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Fox Creek earthquakes linked to completion volume and location of hydraulic fracturing

A UAlberta researcher is the first to link the likelihood of earthquakes caused by hydraulic fracturing to the location of well pads and volume of liquid used in the process.
A UAlberta researcher is the first to link the likelihood of earthquakes caused by hydraulic fracturing to the location of well pads and volume of liquid used in the process.

The volume of hydraulic fracturing fluid and the location of well pads control the frequency and occurrence of measurable earthquakes, new Alberta Geological Survey and UAlberta research has found.

Ryan Schultz has been studying earthquakes in the Fox Creek, Alberta area since they started in December 2013. The seismologist — who works at the Alberta Geological Survey (a branch of the Alberta Energy Regulator) and with the University of Alberta — wanted to better understand what was causing the quakes.

Schultz and his colleagues found that when increased volumes were injected in susceptible locations (i.e., in connection with a nearby slip-ready fault), it transmits increased pressure to the fault line, leading to more numerous measurable earthquakes.

It’s not as simple as more volume equals more earthquakes, though-a link that scientists have long identified in the history of induced seismicity, dating back to the 1950s. There is another factor at play in the Fox Creek area, and it’s all about location, explained Schultz.

“If there is a pre-existing fault, but you’re not connected to it by some sort of fluid pathway, you can hydraulically fracture the formation, and you’re probably not going to cause a significant earthquake,” said Schultz. “It’s conceptually quite simple, but actually determining those things underground is really hard to do in practice.”

Since 2013, there has been a marked increase in the rate of earthquakes near Fox Creek, ranging up to magnitude 4s. While other research has pointed to industry activity as contributing to the quakes, this study is the first to identify specific factors causing the seismic activity.

Schultz said the next steps for the scientists are to build on these findings to better understand the geological factors occurring in this concentrated area of the Duvernay Formation with the future goal of better predicting best places to conduct hydraulic fracturing where it is least likely to cause these earthquakes.

To answer these questions, the UAlberta alumnus continues to work with Jeff Gu, geophysics professor in the Department of Physics and Schultz’s former graduate supervisor, and colleagues at the Alberta Geological Survey.

“We want to characterize everything we can about these earthquakes so that we can describe them in as much detail as possible,” said Schultz. “But when you answer questions, more questions come up.”

“Hydraulic fracturing volume is associated with induced earthquake productivity in the Duvernay play” will be published in the January 19 issue of Science, one of the world’s leading peer-reviewed scientific publications.

Reference:
R. Schultz, G. Atkinson, D. W. Eaton, Y. J. Gu, H. Kao. Hydraulic fracturing volume is associated with induced earthquake productivity in the Duvernay play. Science, 2018; 359 (6373): 304 DOI: 10.1126/science.aao0159

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

World’s oldest known oxygen oasis discovered

Rock layers in the Pongola Basin, South Africa.
Rock layers in the Pongola Basin, South Africa.
Credit: Axel Hofmann/University of Johannesburg

In the Earth’s early history, several billion years ago, only traces of oxygen existed in the atmosphere and the oceans. Today’s air-breathing organisms could not have existed under those conditions. The change was caused by photosynthesizing bacteria, which created oxygen as a by-product — in vast amounts. 2.5-billion-year-old rock layers on several continents have yielded indications that the first big increase in the proportion of oxygen in the atmosphere took place then.

Now, working with international colleagues, Dr. Benjamin Eickmann and Professor Ronny Schönberg, isotope geochemists from the University of Tübingen have discovered layers in South Africa’s Pongola Basin which bear witness to oxygen production by bacteria as early as 2.97 billion years ago. That makes the Basin the earliest known home to oxygen-producing organisms — known as an oxygen oasis. The study has been published in the latest Nature Geoscience.

Conditions on Earth some three billion years ago were inhospitible to say the least. The atmosphere contained only one-one hundred thousandth of the oxygen it has today. The primeval oceans contained hardly any sulfate; but they did contain large amounts of ferrous iron. When bacteria started producing oxygen, it could initially bond with other elements, but began to enrich the atmosphere in a massive oxygen emission event around 2.5 billion years ago.

“We can see that in the disappearance of reduced minerals in the sediments on the continents. Certain sulfur signatures which can only be formed in a low-oxygen atmosphere are no longer to be found,” says Benjamin Eickmann, the study’s lead author. This event, which could be described as global environmental pollution, went down in the Earth’s history as the Great Oxygenation Event. It was a disaster for the early bacteria types which had evolved under low-oxygen conditions; the oxygen poisoned them. “However, after the first big rise, the atmosphere only contained 0.2 percent oxygen; today it’s around 21 percent,” Eickmann explains. Exposed to an atmosphere which contained increasing amounts of oxygen, the continents were subject to enhanced erosion. That led to more trace elements entering the oceans. The improved supply of nutrients in turn led to more life forms in the seas.

Sulfur signatures as an archive of Earth history

In their current study the researchers investigated the 2.97-bilion-year-old sediments deposited in the Pongola Basin in what is now South Africa. From the proportions of sulfur isotopes (particularly the of 34S/32S ratio), in the sediments, the researchers are able to conclude that the bacteria used the sulfate in the primeval seas as a source of energy, reducing it chemically.

“Sulfate is a form of oxidized sulfur. A higher concentration of sulfate in the water indicates that sufficient free oxygen must have been present in the shallow sea of the Pongola Basin,” Ronny Schönberg says. This free oxygen must have been produced by other, photosynthesizing bacteria. At the same time, another sulfur isotope signature (the 33S/32S ratio) in these sediments indicates a continued reduced, very low-oxygen atmosphere.

“That makes the Pongola Basin the oldest oxygen oasis known to date. The oxygen was building up in the water long before the Great Oxygenation Event, Schönberg explains. Several hundred million years later, the steadily rising levels of oxygen led to the oxidation of the atmosphere, and that is what made life on Earth — in all its variety as we know it today — even possible.

Reference:
Benjamin Eickmann, Axel Hofmann, Martin Wille, Thi Hao Bui, Boswell A. Wing, Ronny Schoenberg. Isotopic evidence for oxygenated Mesoarchaean shallow oceans. Nature Geoscience, 2018; DOI: 10.1038/s41561-017-0036-x

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

New details emerge on temperature, mobility of earth’s lower crust in Rocky Mountains

This is Moho temperature at depths varying from 20 to 50 km.
This is Moho temperature at depths varying from 20 to 50 km. Credit: Colorado State University

Everything on the surface of the Earth rests on massive tectonic plates that resemble a jelly sandwich, with two rigid pieces — the upper crust and the upper mantle — enclosing a gooey middle layer of very hot rocks, which is the lower crust. The plates move ever so slowly around the globe over a deeper hot layer called the asthenosphere.

Temperature plays a fundamental role in determining the strength, thickness, and buoyancy of the lower crust. A research team led by Colorado State University has mapped the temperature and viscosity of the lower crust for the first time and found that, under much of the western United States, the layer is hot enough to be near its initial melting point and, therefore, quite runny.

This new research shows that significant regions of the lower crust have little strength, and that over several million years, could lead to many mountains in the western U.S. being flattened.

“Having a map of the temperature gives us an understanding of how strong the plate is,” said Derek Schutt, associate professor in CSU’s Department of Geosciences. “What we found is that there are places where the crust is not strong enough to hold the topography.”

Imagine three slices of Silly Putty, two frozen pieces lying on the top and bottom of one that is room temperature. When you push on the top layer, the warm Silly Putty will be squeezed flat. Similar mechanics are at work in the Earth’s crust.

“Mountains are formed by forces pushing things around, and weak areas collapsing,” according to Schutt.

Outside forces could potentially push on the crust and that force could be transferred deep inland, which is called orogenic float, he said. The new study suggests this process may occur more often than previously thought.

“That can cause mountains to form at a great distance from where you’re pushing on things,” Schutt said. “Because the lower crust is mobile, force can be transmitted over a large distance.”

Scientists generally think of tectonic plates, or lithosphere, as being made up of the crust and a cold uppermost mantle. But in this new analysis, the team saw something akin to ball bearings slipping between the crust and mantle. While not unexpected, this study was able to map the extent of the areas resembling ball bearings.

“The ‘ball bearings’ keep separate what’s happening in the mantle from what’s happening in the crust,” said Schutt.

Researchers calculated temperatures at the bottom of the crust, which varies in thickness, by measuring the velocity of seismic waves that travel near the interface between the lower crust and uppermost mantle.

In the western U.S., the crust is very hot, which is what makes it so weak.

“We know in general that the lower crust in the western United States seems hot,” said Schutt. “But this is the first time we’ve been able to really ascribe a temperature to a specific location.”

The findings, he said, are not too surprising. But the research could lead to more insight about why mountains exist and, more specifically, why they exist in places where the temperatures in the lower crust are so high.

Schutt and the research team will continue to explore the causes of variations in tectonic plate strength as part of an ongoing project between Colorado State University, Utah State University, and Scripps Institution of Oceanography at the University of California, San Diego. This research is funded by the National Science Foundation’s Earthscope Program.

Reference:
Derek L. Schutt, Anthony R. Lowry, Janine S. Buehler. Moho temperature and mobility of lower crust in the western United States. Geology, 2018; DOI: 10.1130/G39507.1

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

‘Rainbow’ dinosaur had iridescent feathers like a hummingbird

Holotype fossil of Caihong juji, including line drawing of fossil skeleton.
This is holotype fossil of Caihong juji, including line drawing of fossil skeleton. Credit: Yu et al., 2018

Scientists discovered a dinosaur fossil with feathers so well-preserved that they were able to see the feathers’ microscopic color-bearing structures. By comparing the shapes of those feather structures with the structures in modern bird feathers, they’re able to infer that the new dino, Caihong juji (‘rainbow with the big crest’) had iridescent rainbow feathers like a hummingbird.

