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Pterosaurs went out with a bang, not a whimper

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Ancient giant shark tooth goes missing in Australia

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Mexico’s 2017 earthquake emerged from a growing risk zone

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Unique diamond impurities indicate water deep in Earth’s mantle

Diamond crystal
Diamond crystal on kimberlite from South Africa. Credit: Shutterstock

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

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

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

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

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

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

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

And now we can add water to the list.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Deep-sea observatories to offer new view of seabed earthquakes

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

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

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

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

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

Studying an undersea earthquake zone

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

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

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

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

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

Best place for slow-slip quake research

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

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

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

Sub-seafloor observatories offer new view of quakes

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

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

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

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

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

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

Vermilion Cliffs

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

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

Geology

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

Geography

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

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

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

Diamond discovery under pressure

Diamond
An example of a super-deep diamond from the Cullinan Mine, where scientists recently discovered a diamond that provides first evidence in nature of Earth’s fourth most abundant mineral–calcium silicate perovskite–indicating very deep recycling of oceanic crust. Credit: Petra Diamonds

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Researchers discover evidence of earthquakes that affected Chilean coast in the past 9,000 years

paleoseismological record of the Liquiñe-Ofqui Fault Zone (LOFZ)
The study presents the first paleoseismological record of the Liquiñe-Ofqui Fault Zone (LOFZ), a geological structure that crosses southern Chile. Credit: Universidad de Barcelona

A scientific team has discovered the geological footprint of earthquakes and tsunamis that affected the Aysén region (southern Chile) up to 9,000 years ago. This new study improves the assessment of seismic hazard in a wide area of the American continent prone to large earthquakes.

The study, published in Journal of Geophysical Research: Solid Earth, enabled the researchers to establish the first paleoseismological record of the Liquiñe-Ofqui Fault Zone (LOFZ), a large geological structure that crosses southern Chile and is partially responsible for the seismic activity of the Andean country.

The LOFZ fracture area, which stretches over more than 1,000 kilometres north-south in Chile, is a geological structure associated with volcanism and that has an impact on the relief of the Andean country. This seismically hazardous area has some active volcanoes –such as Macá, Hudson and Mentolat- and steep reliefs that can enlarge the effects of the most violent geological phenomena.

In this area, AysĂ©n fjord is a model to study geological processes –earthquakes, tsunamis, etc.— that can be a threat to the local population. According to Galderic Lastras, “the AysĂ©n fjord is cross-cut by the strike-slip fault system (LOFZ) that causes local earthquakes, such as the crisis in 2007. The main earthquake of this crisis —magnitude 6.2— caused dozens of landslides and a local tsunami, with some casualties and important damage to fish farms.”

“Moreover, this fjord is quite close to the plate boundary between the South American and the Nazca Plates, an active subduction zone that causes large magnitude earthquakes,” says Lastras, expert on submarine cartography and head of the oceanographic survey DETSUFA that worked on the cartography of the geological footprint of submarine landslides in AysĂ©n.

Aysén fjord: earthquakes and tsunamis in a natural laboratory

When an earthquake occurs –moderate or strong-, it can destabilize the mountain slopes that surround the fjord. Rock masses can slide and fall until reaching the fjord bottom, causing local tsunamis. This forms an increased risk for the population since there is an extremely short warning time. The geological footprint of these landslides ─piled up at the bottom of the fjord and separated by sediments─ is then visible in the sedimentary record.

According to Maarten Van Daele, postdoctoral researcher and expert on sedimentary deposits created by earthquakes, “strong seismic shaking triggers both onshore and subaquatic landslides. These are buried in the fjord and we can image and map them using geophysical methods. In this study, we also retrieved sediment cores, which allowed us to determine ages for the landslide events using radiocarbon dating of organic material in the sediment.”

Combining different geophysical techniques —reflection seismics, geochemistry of volcanic ashes, etc.— the scientific team constructed the first paleoseismic record of the Liquiñe-Ofqui Fault Zone. “For the first time —adds Van Daele— we have a rough idea of earthquake recurrence rates along this fault. Other similar studies are needed along the fault trace, but this is an important first step to improve the assessment of the seismic hazard in the region.”

Looking for the most violent seismic episodes

Earthquakes can destabilize fjord slopes and cause landslides, but other factors such as heavy rainfall can also be involved and enhance slope instability. As a result, the experts could identify evidence of ten earthquakes in Aysén fjord –including the most recent one in 2007— but the amount of such earthquake events is probably even higher since not every earthquake will cause a significant landslide.

According to Katleen Wils, predoctoral researcher at Ghent University and first author of the study, “we know these landslides occurred due to a common trigger: an earthquake. In the AysĂ©n region, the main source of seismic hazard comes from the LOFZ fault rather than the subduction zone. Those earthquakes had intensities similar to those occurring during the 2007 main episode, which was up to IX, corresponding to violent shaking and considerable damage.”

