Scientists from The Australian National University have discovered the have discovered that 558 million-year-old Dickinsonia fossils do not reveal all of the features of the earliest known animals, which potentially had mouths and guts. Credit: Ilya Bobrovskiy, The Australian National University (ANU)
Scientists from The Australian National University (ANU) have discovered that 558 million-year-old Dickinsonia fossils do not reveal all of the features of the earliest known animals, which potentially had mouths and guts.
ANU PhD scholar Ilya Bobrovskiy, lead author of the study, said the study shows that simple physical properties of sediments can explain Dickinsonia’s preservation, and implies that what can be seen today may not be what these creatures actually looked like.
“These soft-bodied creatures that lived 558 million years ago on the seafloor could, in principle, have had mouths and guts — organs that many palaeontologists argue emerged during the Cambrian period tens of millions of years later,” said Mr Bobrovskiy from the ANU Research School of Earth Sciences.
“Our discovery about Dickinsonia — and many other Ediacaran fossils — opens up new possibilities as to what they actually looked like.”
Ediacara biota were strange creatures that lived on the seafloor 571 to 541 million years ago. They grew up to two metres long and include the earliest known animals as well as colonies of bacteria.
The fact that Dickinsonia and other Ediacara biota fossils were preserved at all in the geological record has been a big mystery — until now.
The team, which includes scientists from Russian institutions, discovered how Ediacara biota fossils were preserved, despite the macroorganisms not having skeletons or shells.
“As the organisms decayed, softer sediment from below gradually flowed into the forming void, creating a cast,” Mr Bobrovskiy said.
“Now we know that what we are looking at is an impression of a soft organic skeleton that may have been anywhere within Dickinsonia’s body. What we’re seeing could be a part of Dickinsonia’s bottom, the inside of its body or part of its back.”
Mr Bobrovskiy said Dickinsonia had different types of tissues and must have been a true animal, a Eumetazoa, the lineages eventually leading to humans.
Co-researcher and RSES colleague Associate Professor Jochen Brocks said the team used a melting cast of a Death Star made of ice to show the physical properties of sediments that enabled the soft-bodied Ediacara biota to be preserved.
“This process of fossilisation could tell us more about what Ediacara biota were and how they lived,” he said.
“These fossils comprise our best window into earliest animal evolution and are the key to understanding our own deep origins.”
Reference:
Ilya Bobrovskiy, Anna Krasnova, Andrey Ivantsov, Ekaterina Luzhnaya, Jochen J. Brocks. Simple sediment rheology explains the Ediacara biota preservation. Nature Ecology & Evolution, 2019; DOI: 10.1038/s41559-019-0820-7
Earth’s mantle (dark red) lies below the crust (brown layer near the surface) and above the outer core (bright red). Credit: CC image by Argonne National Laboratory via Flickr
The solid Earth breathes as volcanoes “exhale” gases like carbon dioxide (CO2) — which are essential in regulating global climate — while carbon ultimately from CO2 returns into the deep Earth when oceanic tectonic plates are forced to descend into the mantle at subduction zones. However, the amount of carbon in the sediments and ocean crust that subducts is poorly constrained, as is the fraction of that breaks down in the mantle and contributes to volcanic CO2.
Most subduction zones in the world are complex: the amount of sediment and carbon (C) concentration frequently varies along their length, and at many, some of the sediment reaching the subduction zone is scraped off, so the C in it never gets returned into the Earth. Developing a way to figure out how C cycles at complex subduction margins is therefore critical to understanding our planet.
To establish such a method, researchers Brian M. House and colleagues focused on the Sunda margin along Indonesia, a subduction zone where the amount of sediment changes dramatically as does the proportion of organic and inorganic C, and very little of the sediment actually stays attached to the subducting plate.
Erosion from the Himalayas and underwater sediment “avalanches” bring a tremendous amount of sediment that is rich in organic C to the northeast section of the margin while the southwest portion is inundated by sediment rich in calcium carbonate (CaCO3) microfossils from the Australian continental shelf.
To account for this the team made a 3D model of the sediments and their composition across thousands of square kilometers outboard of the margin, which allowed us to more accurately quantify C in sediments throughout the region. House says they “estimate that only about a tenth of the C reaching the margin makes it past the subduction zone while the rest is scraped off the plate into the enormous wedge of sediment offshore of Sumatra and Java.”