Birds are the last remaining dinosaurs. They’re also some of the most vibrantly colored animals on Earth. A new study in Nature Communications reveals that iridescent feathers go way back — a newly discovered species of dinosaur from 161 million years ago had rainbow coloring.

Caihong juji was tiny, about the size of a duck, with a bony crest on its head and long, ribbon-like feathers. And, based on analysis of its fossilized feathers, the feathers on its head, wings, and tail were probably iridescent, with colors that shimmered and shifted in the light. Its name reflects its appearance — in Mandarin, it means, “rainbow with the big crest.” The new species, which was first discovered by a farmer in northeastern China, was described by an international team of scientists led by Dongyu Hu, a professor in the College of Paleontology at the Shenyang Normal University in China.

“When you look at the fossil record, you normally only see hard parts like bone, but every once in a while, soft parts like feathers are preserved, and you get a glimpse into the past,” says Chad Eliason, a postdoctoral researcher at The Field Museum and one of the study’s authors. Eliason, who began work on the project as a postdoctoral fellow at the University of Texas at Austin, added, “The preservation of this dinosaur is incredible, we were really excited when we realized the level of detail we were able to see on the feathers.”

When the scientists examined the feathers under powerful microscopes, they could see the imprints of melanosomes, the parts of cells that contain pigment. For the most part, the pigment that was once present was long gone, but the physical structure of the melanosomes remained. As it turns out, that was enough for scientists to be able to tell what color the feathers were.

That’s because color isn’t only determined by pigment, but by the structure of the melanosomes containing that pigment. Differently shaped melanosomes reflect light in different colors. “Hummingbirds have bright, iridescent feathers, but if you took a hummingbird feather and smashed it into tiny pieces, you’d only see black dust. The pigment in the feathers is black, but the shapes of the melanosomes that produce that pigment are what make the colors in hummingbird feathers that we see,” explains Eliason.

The scientists were able to match the shapes of the pancake-shaped melanosomes in Caihong with the shapes of melanosomes in birds alive today. By finding birds with similarly shaped melanosomes, they were able to determine what kinds of colors Caihong may have flashed. The best matches: hummingbirds.

Colorful plumage is used in modern birds to attract mates — the rainbow feathers of Caihong might be a prehistoric version of a peacock’s iridescent tail. Caihong is the oldest known example of platelet-shaped melanosomes typically found in bright iridescent feathers.

It’s also the earliest known animal with asymmetrical feathers — a feature used by modern birds to steer when flying. Caihong couldn’t fly, though — its feathers were probably primarily used to attract mates and keep warm. While modern birds’ asymmetrical feathers are on their wingtips, Caihong’s were on its tail. “The tail feathers are asymmetrical but wing feathers not, a bizarre feature previously unknown among dinosaurs including birds,” said co-author Xing Xu of the Chinese Academy of Science. “This suggests that controlling [flight] might have been first evolved with tail feathers during some kind of aerial locomotion.”

But while Caihong’s feathers were a first, it had other traits associated with much earlier species of dinosaurs, including the bony crest on its head. “This combination of traits is rather unusual,” says co-author Julia Clarke of the University of Texas at Austin. “It has a velociraptor-type skull on the body of this very avian, fully feathered, fluffy kind of form.”

This combination of old and new traits, says Eliason, is evidence of mosaic evolution, the concept of different traits evolving independently from each other. “This discovery gives us insight into the tempo of how fast these features were evolving,” he adds.

For Eliason, the study also illuminates the value of big data. “To find the color of Caihong’s feathers, we compared its melanosomes with a growing database of thousands of measurements of melanosomes found in modern birds,” he says. It’s also broadened his own research interests.

“I came out of the project with a whole different set of questions that I wanted answers to — when I open up a drawer full of birds in the Field Museum’s collections, now I want to know when those iridescent feathers first developed, and how.”

Reference:
Dongyu Hu, Julia A. Clarke, Chad M. Eliason, Rui Qiu, Quanguo Li, Matthew D. Shawkey, Cuilin Zhao, Liliana D’Alba, Jinkai Jiang, Xing Xu. A bony-crested Jurassic dinosaur with evidence of iridescent plumage highlights complexity in early paravian evolution. Nature Communications, 2018; 9 (1) DOI: 10.1038/s41467-017-02515-y

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

Digitally preserving important Arkansas dinosaur tracks

Dinosaur tracks.
Dinosaur tracks. Credit: Image courtesy of University of Arkansas, Fayetteville

Scientists using laser-imaging technology have documented and digitally preserved the first known set of theropod dinosaur tracks in the state of Arkansas.

The tracks, discovered in 2011 in a working gypsum quarry near Nashville, Ark., have since been destroyed. But high-resolution digital scans taken over a period of two weeks in 2011 allowed a team of researchers to study the tracks and determine that they were made by Acrocanthosaurus, a large, carnivorous dinosaur. The findings extended the known range of Acrocanthosaurus 56 miles east, to the western shore of an ancient inland sea.

“It actually confirms that the main genus of large theropods in North America was Acrocanthosaurus,” said Celina Suarez, an assistant professor in the Department of Geosciences who was part of the team that documented and studied the tracks. “It now has been found in Wyoming, Utah, Oklahoma, Arkansas and Maryland, a huge range.”

Results of the study were recently published in the journal PLOS ONE. Researchers also created a detailed, publicly accessible online map of the site and the tracks. Brian Platt, an assistant professor of geology from the University of Mississippi, led the study. Researchers from the University of Arkansas Center for Advanced Spatial Technology (CAST) provided the scanning equipment and expertise.

The Rush to Preserve the Site

After the tracks were discovered, researchers received a $10,000 Rapid Grant from the National Science Foundation to quickly document the site. The U of A’s vice provost for research and economic development and the J. William Fulbright College of Arts and Sciences provided matching grants, for a total of $30,000.

The mining company moved its operations to allow researchers a short window of time to document the find. Researchers used LiDAR, which stands for light detection and ranging, because traditional methods would have taken too long, said Suarez. “From a technical standpoint, it’s important that the ability to rapidly scan such a large area is available to paleontologists. It was invaluable for this project since we had such little time to work.”

The site had two different sized Acrocanthosaurus tracks, suggesting both adult and younger animals walked the ancient tidal flat about 100 million years ago, during the Cretaceous Period. It also contained tracks made by sauropods, long-necked plant-eating dinosaurs.

LiDAR uses a pulsed laser to measure distances to the earth in tiny increments, generating a data “point cloud” that is used to digitally recreate a physical space. In this case, the equipment was mounted on a lift over the site. By analyzing carbon and oxygen isotopes of the rock at the track surface, researchers determined that the track surface was indeed the surface that the animals stepped on, rather than an underlying layer that remained when the original surface eroded.

The digital reconstruction of the trackway site: http://trackways.cast.uark.edu/index.html

Reference:
Brian F. Platt, Celina A. Suarez, Stephen K. Boss, Malcolm Williamson, Jackson Cothren, Jo Ann C. Kvamme. LIDAR-based characterization and conservation of the first theropod dinosaur trackways from Arkansas, USA. PLOS ONE, 2018; 13 (1): e0190527 DOI: 10.1371/journal.pone.0190527

Note: The above post is reprinted from materials provided by University of Arkansas, Fayetteville.

Rates of great earthquakes not affected by moon phases, day of year

Seismogram
Seismogram being recorded by a seismograph at the Weston Observatory in Massachusetts, USA. Credit: Wikipedia

There is an enduring myth that large earthquakes tend to happen during certain phases of the Moon or at certain times during the year. But a new analysis published in Seismological Research Letters confirms that this bit of earthquake lore is incorrect.

After matching dates and lunar phases to 204 earthquakes of magnitude 8 or larger, Susan Hough of the U.S. Geological Survey concluded that there is no evidence that the rates of these great earthquakes are affected by the position of the Earth relative to either the Moon or the Sun.

In fact, the patterns that some observers see as linking large earthquakes with specific parts of the lunar cycle “are no different from the kinds of patterns you would get if the data are completely random,” Hough noted.

To determine this, Hough looked at both the day of the year and the lunar phase for 204 large earthquakes from the global earthquake catalog, dating back to the 1600s. To avoid detecting clusters of earthquakes within the data that are related to other factors, she chose to look at larger earthquakes because they are less likely to be an aftershock of a bigger earthquake.

Looking at only large earthquakes also allowed Hough to pare down the list to a manageable number that could be matched to lunar phase information found in online databases.

Her analysis did turn up some clusters of earthquakes on certain days, but to test for any significance in the patterns she was observing, she randomized the dates of the earthquakes to find out what kind of patterns would appear in these random data. The patterns in the random data were no different from the kinds of patterns showing up in the original data set, she found.

This isn’t an unusual finding, Hough noted. “When you have random data, you can get all sorts of apparent signals, just like when you flip a coin, you sometimes end up with five heads in a row.”

Hough did see some unusual “signals” in the original data; for instance, the highest number of earthquakes (16) occurring on a single day came seven days after the new moon. But this signal was not statistically significant, “and the lunar tides would be at a minimum at this point, so it doesn’t make any physical sense,” she noted.

Hough said that the Moon and Sun do cause solid Earth tidal stresses — ripples through the Earth itself, and not the waters hitting the coastline — and could be one of the stresses that contribute in a small way to earthquake nucleation.”

Some researchers have shown that “there is in some cases a weak effect, where there are more earthquakes when tidal stresses are high,” she said, “But if you read those papers, you’ll see that the authors are very careful. They never claim that the data can be used for prediction, because the modulation is always very small.”

The idea that the Sun and Moon’s positions in the sky can modulate earthquake rates has a long history, she said. “I’ve read Charles Richter’s files, the amateur predictors who wrote to him in droves, because he was the one person that people knew to write to … and if you read the letters, they’re similar to what people are saying now, it’s all the same ideas.”