“According to the data, six of the analysed earthquake events took place in the fjord during the last 9,000 years, while the other four occurred before that. This shows that there is an important seismic hazard in the region, mainly originating from the LOFZ, but also from the subduction zone,” notes Wils, expert on geophysics and the study of earthquakes and seismic hazard.

The number of earthquakes recorded in AysĂ©n fjord may be clear, but “it is more difficult to have a clear idea of their magnitude,” warns Galderic Lastras. “One of the identified events has a similar age (about 2,000 years before present) to a tsunami deposit described in the coastal Lake Huelde, in ChiloĂ© Island, and with a turbidite in Lake Riñihue. Identifying signs of an earthquake in different locations far away from each other is a sign of a large magnitude earthquake, which has likely originated in the subduction zone.”

According to the authors, their study reveals that LOFZ is an active fault system that should be characterized in more detail in future studies in order to have more knowledge on the complete seismic system.

Paleoseismology: the unwritten history of great earthquakes

The paleoseismological record of Aysén fjord is an important part of the geological history of the region as a written record of past earthquakes in the area is non-existent. Understanding the rate at which earthquakes took place in the past is essential to infer the occurrence of future earthquakes.

Because of this uncertainty, “geological research is an essential tool to explain the unwritten history of the most violent earthquake events that affected a certain area. It is important to know as much as possible about past seismic activity of a region. This means that technology and scientific knowledge are the key to improve the assessment of seismic hazard, mitigate the effects of natural disasters and help society directly,” the authors write.

Reference:
Katleen Wils et al. Holocene Event Record of Aysén Fjord (Chilean Patagonia): An Interplay of Volcanic Eruptions and Crustal and Megathrust Earthquakes, Journal of Geophysical Research: Solid Earth (2017). DOI: 10.1002/2017JB014573

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

Sinking land will exacerbate flooding from sea level rise in Bay Area

The San Francisco Bay shoreline, where yellow indicates areas where a projected rise in sea level (SLR) will result in flooding by 2100. Red shows where local land subsidence (LLS) will combine with SLR to increase the flood-prone areas.
The San Francisco Bay shoreline, where yellow indicates areas where a projected rise in sea level (SLR) will result in flooding by 2100. Red shows where local land subsidence (LLS) will combine with SLR to increase the flood-prone areas. Credit: ASU/Manoochehr Shirzaei

Hazard maps use estimated sea level rise due to climate change to determine flooding risk for today’s shoreline, but don’t take into account that some land is sinking. A precise study of subsidence around San Francisco Bay shows that for conservative estimates of sea level rise, twice the area is in danger of flooding by 2100 than previously thought. Some landfill is sinking 10 mm per year, threatening the airport and parts of Silicon Valley.

Rising sea levels are predicted to submerge many coastal areas around San Francisco Bay by 2100, but a new study warns that sinking land — primarily the compaction of landfill in places such as Treasure Island and Foster City — will make flooding even worse.

Using precise measurements of subsidence around the Bay Area between 2007 and 2011 from state-of-the-art satellite-based synthetic aperture radar (InSAR), scientists from the University of California, Berkeley, and Arizona State University mapped out the waterfront areas that will be impacted by various estimates of sea level rise by the end of the century.

They found that, depending on how fast seas rise, the areas at risk of inundation could be twice what had been estimated from sea level rise only.

Previous studies, which did not take subsidence into account, estimated that between 20 and 160 square miles (51 to 413 square kilometers) of San Francisco Bay shoreline face a risk of flooding by the year 2100, depending on how quickly sea levels rise.

Adding the effects of sinking ground along the shoreline, the scientists found that the area threatened by rising seawater rose to between 48 and 166 square miles (125 to 429 square kilometers).

“We are only looking at a scenario where we raise the bathtub water a little bit higher and look where the water level would stand,” said senior author Roland BĂĽrgmann, a UC Berkeley professor of earth and planetary science. “But what if we have a 100-year storm, or king tides or other scenarios of peak water-level change? We are providing an average; the actual area that would be flooded by peak rainfall and runoff and storm surges is much larger.”

The data will help state and local agencies plan for the future and provide improved hazard maps for cities and emergency response agencies.

“Accurately measuring vertical land motion is an essential component for developing robust projections of flooding exposure for coastal communities worldwide,” said Patrick Barnard, a research geologist with the U.S. Geological Survey in Menlo Park. “This work is an important step forward in providing coastal managers with increasingly more detailed information on the impacts of climate change, and therefore directly supports informed decision-making that can mitigate future impacts.”

The low-end estimates of flooding reflect conservative predictions of sea level rise by 2100: about one and a half feet. Those are now being questioned, however, since ice sheets in Greenland and West Antarctica are melting faster than many scientists expected. Today, some extreme estimates are as high as five and a half feet.

That said, the subsidence — which the geologists found to be as high as 10 millimeters per year in some areas — makes less of a difference in extreme cases, BĂĽrgmann noted. Most of the Bay Area is subsiding at less than 2 millimeters per year.