House and colleagues estimate that the C returning into the Earth is much less — maybe only a fifth — of what volcanoes expel each year, meaning that the margin represents a net source of C into the atmosphere and that C from something other than the subducting sediments is released. “The sediments subducted into the Earth also have a different C isotope composition than that of volcanic CO2, so we think that inorganic CaCO3 in the ground underneath Sumatra and Java as well as C in the oceanic plate that carries sediment into the subduction zone release CO2 that travels back into the atmosphere.”
These are two possible CO2 sources that, while extremely large, haven’t received much scientific attention. By presenting a new method for investigating tectonic C cycling in a place as complicated as the Sunda margin, says House, “We hope to spur new interest in understanding the full range of processes by which the solid Earth breathes over geologic timescales.”
Reference:
Brian M. House, Gray E. Bebout, and David R. Hilton. Carbon cycling at the Sunda margin, Indonesia: A regional study with global implications. Geology, 2019
Fossil whale barnacles from the Pleistocene were retrieved from the Burica Peninsula of Panama for analyses. Credit: Larry Taylor
Many whales take long journeys each year, spending summers feeding in cold waters and moving to warm tropical waters to breed. One theory suggests that these long-distance migrations originated around 5 million years ago, when ocean productivity became increasingly patchy. But patterns of ancient whale migrations have, until recently, been shrouded in mystery. Scientists from the Smithsonian Tropical Research Institute (STRI) and the University of California, Berkeley approached this question with an ingenious technique: barnacles.
“Instead of looking for clues to migration patterns from the whale’s bones, we used hitch-hiking whale barnacles instead,” said Larry Taylor, STRI visiting scientist and doctoral student at UC Berkeley who led the study.
Barnacles are crustaceans (crabs, lobsters, shrimp) that live stuck in one place in a hard shell. Most glue themselves to rocks, but whale barnacles attach to a whale’s skin by sucking the skin in.
“Whale barnacles are usually species specific — one species of barnacle on one type of whale,” said Aaron O’Dea, staff scientist at STRI and co-author of the study. “This gives the barnacle several advantages — a safe surface to live on, a free ride to some of the richest waters in the world and a chance to meet up with others when the whales get together to mate.”
As whale barnacles grow, their shells record the conditions by taking up oxygen isotopes from the water. By carefully reading the unique isotope signatures left in the shells, the barnacles can reveal the water bodies the barnacle passed through, helping reconstruct the whale’s movements over time.
The study, published in Proceedings of the National Academy of Sciences looked at a number of fossil and modern whale barnacles from the Pacific coast of Panama and California.
“The signals we found in the fossil barnacles showed us quite clearly that ancient humpback and grey whales were undertaking journeys very similar to those that these whales make today,” Taylor said. “It seems like the summer-breeding and winter-feeding migrations have been an integral part of the way of life of these whales for hundreds of thousands of years.”
“We want to push the technique further back in time and across different whale populations,” said Seth Finnegan, co-author from UC Berkeley. “Hunting for fossil whale barnacles is easier than whales, and they provide a wealth of information waiting to be uncovered.”
Reference:
Larry D. Taylor, Aaron O’Dea, Timothy J. Bralower, Seth Finnegan. Isotopes from fossil coronulid barnacle shells record evidence of migration in multiple Pleistocene whale populations. Proceedings of the National Academy of Sciences, 2019; 201808759 DOI: 10.1073/pnas.1808759116
From the field on Svalbard, showing an ancient channel extending into the Barents Sea. Credit: Tore Grane Klausen.
The largest delta plain in Earth’s history formed along the northern coast of the supercontinent Pangea in the late Triassic. Its size out-scales modern counterparts by an order of magnitude, and approximates 1% of the total land area of the modern world. And although contenders are found in the rock record, no ancient counterpart exceeds the extent of the Triassic delta plain mapped in the subsurface Barents Sea either.
An important part of this study by, published in Geology, was to document and compare the size of the delta plain, but also to understand why it grew so large.
Aerially extensive 3-D seismic datasets and rock samples collected for petroleum exploration in the Barents Sea have revealed that delta plains covered the entire basin during the Triassic. Comparing the size of this delta plain to modern and—more challenging—ancient delta plains shows that the Triassic delta plains of the Barents Sea were the largest in Earth’s history that has been preserved in the rock record.