“Sooner or later there is going to be another big earthquake on a full moon, and the lore will pop back up,” said Hough. “The hope is that this will give people a solid study to point to, to show that over time, there isn’t a track record of big earthquakes happening on a full moon.”

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

World’s fifth largest diamond discovered in Lesotho

A diamond thought to be the fifth largest of gem quality ever found has been discovered in Lesotho
A diamond thought to be the fifth largest of gem quality ever found has been discovered in Lesotho, miner Gem Diamonds said. Credit: GEM DIAMONDS/AFP / HO

One of the world’s largest diamonds has been found in the Letseng mine in Lesotho, a small country surrounded by South Africa. The diamond was found by UK mining company Gem Diamonds and could be worth up to $40 million.

A diamond thought to be the fifth largest of gem quality ever found has been discovered in Lesotho, miner Gem Diamonds said Monday, and could be worth as much as $40 million.

The company unearthed the D-colour stone at the Letseng mine in the landlocked southern African country and described the 910-carat find as of “exceptional quality”.

“Since Gem Diamonds acquired Letseng in 2006, the mine has produced some of the world’s most remarkable diamonds, including the 603 carat Lesotho Promise,” Gem Diamonds chief executive Clifford Elphick said in a statement.

“However, this exceptional top quality diamond is the largest to be mined to date… This is a landmark discovery.”

Ben Davis, a mining analyst at Liberum Capital, speculated in a research note to investors that the diamond could be worth as much as $40 million (33 million euros).

Gem Diamonds shares in London were up 14 percent from the market open to £0.92 a piece.

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

Scientists have accidentally found the oldest ever butterfly or moth fossils

Butterfly
Credit: Shutterstock

Butterflies and moths, the Lepidoptera, are among the most beautiful of insects, familiar to almost everyone through thousands of different species from all around the world. But how they evolved has been something of a mystery to scientists because of a surprising lack of Lepidoptera fossils.

Now researchers in the Netherlands have discovered Lepidoptera fossils that are older than any previously found, proving these familiar insects have been around for at least 200m years. The particular type of fossils found mean we have to rethink Lepidoptera evolution. They imply that the long tube butterflies and moths use to suck nectar from flowers actually developed before flowering plants did, so it must have originally evolved for a different purpose.

The fossil record of ancient Lepidoptera is surprisingly meagre. Although butterflies may appear to be delicate creatures, their external skeletons are made of the same tough material, chitin, that all insects are made of. And chitin, or chitin decay products, preserve really very well in the fossil record.

In fact, some of the best ever fossils are of insects entombed in amber. Fossil Lepidoptera have been reported from a few exceptional deposits. For example, butterflies are known from the famous Florissant fossil beds of North America dating from the Eocene epoch, 34 million-years-old. A fossil caterpillar with the characteristic spinneret (the body part that produces silk) typical of all modern butterflies and moths has been reported from 125 million-year-old Lebanese amber. But until now, the fossil record went back no further.

This is especially odd because the Lepidoptera are closely related to another familiar modern group of insects, the caddis flies or Trichoptera. This group has an excellent fossil record extending back to the Permian period of the Palaeozoic era (250m years ago). As these groups share a common ancestor, the earliest Lepidoptera should, theoretically, also be found in the Permian period.

Lucky accident

The newly discovered fossils aren’t quite that old but they do date to the end of the Triassic period, the beginning of the age of dinosaurs. The delicate fossils bear the highly characteristic scales of butterflies and moths. They were discovered entirely by accident when researchers tried to extract pollen grains from rock samples from a borehole in north Germany to date the strata.

The process dissolves the rock (usually with the incredibly powerful hydrofluoric acid) to leave behind an organic residue that is rich in tough organic material. While this is usually pollen material and other so-called phytodebris from plants, it can include the remains of sclerotised (toughened) exoskeleton from insects and other invertebrates. Bits of fossil scorpions can be found this way for example.

Not many insects have scales on their wings, and those found on the wings of butterflies and moths are very different from those of other insects that do possess them. A characteristic feature of lepidopteran scales is a herring bone (V-shaped) pattern of fine lines in between larger ridges that extend along the scale. There are also characteristic outlines and margins that distinguish butterfly scales. So there is no doubt that the fossil scales found in the German borehole are those of ancient butterflies and moths.

Just as interesting, the scales are from a group of butterflies and moths known as the Glossata. Almost all of todays’ butterflies and moths belong to this group, characterised by the tube-shaped mouth part known as a “proboscis” used for feeding on fluids such as nectar. There are some primitive moths with mandibular (biting) mouth parts, and indeed some examples of these have been found from the Early Jurassic epoch (around 190 million-years-old). But the latest discoveries are even older, and push the origin of modern butterflies with proboscises back another 70 million years.

This forces a serious rethink for evolutionary biologists. Until now we’ve thought that the highly modified sucking mouthparts of modern butterflies and moths evolved as flowering plants diversified in the Early Cretaceous, around 100m years after the newly discovered fossils were created.

The researchers who discovered the fossils suggest that Lepidoptera may have first evolved their long proboscis tubes to suck up any available liquids at a time when their environment had become a lot drier. We know this kind of climate change did happen on the super continent of Pangaea in Triassic times, but it’s probably too early to tell if this theory is correct. If the fossil record can be pushed back 70m years in one stroke, it may get pushed back even further, and we’d need another way to explain the change.

Whatever the trigger for the development of the butterfly proboscis, it was clearly an evolutionary innovation that resulted in phenomenal diversity and added immensely to the beauty of planet Earth. Let us hope that many more of these serendipitous discoveries can shed even more light on the wonderful story of biological evolution. The key is in looking for fossils.

Note: The above post is reprinted from materials provided by David Martill, Professor of ​Palaeobiology, University of Portsmouth

This article was originally published on The Conversation. Read the original article.

Tiny dinosaur may have dazzled mates with rainbow ruff and a bony crest

Caihong juji is a newly described, bird-like dinosaur with an iridescent, rainbow crest.
Caihong juji is a newly described, bird-like dinosaur with an iridescent, rainbow crest. It lived in China about 161 million years ago, and may have used its impressive feathers to attract mates. Illustration by Velizar Simeonovski, The Field Museum, for UT Austin Jackson School of Geosciences. Credit: University of Texas at Austin

Ancient dinosaurs were adorned in some amazing ways, from the horns of the triceratops to the plates and spikes of the stegosaurus. A newly discovered, bird-like dinosaur fossil from China contains evidence that could add a new accessory to the list: a shaggy ruff of rainbow feathers.

A team of researchers, including scientists from The University of Texas at Austin, are the first to conduct an in-depth study of the dinosaur and describe it. They dubbed it Caihong juji—a name that means “rainbow with the big crest” in Mandarin—and think the dino used its flashy neck feathers and a bony crest on its snout to attract mates.

“Iridescent coloration is well known to be linked to sexual selection and signaling, and we report its earliest evidence in dinosaurs,” said Julia Clarke, a professor in the Department of Geological Sciences at the UT Jackson School of Geosciences who helped describe the new species. “The dinosaur may have a cute nickname in English, Rainbow, but it has serious scientific implications.”

A description of the exquisitely preserved, chicken-sized dinosaur was published on Jan. 15 in the journal Nature Communications. Dongyu Hu, a professor in the College of Paleontology at the Shenyang Normal University led the study.

Aside from making Jurassic ecosystems of 161 million years ago more colorful, the dinosaur is interesting because it has features that are both ancient and modern, said co-author Xing Xu, a professor at the Chines Academy of Sciences. The bony crest is a feature usually seen in dinosaurs from earlier eras, while its neck feathers show evidence of microscopic wide, flat, pigment-containing packages, or melanosomes, that may represent the first known occurrence of iridescence similar to that found in a variety of hummingbird species living today.

“There are crests associated with sexual selection previously known only in earlier dinosaurs, and yet there is also a bird mechanism of signaling or display appearing for the first time,” said Clarke, who helped lead the study with Hu and Xu.

Caihong is also the earliest known dinosaur with asymmetrical feathers, the feather type found on the wingtips of modern birds that helps control flight. But unlike birds today, Caihong’s asymmetrical feathers were on its tail, not its wings—a finding that suggests that early birds may have had a different steering or flight style.

“The tail feathers are asymmetrical but wing feathers are not, a bizarre feature previously unknown among dinosaurs including birds,” said Xu. “This suggests that controlling [flight] might have first evolved with tail feathers during some kind of aerial locomotion.”

The slab of rock from China’s Hebei Province where the dinosaur was discovered by a farmer in 2014 contained a nearly complete skeleton surrounded by impressions made by feathers. The impressions preserved the shape of the melanosomes. Researchers compared the melanosome impressions to melanosomes found in living birds and found that they most closely resembled those in the iridescent, rainbow feathers of hummingbirds.

Caihong is part of a group of small, bird-like dinosaurs that lived in China during the Jurassic, Xu said, but it stands out even among its closest relatives. While the other dinosaurs have bird-like, triangular skulls and long forearm bones in comparison to birds today, Caihong had a long and narrow skull, and unlike many of these other dinosaurs, its short forelimbs show proportions more akin to modern birds.

“This combination of traits is unusual,” Clarke said. “It has a rather velociraptor-looking low and long skull with this fully feathered, shaggy kind of plumage and a big fan tail. It is really cool… or maybe creepy looking depending on your perspective.”

The next step is figuring out what factors influenced Caihong to evolve such a distinctive look, rainbow feathers and all, said co-author Chad Eliason, a postdoctoral associate at the Field Museum of Natural History. He helped analyze the microstructural fossil evidence for color in the new specimen while he was a postdoctoral researcher at the UT Jackson School of Geosciences.