“The ground goes down, sea level comes up and flood waters go much farther inland than either change would produce by itself,” said first author Manoochehr Shirzaei, a former UC Berkeley postdoctoral fellow who is now an assistant professor in ASU’s School of Earth and Space Exploration and a member of NASA’s Sea Level Change planning team.

Shirzaei and BĂĽrgmann will publish their findings March 7 in the online journal Science Advances.

Combining InSAR and GPS

InSAR, which stands for interferometric synthetic aperture radar, has literally changed our view of Earth’s landscape with its ability to measure elevations to within one millimeter, or four-hundredths of an inch, from Earth orbit. While it has been used to map landscapes worldwide — BĂĽrgmann has used InSAR data to map landslides in Berkeley and land subsidence in Santa Clara County — this may be the first time someone has combined such data with future sea level estimates, he said. The team used continuous GPS monitoring of the Bay Area to link the InSAR data to sea level estimates.

“Flooding from sea level rise is clearly an issue in many coastal urban areas,” BĂĽrgmann said. “This kind of analysis is probably going to be relevant around the world, and could be expanded to a much, much larger scale.”

In the Bay Area, one threatened area is Treasure Island, which is located in the Bay midway between San Francisco and Oakland and was created by landfill for the 1939 Golden Gate International Exposition. It is sinking at a rate of one-half to three-quarters of an inch (12 to 20 millimeters) per year.

Projections for San Francisco International Airport show that when land subsidence is combined with projected rising sea levels, water will cover approximately half the airport’s runways and taxiways by the year 2100. Parts of Foster City were built in the 1960s on engineered landfill that is now subsiding, presenting a risk of flooding by 2100.

Not all endangered areas are landfill, however. Areas where streams and rivers have deposited mud as they flow into the Bay are also subsiding, partly because of compaction and partly because they are drying out. Other areas are subsiding because of groundwater pumping, which depletes the aquifer and allows the land to sink. In the early 20th century, the Santa Clara Valley at the south end of San Francisco Bay subsided as much as nine feet (three meters) due to groundwater depletion, though that has stabilized with restrictions on pumping.

Shirzaei noted that flooding is not the only problem with rising seas and sinking land. When formerly dry land becomes flooded, it causes saltwater contamination of surface and underground water and accelerates coastal erosion and wetland losses.

The work was supported by the National Science Foundation, National Aeronautics and Space Administration and Point Reyes Bird Observatory Conservation Science.

Note: The above post is reprinted from materials provided by University of California – Berkeley. Original written by Robert Sanders.

Desertification and monsoon climate change linked to shifts in ice volume and sea level

Chinese loess plateau
Chinese loess plateau. Credit: Thomas Stevens

The East Asian summer monsoon and desertification in Eurasia is driven by fluctuating Northern Hemisphere ice volume and global sea level during the Ice Age, as shown in a study published in Nature Communications. Today, two thirds of the world’s population is dependent on agriculture sustained by rains of the East Asian summer monsoon, and future climate change in this region can therefore have a major impact on global food production.

Huge areas of central China is covered by a plateau consisting of a fine grained soil type called loess — a sediment deposited here by winds during the Ice Age. The soils formed on loess are very fertile and have been one of the key factors driving cultural development and population growth in China for thousands of years. Additionally, the loess plateau also contains a geological archive that can be used to decipher past climate changes.

Through detailed examination of the loess sediments, a group led by researchers at Uppsala Univirsity together with colleagues from Denmark has identified how changes in climatological phenomena such as ice volume and sea level also affected the extent of deserts in China, as well as the behavior of the East Asian summer monsoon.

“We have conducted the most detailed dating of the loess to date, which has enabled us to identify changes in the monsoon and desertification processes in more detail and with much greater accuracy than previously possible. We can now compare these changes to other known climate changes such as variation in ice volume, sea level and even the Earth’s orbit during the Ice Age,” says Dr. Thomas Stevens, first author and researcher at Uppsala University.

“We can now show that when ice volume decreased and sea level rose, the summer monsoon rainfalls in East Asia intensified and spread further inland, while sandy deserts in China retreated,” says Dr. Stevens.

With today’s shrinking ice caps and rising sea levels, this has implications for how the Eurasian continent will once again experience changes in the summer monsoon rainfall and desertification.

Reference:
T. Stevens, J.-P. Buylaert, C. Thiel, G. Újvári, S. Yi, A. S. Murray, M. Frechen, H. Lu. Ice-volume-forced erosion of the Chinese Loess Plateau global Quaternary stratotype site. Nature Communications, 2018; 9 (1) DOI: 10.1038/s41467-018-03329-2

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

Ancient reptile Captorhinus could detach its tail to escape predator’s grasp

illustration of Captorhinus showing breakable tail vertebrae.
This is an illustration of Captorhinus showing breakable tail vertebrae. Credit: Courtesy Robert Reisz

Imagine that you’re a voracious carnivore who sinks its teeth into the tail of a small reptile and anticipates a delicious lunch, when, in a flash, the reptile is gone and you are left holding a wiggling tail between your jaws.