Its tremendous size accounts for nearly 1% of the land areas of the modern world, and was facilitated by a vast drainage area feeding sediments to a shallow basin were sediments accumulated.
Reference:
Tore Grane Klausen et al, The largest delta plain in Earth’s history, Geology (2019). DOI: 10.1130/G45507.1
Scientists say the fossils have been “exquisitely” preserved. Credit: Ao Sun
Scientists say they have discovered a “stunning” trove of thousands of fossils on a river bank in China.
The fossils are estimated to be about 518 million years old, and are particularly unusual because the soft body tissue of many creatures, including their skin, eyes, and internal organs, have been “exquisitely” well preserved.
Palaeontologists have called the findings “mind-blowing” – especially because more than half the fossils are previously undiscovered species.
The fossils, known as the Qingjiang biota, were collected near Danshui river in Hubei province.
More than 20,000 specimens were collected, and a total of 4,351 have been analysed so far, including worms, jellyfish, sea anemones and algae.
They will become a “very important source in the study of the early origins of creatures”, one of the fieldwork leaders, Prof Xingliang Zhang from China’s Northwest University, told the BBC.
The discovery is particularly remarkable because “the majority of creatures are soft-bodied organisms like jellyfish and worms that normally stand no chance of becoming fossilised”, Prof Robert Gaines, a geologist who also took part in the study, said in an email to the BBC.
The majority of fossils tend to be of hard-bodied animals, as harder substances, like bones, are less likely to rot and decompose.
The Qingjiang biota must have been “rapidly buried in sediment” due to a storm, in order for soft tissues to be so well preserved, Prof Zhang says.
Scientists are especially excited by the jellyfish and sea anemone fossils, which Prof Gaines describes as “unlike anything I have ever seen. Their sheer abundance and their diversity of forms is stunning”.
Meanwhile, Prof Allison Daley, a palaeontologist who was not part of the study but wrote an accompanying analysis in Science, told BBC’s Science in Action programme the find was one of the most significant in the last 100 years.
“It blew my mind – as a palaeontologist I never thought I’d get to witness the discovery of such an incredible site.
“For the first time we’re seeing preservation of jellyfish – [when] you think of jellyfish today, they’re so soft-bodied, so delicate, but they’re preserved unbelievably well at this site.”
The research team are now documenting the remaining specimens, and conducting more drilling in the region to find out more about the ancient local ecosystem, and the fossilisation process.
Prof Zhang says he looks forward to studying “all these new species – I’m always excited when we get something new”.
The fossils are from the Cambrian period, which began 541 million years ago and saw a rapid increase in animal diversity on Earth.
Prof Gaines hopes his work will also strike a chord with modern readers.
“Biotic diversity today is something that we take for granted, even though there are indications that extinction rates are sharply increasing.
“Yet most of the major animal lineages were established in a singular event in the history of life, the Cambrian explosion, the likes of which have never been seen before or after. It also reminds us of our deep kinship to all living animals.”
Reference:
Dongjing Fu et al. The Qingjiang biota—A Burgess Shale–type fossil Lagerstätte from the early Cambrian of South China, Science (2019). DOI: 10.1126/science.aau8800
The towering and battle-scarred ‘Scotty’ reported by UAlberta paleontologists is the world’s largest Tyrannosaurus rex and the largest dinosaur skeleton ever found in Canada. Credit: Amanda Kelley
University of Alberta paleontologists have just reported the world’s biggest Tyrannosaurus rex and the largest dinosaur skeleton ever found in Canada. The 13-metre-long T. rex, nicknamed “Scotty,” lived in prehistoric Saskatchewan 66 million years ago.
“This is the rex of rexes,” said Scott Persons, lead author of the study and postdoctoral researcher in the Department of Biological Sciences. “There is considerable size variability among Tyrannosaurus. Some individuals were lankier than others and some were more robust. Scotty exemplifies the robust. Take careful measurements of its legs, hips, and even shoulder, and Scotty comes out a bit heftier than other T. rex specimens.”
Scotty, nicknamed for a celebratory bottle of scotch the night it was discovered, has leg bones suggesting a living weight of more than 8,800 kg, making it bigger than all other carnivorous dinosaurs. The scientific work on Scotty has been a correspondingly massive project.