This combination of old and new traits, said Eliason, is evidence of mosaic evolution, the concept of different traits evolving independently from each other.

“This discovery gives us insight into the tempo of how fast these features were evolving,” he added.

Quanguo Li, a professor at the China University of Geosciences in Beijing and Matthew D. Shawkey, an associate professor at the University of Ghent in Belgium also participated in the study. The research was funded by the U.S. National Science Foundation and the National Science Foundation of China.

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

What is the Black Stone of Mecca? What is the type of Black Stone?

What is the Black Stone of Mecca? What is the type of Black Stone?

What is the Black Stone of Mecca?

The Black Stone of Mecca, Al-Ḥajaru al-Aswad, “Black Stone”, or Kaaba Stone, is a Muslim relic, which according to Islamic tradition dates back to the time of Adam and Eve. It is the eastern cornerstone of the Kaaba, the ancient sacred stone building towards which Muslims pray, in the center of the Grand Mosque in Mecca, Saudi Arabia. The Stone is a dark rock, polished smooth by the hands of millions of pilgrims, that has been broken into a number of fragments cemented into a silver frame in the side of the Kaaba. Although it has often been described as a meteorite, this hypothesis is still under consideration. It is the eastern cornerstone of the Kaaba, the ancient sacred stone building towards which Muslims pray, in the center of the Grand Mosque in Mecca, Saudi Arabia.

The Stone is roughly 30 cm (12 in.) in diameter, and 1.5 meters (5 ft.) above the ground. When pilgrims circle the Kaaba as part of the Tawaf ritual of the Hajj, many of them try, if possible, to stop and kiss the Black Stone, emulating the kiss that it received from the Islamic prophet Muhammad. If they cannot reach it, they are to point to it on each of their seven circuits around the Kaaba. The Stone is broken into a number of pieces from damage which was inflicted during the Middle Ages. The pieces are held together by a silver frame, which is fastened by silver nails to the Stone.

There are various opinions as to what the Black Stone actually is. Muslims say that the Stone was found by Abraham (Ibrahim) and his son Ishmael (Ismail) when they were searching for stones with which to build the Kaaba. They recognized its worth and made it one of the building’s cornerstones.

Secular historians point to the history of stone worship, and especially meteorite worship, in pre-Islamic Arabia, and say that it is likely that the Stone is a meteorite. There is no way to test this hypothesis without removing and examining the Stone, which would not be permitted by its guardians.

Many geologists across the world have tried their best to ascertain the type and nature of the Black Stone, but couldn’t achieve the ultimate findings because of cultural and religious restrictions which didn’t allow anyone to drill the stone for scientific purpose.

The nature of the Black Stone has been much debated. It has been described variously as basalt stone, an agate, a piece of natural glass or — most popularly — a stony meteorite.

Anthony Hampton and his team of geologists from Oxford University studied the local samples collected from the emplacement of the stone and found important quantities of iridium and many shatter cones, a rare geological feature only known to form in the bedrock beneath meteorite impact craters which favored the findings of Paul Partsch who published the first comprehensive history of the Black stone in 1857.

In 1974, Robert Dietz and John McHone commented that the stone contained clearly discernible diffusion banding characteristics of agates.

They also mentioned that the color of the stone is jet black and looks polished, which is the result of constant handling by the pilgrims, and this rules out again the possibility of a chondrite which wouldn’t withstand the constant rubbing nor would it take such a high polish.

At present, the Black Stone is comprised of eight small pieces of varying sizes, the largest one being the size of a date. Six (additional) pieces are found to be in Istanbul and Turkey.

In 1294 A.H. Al-Kurdi said that there were 15 visible pieces and some of the pieces were hidden under the putty with which the stone had been repaired, and whenever any piece became loose, they were attached to the top of the stone with wax, musk and ambergris which were kneaded together.

What is the type of Black Stone? “Meteor Impact or Volcanic Lava?”

In 1980, Elsebeth Thomsen of the University of Copenhagen proposed that the Black Stone may be a glass fragment or impactite from the impact of a fragmented meteorite that fell some 6000 years ago at Wabar.

That impact site is located in Rub’al Khali Desert which lies 1,100 km east of Makkah.

At that site there are blocks of silica glass of white or yellow interior and gas-filled hollows which allow them to float in water which coincides with the property of Black Stone which floats in water and doesn’t get hot in fire.

On the contrary, a study by the United States Geological Survey have proved from Thermoluminescence (TL) dating analysis that the Wabar impact event occurred at or after 250 years from now, so surely the Black Stone wasn’t part of Wabar.

They also say that the Black Stone is probably obsidian from a common lava flow in one of the Harrats (volcanic fields) found in the western Arabian Shield.

Harrat Rahat, which lies just east of Madinah Al-Munnawarrah, erupted last around 1270 AD (anno Domini), and among other things flowed west towards Madinah and then down (northwards) the big Wadi to the east of the city where the modern airport lies.

It’s not unreasonable to think that lava at some point in western Arabia encountered water and solidified to obsidian.

There are lots of glass fragments from the Wabar impact event at the site. They are so dense, in fact, that they serve effectively as a lag-gravel and have anchored the pre-impact dune surface at the site.

Probably 99.9% of the incoming iron asteroids were converted into this glass, which is 10% iron-nickel and 90% local sand from chemical analysis.

The glass does have fragments of white impactite (instantaneously-formed quasi-sandstone from the shockwave) in it, but the surface is always extremely rugged and full of vessicles.

For this reason, the Black Stone is probably obsidian, though it could conceivably be a highly-hand-polished stony meteorite.

Nevertheless, geologists are still on their anxious seats to unveil about Al-Hajar Al-Aswad as there isn’t still any irrefutable scientific evidence.

Reference:
Wikipedia: Black Stone
Crystalinks: The Black Stone of Mecca
About Islam: Obscurity of Al-Hajar Al-Aswad
Meteoritical Society: Kaaba Stone: Not A Meteorite, Probably an AGATE

A new species of turkey-sized dinosaur is discovered from Australia

Diluvicursor pickeringi holotype
Diluvicursor pickeringi holotype

The partial skeleton of a new species of turkey-sized herbivorous dinosaur has been discovered in 113 million year old rocks in southeastern Australia. As reported in open access journal PeerJ, the fossilized tail and foot bones give new insight into the diversity of the small, bipedal herbivorous dinosaurs called ornithopods that roamed the great rift valley that once existed between Australia and Antarctica. The new dinosaur has been named Diluvicursor pickeringi, which means Pickering’s Flood-Running dinosaur.

Lower Cretaceous rocks of the deep sedimentary basins that formed within the Australian-Antarctic rift are now exposed as wave-cut rock platforms and sea-cliffs along the south coast of Victoria. The skeleton of Diluvicursor pickeringi was discovered in 2005 by volunteer prospector George Caspar, eroding from such a rock platform at a locality called Eric the Red West, near Cape Otway.

“Diluvicursor shows for the first time that there were at least two distinct body-types among closely related ornithopods in this part of Australia,” Dr Matt Herne, lead author of the new study said.

“One was lightly built with an extraordinarily long tail, while the other, Diluvicursor, was more solidly built, with a far shorter tail. Our preliminary reconstruction of the tail musculature of Diluvicursor suggests this dinosaur was a good runner, with powerful leg retracting muscles,” Dr Herne said.

“Understanding the ecology of these dinosaurs — what they ate, how they moved, where they roamed — based on the interplay between anatomy and the environment presents exciting challenges for future research.”

The species name honors the late David Pickering, who was Museums Victoria’s Collection Manager, Vertebrate Palaeontology. David contributed significantly to Australian paleontology in the lab and field, and tirelessly assisted countless students of paleontology and researchers to achieve their goals. Sadly, David passed away just over a year ago on Christmas Eve 2016.

The site of Eric the Red West has additional importance as it helps build a picture the ancient rift valley ecosystem. Fossil vertebrate remains at this site were buried in deep scours at the base of a powerful river, along with flood-transported tree stumps, logs and branches.

“The carcass of the Diluvicursor pickeringi holotype appears to have become entangled in a log-jam at the bottom of this river,” explained Dr Herne. “The sizes of some of the logs in the deposit and the abundance of wood suggest the river traversed a well-forested floodplain. The logs preserved at the site are likely to represent conifer forests of trees within families still seen in Australia today.”

“Much of the fossil vertebrate material from Eric the Red West has yet to be described, so further dinosaurs and other exciting animals from this site are now anticipated.”

Reference:
Matthew C. Herne, Alan M. Tait, Vera Weisbecker, Michael Hall, Jay P. Nair, Michael Cleeland and Steven W. Salisbury. A new small-bodied ornithopod (Dinosauria, Ornithischia) from a deep, high-energy Early Cretaceous river of the Australian–Antarctic rift system. PeerJ, 2018; DOI: 10.7717/peerj.4113

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

Steep slopes on Mars reveal structure of buried ice on Red Planet

A cross-section of underground ice is exposed at the steep slope that appears bright blue in this enhanced-color view from the HiRISE camera on NASA's Mars Reconnaissance Orbiter.
A cross-section of underground ice is exposed at the steep slope that appears bright blue in this enhanced-color view from the HiRISE camera on NASA’s Mars Reconnaissance Orbiter. The scene is about 550 yards wide. The scarp drops about 140 yards from the level ground in the upper third of the image. Credit: NASA/JPL-Caltech/UA/USGS

Researchers using NASA’s Mars Reconnaissance Orbiter (MRO) have found eight sites where thick deposits of ice beneath Mars’ surface are exposed in faces of eroding slopes.

These eight scarps, with slopes as steep as 55 degrees, reveal new information about the internal layered structure of previously detected underground ice sheets in Mars’ middle latitudes.