A new study by the University of Toronto Mississauga research team led by Professor Robert Reisz and PhD student Aaron LeBlanc, published March 5 in the open source journal, Scientific Reports, shows how a group of small reptiles who lived 289 million years ago could detach their tails to escape the grasp of their would-be predators — the oldest known example of such behaviour. The reptiles, called Captorhinus, weighed less than 2 kilograms and were smaller than the predators of the time. They were abundant in terrestrial communities during the Early Permian period and are distant relatives of all the reptiles today.

As small omnivores and herbivores, Captorhinus and its relatives had to scrounge for food while avoiding being preyed upon by large meat-eating amphibians and ancient relatives of mammals. “One of the ways captorhinids could do this,” says first author LeBlanc, “was by having breakable tail vertebrae.” Like many present-day lizard species, such as skinks, that can detach their tails to escape or distract a predator, the middle of many tail vertebrae had cracks in them.

It is likely that these cracks acted like the perforated lines between two paper towel sheets, allowing vertebrae to break in half along planes of weakness. “If a predator grabbed hold of one of these reptiles, the vertebra would break at the crack and the tail would drop off, allowing the captorhinid to escape relatively unharmed,” says Reisz, a Distinguished Professor of Biology at the University of Toronto Mississauga.

The authors note that being the only reptiles with such an escape strategy may have been a key to their success, because they were the most common reptiles of their time, and by the end of the Permian period 251 million years ago, captorhinids had dispersed across the ancient supercontinent of Pangaea. This trait disappeared from the fossil record when Captorhinus died out; it re-evolved in lizards only 70 million years ago.

They were able to examine more than 70 tail vertebrae — both juveniles and adults — and partial tail skeletons with splits that ran through their vertebrae. They compared these skeletons to those of other reptilian relatives of captorhinids, but it appears that this ability is restricted to this family of reptiles in the Permian period.

Using various paleontological and histological techniques, the authors discovered that the cracks were features that formed naturally as the vertebrae were developing. Interestingly, the research team found that young captorhinids had well-formed cracks, while those in some adults tended to fuse up. This makes sense, since predation is much greater on young individuals and they need this ability to defend themselves.

This study was possible thanks to the treasure trove of fossils available at the cave deposits near Richards Spur, Oklahoma.

Reference:
A. R. H. LeBlanc, M. J. MacDougall, Y. Haridy, D. Scott, R. R. Reisz. Caudal autotomy as anti-predatory behaviour in Palaeozoic reptiles. Scientific Reports, 2018; 8 (1) DOI: 10.1038/s41598-018-21526-3

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

Human-made earthquake risk reduced if fracking is 895m from faults

Representative Image

The risk of human-made earthquakes due to fracking is greatly reduced if high-pressure fluid injection used to crack underground rocks is 895m away from faults in the Earth’s crust, according to new research.

The recommendation, from the ReFINE (Researching Fracking) consortium, is based on published microseismic data from 109 fracking operations carried out predominantly in the USA.

Jointly led by Durham and Newcastle Universities, UK, the research looked at reducing the risk of reactivating geological faults by fluid injection in boreholes.

Researchers used microseismic data to estimate how far fracking-induced fractures in rock extended horizontally from borehole injection points.

The results indicated there was a one per cent chance that fractures from fracking activity could extend horizontally beyond 895m in shale rocks.

There was also a 32 per cent chance of fractures extending horizontally beyond 433m, which had been previously suggested as a horizontal separation distance between fluid injection points and faults in an earlier study.

The research is published in the journal Geomechanics and Geophysics for Geo-Energy and Geo-Resources.

Fracking — or hydraulic fracturing — is a process in which rocks are deliberately fractured to release oil or gas by injecting highly pressurised fluid into a borehole. This fluid is usually a mixture of water, chemicals and sand.

In 2011 tremors in Blackpool, UK, were caused when injected fluid used in the fracking process reached a previously unknown geological fault at the Preese Hall fracking site.

Fracking is now recommencing onshore in the UK after it was halted because of fracking-induced earthquakes.

Research lead author Miles Wilson, a PhD student in Durham University’s Department of Earth Sciences, said: “Induced earthquakes can sometimes occur if fracking fluids reach geological faults. Induced earthquakes can be a problem and, if they are large enough, could damage buildings and put the public’s safety at risk.

“Furthermore, because some faults allow fluids to flow along them, there are also concerns that if injected fluids reach a geological fault there is an increased risk they could travel upwards and potentially contaminate shallow groundwater resources such as drinking water.

“Our research shows that this risk is greatly reduced if injection points in fracking boreholes are situated at least 895m away from geological faults.”

The latest findings go further than a 2017 ReFINE study which recommended a maximum distance of 433m between horizontal boreholes and geological faults. That research was based upon numerical modelling in which a number of factors, including fluid injection volume and rate, and fracture orientation and depth, were kept constant.