The skeleton was first discovered in 1991, when paleontologists including T. rex expert and UAlberta professor Phil Currie were called in on the project. But the hard sandstone that encased the bones took more than a decade to remove — only now have scientists been able to study Scotty fully-assembled and realize how unique a dinosaur it is.
It is not just Scotty’s size and weight that set it apart. The Canadian mega rex also lays claim to seniority.
“Scotty is the oldest T. rex known,” Persons explains. “By which I mean, it would have had the most candles on its last birthday cake. You can get an idea of how old a dinosaur is by cutting into its bones and studying its growth patterns. Scotty is all old growth.”
But age is relative, and T. rexes grew fast and died young. Scotty was estimated to have only been in its early 30s when it died.
“By Tyrannosaurus standards, it had an unusually long life. And it was a violent one,” Persons said. “Riddled across the skeleton are pathologies — spots where scarred bone records large injuries.”
Among Scotty’s injures are broken ribs, an infected jaw, and what may be a bite from another T. rex on its tail — battle scars from a long life.
“I think there will always be bigger discoveries to be made,” said Persons “But as of right now, this particular Tyrannosaurus is the largest terrestrial predator known to science.”
A new exhibit featuring the skeleton of Scotty is set to open at the Royal Saskatchewan Museum in May 2019.
Reference:
W. Scott Persons, Philip J. Currie, Gregory M. Erickson. An Older and Exceptionally Large Adult Specimen of Tyrannosaurus rex. The Anatomical Record, 2019; DOI: 10.1002/ar.24118
The string of volcanoes in the Cascades Arc, ranging from California’s Mt. Lassen in the south to Washington’s Mt. Baker in the north, have been studied by geologists and volcanologists for over a century. Spurred on by spectacular events such as the eruption of Mount Lassen in 1915 and Mount St. Helens in 1980, scientists have studied most of the Cascade volcanoes in detail, seeking to work out where the magma that erupts comes from and what future eruptions might look like.
However, mysteries still remain about why nearby volcanoes often have radically different histories of eruption or erupt different types of magma. Now scientists would like to find out why — both for the Cascades and for other volcanic ranges.
In a perspective essay published today (March 22) in Nature Communications, scientists argue for more “synthesis” research looking at the big picture of volcanology to complement myriad research efforts looking at single volcanoes.
“The study of volcanoes is fascinating in detail, and it has largely been focused on research into individual volcanoes rather than the bigger picture,” said Adam Kent, a volcano expert at Oregon State University and a co-author on the essay. “We now have the insight and data to go beyond looking at just Mount St. Helens and other well-known volcanoes. We can take a step back and ask why is St. Helens different from Mount Adams, why is that different from Mount Hood?”
The study takes a novel approach to this topic. “One way to do this is to consider the heat it took to create each of the volcanoes in the Cascades Arc, for example, and also compare this to the local seismic wave speeds and heat flow within the crust, Kent said. “Linking these diverse data sources together this way gives us a better glimpse into the past, but offer some guidance on what we might expect in the future.”
The need for studying volcanoes more thoroughly is simple, noted Christy Till of Arizona State University, lead author of the Nature Communications essay.
Worldwide almost a billion people live in areas at risk from volcanic eruptions, 90 percent of which live in the so-called Pacific Ring of Fire.
The subduction of the Juan de Fuca tectonic plate beneath the North American plate is the ultimate driver for the formation of the Cascade Range, as well as many of the earthquakes the Northwest has experienced. Subduction results in deep melting of the Earth’s mantle, and the magma then heads upward towards the crust and surface, eventually reaching the surface to produce volcanoes.
But there are differences among the volcanoes, the researchers note, including in the north and south of the Cascade Range.
“The volcanoes in the north stand out because they stand alone,” Kent said. “In the south, you also have recognizable peaks like the Three Sisters and Mount Jefferson, but you also many thousands of smaller volcanoes like Lava Butte and those in the McKenzie Pass area in between. Our work suggests that, together with the larger volcanoes, these small centers require almost twice the amount of magma being input into the crust in the southern part of the Cascade Range.”
Why is that important?
