites,” Lin said. “This significant difference thus represents a different source or origin of our planet.”

Lin said that one of the most popular theories to explain the Earth’s iron signature is that the relatively large size of the planet (compared with other rocky bodies in the solar system) created high pressure and high temperature conditions during core formation that made different proportions of heavy and light iron isotopes accumulate in the core and mantle. This resulted in a larger share of heavy iron isotopes bonding with elements that make up the rocky mantle, while lighter iron isotopes bonded together and with other trace metals to form the Earth’s core.

But when the research team used a diamond anvil to subject small samples of metal alloys and silicate rocks to core formation pressures, they not only found that the iron isotopes stayed put, but that the bonds between iron and other elements got stronger. Instead of breaking and rebonding with common mantle or core elements, the initial bond configuration got sturdier.

“Our high pressure studies find that iron isotopic fractionation between silicate mantle and metal core is minimal,” said Liu, the lead author.

Co-author Nicolas Dauphas, a professor at the University of Chicago, emphasized that analyzing the atomic scale measurements was a feat unto itself.

“One has to use sophisticated mathematical techniques to make sense of the measurements,” he said. “It took a dream team to pull this off.”

Helen Williams, a geology lecturer at the University of Cambridge, said it’s difficult to know the physical conditions of Earth’s core formation, but that the high pressures in the experiment make for a more realistic simulation.

“This is a really elegant study using a highly novel approach that confirms older experimental results and extends them to much higher pressures appropriate to the likely conditions of core-mantle equilibrium on Earth,” Williams said.

Lin said it will take more research to uncover the reason for the Earth’s unique iron signature, and that experiments that approximate early conditions on Earth will play a key role because rocks from the core are impossible to attain.

Reference:
Jin Liu, Nicolas Dauphas, Mathieu Roskosz, Michael Y. Hu, Hong Yang, Wenli Bi, Jiyong Zhao, Esen E. Alp, Justin Y. Hu, Jung-Fu Lin. Iron isotopic fractionation between silicate mantle and metallic core at high pressure. Nature Communications, 2017; 8: 14377 DOI: 10.1038/ncomms14377

Note: The above post is reprinted from materials provided by University of Texas at Austin.

400 million year old gigantic extinct monster worm discovered in Canadian museum

February 21, 2017

This is a photograph showing the holotype of Websteroprion armstrongi. Credit: Luke Parry

A previously undiscovered species of an extinct primordial giant worm with terrifying snapping jaws has been identified by an international team of scientists.

Researchers from the University of Bristol, Lund University in Sweden and the Royal Ontario Museum studied an ancient fossil, which has been stored at the museum since the mid-1990s, and discovered the remains of a giant extinct bristle worm (the marine relatives of earthworms and leeches).

The findings are published in Scientific Reports.

The new species is unique among fossil worms and possessed the largest jaws ever recorded in this type of creature, reaching over one centimetre in length and easily visible to the naked eye. Typically, such fossil jaws are only a few millimetres in size and need to be studied using microscopes.

Despite being only knows from the jaws, comparison with living species suggests that this animal achieved a body length in excess of a metre.

This is comparable to that of ‘giant eunicid’ species, colloquially referred to as ‘Bobbit worms’ which are fearsome and opportunistic ambush predators, using their powerful jaws to capture prey such as fish and cephalopods (squids and octopuses) and dragging them into their burrows.

Lead author Mats Eriksson from Lund University said: “Gigantism in animals is an alluring and ecologically important trait, usually associated with advantages and competitive dominance.

“It is, however, a poorly understood phenomenon among marine worms and has never before been demonstrated in a fossil species.

“The new species demonstrates a unique case of polychaete gigantism in the Palaeozoic, some 400 million years ago.”

Co-author Luke Parry from the University of Bristol’s School of Earth Sciences, added: “It also shows that gigantism in jaw-bearing polychaetes was restricted to one particular evolutionary clade within the Eunicida and has evolved many times in different species.”

The specimens were collected over the course of a few hours in a single day in June 1994, when Derek K Armstrong of Ontario Geological Survey was dropped by helicopter to investigate the rocks and fossils at a remote and temporary exposure in Ontario.

Sample materials, from what proved to belong to the Devonian Kwataboahegan Formation, were brought back to the Royal Ontario Museum, where they have been stored until they caught the eyes of the authors’.

avid Rudkin from the museum said: “This is an excellent example of the importance of looking in remote and unexplored areas for finding new exciting things, but also the importance of scrutinizing museum collections for overlooked gems.”

The species has been named Websteroprion armstrongi. This honours Armstrong, who collected the material, and bass player extraordinaire, Alex Webster of Death Metal band Cannibal Corpse, since he can be regarded as a ‘giant’ when it comes to handling his instrument.

Luke Parry added: “This is fitting also since, beside our appetite for evolution and paleontology, all three authors have a profound interest in music and are keen hobby musicians.”

Reference:
Mats E. Eriksson, Luke A. Parry, David M. Rudkin. Earth’s oldest ‘Bobbit worm’ – gigantism in a Devonian eunicidan polychaete. Scientific Reports, 2017; 7: 43061 DOI: 10.1038/srep43061

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

‘Tully monster’ mystery is far from solved, group argues

February 20, 2017

An illustration depicts what Mazon Creek may have looked like 300 million years ago, complete with Tully monsters (the two small swimming creatures), a large shark and a salamander relative. Credit: John Megahan

Last year, headlines in The New York Times, The Atlantic, Scientific American and other outlets declared that a decades-old paleontological mystery had been solved. The “Tully monster,” an ancient animal that had long defied classification, was in fact a vertebrate, two groups of scientists claimed. Specifically, it seemed to be a type of fish called a lamprey.

The problem with this resolution? According to a group of paleobiologists led by the University of Pennsylvania’s Lauren Sallan, it’s plain wrong.

“This animal doesn’t fit easy classification because it’s so weird,” said Sallan, an assistant professor in Penn’s School of Arts & Sciences’ Department of Earth and Environmental Science. “It has these eyes that are on stalks and it has this pincer at the end of a long proboscis and there’s even disagreement about which way is up. But the last thing that the Tully monster could be is a fish.”

In a new report in the journal Palaeontology, Sallan and colleagues argue that the two papers that seemingly settled the Tully monster debate are flawed, failing to definitively classify it as a vertebrate. The mystery of the Tully monster, known to scientists as Tullimonstrum gregarium, remains.

“It’s important to incorporate all lines of evidence when considering enigmatic fossils: anatomical, preservational and comparative,” said Sam Giles, a junior research fellow at the University of Oxford and coauthor of the study. “Applying that standard to the Tully monster argues strongly against a vertebrate identity.”

Sallan and Giles coauthored the work with Robert Sansom of the University of Manchester, Penn postdoctoral researcher John Clarke, Zerina Johnason of the Natural History Museum London, Ivan Sansom of the University of Birmingham and Philippe Janvier of France’s Muséum National d’Histoire Naturelle.

The Tully monster has been known since the 1950s, when the first fossils were found in Mazon Creek fossil beds in central Illinois. Since then, thousands of specimens have been identified from the area. The species is the state fossil of Illinois and even graces the side of UHauls. But none of the attempts to classify it to an animal group over the last half century had stuck.

“Initially it was published as a worm,” Sallan said. “There is a well-constructed argument that it is some kind of mollusc, like a sea cucumber. And there’s another very strong argument that it’s some kind of arthropod, similar to a lobster.”

That’s why it took the scientific community by surprise when in 2016 two studies came out in close succession both claiming they had firm evidence that the Tully monster was in fact a vertebrate.