Researchers behind the latest study said that changing these parameters might lead to different horizontal extents of fractures from fluid injection points.

The researchers added that this did not mean the modelling results of the previous study were wrong. Instead they said the previous study was approaching the same problem using a different method and the new study provided further context.

In the latest research the researchers used data from previous fracking operations to measure the distance between the furthest detected microseismic event — a small earthquake caused by hydraulic fracturing of the rock or fault reactivation — and the injection point in the fracking borehole.

From the 109 fracking operations analysed, the researchers found that the horizontal extent reached by hydraulic fractures ranged from 59m to 720m.

There were 12 examples of fracking operations where hydraulic fractures extended beyond the 433m proposed in the 2017 study.

According to the new study, the chance of a hydraulic fracture extending beyond 433m in shale was 32 per cent and beyond 895m was one per cent.

The research also found that fracking operations in shale rock generally had their furthest detected microseismic events at greater distances than those in coal and sandstone rocks.

Microseismic data was used in previous Durham University research from 2012. This suggested a minimum vertical distance of 600m between the depth of fracking and aquifers used for drinking water, which now forms the basis of hydraulic fracturing regulation in the UK’s Infrastructure Act 2015.

Professor Richard Davies, Newcastle University, who leads the ReFINE project, said: “We strongly recommend that for the time being, fracking is not carried out where faults are within 895m of the fracked borehole to avoid the risk of fracking causing earthquakes and that this guideline is adopted world-wide.”

ReFINE is led jointly by Durham and Newcastle Universities and has been funded by the Natural Environment Research Council (UK), Total, Shell, Chevron, GDF Suez, Centrica and Ineos.

Working closely with a global network of leading scientists and institutions, ReFINE focuses on researching the potential environmental risks of hydraulic fracturing for shale gas and oil exploitation.

Reference:
M. P. Wilson, F. Worrall, R. J. Davies, S. Almond. Fracking: How far from faults? Geomechanics and Geophysics for Geo-Energy and Geo-Resources, 2018; DOI: 10.1007/s40948-018-0081-y

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

Another clue for fast motion of the Hawaiian hotspot

The graph shows the dates of volcanoes of the three volcanic chains in the Pacific and their relative movement over time (left). The location of the three volcanic chains shown in the map (right). The stars mark the youngest end or the active volcanoes today.
The graph shows the dates of volcanoes of the three volcanic chains in the Pacific and their relative movement over time (left). The location of the three volcanic chains shown in the map (right). The stars mark the youngest end or the active volcanoes today. Credit: Nature Communications, Kevin Konrad et al.

The island chain of Hawaii consists of several volcanoes, which are fed by a “hotspot.” In geosciences a “hotspot” refers to a phenomenon of columnar shaped streams, which transport hot material from the deep mantle to the surface. Like a blow torch, the material burns through the Earth’s crust and forms volcanoes. For a long time, it was assumed that these hotspots are stationary. If the tectonic plate moves across it, a chain of volcanoes evolves, with the youngest volcano at one end, the oldest at the other.

This concept was initially proposed for the Hawaiian Islands. They are the youngest end of the Hawaiian-Emperor chain that lies beneath the Northwest Pacific. But soon there was doubt over whether hotspots are truly stationary. The biggest contradiction was a striking bend of about 60 degrees in this volcanic chain, which originated 47 million years ago. “If you try to explain this bend with just a sudden change in the movement of the Pacific Plate, you would expect a significantly different direction of motion at that time relative to adjacent tectonic plates,” says Bernhard Steinberger of the GFZ German Research Center for Geosciences. “But we have not found any evidence for that.” Recent studies have suggested that apparently two processes were effective: On the one hand, the Pacific Plate has changed its direction of motion. On the other hand, the Hawaiian hotspot moved relatively quickly southward in the period from 60 to about 50 million years ago — and then stopped. If this hotspot motion is considered, only a smaller change of Pacific plate motions is needed to explain the volcano chain.

This hypothesis is now supported by work in which Steinberger is also involved. First author Kevin Konrad, Oregon State University in Corvallis, Oregon, and his team have evaluated new rock dating of volcanoes in the Rurutu volcanic chain, including, for example, the Tuvalu volcanic islands in the Western Pacific. Furthermore, they added similar data from the Hawaiian-Emperor chain and the Louisville chain in the Southern Pacific. Based on the geography and the age of volcanoes in these three chains, researchers can look into the geological past and see how the three hotspots have moved relative to each other over millions of years.

The new data published in the journal Nature Communications shows that the relative motion of hotspots under the Rurutu and Louisville is small while the Hawaiian-Emperor hotspot displays strong motion between 60 and 48 million years ago relative to the other two hotspots. “This makes it very likely that mainly the Hawaii hotspot has moved,” says Steinberger. According to his geodynamic modelling the Hawaiian hotspot moved at a rate of several tens of kilometers per million years. Paleomagnetic data support this interpretation, says Steinberger. “Our models for the motion of the Pacific Plate and the hotspots therein still have some inaccuracies. With more field data and information about the processes deep in the mantle, we hope to explain in more detail how the bend in the Hawaiian-Emperor chain has evolved.”