“If you live around a volcano, you have to be prepared for hazards and the hazards are different with each different type of volcano,” Kent said. “The northern Cascades are likely to have eruptions in the future, but we know where they’ll probably be — at the larger stratovolcanoes like Mount Rainier, Mount Baker and Glacier Peak. In the south the larger volcanoes might also have eruptions, but then we have these large fields of smaller — so called ‘monogenetic’ volcanoes. For these it is harder to pinpoint where future eruptions will occur.”
The field of volcanology has progressed quite a bit, the researchers acknowledge, and the need now exists to integrate some of the methodology of individual detailed studies to give a more comprehensive look at the entire volcanic system. The past is the best informer of the future.
“If you look at the geology of a volcano, you can tell what kind of eruption is most likely to happen,” Kent said. “Mount Hood, for example, is known to have had quite small eruptions in the past, and the impact of these is mostly quite local. Crater Lake, on the other hand, spread ash across much of the contiguous United States.
“What we would like to know is why one volcano turns out to be a Mount Hood while another develops into a Crater Lake, with a very different history of eruptions. This requires us to think about the data that we have in new ways.”
The 1980 eruption of Mt. St. Helens was a wake-up call to the threat of volcanoes in the continental United States, and though noteworthy, its eruption was relatively minor. The amount of magma involved in the eruption was estimated to be 1 kilometer cubed (enough to fill about 400,000 Olympic swimming pools), whereas the eruption of Mt. Mazama 6,000 years ago that created Crater Lake was 50 km cubed, or 50 times as great.
The researchers say the process of building and tearing down volcanoes continues today, though it is difficult to observe on a day-to-day basis.
“If you could watch a time-lapse camera over millions of years, you would see volcanoes building up slowly, and then eroding fairly quickly,” said Kent, who is in OSU’s College of Earth, Ocean, and Atmospheric Sciences. “Sometimes, both are happening at once.”
Which of the Cascades is most likely to erupt? The smart money is on Mount St. Helens, because of its recent activity, but many of the volcanoes are still considered active.
“I can tell you unequivocally that Mount Hood will erupt in the future,” Kent said. “I just can’t tell you when.”
For the record, Kent said the odds of Mt. Hood erupting in the next 30 to 50 years are less than 5 percent.
Reference:
C. B. Till, A. J. R. Kent, G. A. Abers, H. A. Janiszewski, J. B. Gaherty, B. W. Pitcher. The causes of spatiotemporal variations in erupted fluxes and compositions along a volcanic arc. Nature Communications, 2019; 10 (1) DOI: 10.1038/s41467-019-09113-0
Feathers revealed in a ~125 million-year-old fossil of a bird hatchling shows it came “out of the egg running”. Specimen MPCM-LH-26189 from Los Hoyas, Spain is preserved between two slabs of rock: (a) ‘counter’ slab under normal light (b) Laser-Stimulated Fluorescence (LSF) image combining the results from both rock slabs. This reveals brown patches around the specimen that include clumps of elongate feathers associated with the neck and wings and a single long vaned feather associated with the left wing. (c) Normal light image of the main slab. Scale is 5mm. Credit: Copyright Kaye et al. 2019
The ~125 million-year-old Early Cretaceous fossil beds of Los Hoyas, Spain have long been known for producing thousands of petrified fish and reptiles. However, one special fossil stands unique and is one of the rarest of fossils — a nearly complete skeleton of a hatchling bird. Using their own laser imaging technology, Dr Michael Pittman from the Department of Earth Sciences at The University of Hong Kong and Thomas G Kaye from the Foundation for Scientific Advancement in the USA determined the lifestyle of this ~3cm long hatchling bird by revealing the previously unknown feathering preserved in the fossil specimen.
Chickens and ducks are up and about within hours of hatching, they are “precocial.” Pigeons and eagles are “altricial,” they stay in the nest and are looked after by their parents. How do you tell if a hatchling came “out of the egg running” or was “naked and helpless in the nest”? Feathers. When precocial birds hatch they have developed down feathers and partly developed large feathers and can keep warm and get around without mum’s help. “Previous studies searched for but failed to find any hints of feathers on the Los Hoyas hatchling. This meant that its original lifestyle was a mystery,” says Dr Pittman.