The first examined more than 1,200 Tully monster fossils. In some, the researchers observed a light band running down the creature’s midline, which they determined was a notochord, a kind of primitive backbone. They also claimed it contained other internal organ structures, such as gill sacs, that identified it as a vertebrate, and that the animal’s teeth resembled those of lamprey.

But Sallan and colleagues noted that these conclusions are based on a misunderstanding of how fossils in Mazon Creek are preserved. The Tully monster samples come from what was once a marine area.

“In the marine rocks you just see soft tissues, you don’t see much internal structure preserved,” Sallan said.

The Penn-led team further noted that there have been lampreys found in this area of Mazon Creek, and that these animals don’t resemble the Tully monster.

The other 2016 study reported that scanning electron microscope images of the Tully monsters’ eyes had revealed structures called melanosomes, which produce and store melanin. That paper’s authors argued that the complex tissue structure they saw in the animals’ eyes indicated it was likely a vertebrate.

Yet species besides vertebrates, such as arthropods and cephalopods like octopuses, also have complex eyes, the Penn-led team wrote.

“Eyes have evolved dozens of times,” Sallan said. “It’s not too much of a leap to imagine Tully monsters could have evolved an eye that resembled a vertebrate eye.”

Based on Sallan’s and her colleagues’ examination of Tullimonstrum eyes, these creatures in fact possess what is known as a cup eye, a relatively simpler structure that lacks a lens.

“So the problem is, if it does have cup eyes, then it can’t be a vertebrate because all vertebrates either have more complex eyes than that or they secondarily lost them,” Sallan said. “But lots of other things have cup eyes, like primitive chordates, molluscs and certain types of worms.”

Their Palaeontology report noted that none of the more than 1,000 examined Tully specimens appeared to possess structures that are believed to be universal in aquatic vertebrates, notably otic capsules, components of the ear that allow animals to balance, and a lateral line, a sensory structure that enables fishes to orient themselves in space.

“You would expect at least a handful of the specimens to have preserved these structures,” Sallan said. “Not only does this creature have things that should not be preserved in vertebrates, it doesn’t have things that absolutely should be preserved.”

The researchers said that an improper classification of such an unusual species has ripple effects on the larger field of evolution.

“Having this kind of misassignment really affects our understanding of vertebrate evolution and vertebrate diversity at this given time,” Sallan said. “It makes it harder to get at how things are changing in response to an ecosystem if you have this outlier. And though of course there are outliers in the fossil record—there are plenty of weird things and that’s great—if you’re going to make extraordinary claims, you need extraordinary evidence.”

As for the true identity of the Tully monster, the Penn-led team said that’s still up in the air.

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

Study signals new hope for Rockall oil and gas exploration

February 20, 2017

The geological analysis of the Rockall Basin has revealed previously unknown insights that could aid oil and gas exploration in the North Atlantic. Credit: University of Aberdeen

A geological analysis of the Rockall area of the North Atlantic has revealed previously unknown insights that could lead to new oil and gas discoveries in the UK Continental Shelf (UKCS).

By studying the latest seismic data supplied by the Oil and Gas Authority (OGA) and employing lessons learned elsewhere in the UKCS, geologists from the University of Aberdeen have gained a clearer understanding of the Rockall Basin and identified potential areas for future exploration activity.

Previous attempts to find hydrocarbons in Rockall have been largely unsuccessful, with only one gas discovery out of 12 wells drilled.

Those behind the study believe that misconceptions regarding the character of the Basin – as well as challenging weather conditions and a lack of supporting infrastructure due to its remoteness – have hampered these exploration efforts.

Dr Nick Schofield from the University’s Department of Geology and Petroleum Geology led the analysis, which has been funded by a £250,000 award from the Oil and Gas Authority (OGA) as part of its Frontier Basins Research effort to boost future exploration in the UKCS.

Dr Schofield said: “The Rockall Basin is one of the most challenging environments on Earth when it comes to hydrocarbon exploration, but our analysis has revealed that one of the barriers to success may have been a misunderstanding of the subsurface geology.

“By analysing seismic data provided by the OGA and Petroleum Geo-Services (PGS), and using what we have learned through our work in the Faroe-Shetland Basin, we found that the character of areas where operators hoped to find oil may have been misleading.”

Dr Schofield explained that one issue is the previous targeting of so-called ‘bumps’ in the sub-surface, commonly referred to in the industry as a ‘four-way closure’, where it is hoped oil has been trapped.

“In the case of Rockall, these bumps, in many cases, appear to have actually been caused by volcanic intrusions in the sub-surface,” he said.

“We believe that the oil and gas is more likely to have migrated to the outer fringes of Rockall instead, away from these previous exploration targets.”

The study has identified the eastern edge of the Basin against the Outer Hebrides Shelf as an area of interest for future exploration activity.

Looking ahead, Dr Schofield said that work will continue to gain an understanding of the area’s potential, using innovative techniques that complement the valuable seismic data provided by the OGA and companies such as PGS, GeoPartners Ltd and Spectrum Geo.

“This analysis is very much a starter for ten in terms of our work to gain a clearer understanding of what’s going on in Rockall, and we are using a variety of methods to build on what we have discovered so far,” he said.

“We have also collected data from an aerial drone we have used to map outcrops, for example Kilt Rock on the Isle of Skye, where the rock structure is similar to what you would find in the subsurface and helps us visualise what we can’t see.

“What we are ultimately working towards is the most detailed geological understanding for Rockall which will be made freely available to industry as part of efforts to maximise economic recovery in the UKCS.”

Nick Richardson, OGA Head of Exploration and New Ventures, said: “The seismic acquisition programme and subsequent work by Aberdeen and Heriot Watt Universities are an important part of our strategy to revitalise exploration.

“The findings of Dr Schofield’s paper demonstrate the value in applying the latest geological knowledge and understanding to seismic data to increase industry’s awareness of the opportunities that still exist in frontier areas.”

Reference:
Nick Schofield et al. Challenges of future exploration within the UK Rockall Basin, Geological Society, London, Petroleum Geology Conference series (2017). DOI: 10.1144/PGC8.37

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

Why are there different ‘flavors’ of iron around the Solar System?

February 20, 2017

A scanning electron microscope image of one of the experiments in Elardo and Shahar’s paper that shows a bright, semi-spherical metal (representing a core) next to a gray, quenched silicate (representing a magma ocean). Credit: Stephen Elardo.

New work from Carnegie’s Stephen Elardo and Anat Shahar shows that interactions between iron and nickel under the extreme pressures and temperatures similar to a planetary interior can help scientists understand the period in our Solar System’s youth when planets were forming and their cores were created. Their findings are published by Nature Geoscience.

Earth and other rocky planets formed as the matter surrounding our young Sun slowly accreted. At some point in Earth’s earliest years, its core formed through a process called differentiation—when the denser materials, like iron, sunk inward toward the center. This formed the layered composition the planet has today, with an iron core and a silicate upper mantle and crust.

Scientists can’t take samples of the planets’ cores. But they can study iron chemistry to help understand the differences between Earth’s differentiation event and how the process likely worked on other planets and asteroids.

One key to researching Earth’s differentiation period is studying variations in iron isotopes in samples of ancient rocks and minerals from Earth, as well as from the Moon, and other planets or planetary bodies.

Every element contains a unique and fixed number of protons, but the number of neutrons in an atom can vary. Each variation is a different isotope. As a result of this difference in neutrons, isotopes have slightly different masses. These slight differences mean that some isotopes are preferred by certain reactions, which results in an imbalance in the ratio of each isotope incorporated into the end products of these reactions.