Reference:
Kevin Konrad, Anthony A. P. Koppers, Bernhard Steinberger, Valerie A. Finlayson, Jasper G. Konter, Matthew G. Jackson. On the relative motions of long-lived Pacific mantle plumes. Nature Communications, 2018; 9 (1) DOI: 10.1038/s41467-018-03277-x

Note: The above post is reprinted from materials provided by GFZ GeoForschungsZentrum Potsdam, Helmholtz Centre.

Photosynthesis originated a billion years earlier than we thought, study shows

This image is the crystal structure of Photosystem I. Credit: Image courtesy of Elsevier

The earliest oxygen-producing microbes may not have been cyanobacteria.

Ancient microbes may have been producing oxygen through photosynthesis a billion years earlier than we thought, which means oxygen was available for living organisms very close to the origin of life on earth. In a new article in Heliyon, a researcher from Imperial College London studied the molecular machines responsible for photosynthesis and found the process may have evolved as long as 3.6 billion years ago.

The author of the study, Dr. Tanai Cardona, says the research can help to solve the controversy around when organisms started producing oxygen — something that was vital to the evolution of life on earth. It also suggests that the microorganisms we previously believed to be the first to produce oxygen — cyanobacteria — evolved later, and that simpler bacteria produced oxygen first.

“My results mean that the process that sustains almost all life on earth today may have been doing so for a lot longer than we think,” said Dr. Cardona. “It may have been that the early availability of oxygen was what allowed microbes to diversify and dominate the world for billions of years. What allowed microbes to escape the cradle where life arose and conquer every corner of this world, more than 3 billion years ago.”

Photosynthesis is the process that sustains complex life on earth — all of the oxygen on our planet comes from photosynthesis. There are two types of photosynthesis: oxygenic and anoxygenic. Oxygenic photosynthesis uses light energy to split water molecules, releasing oxygen, electrons and protons. Anoxygenic photosynthesis use compounds like hydrogen sulfide or minerals like iron or arsenic instead of water, and it does not produce oxygen.

Previously, scientists believed that anoxygenic evolved long before oxygenic photosynthesis, and that the earth’s atmosphere contained no oxygen until about 2.4 to 3 billion years ago. However, the new study suggests that the origin of oxygenic photosynthesis may have been as much as a billion years earlier, which means complex life would have been able to evolve earlier too.

Dr. Cardona wanted to find out when oxygenic photosynthesis originated. Instead of trying to detect oxygen in ancient rocks, which is what had been done previously, he looked deep inside the molecular machines that carry out photosynthesis — these are complex enzymes called photosystems. Oxygenic and anoxygenic photosynthesis both use an enzyme called Photosystem I. The core of the enzyme looks different in the two types of photosynthesis, and by studying how long ago the genes evolved to be different, Dr. Cardona could work out when oxidative photosynthesis first occurred.

He found that the differences in the genes may have occurred more than 3.4 billion years ago — long before oxygen was thought to have first been produced on earth. This is also long before cyanobacteria — microbes that were thought to be the first organisms to produce oxygen — existed. This means there must have been predecessors, such as early bacteria, that have since evolved to carry out anoxygenic photosynthesis instead.

“This is the first time that anyone has tried to time the evolution of the photosystems,” said Dr. Cardona. “The result hints towards the possibility that oxygenic photosynthesis, the process that have produced all oxygen on earth, actually started at a very early stage in the evolutionary history of life — it helps solve one of the big controversies in biology today.”

One surprising finding was that the evolution of the photosystem was not linear. Photosystems are known to evolve very slowly — they have done so since cyanobacteria appeared at least 2.4 billion years ago. But when Dr. Cardona used that slow rate of evolution to calculate the origin of photosynthesis, he came up with a date that was older than the earth itself. This means the photosystem must have evolved much faster at the beginning — something recent research suggests was due to the planet being hotter.

“There is still a lot we don’t know about why life is the way it is and how most biological process originated,” said Dr. Cardona. “Sometimes our best educated guesses don’t even come close to representing what really happened so long ago.”

Dr. Cardona hopes his findings may also help scientists who are looking for life on other planets answer some of their biggest questions.

Reference:
Tanai Cardona. Early Archean origin of heterodimeric Photosystem I. Heliyon, 2018; 4 (3): e00548 DOI: 10.1016/j.heliyon.2018.e00548

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

127 million year old baby bird fossil sheds light on avian evolution

Tiny fossil of a prehistoric baby bird
“Enantiornithes” Phosphorous mapping image and photo of fossil. Credit: Dr. Fabien Knoll

The tiny fossil of a prehistoric baby bird is helping scientists understand how early avians came into the world in the Age of Dinosaurs.