Michael Pittman and Thomas Kaye brought new technology to the study of Los Hoyas fossils in the form of a high power laser. This made very small chemical differences in the fossils become visible by fluorescing them different colours, revealing previously unseen anatomical details.
They recently had tremendous success with the first discovered fossil feather which they disassociated from the famous early bird Archaeopteryx by recovering the chemical signature of its fossil quill, a key part of the feather’s identification that had been previously unverified for ~150 years.
The new results on the hatchling bird finally answered the question about its lifestyle as it did indeed have feathers at birth and was thus precocial and out of the egg running. The feathers were made of carbon which has low fluorescence using Laser-Stimulated Fluorescence (LSF), but the background matrix did glow making the feathers stand out in dramatic dark silhouette.
“Previous attempts using UV lights and synchrotron beams failed to detect the feathers, underscoring that the laser technology stands alone as a new tool in palaeontology” added Tom Kaye, the study’s lead author.
This discovery via new technology demonstrates that some early birds adopted a precocial breeding strategy just like modern birds. Thus, in the time of the dinosaurs, some enantiornithine bird babies had the means to avoid the dangers of Mesozoic life perhaps by following their parents or moving around themselves.
“One of the feathers discovered was of a substantial size and preserves features seen in other hatchlings. It indicates that our hatchling had reasonably well-developed flight feathers at the time of birth,” says Jesús Marugán-Lobón, a co-author from the Universidad Autónoma of Madrid, Spain.
This and other “illuminating” discoveries are adding to our knowledge of ancient life with details surviving in the fossil record that were never thought possible even a couple decades ago.
Reference:
Thomas G. Kaye, Michael Pittman, Jesús Marugán-Lobón, Hugo Martín-Abad, José Luis Sanz, Angela D. Buscalioni. Fully fledged enantiornithine hatchling revealed by Laser-Stimulated Fluorescence supports precocial nesting behavior. Scientific Reports, 2019; 9 (1) DOI: 10.1038/s41598-019-41423-7
Volcano Credit: Jessica Johnson/University of East Anglia
New research led by the University of East Anglia (UEA) reveals that sharp variations of the surface of volcanoes can affect data collected by monitoring equipment.
The surfaces of many volcanoes feature steep walls or cliffs. These are often part of calderas — large craters left by a previous collapse — but can also be caused by the volcano ‘rifting’ — or splitting — or sector collapse, when part of the side of the volcano slides away.
However, the effect of these variations in landscape has not previously been considered in studies of surface deformation in volcanic regions, even though they are a common feature.
In addition, monitoring equipment such as tiltmeters are usually placed on caldera rims as they are often more accessible, especially if the caldera is lake-filled. Tiltmeters measure the horizontal gradient of vertical displacement and can emphasise small variations that go unnoticed using other monitoring methods.
Now researchers from UEA, the US Geological Survey and University of Bristol have found that features such as cliffs can cause a reversal in the pattern of deformation, leading to misleading data being recorded by the tiltmeters. Their findings are published in the journal Geophysical Research Letters.
The team studied Kilauea volcano in Hawaii, which erupted last April, resulting in a summit collapse that has reshaped the cliffs around the caldera. It now has near-vertical cliffs of up to 500 metres and terrace-like steps of 50-150 metres.
The researchers say these new structures may have an impact on tilt measured at the existing network of tiltmeters and have implications for any new monitoring equipment that is installed.
Lead researcher Dr Jessica Johnson, lecturer in geophysics at UEA’s School of Environmental Sciences, said: “Tilt measurements have played a significant role in the knowledge of volcanic processes on at least 40 volcanoes worldwide. Our analysis highlights the importance of considering surface features when assessing tilt measurements at active volcanoes, something that hasn’t generally been taken into account.
“While the inconsistent data at Kilauea cannot be completely explained by topography, it may have some influence. Following the most recent collapse at Kilauea this problem is likely to be even more pronounced and should be considered when new monitoring instruments are installed.”
The researchers investigated after finding anomalies in data collected from one of the tiltmeters on the caldera rim at Kilauea before the last eruption. They looked at whether this could be due to topography and found that the then 80 metre-high caldera wall caused data from one of the monitoring tiltmeters to rotate away from the true centre of deformation.
“These findings have implications for network design and ongoing monitoring,” said Dr Johnson, who visited Kilauea last July and previously spent two years on a research fellowship at the Hawaiian Volcano Observatory.