One outstanding mystery on this front has been the significant variation between iron isotope ratios found in samples of hardened lava that erupted from Earth’s upper mantle and samples from primitive meteorites, asteroids, the Moon, and Mars. Other researchers had suggested these variations were caused by the Moon-forming giant impact or by chemical variations in the solar nebula.

Elardo and Shahar were able to use laboratory tools to mimic the conditions found deep inside the Earth and other planets in order to determine why iron isotopic ratios can vary under different planetary formation conditions.

They found that nickel is the key to unlocking the mystery.

Under the conditions in which the Moon, Mars, and the asteroid Vesta’s cores were formed, preferential interactions with nickel retain high concentrations of lighter iron isotopes in the mantle. However, under the hotter and higher-pressure conditions expected during Earth’s core formation process, this nickel effect disappears, which can help explain the differences between lavas from Earth and other planetary bodies, and the similarity between Earth’s mantle and primitive meteorites.

“There’s still a lot to learn about the geochemical evolution of planets,” Elardo said. “But laboratory experiments allow us to probe to depths we can’t reach and understand how planetary interiors formed and changed through time.”

Reference:
Non-Chondritic Iron Isotope Ratios in Planetary Mantles as a Result of Core Formation, Nature Geoscience, DOI:10.1038/ngeo2896

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

Ventura fault could cause stronger shaking, new research finds

February 15, 2017

The figure shows the location of the Ventura-Pitas Point fault with respect to the cities involved. The view is of Southern California, as seen from the Pacific coast looking east. The thin white line is the coastline; the outlines of the Channel Islands can be seen off to the right (the south). The pink triangulated surface is the Ventura-Pitas Point fault. At the edge of it can be seen the stair-step cross-section, the flat part being under Santa Barbara. Credit: Gareth J. Funning and Scott T. Marshall

A new study by a team of researchers, including one from the University of California, Riverside, found that the fault under Ventura, Calif., would likely cause stronger shaking during an earthquake and more damage than previously suspected.

The Ventura-Pitas Point fault in southern California has been the focus of a lot of recent attention because it is thought to be capable of magnitude 8 earthquakes. It underlies the city of Ventura and runs offshore, and thus may be capable of generating tsunamis.

Since it was identified as an active and potentially dangerous fault in the late 1980s, there has been a controversy about its location and geometry underground, with two competing models.

Originally, researchers assumed the fault was planar and steeply dipping, like a sheet of plywood positioned against a house, to a depth of about 13 miles. But a more recent study, published in 2014, suggested the fault had a “ramp-flat geometry,” with a flat section between two tilting sections, similar to a portion of a staircase.

In a recently published paper in Geophysical Research Letters, a team of researchers used computer modeling to test the two alternatives.

In these computer models, the crust — outermost layer of rock — in the Ventura-Santa Barbara region is represented as a three-dimensional volume, with the surfaces of the region’s faults as weaknesses within it. That volume is then “squeezed” at the rate and direction that the region is being squeezed by plate tectonics. In comparisons of the expected movement in the models with GPS data, the fault with the staircase-like structure was favored.

That means more of the fault, which runs westward 60 miles from the city of Ventura, through the Santa Barbara Channel, and beneath the cities of Santa Barbara and Goleta, is closer to the surface. That would likely cause stronger shaking during an earthquake and more damage.

“Our models confirm that the Ventura-Pitas Point fault is a major fault, that lies flat under much of the coast between Ventura and Santa Barbara,” said Gareth Funning, an associate professor of geophysics at UC Riverside, one of the authors of the study. “This means that a potential source of large earthquakes is just a few miles beneath the ground in those cities. We would expect very strong shaking if one occurred.”

Future research will address the consequences of there being a fault ramp under Ventura. Researchers now can run more accurate simulations based on the ramp model to predict where the shaking will be strongest, and whether they would expect a tsunami.

Reference:
Scott T. Marshall, Gareth J. Funning, Hannah E. Krueger, Susan E. Owen, John P. Loveless. Mechanical models favor a ramp geometry for the Ventura-pitas point fault, California. Geophysical Research Letters, 2017; DOI: 10.1002/2016GL072289

Note: The above post is reprinted from materials provided by University of California – Riverside. Original written by Sean Nealon.

3-D reconstruction of skull suggests a small crocodile is a new species

February 15, 2017

Limestone slab contains the partial skeleton of Knoetschkesuchus.Taken from Figure 3 of the manuscript. Credit: Schwarz et al (2017)

A small crocodile discovered in Germany’s Langenberg Quarry may be a new species, according to a study published February 15, 2017 in the open-access journal PLOS ONE by Daniela Schwarz from Leibniz Institute for Evolutionary and Biodiversity Research, Germany, and colleagues.

The Langenberg Quarry has proven to be a rich source of marine-related fossils, including small crocodile-like atoposaurid species. The fossilized remains of this crocodile were exceptionally well-preserved but were still partly in sediment, making it difficult to examine the fossils fully. After initial analysis, the crocodile was assigned to the Theriosuchus genus. To study this atopasaurid in more detail, Schwarz and colleagues did a 3-D reconstruction of one of the fossil skulls based on micro-computed tomography.

The researchers concluded that the atoposaurid they studied is actually a new species, which they call Knoetschkesuchus. This conclusion is based on unique features of the skull, such as openings in the jaw bone and in front of the eye, as well as of tooth morphology. The latter may have reflected dietary specialization, and diversity of tooth morphology is thought to have been a driver of atoposaurid evolution during the Jurassic.

“The study describes a new diminutive crocodile Knoetschkesuchus langenbergensis that lived around 154 Million years ago in Northwestern Germany,” says Schwarz. “Knoetschkesuchus belongs to the evolutionary lineage that leads to modern crocodiles and preserves for the first time in this group two skulls in 3D, allowing us detailed anatomical studies via micro-CT images. Our research is part of the Europasaurus-Project which studies the remains of a unique Jurassic island ecosystem in Northern Germany.”

Reference:
Schwarz D, Raddatz M, Wings O (2017) Knoetschkesuchus langenbergensis gen. nov. sp. nov., a new atoposaurid crocodyliform from the Upper Jurassic Langenberg Quarry (Lower Saxony, northwestern Germany), and its relationships to Theriosuchus. PLoS ONE 12(2): e0160617. DOI: 10.1371/journal.pone.0160617

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

Old rocks, biased data: Overcoming challenges studying the geodynamo

February 15, 2017

Michigan Tech undergraduate Katie Bristol preps a magnetized rock sample with liquid nitrogen. Credit: Michigan Tech, Sarah Bird

Gleaning data from old rocks may result in bias. Now, geophysicists have a way to improve their methods to overcome challenges in studying the history of the Earth’s core and magnetic field that make up the geodynamo.

Since researchers cannot visit the core, they use rocks at the surface as a proxy. Specifically, volcanic rocks record the intensity and changes in Earth’s magnetic field. The record extends back billions of years to the early days of the planet’s young core and the development of the geodynamo. The problem is that most data gleaned from these old rocks can be biased.

In a new study published in Science Advances and led by geophysicists from Michigan Technological University, the research team lays out how bias is introduced and what to do about it.

Start with the Jurassic—a time of terrible lizards, high carbon dioxide levels and frequent magnetic pole flipping. The rock record shows that with more flips, the intensity of the magnetic field waned. It’s an inverse relationship that geodynamo models predict; however, it has been difficult to back up with data from field samples, which to date have not shown a correlation between magnetic reversals and past magnetic fields’ strength, or paleointensity.

The discrepancy has been debated but remained unresolved, says Aleksey Smirnov, an associate professor of geophysics at Michigan Tech and lead author of the study. The bias, introduced by the conventional Thellier method for analyzing rock sample magnetism, produces lower than expected paleointensity strengths and may resolve this controversy.