The fossil, which dates back to the Mesozoic Era (250-65 million years ago), is a chick from a group of prehistoric birds called, Enantiornithes. Made up of a nearly complete skeleton, the specimen is amongst the smallest known Mesozoic avian fossils ever discovered.

It measures less than five centimetres — smaller than the little finger on an average human hand — and would have weighed just three ounces when it was alive. What makes this fossil so important and unique is the fact it died not long after its birth. This is a critical stage in a bird’s skeletal formation. That means this bird’s extremely short life has given researchers a rare chance to analyse the species’ bone structure and development.

Studying and analysing ossification — the process of bone development — can explain a lot about a young bird’s life the researchers say. It can help them understand everything from whether it could fly or if it needed to stay with its parents after hatching or could survive on its own.

The lead author of the study, Fabien Knoll, from The University of Manchester’s Interdisciplinary Centre for Ancient Life (ICAL), School of Earth and Environmental Sciences, and the ARAID — Dinopolis in Spain explains: ‘The evolutionary diversification of birds has resulted in a wide range of hatchling developmental strategies and important differences in their growth rates. By analysing bone development we can look at a whole host of evolutionary traits.’

With the fossil being so small the team used synchrotron radiation to picture the tiny specimen at a ‘submicron’ level, observing the bones’ microstructures in extreme detail.

Knoll said: ‘New technologies are offering palaeontologists unprecedented capacities to investigate provocative fossils. Here we made the most of state-of-the-art facilities worldwide including three different synchrotrons in France, the UK and the United States.’

The researchers found the baby bird’s sternum (breastplate bone) was still largely made of cartilage and had not yet developed into hard, solid bone when it died, meaning it wouldn’t have been able to fly.

The patterns of ossification observed in this and the other few very young enantiornithine birds known to date also suggest that the developmental strategies of this particular group of ancient avians may have been more diverse than previously thought.

However, the team say that its lack of bone development doesn’t necessarily mean the hatchling was over reliant on its parents for care and feeding, a trait known as being ‘altricial’. Modern day species like love birds are highly dependent on their parents when born. Others, like chickens, are highly independent, which is known as ‘precocial’. Although, this is not a black-and-white issue, but rather a spectrum, hence the difficulty in clarifying the developmental strategies of long gone bird species.

Luis Chiappe, from the LA Museum of Natural History and study’s co-author added: ‘This new discovery, together with others from around the world, allows us to peek into the world of ancient birds that lived during the age of dinosaurs. It is amazing to realise how many of the features we see among living birds had already been developed more than 100 million years ago.’

Reference:
Fabien Knoll, Luis M. Chiappe, Sophie Sanchez, Russell J. Garwood, Nicholas P. Edwards, Roy A. Wogelius, William I. Sellers, Phillip L. Manning, Francisco Ortega, Francisco J. Serrano, Jesús Marugán-Lobón, Elena Cuesta, Fernando Escaso, Jose Luis Sanz. A diminutive perinate European Enantiornithes reveals an asynchronous ossification pattern in early birds. Nature Communications, 2018; 9 (1) DOI: 10.1038/s41467-018-03295-9

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

Fossilised plant leaf wax provides new tool for understanding ancient climates

Calatayud-Daroca Basin in Central Spain.
This is the Calatayud-Daroca Basin in Central Spain. Credit: Michael Hren

New research, published in Scientific Reports, has outlined a new methodology for estimating ancient atmospheric water content based on fossil plant leaf waxes.

As the Earth’s surface and atmosphere warm, the amount of moisture — water vapour — in the atmosphere will increase. Understanding the size of this increase is important for predicting future climates as water vapour is a significant greenhouse gas. Atmospheric moisture content also influences the patterns and intensity of rainfall events.

The relationship between temperature and moisture content can be explored by the study of intervals in Earth’s history when climates where significantly warmer than those seen in modern times, which necessitates a method for estimating ancient atmospheric moisture content.

Dr Yvette Eley, from the University of Birmingham, explained, “If we want to understand how the Earth would work with a climate substantially warmer than today, we have to study intervals millions of years in the past — made difficult because these warm climates are much older than our oldest climate records from Antarctic ice cores (less than one million years old).”

To try and understand climate properties related to the atmosphere — like rainfall and atmospheric moisture content — in such ancient times is very challenging. Existing methods, using calcium carbonate concretions that form in soils, or the chemistry of fossilised mammal teeth, are both hampered by their relative rarity in ancient sediments.

Dr Eley added, “Our new approach to quantifying ancient atmospheric moisture content relies on the fundamental properties of plant leaves, and how they alter their protective waxy coverings in response to water stress. These leaf waxes are tough and resistant, and are regularly found as what we call biomarker compounds in ancient river, lake and even marine sediments.”

A method of estimating ancient moisture content based on these plant wax compounds overcomes the limitations of other methods because plant waxes are commonly found in soils and sediments stretching back tens or even hundreds of millions of years and across many environments.