The ice was likely deposited as snow long ago. The deposits are exposed in cross section as relatively pure water ice, capped by a layer one to two yards (or meters) thick of ice-cemented rock and dust. They hold clues about Mars’ climate history. They also may make frozen water more accessible than previously thought to future robotic or human exploration missions.

Researchers who located and studied the scarp sites with the High Resolution Imaging Science Experiment (HiRISE) camera on MRO reported the findings today in the journal Science. The sites are in both northern and southern hemispheres of Mars, at latitudes from about 55 to 58 degrees, equivalent on Earth to Scotland or the tip of South America.

“There is shallow ground ice under roughly a third of the Martian surface, which records the recent history of Mars,” said the study’s lead author, Colin Dundas of the U.S. Geological Survey’s Astrogeology Science Center in Flagstaff, Arizona. “What we’ve seen here are cross-sections through the ice that give us a 3-D view with more detail than ever before.”

Windows into underground ice

The scarps directly expose bright glimpses into vast underground ice previously detected with spectrometers on NASA’s Mars Odyssey (MRO) orbiter, with ground-penetrating radar instruments on MRO and on the European Space Agency’s Mars Express orbiter, and with observations of fresh impact craters that uncover subsurface ice. NASA sent the Phoenix lander to Mars in response to the Odyssey findings; in 2008, the Phoenix mission confirmed and analyzed the buried water ice at 68 degrees north latitude, about one-third of the way to the pole from the northernmost of the eight scarp sites.

The discovery reported today gives us surprising windows where we can see right into these thick underground sheets of ice,” said Shane Byrne of the University of Arizona Lunar and Planetary Laboratory, Tucson, a co-author on today’s report. “It’s like having one of those ant farms where you can see through the glass on the side to learn about what’s usually hidden beneath the ground.”

Scientists have not determined how these particular scarps initially form. However, once the buried ice becomes exposed to Mars’ atmosphere, a scarp likely grows wider and taller as it “retreats,” due to sublimation of the ice directly from solid form into water vapor. At some of them, the exposed deposit of water ice is more than 100 yards, or meter, thick. Examination of some of the scarps with MRO’s Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) confirmed that the bright material is frozen water. A check of the surface temperature using Odyssey’s Thermal Emission Imaging System (THEMIS) camera helped researchers determine they’re not seeing just thin frost covering the ground.

Researchers previously used MRO’s Shallow Radar (SHARAD) to map extensive underground water-ice sheets in middle latitudes of Mars and estimate that the top of the ice is less than about 10 yards beneath the ground surface. How much less? The radar method did not have sufficient resolution to say. The new ice-scarp studies confirm indications from fresh-crater and neutron-spectrometer observations that a layer rich in water ice begins within just one or two yards of the surface in some areas.

Astronauts’ access to Martian water

The new study not only suggests that underground water ice lies under a thin covering over wide areas, it also identifies eight sites where ice is directly accessible, at latitudes with less hostile conditions than at Mars’ polar ice caps. “Astronauts could essentially just go there with a bucket and a shovel and get all the water they need,” Byrne said.

The exposed ice has scientific value apart from its potential resource value because it preserves evidence about long-term patterns in Mars’ climate. The tilt of Mars’ axis of rotation varies much more than Earth’s, over rhythms of millions of years. Today the two planets’ tilts are about the same. When Mars tilts more, climate conditions may favor buildup of middle-latitude ice. Dundas and co-authors say that banding and color variations apparent in some of the scarps suggest layers “possibly deposited with changes in the proportion of ice and dust under varying climate conditions.”

This research benefited from coordinated use of multiple instruments on Mars orbiters, plus the longevities at Mars now exceeding 11 years for MRO and 16 years for Odyssey. Orbital observations will continue, but future missions to the surface could seek additional information.

“If you had a mission at one of these sites, sampling the layers going down the scarp, you could get a detailed climate history of Mars,” suggested MRO Deputy Project Scientist Leslie Tamppari of NASA’s Jet Propulsion Laboratory, Pasadena, California. “It’s part of the whole story of what happens to water on Mars over time: Where does it go? When does ice accumulate? When does it recede?”

The University of Arizona operates HiRISE, which was built by Ball Aerospace & Technologies Corp., Boulder, Colorado. The Johns Hopkins University Applied Physics Laboratory, Laurel, Maryland, leads MRO’s CRISM investigation. The Italian Space Agency provided MRO’s SHARAD instrument, Sapienza University of Rome leads SHARAD operations, and the Planetary Science Institute, based in Tucson, Arizona, leads U.S. involvement in SHARAD. Arizona State University, Tempe, leads the Odyssey mission’s THEMIS investigation. JPL, a division of Caltech in Pasadena, California, manages the MRO and Odyssey projects for the NASA Science Mission Directorate in Washington. Lockheed Martin Space, Denver, built both orbiters and supports their operation.

Reference:
Colin M. Dundas et al. Exposed subsurface ice sheets in the Martian mid-latitudes. Science, 2018 DOI: 10.1126/science.aao1619

Note: The above post is reprinted from materials provided by NASA/Jet Propulsion Laboratory.

Machine learning predicts new details of geothermal heat flux beneath the Greenland Ice Sheet

These are geothermal heat flux predictions for Greenland. Direct GHF measurements from the coastal rock cores, inferences from ice cores, and additional Gaussian-fit GHF data around ice core sites are used as training samples.
These are geothermal heat flux predictions for Greenland. Direct GHF measurements from the coastal rock cores, inferences from ice cores, and additional Gaussian-fit GHF data around ice core sites are used as training samples. Predictions are shown for three different values. The white dashed region roughly shows the extent of elevated heat flux and a possible trajectory of Greenland’s movement over the Icelandic plume. Credit: KU News Service

A paper appearing in Geophysical Research Letters uses machine learning to craft an improved model for understanding geothermal heat flux — heat emanating from the Earth’s interior — below the Greenland Ice Sheet. It’s a research approach new to glaciology that could lead to more accurate predictions for ice-mass loss and global sea-level rise.

Among the key findings:

Greenland has an anomalously high heat flux in a relatively large northern region spreading from the interior to the east and west.

Southern Greenland has relatively low geothermal heat flux, corresponding with the extent of the North Atlantic Craton, a stable portion of one of the oldest extant continental crusts on the planet. The research model predicts slightly elevated heat flux upstream of several fast-flowing glaciers in Greenland, including Jakobshavn Isbræ in the central-west, the fastest moving glacier on Earth.

“Heat that comes up from the interior of the Earth contributes to the amount of melt on the bottom of the ice sheet — so it’s extremely important to understand the pattern of that heat and how it’s distributed at the bottom of the ice sheet,” said Soroush Rezvanbehbahani, a doctoral student in geology at the University of Kansas who spearheaded the research. “When we walk on a slope that’s wet, we’re more likely to slip. It’s the same idea with ice — when it isn’t frozen, it’s more likely to slide into the ocean. But we don’t have an easy way to measure geothermal heat flux except for extremely expensive field campaigns that drill through the ice sheet. Instead of expensive field surveys, we try to do this through statistical methods.”

Rezvanbehbahani and his colleagues have adopted machine learning — a type of artificial intelligence using statistical techniques and computer algorithms — to predict heat flux values that would be daunting to obtain in the same detail via conventional ice cores.

Using all available geologic, tectonic and geothermal heat flux data for Greenland — along with geothermal heat flux data from around the globe — the team deployed a machine learning approach that predicts geothermal heat flux values under the ice sheet throughout Greenland based on 22 geologic variables such as bedrock topography, crustal thickness, magnetic anomalies, rock types and proximity to features like trenches, ridges, young rifts, volcanoes and hot spots.

“We have a lot of data points from around the Earth — we know in certain parts of the world the crust is a certain thickness, composed of a specific kind of rock and located a known distance from a volcano — and we take those relationships and apply them to what we know about Greenland,” said co-author Leigh Stearns, associate professor of geology at KU.

The researchers said their new predictive model is a “definite improvement” over current models of geothermal heat flux that don’t incorporate as many variables. Indeed, many numerical ice sheet models of Greenland assume that a uniform value of geothermal heat flux exists everywhere across Greenland.

“Most other models really only honor one particular data set,” Stearns said. “They look at geothermal heat flux through seismic signals or magnetic data in Greenland, but not crustal thickness or rock type or distance from a hot spot. But we know those are related to geothermal heat flux. We try to incorporate as many geologic data sets as we can rather than assuming one is the most important.”

In addition to Rezvanbehbahani and Stearns, the research team behind the new paper includes KU’s J. Doug Walker and C.J. van der Veen, as well as Amir Kadivar of McGill University. Rezvanbehbahani and Stearns also are affiliated with the Center for the Remote Sensing of Ice Sheets, headquartered at KU.

The authors found the five most important geologic features in predicting geothermal flux values are topography, distance to young rifts, distance to trench, depth of lithosphere-asthenosphere boundary (layers of the Earth’s mantle) and depth to Mohorovičić discontinuity (the boundary between the crust and the mantle in the Earth). The researchers said their geothermal heat flux map of Greenland is expected to be within about 15 percent of true values.

“The most interesting finding is the sharp contrast between the south and the north of Greenland,” said Rezvanbehbahani. “We had little information in the south, but we had three or four more cores in the northern part of the ice sheet. Based on the southern core we thought this was a localized low heat-flux region — but our model shows that a much larger part of the southern ice sheet has low heat flux. By contrast, in the northern regions, we found large areas with high geothermal heat flux. This isn’t as surprising because we have one ice core with a very high reading. But the spatial pattern and how the heat flux is distributed, that a was a new finding. That’s not just one northern location with high heat flux, but a wide region.”

The investigators said their model would be made even more accurate as more information on Greenland is compiled in the research community.