“Previous data may need to be reconsidered,” Smirnov says, adding that in the new study, his team tested systemic bias on synthetic samples first. “See, when you work with natural rocks, it’s difficult to separate the effects of nonideal grains and alterations.”

In theory, the Thellier method requires very small magnetic grains and they should plot as a line during analysis; however, because most rocks contain much larger nonideal grains the plots are warped. This problem has been known but largely ignored, says Smirnov, instead researchers tend to only use a section of the curved plot to best estimate the linear relationship. This consistently produces lower than expected measurements and systemic bias in paleointensity datasets, Smirnov says.

The key to gathering better data, he suggests, is using low-temperature demagnetization along with the Thellier method. The additional steps are immersing the sample in liquid nitrogen in a magnetic field-free environment, then letting it naturally warm back up to room temperature before following through with magnetometer tests. The procedure stabilizes the sample. Another option is to calculate the bias introduced by grain size. Unfortunately, because most datasets don’t include grain size for each sample, older data will need to be re-analyzed.

“This is a more rigorous way of doing this particular science,” Smirnov says. “I’ve been doing this a long time—and if we want good data, we need to use good methods.”

Reference:
“Intrinsic paleointensity bias and the long-term history of the geodynamo” Science Advances , DOI: 10.1126/sciadv.1602306

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

Ancient jars found in Judea reveal Earth’s magnetic field is fluctuating, not diminishing

February 15, 2017

A snapshot of the 3D magnetic field structure simulated with the Glatzmaier-Roberts geodynamo model. Magnetic field lines are blue where the field is directed inward and yellow where directed outward. The rotation axis of the model Earth is vertical and through the center.

Albert Einstein considered the origin of Earth’s magnetic field one of the five most important unsolved problems in physics. The weakening of the geomagnetic field, which extends from the planet’s core into outer space and was first recorded 180 years ago, has raised concern by some for the welfare of the biosphere.

But a new study published in PNAS from Tel Aviv University, Hebrew University of Jerusalem, and University of California San Diego researchers finds there is no reason for alarm: Earth’s geomagnetic field has been undulating for thousands of years. Data obtained from the analysis of well-dated Judean jar handles provide information on changes in the strength of the geomagnetic field between the 8th and 2nd centuries BCE, indicating a fluctuating field that peaked during the 8th century BCE.

“The field strength of the 8th century BCE corroborates previous observations of our group, first published in 2009, of an unusually strong field in the early Iron Age. We call it the ‘Iron Age Spike,’ and it is the strongest field recorded in the last 100,000 years,” says Dr. Erez Ben-Yosef of TAU’s Institute of Archaeology, the study’s lead investigator. “This new finding puts the recent decline in the field’s strength into context. Apparently, this is not a unique phenomenon — the field has often weakened and recovered over the last millennia.”

Additional researchers included Prof. Oded Lipschits and Michael Millman of TAU, Dr. Ron Shaar of Hebrew University, and Prof. Lisa Tauxe of UC San Diego.

Delving into the inner structure of the planet

“We can gain a clearer picture of the planet and its inner structure by better understanding proxies like the magnetic field, which reaches more than 1,800 miles deep into the liquid part of Earth’s outer core,” Dr. Ben-Yosef observes.

The new research is based on a set of 67 ancient, heat-impacted Judean ceramic storage jar handles, which bear royal stamp impressions from the 8th to 2nd century BCE, providing accurate age estimates.

“The period spanned by the jars allowed us to procure data on Earth’s magnetic field during that time — the Iron Age through the Hellenistic Period in Judea,” says Dr. Ben-Yosef. “The typology of the stamp impressions, which correspond to changes in the political entities ruling this area, provides excellent age estimates for the firing of these artifacts.”

To accurately measure the geomagnetic intensity, the researchers conducted experiments at the Paleomagnetic Laboratory of Scripps Institution of Oceanography (SIO), University of California San Diego, using laboratory-built paleomagnetic ovens and a superconducting magnetometer.

“Ceramics, baked clay, burned mud bricks, copper slag — almost anything that was heated and then cooled can become a recorder of the components of the magnetic field at the time of the event,” said Dr. Ben-Yosef. “Ceramics have tiny minerals — magnetic ‘recorders’ — that save information about the magnetic field of the time the clay was in the kiln. The behavior of the magnetic field in the past can be studied by examining archaeological artifacts or geological material that were heated then cooled, such as lava.”

Advanced dating method

Observed changes in the geomagnetic field can, in turn, be used as an advanced dating method complementary to the radiocarbon dating, according to Dr. Ben-Yosef. “The improved Levantine archaeomagnetic record can be used to date pottery and other heat-impacted archaeological materials whose date is unknown.

“Both archaeologists and Earth scientists benefit from this. The new data can improve geophysical models — core-mantle interactions, cosmogenic processes and more — as well as provide an excellent, accurate dating reference for archaeological artefacts,” says Dr. Ben-Yosef.

The researchers are currently working on enhancing the archaeomagnetic database for the Levant, one of the most archaeologically-rich regions on the planet, to better understand the geomagnetic field and establish a robust dating reference.

Reference:
Erez Ben-Yosef, Michael Millman, Ron Shaar, Lisa Tauxe, Oded Lipschits. Six centuries of geomagnetic intensity variations recorded by royal Judean stamped jar handles. Proceedings of the National Academy of Sciences, 2017; 201615797 DOI: 10.1073/pnas.1615797114

Note: The above post is reprinted from materials provided by American Friends of Tel Aviv University.

‘Firefall’ phenomenon wows visitors to Yosemite’s El Capitan

February 15, 2017

In this Feb. 16, 2010, file photo, a shaft of sunlight creates a glow near Horsetail Fall, in Yosemite National Park, Calif. Mother Nature is again putting on a show at California’s Yosemite National Park, where every February the setting sun draws a narrow sliver on a waterfall to make it glow like a cascade of molten lava. The phenomenon known as “firefall” draws scores of photographers to the spot, which flows down the granite face of the park’s famed rock formation, El Capitan. Credit: Eric Paul Zamora/The Fresno Bee via AP

Mother Nature is again putting on a show at California’s Yosemite National Park, where every February the setting sun draws a narrow sliver of light on a waterfall to make it glow like a cascade of molten lava.

The phenomenon known as “firefall” draws scores of photographers to a spot near Horsetail Fall, which flows down the granite face of the park’s famed rock formation, El Capitan.

Capturing the sight is a challenge. Horsetail Fall only flows in the winter or spring, when there is enough rain and snow. The sun lights up the fall for only about two minutes at dusk for a few days in February.

Some photographers have had success this year as pictures of the glowing falls are showing up on social media.

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

New theory explains how Earth’s inner core remains solid despite extreme heat

February 14, 2017

Seismic waves traveling in between the Earth’s poles travel faster than those between the equator – one sign of the textured nature of Earth’s solid iron inner core. A recent study from KTH explains how the core retains its unique solid form. Credit: Dixon Rohr

Even though it is hotter than the surface of the Sun, the crystallized iron core of Earth remains solid. A new study from KTH Royal Institute of Technology in Sweden may finally settle a longstanding debate over how that’s possible, as well as why seismic waves travel at higher speeds between the planet’s poles than through the equator.

Spinning within Earth’s molten core is a crystal ball — actually a mass formation of almost pure crystallized iron — nearly the size of the moon. Understanding this strange, unobservable feature of our planet depends on knowing the atomic structure of these crystals — something scientists have been trying to do for years.