The validity of this new tool was proven in studies of modern soils across the US and Central America, carried out by the research team of Associate Professor Michael Hren in the Center for Integrative Geosciences at the University of Connecticut. These studies showed a clear relationship between the chemistry of these waxy compounds and the amount of moisture in the atmosphere.

“What we see is that the distribution of organic compounds preserved in soils seems to be strongly related to the difference between how much water is in an air mass, and how much the air mass can hold, or what is known as the vapour pressure deficit,” says Dr Hren.

Eley and Hren then applied their new proxy to reconstruct atmospheric moisture content in Central Spain during an interval 15 to 17 million years ago.

Although consistently much warmer than pre-industrial conditions, this interval marks one of the cooling steps that led to the development of the modern world. The new data confirms the expectations of climate models, that atmospheric cooling is coupled to less atmospheric moisture. The reconstructed changes in atmospheric moisture also align with results from other independent proxies used to investigate changes in temperature and rainfall in the region.

Dr Eley said, “This gives us the confidence that our proxy works, and we have every reason to believe that it will do so for future exploration into the even deeper past. We hope the results of this exploration will provide direct data to test our understanding of the relationship between global warming, atmospheric moisture content and rainfall systems.”

Reference:
Yvette L. Eley, Michael T. Hren. Reconstructing vapor pressure deficit from leaf wax lipid molecular distributions. Scientific Reports, 2018; 8 (1) DOI: 10.1038/s41598-018-21959-w

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

Deep-sea fish choose habitat according to genotype, new research says

This is a roundnose grenadier at 1,300m off the Hebrides, Scotland.
This is a roundnose grenadier at 1,300m off the Hebrides, Scotland. The photo is from a towed camera. Credit: Marine Scotland Science

Scientists have found evidence of natural selection in a deep-sea fish species adapting to the depth of ocean that it inhabits.

The team of researchers, led by Professor Rus Hoelzel in Durham University’s (UK) Department of Biosciences (together with collaborators from the Department of Earth Sciences in Durham, the University of Liverpool and Marine Scotland), studied a species of fish called the roundnose grenadier.

They say this is the first evidence of natural selection maintaining separate specialised types of the same species of fish, each adapting to different habitat depths within a single population spanning two kilometres of depth in the deep sea.

Their study is published in the journal Nature Ecology & Evolution.

The researchers said that an important transition in the deep sea is where the penetration of light ends dividing the relatively vibrant mesopelagic from the dark bathypelagic part of the ocean below approximately 1,000m.

The roundnose grenadier has a remarkably broad habitat range in the deep sea, from 180-2,600m in depth.

The research looked at a section of ocean inhabited by this species running from 750m to 1,800m at a single location, crossing the boundary between the “light” and “dark” parts of the ocean.

They sequenced the entire nuclear genome of this species, and identified all of the genes within that genome that code for biological functions. They then sequenced 60 more genomes, 15 from each of four depths (750m, 1,000m, 1,500m and 1,800m). This revealed adaptation to depth at functional genes, with all of the 1,800m fish different from the others that lived at shallower depths.

Those adapted genes were associated with the building of different body forms and functions as the individual matures. Furthermore, they found strong evidence for ongoing natural selection such that either extreme form was favoured at the expense of the intermediate type.

This “disruptive” selection can lead to the evolution of new species when the different types also mate preferentially with their own type.

However, in this case, there was no clear evidence for mating with one’s own type. Instead, the young (‘fry’) fish stay at approximately1,000m until they mature, and then segregate to different depths according to their genetic makeup.

This provides a uniquely clear example of how different specialists within the same species, in this case adaption to life at different habitat depths, can be maintained even within the same geographic population. This might help prepare a species for a rapid response to a changing environment, such as rapid climate change.

Differentiation among ecotypes may be driven by the distinction between a resource rich environment in shallower water, and a relatively resource poor environment deeper down the slope.

Lead author, Professor Rus Hoelzel, in Durham University’s, Department of Biosciences, said: “The oceans represent vast expanses across which there are few obvious barriers to movement.

“As in the environment above the sea, we tend to think about movement in a horizontal dimension, across the breadth of the oceans, but at sea there are perhaps even greater habitat boundaries and gradients as species move vertically with depth.

“Our research shows that these fish have adapted to life at different depths, and that they segregate by depth as they mature, based on their genetic makeup.”

The research was funded by the Natural Environment Research Council (NERC)

Reference:
Michelle R. Gaither, Georgios A. Gkafas, Menno de Jong, Fatih Sarigol, Francis Neat, Thomas Regnier, Daniel Moore, Darren R. GrÓ§cke, Neil Hall, Xuan Liu, John Kenny, Anita Lucaci, Margaret Hughes, Sam Haldenby, A. Rus Hoelzel. Genomics of habitat choice and adaptive evolution in a deep-sea fish. Nature Ecology & Evolution, 2018; DOI: 10.1038/s41559-018-0482-x

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

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