“We give the slight disclaimer that this is just another model — it’s our best statistical model — but we have not reproduced reality,” said Stearns. “In Earth science and glaciology, we’re seeing an explosion of publicly available data. Machine learning technology that synthesizes this data and helps us learn from the whole range of data sensors is becoming increasingly important. It’s exciting to be at the forefront.”

Reference:
Soroush Rezvanbehbahani, Leigh A. Stearns, Amir Kadivar, J. Doug Walker, C. J. van der Veen. Predicting the Geothermal Heat Flux in Greenland: A Machine Learning Approach. Geophysical Research Letters, 2017; DOI: 10.1002/2017GL075661

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

A close-up look at an uncommon underwater eruption

High-resolution seafloor topography of the Havre caldera mapped by the autonomous underwater vehicle (AUV) Sentry shows the new 2012 erupted lavas in red.
High-resolution seafloor topography of the Havre caldera mapped by the autonomous underwater vehicle (AUV) Sentry shows the new 2012 erupted lavas in red. The volcano is nearly a mile deep (1,519 meters). The top of the volcano is at 650 meters below sea level.
Credit: Rebecca Carey, University of Tasmania, Adam Soule, WHOI, ©Woods Hole Oceanographic Institution

On July 18, 2012, passengers on an airline flight over the Southwest Pacific Ocean glimpsed something unusual — a raft of floating rock known as pumice that indicated an underwater volcanic eruption had occurred on the seafloor northeast of New Zealand. The raft eventually grew to more than 150 square miles (roughly the size of Philadelphia), a sign that the eruption was unusually large.

A new paper published January 10, 2018, in the journal Science Advances describes the first up-close investigation of the largest underwater volcanic eruption of the past century. The international research team led by the University of Tasmania and the Woods Hole Oceanographic Institution (WHOI) used the autonomous underwater vehicle (AUV) Sentry and the remotely operated vehicle (ROV) Jason to explore, map, and collect erupted materials from the Havre volcano during a 2015 expedition. They found that the eruption was surprising in many ways.

“We knew it was a large-scale eruption, approximately equivalent to the biggest eruption we’ve seen on land in the 20th Century,” said Rebecca Carey, a volcanologist at University of Tasmania and Co-Chief Scientist on the expedition.

“Heading to the site, we were fully prepared to investigate a typical deep-sea explosive eruption,” added Adam Soule, WHOI associate scientist and chief scientist for the National Deep Submergence Facility. “When we looked at the detailed maps from the AUV, we saw all these bumps on the seafloor and I thought the vehicle’s sonar was acting up. It turned out that each bump was a giant block of pumice, some of them the size of a van. I had never seen anything like it on the seafloor.”

More than 70 percent of all volcanic activity on Earth occurs on the seafloor, but details of these events are largely hidden from view by seawater. Based on the size of the 2012 pumice raft, the eruption of the Havre Volcano was estimated to be the largest documented underwater silicic eruption — a particular type of eruption that produces viscous, gas-filled lava that often occurs explosively. Despite their violence, very little is known about silicic eruptions and most knowledge about them comes from ancient rock records, which lack details such as the timing, duration, source, and water depth of the events. Scientists have never been able to study a large underwater silicic eruption shortly after it occurred in order to better understand how they happen and what they produce.

Havre is part of the Kermadec Arc, a chain of volcanoes, some of which reach the surface to form the Kermadec Islands, between New Zealand and American Samoa. The volcanoes are formed by conditions at the subduction zone where one of Earth’s largest tectonic plates, the Pacific Plate, dives beneath the Australian Plate. New Zealand scientists mapped the Havre volcano, a caldera nearly three miles (4.5 kilometers) across on the seafloor northeast of the North Island of New Zealand, using shipboard sonar instruments in 2002 and again immediately after the eruption in 2012, revealing the presence of new volcanic material on the seafloor.

In 2015, scientists from the University of Tasmania, WHOI, the University of California Berkeley, the University of Otago in New Zealand, and others traveled to the region on board the research vessel Roger Revelle operated by the Scripps Institution of Oceanography. They deployed the AUV Sentry in a series of 11 dives that mapped more than 19 square miles (50 square kilometers) of seafloor. They also conducted 12 ROV Jason dives totaling 250 hours to collect samples of erupted material and to capture high-resolution imagery of the seafloor inside the crater.

The team found that the eruption history of the Havre volcano was much more complicated than they previously thought, with the most recent eruption alone consisting of lava from 14 volcanic vent sites between 900 and 1220 meters (3000 and 4000 feet) below the surface. They also discovered that, what they thought was initially an explosive eruption that would produce mainly pumice, also created ash, lava domes, and seafloor lava flows. Mapping and seafloor observations revealed that, of the material that erupted, which was nearly 1.5 times larger than the 1980 eruption of Mount St. Helens, about 75 percent floated to the surface and drifted away with winds and currents. The rest was spread across the seafloor up to several miles away.

“Ultimately we believe that none of the magma was erupted in the ways we assume an explosive eruption occurs on land,” said Soule.

Material collected using ROV Jason confirmed the diverse nature of the eruption, bringing samples of dense lava, ash, pumice, and giant pumice to the surface, including one piece measuring 5 feet (1.5 meters) in diameter that is the first of its kind ever collected and is currently on display at the National Museum of Science and Nature in Tokyo. The physical and chemical composition of these samples are helping scientists learn how the eruption proceeded, what made it act the way it did, and how the material changes over time.

This work was supported by a grant from the National Science Foundation.

Reference:
Rebecca Carey et al. The largest deep-ocean silicic volcanic eruption of the past century. Science Advances, 2018 DOI: 10.1126/sciadv.1701121

Note: The above post is reprinted from materials provided by Woods Hole Oceanographic Institution.

Giant extinct burrowing bat discovered in New Zealand

An artist's impression of a New Zealand burrowing bat, Mystacina robusta, that went extinct last century.
An artist’s impression of a New Zealand burrowing bat, Mystacina robusta, that went extinct last century. The new fossil find, Vulcanops jennyworthyae, that lived millions of years ago in New Zealand, is an ancient relative of burrowing or short-tailed bats. Credit: Gavin Mouldey.

The fossilized remains of a giant burrowing bat that lived in New Zealand millions of years ago have been found by a UNSW Sydney-led international team of scientists.

Teeth and bones of the extinct bat — which was about three times the size of an average bat today — were recovered from 19 to 16-million-year-old sediments near the town of St Bathans in Central Otago on the South Island.

The study, by researchers from Australia, New Zealand, the UK and USA, is published in the journal Scientific Reports.

Burrowing bats are only found now in New Zealand, but they once also lived in Australia. Burrowing bats are peculiar because they not only fly; they also scurry about on all fours, over the forest floor, under leaf litter and along tree branches, while foraging for both animal and plant food.

With an estimated weight of about 40 grams, the newly found fossil bat was the biggest burrowing bat yet known. It also represents the first new bat genus to be added to New Zealand’s fauna in more than 150 years

It has been named Vulcanops jennyworthyae, after team member Jenny Worthy who found the bat fossils, and after Vulcan, the mythological Roman god of fire and volcanoes, in reference to New Zealand’s tectonic nature, but also to the historic Vulcan Hotel in the mining town St Bathans.

Other research team members include scientists from UNSW Sydney, University of Salford, Flinders University, Queensland University, Canterbury Museum, Museum of New Zealand Te Papa Tongarewa, the American Museum of Natural History, and Duke University.

“Burrowing bats are more closely related to bats living in South America than to others in the southwest Pacific,” says study first author and UNSW Professor Sue Hand.

“They are related to vampire bats, ghost-faced bats, fishing and frog-eating bats, and nectar-feeding bats, and belong to a bat superfamily that once spanned the southern landmasses of Australia, New Zealand, South America and possibly Antarctica.”

Around 50 million years ago, these landmasses were connected as the last vestiges of the southern supercontinent Gondwana. Global temperatures were up to 12 degrees Celsius higher than today and Antarctica was forested and frost-free. With subsequent fragmentation of Gondwana, cooling climates and the growth of ice-sheets in Antarctica, Australasia’s burrowing bats became isolated from their South American relatives.

“New Zealand’s burrowing bats are also renowned for their extremely broad diet. They eat insects and other invertebrates such as weta and spiders, which they catch on the wing or chase by foot. And they also regularly consume fruit, flowers and nectar,” says Professor Hand, who is Director of the PANGEA Research Centre at UNSW.

“However, Vulcanops’s specialized teeth and large size suggest it had a different diet, capable of eating even more plant food as well as small vertebrates — a diet more like some of its South American cousins. We don’t see this in Australasian bats today,” she says.

Study co-author, Associate Professor Trevor Worthy of Flinders University says: “The fossils of this spectacular bat and several others in the St Bathans Fauna show that the prehistoric aviary that was New Zealand also included a surprising diversity of furry critters alongside the birds.”

Study co-author Professor Paul Scofield of Canterbury Museum says: “These bats, along with land turtles and crocodiles, show that major groups of animals have been lost from New Zealand. They show that the iconic survivors of this lost fauna — the tuataras, moas, kiwi, acanthisittid wrens, and leiopelmatid frogs — evolved in a far more complex community that hitherto thought.”

This diverse fauna lived in or around a 5600-square-km prehistoric Lake Manuherikia that once covered much of the Maniototo region of the South Island. When they lived, in the early Miocene, temperatures in New Zealand were warmer than today and semitropical to warm temperate forests and ferns edged the vast palaeolake.

Vulcanops provides new insight into the original diversity of bats in Australasia. Its lineage became extinct sometime after the early Miocene, as did a number of other lineages present in the St Bathans assemblage. These include crocodiles, terrestrial turtles, flamingo-like palaelodids, swiftlets, several pigeon, parrot and shorebird lineages and non-flying mammals. Most of these were probably warm-adapted species. After the middle Miocene, global climate change brought colder and drier conditions to New Zealand, with significant changes to vegetation and environments.