As with all metals, the atomic-scale crystal structures of iron change depending on the temperature and pressure the metal is exposed to. Atoms are packed into variations of cubic, as well as hexagonal formations. At room temperatures and normal atmospheric pressure, iron is in what is known as a body-centered cubic (BCC) phase, which is a crystal architecture with eight corner points and a center point. But at extremely high pressure the crystalline structures transform into 12-point hexagonal forms, or a close packed (HCP) phase.

At Earth’s core, where pressure is 3.5 million times higher than surface pressure — and temperatures are some 6,000 degrees higher — scientists have proposed that the atomic architecture of iron must be hexagonal. Whether BCC iron exists in the center of Earth has been debated for the last 30 years, and a recent 2014 study ruled it out, arguing that BCC would be unstable under such conditions.

However, in a recent study published in Nature Geosciences, researchers at KTH found that iron at Earth’s core is indeed in the BCC phase. Anatoly Belonoshko, a researcher in the Department of Physics at KTH, says that when the researchers looked into larger computational samples of iron than studied previously, characteristics of the BCC iron that were thought to render it unstable wound up doing just the opposite.

“Under conditions in Earth’s core, BCC iron exhibits a pattern of atomic diffusion never before observed,” Belonoshko says.

Belonoshko says the data also shows that pure iron likely accounts for 96 percent of the inner core’s composition, along with nickel and possibly light elements.

Their conclusions are drawn from laborious computer simulations performed using Triolith, one of the largest Swedish supercomputers. These simulations allowed them to reinterpret observations collected three years ago at Livermore Lawrence National Laboratory in California. “It appears that the experimental data confirming the stability of BCC iron in the Core were in front of us — we just did not know what that really meant,” he says.

At low temperature BCC is unstable and crystalline planes slide out of the ideal BCC structure. But at high temperatures, the stabilization of these structures begins much like a card game — with the shuffling of a “deck.” Belonoshko says that in the extreme heat of the core, atoms no longer belong to planes because of the high amplitude of atomic motion.

“The sliding of these planes is a bit like shuffling a deck of cards,” he explains. “Even though the cards are put in different positions, the deck is still a deck. Likewise, the BCC iron retains its cubic structure.”

Such a shuffling leads to an enormous increase in the distribution of molecules and energy — which leads to increasing entropy, or the distribution of energy states. That, in turn, makes the BCC stable.

Normally, diffusion destroys crystal structures turning them into liquid. In this case, diffusion allows iron to preserve the BCC structure. “The BCC phase goes by the motto: ‘What does not kill me makes me stronger’,” Belonoshko says. “The instability kills the BCC phase at low temperature, but makes the BCC phase stable at high temperature.”

He says that this diffusion also explains why Earth’s core is anisotropic — that is, it has a texture that is directional — like the grain of wood. Anisotropy explains why seismic waves travel faster between Earth’s poles, than through the equator.

“The unique features of the Fe BCC phase, such as high-temperature self-diffusion even in a pure solid iron, might be responsible for the formation of large-scale anisotropic structures needed to explain Earth inner core anisotropy,” he says. “The diffusion allows easy texturing of iron in response to any stress.”

The prediction opens the path to understanding the interior of Earth and eventually to predicting Earth’s future, Belonoshko says. “The ultimate goal of Earth Sciences is to understand the past, present and future of Earth — and our prediction allows us to do just that.”

Reference:
Anatoly B. Belonoshko, Timofei Lukinov, Jie Fu, Jijun Zhao, Sergio Davis, Sergei I. Simak. Stabilization of body-centred cubic iron under inner-core conditions. Nature Geoscience, 2017; DOI: 10.1038/ngeo2892

Note: The above post is reprinted from materials provided by KTH The Royal Institute of Technology. Original written by David Callahan.

Kiss of death: Mammals were the first animals to produce venom

February 14, 2017

This is an artist’s impression of the Euchambersia. Credit: Wits University

Africa is a tough place. It always has been. Especially if you have to fend off gigantic predators like sabre-toothed carnivores in order to survive. And, when you’re a small, dog-sized pre-mammalian reptile, sometimes the only way to protect yourself against these monsters is to turn your saliva into a deadly venomous cocktail.

That is exactly what a distant, pre-mammalian reptile, the therapsid Euchambersia, did about 260 million years ago, in order to survive the rough conditions offered by the deadly South African environment. Living in the Karoo, near Colesberg in South Africa, the Euchambersia developed a deep and circular fossa, just behind its canine teeth in the upper jaw, in which a deadly venomous cocktail was produced, and delivered directly into the mouth through a fine network of bony grooves and canals.

“This is the first evidence of the oldest venomous vertebrate ever found, and what is even more surprising is that it is not in a species that we expected it to be, ” says Dr Julien Benoit, researcher at the Bernard Price Institute for Palaeontological Research at the University of the Witwatersrand in South Africa.

“Today, snakes are notorious for their venomous bite, but their fossil record vanishes in the depth of geological times at about 167 million years ago, so, at 260 million years ago, the Euchambersia evolved venom more than a 100 million years before the very first snake was even born. ”

As venom glands don’t fossilise, Benoit and his colleagues from at Wits University, in association with the Natural History Museum of London used cutting edge CT scanning and 3D imagery techniques to analyse the only two fossilised skulls of the Euchambersia ever found, and discovered stunning anatomical adaptions that are compatible with venom production. Their results were published in the open access journal, PlosOne, in February.

“First, a wide, deep and circular fossa (a space in the skull) to accommodate a venom gland was present on the upper jaw and was connected to the canine and the mouth by a fine network of bony grooves and canals,” says Benoit. “Moreover, we discovered previously undescribed teeth hidden in the vicinity of the bones and rock: two incisors with preserved crowns and a pair of large canines, that all had a sharp ridge. Such a ridged dentition would have helped the injection of venom inside a prey. ”

Unlike snakes like vipers or cobras, which actively inject their prey with venom through needle-like grooves in their teeth, the Euchambersia’s venom flowed directly into its mouth, and the venom was passively introduced into its victim through ridges on the outside of its canine teeth.

“Euchambersia could have used its venom for protection or hunting. Most venomous species today use their venom for hunting, so I would rather go for this option. In addition, animals at that time were not all insectivorous, particularly among therapsids, which were very diverse.”

Reference:
Julien Benoit, Luke A. Norton, Paul R. Manger, Bruce S. Rubidge. Reappraisal of the envenoming capacity of Euchambersia mirabilis (Therapsida, Therocephalia) using μCT-scanning techniques. PLOS ONE, 2017; 12 (2): e0172047 DOI: 10.1371/journal.pone.0172047

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

Super scavengers and the meat-thieving traits that have stood the test of time

February 14, 2017

An evolutionary timescale of scavenging in the air, on the land, and in the sea. Credit: Adam Kane et al.

Take a look at the teeth of any animal. The chances are you’ll then have a good idea if it’s a meat eater or a vegetarian. Sharp canines? Easy. All the better to eat you with. But how would you find out whether your chosen species got by on dead meat, or if it survived and thrived by catching live prey? To answer that kind of question you have to go beyond teeth and look at many other aspects of its biology — from the way the creature moves to how far it can see.

That’s according to collaborative research from scientists at University College Cork, Trinity College Dublin, St Andrews University, and Imperial College London, who argue that Mother Nature requires the right mix of biological ingredients to make a good scavenger. Their work also suggests that the same ingredients produce different end results when the recipe is varied, because good scavengers can live in vastly different environments and look very different from one another.