“They suggest that other tiltmeters around Kilauea and at volcanoes globally could be affected by caldera rims and other sharp variations in the landscape.”
Dr Johnson added: “If this this monitoring method is already being used there are things that can be done to fix the data stream. If new tilt monitors are being installed then we have got to be careful where they are deployed.”
Co-author Dr Juliet Biggs, from the University of Bristol, said: “Understanding what drives volcano deformation is critical for improving the interpretation of volcano monitoring data, and developing probabilisitic eruption forecasts. Tiltmeters are very sensitive to small changes in the volcanic conduit, but their measurements have been challenging to interpret.
“This study sheds new light on how these measurements are influenced by surface features such as steep cliffs, and will undoubtedly improve our ability to interpret the complex monitoring signals.”
Reference:
Jessica H Johnson, Michael P Poland, Kyle R Anderson, and Juliet Biggs. A cautionary tale of topography and tilt from Kilauea Caldera. Geophysical Research Letters, 2019
The Washington coast is geologically complex. The bubbles emerge from a region off the coast above where the Juan de Fuca ocean plate plunges beneath the North American continental plate.Credit: Paul Johnson/University of Washington
Off the coast of Washington, columns of bubbles rise from the seafloor, as if evidence of a sleeping dragon lying below. But these bubbles are methane that is squeezed out of sediment and rises up through the water. The locations where they emerge provide important clues to what will happen during a major offshore earthquake.
The study, from the University of Washington and Oregon State University, was recently published in the Journal of Geophysical Research: Solid Earth.
The first large-scale analysis of these gas emissions along Washington’s coast finds more than 1,700 bubble plumes, primarily clustered in a north-south band about 30 miles (50 kilometers) from the coast. Analysis of the underlying geology suggests why the bubbles emerge here: The gas and fluid rise through faults generated by the motion of geologic plates that produce major offshore earthquakes in the Pacific Northwest.
“We found the first methane vents on the Washington margin in 2009, and we thought we were lucky to find them, but since then, the number has just grown exponentially,” said lead author Paul Johnson, a UW professor of oceanography.
“These vents are a little ephemeral,” Johnson added. “Sometimes they turn off-and-on with the tides, and they can move around a little bit on the seafloor. But they tend to occur in clusters within a radius of about three football fields. Sometimes you’ll go out there and you’ll see one active vent and you’ll go back to the same location and it’s gone. They’re not reliable, like the geysers at Yellowstone.”
The authors analyzed data from multiple research cruises over the past decade that use modern sonar technology to map the seafloor and also create sonar images of gas bubbles within the overlying water. Their new results show more than 1,778 methane bubble plumes issuing from the waters off Washington state, grouped into 491 clusters.
“If you were able to walk on the seafloor from Vancouver Island to the Columbia River, you would never be out of sight of a bubble plume,” Johnson said.
The sediments off the Washington coast are formed as the Juan de Fuca oceanic plate plunges under the North American continental plate, scraping material off the ocean crust. These sediments are then heated, deformed and compressed against the rigid North American plate. The compression forces out both fluid and methane gas, which emerges as bubble streams from the seafloor.
The bubble columns are located most frequently at the boundary between the flat continental shelf and the steeply sloped section where the seafloor drops to the abyssal depths of the open ocean. This abrupt change in slope is also a tectonic boundary between the oceanic and continental plates.
“Although there are some methane plumes from all depths on the margin, the vast majority of the newly observed methane plume sites are located at the seaward side of the continental shelf, at about 160 meters water depth,” Johnson said.
A previous study from the UW had suggested that warming seawater might be releasing frozen methane in this region, but further analysis showed the methane bubbles off the Pacific Northwest coast arise from sites that have been present for hundreds of years, and are not related to global warming, Johnson said.
Instead, these gas emissions are a long-lived natural feature, and their prevalence contributes to the continental shelf area being such productive fishing grounds. Methane from beneath the seafloor provides food for bacteria, which then produce large quantities of bacterial film. This biological material then feeds an entire ecological chain of life that enhances fish populations in those waters.
“If you look online at where the satellite transponders show where the fishing fleet is, you can see clusters of fishing boats around these methane plume hotspots,” Johnson said.