It is likely that this general cooling and drying trend drove overall loss in bat diversity in New Zealand, where just two bat species today comprise the entire native land mammal fauna. All other modern land mammals in New Zealand have been introduced by people within the last 800 years.

Reference:
Suzanne J. Hand, Robin M. D. Beck, Michael Archer, Nancy B. Simmons, Gregg F. Gunnell, R. Paul Scofield, Alan J. D. Tennyson, Vanesa L. De Pietri, Steven W. Salisbury, Trevor H. Worthy. A new, large-bodied omnivorous bat (Noctilionoidea: Mystacinidae) reveals lost morphological and ecological diversity since the Miocene in New Zealand. Scientific Reports, 2018; 8 (1) DOI: 10.1038/s41598-017-18403-w

Note: The above post is reprinted from materials provided by University of New South Wales.

Ingredients for life revealed in meteorites that fell to Earth

A blue crystal recovered from a meteorite that fell near Morocco in 1998.
A blue crystal recovered from a meteorite that fell near Morocco in 1998. The scale bar represents 200 microns (millionths of a meter). Credit: Queenie Chan/The Open University, U.K.

Two wayward space rocks, which separately crashed to Earth in 1998 after circulating in our solar system’s asteroid belt for billions of years, share something else in common: the ingredients for life. They are the first meteorites found to contain both liquid water and a mix of complex organic compounds such as hydrocarbons and amino acids.

A detailed study of the chemical makeup within tiny blue and purple salt crystals sampled from these meteorites, which included results from X-ray experiments at the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab), also found evidence for the pair’s past intermingling and likely parents. These include Ceres, a brown dwarf planet that is the largest object in the asteroid belt, and the asteroid Hebe, a major source of meteorites that fall on Earth.

The study, published Jan. 10 in the journal Science Advances, provides the first comprehensive chemical exploration of organic matter and liquid water in salt crystals found in Earth-impacting meteorites. The study treads new ground in the narrative of our solar system’s early history and asteroid geology while surfacing exciting possibilities for the existence of life elsewhere in Earth’s neighborhood.

“It’s like a fly in amber,” said David Kilcoyne, a scientist at Berkeley Lab’s Advanced Light Source (ALS), which provided X-rays that were used to scan the samples’ organic chemical components, including carbon, oxygen, and nitrogen. Kilcoyne was part of the international research team that prepared the study.

While the rich deposits of organic remnants recovered from the meteorites don’t provide any proof of life outside of Earth, Kilcoyne said the meteorites’ encapsulation of rich chemistry is analogous to the preservation of prehistoric insects in solidified sap droplets.

Queenie Chan, a planetary scientist and postdoctoral research associate at The Open University in the U.K. who was the study’s lead author, said, “This is really the first time we have found abundant organic matter also associated with liquid water that is really crucial to the origin of life and the origin of complex organic compounds in space.”

She added, “We’re looking at the organic ingredients that can lead to the origin of life,” including the amino acids needed to form proteins.

If life did exist in some form in the early solar system, the study notes that these salt crystal-containing meteorites raise the “possibility of trapping life and/or biomolecules” within their salt crystals. The crystals carried microscopic traces of water that is believed to date back to the infancy of our solar system — about 4.5 billion years ago.

Chan said the similarity of the crystals found in the meteorites — one of which smashed into the ground near a children’s basketball game in Texas in March 1998 and the other which hit near Morocco in August 1998 — suggest that their asteroid hosts may have crossed paths and mixed materials.

There are also structural clues of an impact — perhaps by a small asteroid fragment impacting a larger asteroid, Chan said.

This opens up many possibilities for how organic matter may be passed from one host to another in space, and scientists may need to rethink the processes that led to the complex suite of organic compounds on these meteorites.

“Things are not as simple as we thought they were,” Chan said.

There are also clues, based on the organic chemistry and space observations, that the crystals may have originally been seeded by ice- or water-spewing volcanic activity on Ceres, she said.

“Everything leads to the conclusion that the origin of life is really possible elsewhere,” Chan said. “There is a great range of organic compounds within these meteorites, including a very primitive type of organics that likely represent the early solar system’s organic composition.”

Chan said the two meteorites that yielded the 2-millimeter-sized salt crystals were carefully preserved at NASA’s Johnson Space Center in Texas, and the tiny crystals containing organic solids and water traces measure just a fraction of the width of a human hair. Chan meticulously collected these crystals in a dust-controlled room, splitting off tiny sample fragments with metal instruments resembling dental picks.

“What makes our analysis so special is that we combined a lot of different state-of-the-art techniques to comprehensively study the organic components of these tiny salt crystals,” Chan said.

Yoko Kebukawa, an associate professor of engineering at Yokohama National University in Japan, carried out experiments for the study at Berkeley Lab’s ALS in May 2016 with Aiko Nakato, a postdoctoral researcher at Kyoto University in Japan. Kilcoyne helped to train the researchers to use the ALS X-ray beamline and microscope.

The beamline equipped with this X-ray microscope (a scanning transmission X-ray microscope, or STXM) is used in combination with a technique known as XANES (X-ray absorption near edge structure spectroscopy) to measure the presence of specific elements with a precision of tens of nanometers (tens of billionths of a meter).

“We revealed that the organic matter was somewhat similar to that found in primitive meteorites, but contained more oxygen-bearing chemistry,” Kebukawa said. “Combined with other evidence, the results support the idea that the organic matter originated from a water-rich, or previously water-rich parent body — an ocean world in the early solar system, possibly Ceres.”

Kebukawa also used the same STXM technique to study samples at the Photon Factory, a research site in Japan. And the research team enlisted a variety of other chemical experimental techniques to explore the samples’ makeup in different ways and at different scales.

Chan noted that there are some other well-preserved crystals from the meteorites that haven’t yet been studied, and there are plans for follow-up studies to identify if any of those crystals may also contain water and complex organic molecules.

Kebukawa said she looks forward to continuing studies of these samples at the ALS and other sites: “We may find more variations in organic chemistry.”

Reference:
Queenie H. S. Chan et al. Organic matter in extraterrestrial water-bearing salt crystals. Science Advances, 2018 DOI: 10.1126/sciadv.aao3521

Note: The above post is reprinted from materials provided by DOE/Lawrence Berkeley National Laboratory.

New depth limit for deep-sea marine burrows

These are burrows on the margins of a sandstone dyke.
These are burrows on the margins of a sandstone dyke. Credit: Sarah Cobain, University of Leeds

Scientists have found fossil evidence of deep-sea marine life burrowing up to eight metres below the seabed — four times the previously observed depth for modern deep-sea life.

A team of scientists from the University of Leeds and the National Oceanography Centre examined remains of deep-sea burrows in rocky outcrops that were part of the ocean floor roughly 250 million years ago.

These outcrops are made up of sand-sheets that are widespread on modern ocean floors, suggesting that deep-sea burrowing marine life may be much more abundant than previously considered.

Study author Professor David Hodgson, from the School of Earth and Environment at Leeds, said: “Ocean ecology shows us that deep-sea burrowers have only become more prevalent and diverse through time.

“Their adaptability to new environments strengthens the idea that if their pre-historic ancestors were burrowing to these depths, then it’s likely we’d find them there today.”

The team’s findings, published today in Scientific Reports, highlights the need for new future sampling strategies to better capture the depth range of animals living in modern deep-sea sands.

Collecting intact samples from the deep-ocean floor is technologically challenging. The distance to the ocean seabed and the difficulties of extracting samples makes it problematic to determine how deeply modern animals burrow. Modern deep-sea biological studies target muds as these are simpler to sample than the shifting sands of the deep seabed.

Lead author Dr Sarah Cobain conducted this research while a PhD student at the School of Earth and Environment, she is now based at Petrotechnical Data Systems in London. She said: “These outcrops give us a snapshot of ancient deep-sea life. We know that modern marine burrowing animals are living in the same material that has been fossilised in these rocks.

“The burrowers use the networks that are already present in the deep ocean sediment below the seabed and leave behind living traces. These networks — what we call injectites after they’ve been fossilised — are caused by sand-rich water being forcibly injected into mud. They provide the animals easy pathways to burrow and find nutrients and oxygen.

“Our understanding of the process by which these injectites form allows us to not only assess how these creatures lived but also how deeply they burrowed into the sediment below the seabed.”

The branching structures that make up the trace fossils are believed to have been made by organisms that were previously thought to live mainly in the top 20 centimetres of sediment, rarely reaching further than 1.5 metres, due to the decline of oxygen and food in deeper levels of the sediment.

The team documented the creatures’ living traces — known as bioturbation — on the margins of clastic injectites from at least eight metres below the seabed.

In order to produce living traces, organisms would need to survive long enough to burrow for hours or even days. The size of the burrows suggests macro-infaunal invertebrates (tiny shrimps and worms).

Study author, Jeffrey Peakall, Professor of Process Sedimentology at Leeds, said: “This discovery gives us a window into a widespread yet barely explored environment on our planet. Little is known about modern deep seabed environments, and less about the ancient.

“These trace fossils can give us new insight into the possibility that the deepest organisms may be present in sandy sediments, rather than the clays and silts typically targeted in modern seabed investigations.”

Reference:
S. L. Cobain, D. M. Hodgson, J. Peakall, P. B. Wignall, M. R. D. Cobain. A new macrofaunal limit in the deep biosphere revealed by extreme burrow depths in ancient sediments. Scientific Reports, 2018; 8 (1) DOI: 10.1038/s41598-017-18481-w

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

Earthquakes as a driver for the deep-ocean carbon cycle

An international team led by geologist Michael Strasser has used novel methods to analyze sediment deposits in the Japan Trench in order to gain new insights into the carbon cycle.