Any sense that allows you to detect an unmoving meal is a particularly useful trait for a would-be scavenger — especially when it is coupled with an ability to search far and wide for scattered food. But location matters too. An environment containing next to no wildlife isn’t going to be a good place to start your search, and it’s even tougher in fast-moving rivers where any bodies soon become swept away.

Typically, vultures and hyenas are the species that come to mind when we think of scavengers, and for good reason. Both can detect carcasses from huge distances away, and both are able to move over vast areas without breaking a sweat. But research shows there is no sharp distinction between a scavenger and a predator. Instead, meat-eating species are spread along a gradient. Even a hungry vulture will hunt, should the opportunity arise, while regal lions will regularly “lower” themselves to taking carrion if it provides a free lunch.

We should, therefore, think of different species in terms of where they sit on a scavenging scale, on which those best suited to the lifestyle appear at one end, and those ill-suited to scavenging are sited at the other. This was the idea set out by the research team, whose work shows that you can position any animal — extinct or alive — on this scale, based on its biological traits and by its environment.

Interestingly, the same useful meat-thieving traits can and do work in different environments; albatrosses regularly take dead squid floating on the sea surface, and these birds have so many similarities to vultures that they have been dubbed the “vultures of the sea.”

But there are surprises too. For example, on the African savannah, cheetahs are at a severe disadvantage; despite the bounty of carrion, they’re built for bursts of speed over short distances, and are easily bullied off their food by stockier big cats and hyenas.

Research Fellow at University College Cork, Adam Kane, is lead author of the article just published in the journal Ecography. He said: “What’s really interesting is that we can also place long-extinct species on this scavenging scale and get a sense of whether or not they were likely capable scavengers, which helps us build a more complete picture of the past.”

“For example, despite having keen senses, it would have been too metabolically costly for large meat-eating dinosaurs to search the huge areas required to find enough food from carrion alone. And so, Tyrannosaurus only finds itself in the middle of the scale.”

Co-author and Research Fellow in Trinity College Dublin’s School of Natural Sciences, Kevin Healy, said: “The scale is also interesting from the perspective of evolution — the contrast between past and present is really striking for some groups that evolved millions of years ago but persist to this day. Most notably, modern-day bats are poor performers on the scale — they’re clumsy on the ground and they stand little chance against competitors in a food fight, but the history of the group tells a different story.”

“The curiously named ‘death-eater bat’, which lived tens of millions of years ago, had a jaw and teeth that look fit for scavenging, but modern-day bats have lost these adaptations.”

Even human beings and our ancestors have their place on this scale, and we fare quite well. Tool use and cooperative nature meant it was likely that prehistoric people regularly had carrion for dinner.

Reference:
Adam Kane, Kevin Healy, Thomas Guillerme, Graeme D. Ruxton, Andrew L. Jackson. A recipe for scavenging in vertebrates – the natural history of a behaviour. Ecography, 2017; 40 (2) DOI: 10.1111/ecog.02817

Note: The above post is reprinted from materials provided by Trinity College Dublin.

Cold plates and hot melts

February 14, 2017

The graphic shows the early stages of the Izu-Bonin subduction zone. The active subduction zone has been moving eastwards throughout its history. The drilling took place where the process has begun. Credit/Graphic: Philipp Brandl, GEOMAR

The movements of Earth’s tectonic plates shape the face of our planet. The sinking of one plate beneath another, known as subduction, causes volcanism and earthquakes. Subduction zones lie, for example, off the coast of Indonesia, Chile and Japan. But how exactly did this process begin? As part of the International Ocean Discovery Program, an international science team was able to drill and investigate the origin of a subduction zone for the first time in 2014. The team is now publishing its data in the international scientific journal Earth and Planetary Science Letters.

About 2000 kilometers east of the Philippine Islands lies one of the most famous topographical peculiarities of the oceans: the Mariana trench. Reaching depths of up to 11,000 meters below sea level, it holds the record as the deepest point of the world’s ocean. This 4000-kilometer-long trench extends from the Mariana Islands in the south through the Izu-Bonin Islands to Japan in the north. Here, the Pacific Plate is subducted beneath the Philippine Sea Plate, resulting in intense volcanic activity and a high number of earthquakes. The entire area is part of the “Pacific Ring of Fire.”

But when and how exactly did the subduction of the Pacific Plate begin? This is a controversial topic among scientists. An international team led by the GEOMAR Helmholtz Center for Ocean Research Kiel, the Japan Agency for Marine Earth Science and Technology (JAMSTEC) and the Australian National University investigated this early phase of subduction along the Izu-Bonin-Mariana trench, with findings published in the March edition of the scientific journal Earth and Planetary Science Letters.

The study is based on a drill core that was obtained by the International Ocean Discovery Program (IODP) in 2014 with the US research drilling vessel JOIDES RESOLUTION some 600 kilometers west of the current Izu-Bonin Trench. “For the first time, we were able to obtain samples of rocks that originate from the first stages of subduction,” says Dr. Philipp Brandl from GEOMAR, first author of the study. “It is known that the active subduction zone has been moving eastwards throughout its history and has left important geological traces on the seabed during its migration. We have now drilled where the process has begun.”

The team of the JOIDES RESOLUTION was able to drill more than 1600 meters deep on the seabed, starting at a water depth of around 4700 meters below sea level. “This is already at the limit of the technically feasible”, emphasizes Dr. Brandl. Based on analysis of this drill core, the researchers were able to trace the history of the subduction zone layer by layer up to the approximately 50 million year-old rocks at the bottom of the core, which are typical for the birth of a subduction zone. “There has not been such a complete overview yet,” says Dr. Brandl.

Brandl and his colleagues were now able to acquire and analyze microscopic inclusions of cooled magma from the rocks. The data obtained provide the scientists with insights into the history of volcanic activity at the Pacific Ring of Fire 30-40 million years ago. The researchers found evidence that volcanism was only beginning to gain momentum. The volcanic activity intensified with the rollback of the subduction zone towards the east and the huge explosive stratovolcanoes formed, similar to those present nowadays, for example along the western rim of the Pacific Ring of Fire.

However, further drilling is necessary to test the validity of these observations. “The more drill cores we can gain from such old strata, the better we learn to understand our own planet,” Dr. Brandl says. The question of how subduction zones develop is not only interesting to understand the history of the earth. Subduction zones are the drivers for the chemical exchange between the earth’s surface and the earth’s interior. “The dynamics of a subduction zone can thus also influence the speed of global elemental cycles”, summarizes Dr. Brandl.

Reference:
Philipp A. Brandl, Morihisa Hamada, Richard J. Arculus, Kyle Johnson, Kathleen M. Marsaglia, Ivan P. Savov, Osamu Ishizuka, He Li. The arc arises: The links between volcanic output, arc evolution and melt composition. Earth and Planetary Science Letters, 2017; 461: 73 DOI: 10.1016/j.epsl.2016.12.027

Note: The above post is reprinted from materials provided by Helmholtz Centre for Ocean Research Kiel (GEOMAR).

Fossil discovery rewrites understanding of reproductive evolution

February 14, 2017

This is an artist’s impression of what Dinocephalosaurus might have looked like. Credit: Drawn by Dinghua Yang

A remarkable 250 million-year-old “terrible-headed lizard” fossil found in China shows an embryo inside the mother — clear evidence for live birth.

Head of The University of Queensland’s School of Earth and Environmental Sciences and co-author Professor Jonathan Aitchison said the fossil unexpectedly provided the first evidence for live birth in an animal group previously thought to exclusively lay eggs.

“Live birth is well known in mammals, where the mother has a placenta to nourish the developing embryo,” Professor Aitchison said.

“Live birth is also very common among lizards and snakes, where the babies sometimes ‘hatch’ inside their mother and emerge without a shelled egg.”

Until recently it was thought the third major group of living land vertebrates, the crocodiles and birds (part of the wider group Archosauromorpha) only laid eggs.

“Indeed, egg-laying is the primitive state, seen at the base of reptiles, and in their ancestors such as amphibians and fishes,” Professor Aitchison said.

He said the new fossil was an unusual, long-necked marine animal called an archosauromorph that flourished in shallow seas of South China in the Middle Triassic Period.

The creature was a fish-eater, snaking its long neck from side to side to snatch its prey.

Its fossil was one of many astonishingly well-preserved specimens from new “Luoping biota” locations in south-western China. There were no known fossils like this (marine vertebrates of this age) from Australia.

Lead author Professor Jun Liu from Hefei University of Technology China, said the researchers were “excited” when they first saw this embryonic specimen.

“We were not sure if the embryonic specimen was the mother’s last lunch or its unborn baby,” Professor Liu said.

“Upon further preparation and closer inspection, we discovered something unusual.”

He said the embryo was inside the mother’s rib cage, and it faced forward; swallowed animals generally face backward because the predator swallows its prey head-first to help it go down its throat.

Furthermore, the small reptile inside the mother was an example of the same species.

“Further evolutionary analysis revealed the first case of live birth in such a wide group containing birds, crocodilians, dinosaurs and pterosaurs among others, and pushes back evidence of reproductive biology in the group by 50 million years,” Professor Liu said.

“Information on reproductive biology of archosauromorphs before the Jurassic Period was not available until our discovery, despite a 260 million-year history of the group.”

Professor Chris Organ from Montana State University said evolutionary analysis showed that this instance of live birth was also associated with genetic sex determination.

“Some reptiles today, such as crocodiles, determine the sex of their offspring by the temperature inside the nest,” he said.

“We identified that Dinocephalosaurus, a distant ancestor of crocodiles, determined the sex of its babies genetically, like mammals and birds.

“This new specimen from China rewrites our understanding of the evolution of reproductive systems.”

Professor Mike Benton of the University of Bristol said analysis of the evolutionary position of the new specimens showed no fundamental reason why archosauromorphs could not have evolved live birth.

“This combination of live birth and genotypic sex determination seems to have been necessary for animals such as Dinocephalosaurus to become aquatic,” he said.

“It’s great to see such an important step forward in our understanding of the evolution of a major group coming from a chance fossil find in a Chinese field.”

The work is part of ongoing wider collaborations between palaeontologists in China, the United States, the UK and Australia.

Reference:
Jun Liu, Chris L. Organ, Michael J. Benton, Matthew C. Brandley, Jonathan C. Aitchison. Live birth in an archosauromorph reptile. Nature Communications, 2017; 8: 14445 DOI: 10.1038/ncomms14445

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

Ancient Earth as a model for studying hazy exoplanets

February 14, 2017

When haze built up in the atmosphere of Archean Earth, the young planet might have looked like this artist’s interpretation — a pale orange dot. A team led by Goddard scientists thinks the haze was self-limiting, cooling the surface by about 36 degrees Fahrenheit (20 Kelvins) — not enough to cause runaway glaciation. The team’s modeling suggests that atmospheric haze might be helpful for identifying earthlike exoplanets that could be habitable. Credit: NASA’s Goddard Space Flight Center/Francis Reddy

For astronomers trying to understand which distant planets might have habitable conditions, the role of atmospheric haze has been hazy. To help sort it out, a team of researchers has been looking to Earth — specifically Earth during the Archean era, an epic 1-1/2-billion-year period early in our planet’s history.

Earth’s atmosphere seems to have been quite different then, probably with little available oxygen but high levels of methane, ammonia and other organic chemicals. Geological evidence suggests that haze might have come and gone sporadically from the Archean atmosphere — and researchers aren’t quite sure why. The team reasoned that a better understanding of haze formation during the Archean era might help inform studies of hazy earthlike exoplanets.

“We like to say that Archean Earth is the most alien planet we have geochemical data for,” said Giada Arney of NASA’s Goddard Spaceflight Center in Greenbelt, Maryland, and a member of the NASA Astrobiology Institute’s Virtual Planetary Laboratory based at the University of Washington, Seattle. Arney is the lead author of two related papers published by the team.

In the best case, haze in a planet’s atmosphere could serve up a smorgasbord of carbon-rich, or organic, molecules that could be transformed by chemical reactions into precursor molecules for life. Haze also might screen out much of the harmful UV radiation that can break down DNA.

In the worst case, haze could become so thick that very little light gets through. In this situation, the surface might get so cold it freezes completely. If a very thick haze occurred on Archean Earth, it might have had a profound effect, because when the era began roughly four billion years ago, the sun was fainter, emitting perhaps 80 percent of the light that it does now.

Arney and her colleagues put together sophisticated computer modeling to look at how haze affected the surface temperature of Archean Earth and, in turn, how the temperature influenced the chemistry in the atmosphere.

The new modeling indicates that as the haze got thicker, less sunlight would have gotten through, inhibiting the types of sunlight-driven chemical reactions needed to form more haze. This would lead to the shutdown of haze-formation chemistry, preventing the planet from undergoing runaway glaciation due to a very thick haze.

The team calls this self-limiting haze, and their work is the first to make the case that this is what occurred on Archean Earth — a finding published in the November 2016 issue of the journal Astrobiology. The researchers concluded that self-limiting haze could have cooled Archean Earth by about 36 degrees Fahrenheit (20 Kelvins) — enough to make a difference but not to freeze the surface completely.

“Our modeling suggests that a planet like hazy Archean Earth orbiting a star like the young sun would be cold,” said Shawn Domagal-Goldman, a Goddard scientist and a member of the Virtual Planetary Laboratory. “But we’re saying it would be cold like the Yukon in winter, not cold like modern-day Mars.”

Such a planet might be considered habitable, even if the mean global temperature is below freezing, as long as there is some liquid water on the surface.

In subsequent modeling, Arney and her colleagues looked at the effects of haze on planets that are like Archean Earth but orbiting several kinds of stars.

“The parent star controls whether a haze is more likely to form, and that haze can have multiple impacts on a planet’s habitability,” said co-author Victoria Meadows, the principal investigator for the Virtual Planetary Laboratory and an astronomy professor at the University of Washington.

It looks as if the Archean Earth hit a sweet spot where the haze served as a sunscreen layer for the planet. If the sun had been a bit warmer, as it is today, the modeling suggests the haze particles would have been larger — a result of temperature feedbacks influencing the chemistry — and would have formed more efficiently, but still would have offered some sun protection.

The same wasn’t true in all cases. The modeling showed that some stars produce so much UV radiation that haze cannot form. Haze did not cool planets orbiting all types of stars equally, either, according to the team’s results. Dim stars, such as M dwarfs, emit most of their energy at wavelengths that pass right through atmospheric haze; in the simulations, these planets experience little cooling from haze, so they benefit from haze’s UV shielding without a major drop in temperature.

For the right kind of star, though, the presence of haze in a planet’s atmosphere could help flag that world as a good candidate for closer study. The team’s simulations indicated that, for some instruments planned for future space telescopes, the spectral signature of haze would appear stronger than the signatures for some atmospheric gases, such as methane. These findings are available in the Astrophysical Journal as of Feb. 8, 2017.

“Haze may turn out to be very helpful as we try to narrow down which exoplanets are the most promising for habitability,” said Arney.