In a paper recently published in Nature Communications, geologist Michael Strasser presented the initial findings of a month-long research expedition off the coast of Japan. The research initiative had been organised in March 2012 by MARUM – Center for Marine Environmental Sciences. Strasser, who until 2015 was Assistant Professor for Sediment Dynamics at ETH Zurich and is now a Full Professor for Sediment Geology at the University of Innsbruck, took an international team there to study dynamic sediment remobilisation processes triggered by seismic activity.

At a depth of 7,542 metres below sea level, the team took a core sample from the Japan Trench, an 800-km-long oceanic trench in the northwestern part of the Pacific Ocean. The trench, which is seismically active, was the epicentre of the Tohoku earthquake in 2011, which made headlines when it caused the nuclear meltdown at Fukushima. Such earthquakes wash enormous amounts of organic matter from the shallows down into deeper waters. The resulting sediment layers can thus be used later to glean information about the history of earthquakes and the carbon cycle in the deep ocean.

New dating methods in the deep ocean

The current study provided the researchers with a breakthrough. They analysed the carbon-rich sediments using radiocarbon dating. This method – measuring the amount of organic carbon as well as radioactive carbon (14C) in mineralised compounds – has long been a means of determining the age of individual sediment layers. Until now, however, it has not been possible to analyse samples from deeper than 5,000 metres below the surface, because the mineralised compounds dissolve under increased water pressure.

Strasser and his team therefore had to use new methods for their analysis. One of these was what is known as the online gas radiocarbon method, developed by ETH doctoral student Rui Bao and the Biogeoscience Group at ETH Zurich. This greatly increases efficiency, since it takes just a single core sample to make more than one hundred 14C age measurements directly on the organic matter contained within the sediment.

In addition, the researchers applied the Ramped PyrOx measurement method (pyrolysis) for the first time in the dating of deep-ocean sediment layers. This was done in cooperation with the Woods Hole Oceanographic Institute (U.S.), which developed the method. The process involves burning organic matter at different temperatures. Because older organic matter contains stronger chemical bonds, it requires higher temperatures to burn. What makes this method novel is that the relative age variation of the individual temperature fractions between two samples very precisely distinguishes the age difference between sediment levels in the deep sea.

Dating earthquakes to increase forecast accuracy

Thanks to these two innovative methods, the researchers could determine the relative age of organic matter in individual sediment layers with a high degree of precision. The core sample they tested contained older organic matter in three places, as well as higher rates of carbon export to the deep ocean. These places correspond to three historically documented yet hitherto imprecisely dated seismic events in the Japan Trench: the Tohoku earthquake in 2011, an unnamed earthquake in 1454, and the Sanriku earthquake in 869.

At the moment, Strasser is working on a large-scale geological map of the origin and frequency of sediments in deep-ocean trenches. To do so, he is analysing multiple core samples taken during a follow-up expedition to the Japan Trench in 2016. “The identification and dating of tectonically triggered sediment deposits is also important for future forecasts about the likelihood of earthquakes,” Strasser says. “With our new methods, we can predict the recurrence of earthquakes with much more accuracy.”

Reference:
Rui Bao et al, Tectonically-triggered sediment and carbon export to the Hadal zone, Nature Communications (2018). DOI: 10.1038/s41467-017-02504-1

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

Between the lines: Tree rings hold clues about a river’s past

By analyzing centuries-old growth rings from trees in the Intermountain West, researchers at USU are extracting data about monthly streamflow trends from periods long before the early 1900s when recorded observations began.
By analyzing centuries-old growth rings from trees in the Intermountain West, researchers at USU are extracting data about monthly streamflow trends from periods long before the early 1900s when recorded observations began. Credit: Matt Jensen/USU

Hydrologists are looking centuries into the past to better understand an increasingly uncertain water future.

By analyzing centuries-old growth rings from trees in the Intermountain West, researchers at Utah State University are extracting data about monthly streamflow trends from periods long before the early 1900s when recorded observations began.

Their findings were published Jan. 6 in the Journal of Hydrology and, for the first time, show that monthly streamflow data can be reconstructed from annual tree-ring chronologies — some of which date back to the 1400s.

“By linking tree rings and flow during the past 100 years when we have recorded observations, we can use trees as a tool for measuring flow long before there were gauges on the rivers,” said USU’s Dr. James Stagge, a hydrologist and civil engineer who led the research. “Our study takes this one step further and uses different tree species and locations to reconstruct monthly flow, rather than annual flow.”

Knowing monthly streamflow, the authors explain, is key to making better-informed decisions about water use and management. In Utah and around the world, populations in arid climates depend on seasonal and often inconsistent water supplies for agriculture and urban use.

“One data point per year gives a very limited picture,” said co-author Dr. David Rosenberg, an associate professor of civil and environmental engineering at USU. “Decisions about water management happen much more frequently than just once per year. Water managers have to make decisions every month, every week, sometimes every day.”

To fill in the missing monthly data, Stagge and co-authors built a model that reconstructs monthly streamflow for three rivers in Northern Utah. The reconstructions are available to the public at http://www.paleoflow.org and show monthly streamflows dating back to 1605 for the Logan River and as far back as 1400 for the Bear and Weber rivers.

The team used tree-ring chronologies from seven species selected from a range of locations and elevations. Stagge says different tree species at different elevations respond to the changing seasons at different times of the year and in slightly different ways, recording unique parts of the seasonal flow. The model overlaps the tree-ring chronologies and combines annual streamflow information and climate data to arrive at a monthly streamflow estimate.

“Now we can get down into a monthly scale and pick up seasonal patterns within the streamflow,” said Stagge. “It’s the seasonality that determines drought, how reservoirs fill, and when there are shortages. Now that we have this method, we can start looking at what major droughts over the past 600 years would mean for today’s water supply.”

Reference:
J.H. Stagge, D.E. Rosenberg, R.J. DeRose, T.M. Rittenour. Monthly paleostreamflow reconstruction from annual tree-ring chronologies. Journal of Hydrology, 2018; 557: 791 DOI: 10.1016/j.jhydrol.2017.12.057

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

Evolution of Alpine landscape recorded by sedimentary rocks

Headwaters of Alpine streams approximately 30 million years ago (left) with an Alpine plateau and a meadow countryside.
Headwaters of Alpine streams approximately 30 million years ago (left) with an Alpine plateau and a meadow countryside. The handcraft on the right side illustrates the landscape of the Alps at 25 million years before present with steep valleys where torrents originated. Credit: Philippos Garefalakis, University of Bern.

Rock avalanches and torrents started to form V-shaped valleys in the Swiss Alps approximately 25 million years ago. This landscape contrasts to the flat and hilly scenery, which characterized the Alps a few millions of years before. Geologists from the University of Bern applied digital technologies to unravel these changes in landscape evolution. They analysed 30 to 25 million-year old lithified rivers in Central Switzerland and came out with a detailed picture of how the Alps evolved within a short time interval.

The current shape of the Alps with steep V-shaped valleys and torrents have evolved during approximately five millions of years. This time span might be perceived as very long, but it is a few seconds for geologists. This was the major outcome of a study by Philippos Garefalakis and Fritz Schlunegger from the University of Bern, Switzerland, who analysed thousands of pebbles at Mount Rigi situated in Central Switzerland. This mountain, which has been considered by Goethe as the Queen of the Mountains, because of its spectacular view, consists of lithified rivers with pebbles. These rocks have been transported by the Alpine rivers in the geologic past, and they document the rise of the Alps and the related change of the landscape. The scientists found out that the Central Swiss Alps evolved from British-type of hillslopes and flats to a rugged region with torrents and deep gorges. The results of their study have recently been published by the Nature-Group in Scientific Reports.

From a meadow countryside to the Alpine landscape

30 million years ago, the headwaters of the Alpine rivers were situated on a plateau with flat hillslopes, similar to what we currently find in Great Britain. “The leisurely streams deposited tons of pebbles, which resulted in a stack of thousands of lithified rivers, referred to as conglomerates,” explains Philippos Garefalakis, the senior author of the published article. “Accordingly, each bed represents the deposits of a river back in geologic times.” Philippos and his team analysed bed by bed and thousands of pebbles from the base to the top of Mount Rigi. The changes surprised the scientist. “The 30 million-year old deposits at the base of Mount Rigi contain pebbles that have the size of an apple, and the streams were 2-4 meters deep. On top of the mountain range, the 25 million-year old sediments expose boulders as large as a football, and torrents were less than 1 meter deep.” The Alpine streams must have gained in power, and they adapted a chaotic flow pattern.

Dramatic evolution

“The change in the Alpine landscape must have been dramatic and fast,” explains Philippos and looks toward the Alps, which are clearly visible from Bern on a sunny day like this. “Boulders as large as a football can only be entrained by strong torrents during floods.” These processes are typical in a steep landscape where rock avalanches and landslides supply large volumes of boulders and material. The Alps thus had their current shape as early as 25 million years ago. The situation, however, was different 30 million years ago. Streams were smooth and had their headwaters in a meadow countryside, which characterized the Alps at that time. “These changes occurred as the Alps started to rise and to steepen, which occurred — for geological standards — within a short time interval.”

Application of digital technologies

Engineers have disclosed quantitative relationships between the size of gravels in rivers and stream power. “We can apply the identical concepts to stream deposits of the geologic past, but we need to measure the size of thousands of pebbles,” says Philippos. This was only possible thanks to computer technologies, which allows to measure a large number of pebbles on digital photographs. This new technology has been applied for the first time to rocks and will yield new insights about our streams on Earth in the geological past.

Reference:
Philippos Garefalakis, Fritz Schlunegger. Link between concentrations of sediment flux and deep crustal processes beneath the European Alps. Scientific Reports, 2018; 8 (1) DOI: 10.1038/s41598-017-17182-8

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

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