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

Giant flying reptile ruled ancient Transylvania

February 11, 2017

Hatzegopteryx, depicted as a short-necked, powerful predator, consumes the dwarfed dinosaur Zalmoxes. Credit: Dr Mark Witton, University of Portsmouth

New research suggests that a giant pterosaur — a toothless flying reptile with a 10 metre wingspan — may have been the dominant predator in ancient Romania.

Palaeontologists examined the creature’s unusual gigantic neck vertebra and believe it was a formidable carnivore and major predator that terrorised dinosaurs and other prehistoric animals of Cretaceous-age Transylvania. It provides the first evidence of large predatory animals in the region at that time.

Dr Mark Witton, from the University of Portsmouth and Dr Darren Naish from University of Southampton, both in the UK, examined several fossilised remains of the creature, known as Hatzegopteryx, which belongs to the flying reptile group Azhdarchidae.

Usually this species’ tubular neck bones give them extremely long necks, over 2.5 metres in length in the largest species. However, the researchers suggest Hatzegopteryx had a considerably shorter and stronger neck, and with larger muscle masses. Other remains of Hatzegopteryx include a jaw joint indicative of a half-metre wide skull and reinforced limb bones. Dr Witton suggests that the proportions and structural reinforcement of all these elements are unlike those of any other azhdarchid species and would have made Hatzegopteryx a powerful and dominant predator.

He said: “The difference in structural properties between giant azhdarchid neck bones is remarkable — they’re in different biomechanical leagues, with Hatzegopteryx many times stronger than anything else on record. This, along with our calculations of neck length and muscle mass, suggests giant azhdarchids may have been radically different in appearance and behaviour.

“The large, reinforced skeleton and muscle power would have made it a formidable predator of other animals when stalking ancient prairies and woodlands. It may have even been capable of attacking animals too large or vigorous for other flying reptiles, even the other giants.”

Dr Witton said that Hatzegopteryx lived in a peculiar island ecosystem where many of the dinosaurs were dwarfed or belonged to relict lineages extinct in the rest of the Cretaceous world. “Ancient Transylvania was a strange place for a number of reasons, including the fact that we’ve yet to find evidence of large predatory animals that lived alongside Hatzegopteryx, such as giant carnivorous dinosaurs. This is despite centuries of sampling.”

The study thus potentially provides an answer to a mystery about life in Late Cretaceous Romania.

“Perhaps without large predators to challenge them, this island provided an opportunity for giant pterosaurs — already formidable animals — to become the dominant predators,” said Dr Witton.

“The finer details of ecology and lifestyle for Hatzegopteryx remain unknown because we’re still working from scraps of its skeleton, but the emerging picture of its lifestyle are fascinating. In some respects our unexpected findings highlight how little we actually know about these animals. We’ve had these scrappy remains for years, but we need to ask the right questions, and perform the right tests, to realise their significance. Future giant pterosaur research and discoveries almost certainly have many more surprises for us.”

The research was published in PeerJ.

Reference:
Darren Naish, Mark P. Witton. Neck biomechanics indicate that giant Transylvanian azhdarchid pterosaurs were short-necked arch predators. PeerJ, 2017; 5: e2908 DOI: 10.7717/peerj.2908

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

Long-term impacts of deep-sea mineral mining

February 11, 2017

Image of the seafloor in the abyssal Pacific showing nodules and large deep-water prawn (Bathystylodactyloidea). Image shows an area of seafloor approximately 50cm across. Credit: Image courtesy of National Oceanography Centre (NOC)

A new international study has demonstrated that deep-sea nodule mining will cause long-lasting damage to deep-sea life. This study, led by scientists at the National Oceanography Centre (NOC), was the first to review all the available information on the impacts of small-scale sea-floor disturbances simulating mining activity. It found clear impacts on marine ecosystems from deep-sea nodule mining activities, which lasted at least for decades.

New sources of high-quality reserves of metals necessary for the modern world are now being sought, including the huge expanses of nodules covering significant amounts off the global deep sea floor. These nodules are potato-sized rocks, containing high levels of metals, including copper, manganese and nickel, which grow very slowly on the sea bed, over millions of years. Although no commercial operations exist to extract these resources, many are planned. The International Seabed Authority, who manage this area, have issued exploration licences across the central Pacific to a variety of countries, including the UK. However, exploiting these resources will have an environmental cost.

Dr Daniel Jones from the NOC, the lead author of the study, said, “the deep-sea is a remote, cold and dark environment kilometres below the surface of the ocean, yet it is home to a wide variety of marine life, much of which is very poorly understood. This research analysed all available studies on impacts to ecosystems in nodule areas and shows mining for nodule resources on the seafloor is likely to be highly destructive in the mined area, with long lasting impacts. We also think that these studies will underestimate the impacts of mining. Many would not even represent one month’s work for a full-scale commercial operation, which might last for twenty years.

This study helps provide the best available information on the potential impacts of mining disturbance. This information is important to inform decisions on how these mining activities should be carried out.”

Although no seabed mining has currently taken place, equipment tests and scientific experiments have been carried out since the 1970s that simulate some of the impacts of mining activities. In isolation, these are often limited in their conclusions, but through combining the results of multiple studies NOC scientists were able to understand more general patterns relevant to managing the impacts of this new industry.

The experiments evaluated were much smaller than any planned mining program, which may impact an area the size of London every few years, but they show that the amount and diversity of marine life was reduced by the action of mining, often severely and for a long time. The oldest experiment, assessed twenty-six years after the impact, still leaves an obvious disturbance on the sea-floor and both the number of animals and species present in the disturbed area was reduced. Although some evidence of recovery was found, very few types of animals returned to previous levels even after decades.

Professor Edward Hill, Executive Director at the NOC commented, “By 2050 there will be 9 billion people on earth and attention is increasingly turning to the ocean, particularly the deep ocean, for food, clean supplies of energy and strategic minerals. The NOC is undertaking research related to many aspects and perspectives involved in exploiting ocean resources. This research is aimed at informing with sound scientific evidence the decisions that will need to be taken in the future, as people increasingly turn to the oceans to address some of society’s greatest challenges.”

The study is published in the international journal PLOS ONE.

Reference:
Daniel O. B. Jones, Stefanie Kaiser, Andrew K. Sweetman, Craig R. Smith, Lenaick Menot, Annemiek Vink, Dwight Trueblood, Jens Greinert, David S. M. Billett, Pedro Martinez Arbizu, Teresa Radziejewska, Ravail Singh, Baban Ingole, Tanja Stratmann, Erik Simon-Lledó, Jennifer M. Durden, Malcolm R. Clark. Biological responses to disturbance from simulated deep-sea polymetallic nodule mining. PLOS ONE, 2017; 12 (2): e0171750 DOI: 10.1371/journal.pone.0171750

Note: The above post is reprinted from materials provided by National Oceanography Centre (NOC).

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Study signals new hope for Rockall oil and gas exploration

Why are there different ‘flavors’ of iron around the Solar System?

Ventura fault could cause stronger shaking, new research finds

3-D reconstruction of skull suggests a small crocodile is a new species

Old rocks, biased data: Overcoming challenges studying the geodynamo

Ancient jars found in Judea reveal Earth’s magnetic field is fluctuating, not diminishing

Delving into the inner structure of the planet

Advanced dating method

‘Firefall’ phenomenon wows visitors to Yosemite’s El Capitan

New theory explains how Earth’s inner core remains solid despite extreme heat

Kiss of death: Mammals were the first animals to produce venom

Super scavengers and the meat-thieving traits that have stood the test of time

Cold plates and hot melts

Fossil discovery rewrites understanding of reproductive evolution

Ancient Earth as a model for studying hazy exoplanets

Giant flying reptile ruled ancient Transylvania

Long-term impacts of deep-sea mineral mining

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