To understand why the methane bubbles occur here, the authors used archive geologic surveys conducted by the oil and gas companies in the 1970s and 1980s. The surveys, now publicly accessible, show fault zones in the sediment where the gas and fluid migrate upward until emerging from the seafloor.
“Seismic surveys over the areas with methane emission indicate that the continental shelf edge gets thrust westward during a large megathrust, or magnitude-9, earthquake,” Johnson said. “Faults at this tectonic boundary provide the permeable pathways for methane gas and warm fluid to escape from deep within the sediments.”
The location of these faults could potentially provide new understanding of the earthquake hazard from the Cascadia Subduction Zone, which last ruptured more than 300 years ago. If the seafloor movement during a subduction-zone earthquake occurs closer to shore, and a major component of this motion occurs within the shallower water, this would generate a smaller tsunami than if the seafloor motion were entirely in deep water.
“If our hypothesis turns out to be true, then that has major implications for how this subduction zone works,” Johnson said.
Reference:
H. Paul Johnson, Susan Merle, Marie Salmi, Robert Embley, Erica Sampaga, Michelle Lee. Anomalous Concentration of Methane Emissions at the Continental Shelf Edge of the Northern Cascadia Margin. Journal of Geophysical Research: Solid Earth, 2019; DOI: 10.1029/2018JB016453
Explosive volcanic crater (maar) with small lake at the bottom close to Dilo. Credit: Giacomo Corti, National Research Council Italy
Continental rift valleys are huge fractures on the surface of our planet that progressively break continental plates with the eventual development of new oceans. The African rift valley between Ethiopia and Kenya is a classical example of this geodynamic process. There, volcanism, earthquakes, and fracturing of the Earth’s surface result from the enormous forces that tear the eastern portion of the African continent apart. This system of linear valleys extending for thousands of kilometers is believed to result from the growth and propagation of isolated rift segments that evolve into a continuous zone of deformation. However, although instrumental in driving climate and biosphere of that region which in turn may have influenced habitats and the pattern of migration of human species in East Africa, and possibly even conditioned hominin evolution, this process is poorly documented and understood.
In a study published in Nature Communications and funded by the National Geographic Society, an international group of scientists from universities and research institutions from Ethiopia, France, Germany, Italy, New Zealand and the United Kingdom, of which Sascha Brune from the GFZ German Research Centre for Geosciences was a part, has shed new light into the recent evolution of the African rift valley. Its focus was on the spatial and temporal sequence of the propagation, interaction and linking of the Ethiopian rift section with the Kenyan part of the rift fracture. By conducting fieldwork in a remote area at the border between Ethiopia and Kenya, and integrating the results of that field campaign with laboratory analysis of volcanic rocks, analysis of the seismicity, morphology and numerical modelling, the authors have been able to reconstruct the geological history of an almost unknown sector of the African rift valley: the Ririba rift in South Ethiopia. The scientists showed that the Ririba trench formed about 3.7 million years ago as the southernmost advance of the Ethiopian rift segment.
Sascha Brune says: “In my research group at the GFZ we were able to substantiate the geological observations with numerical experiments. To this end, we brought together regional structures, deformation laws and basic physical equations to modelling in a supercomputer. In this way, we were able to show how the focusing of the rift valley contributed to a direct connection between the Kenyan and Ethiopian Rift.”
In contrast with previous theories of rifting in the region, the new data indicate that the southward growth was short-lived and aborted around 2.5 million years ago. At this time, deformation migrated westward into the Lake Turkana region, where the Ethiopian and Kenyan sectors of the rift valley are now directly connected. A later phase of volcanism, expressed by numerous lava flows and impressive explosive volcanic craters (maars), have since affected the Ririba area; however, this volcanic activity was unrelated to tectonic activity, opening new questions on how volcanism and faulting interact during rifting.
Overall, the results of this work provide new insights into the break-up of continents: “In the East African rift, we can observe processes that are important far beyond the region,” says Sascha Brune. “The same dynamics that determine the rift development in East Africa led to the opening of the Atlantic and Indian Oceans many millions of years ago and thus had a decisive influence on the face of the Earth.”
Reference:
Giacomo Corti, Raffaello Cioni, Zara Franceschini, Federico Sani, Stéphane Scaillet, Paola Molin, Ilaria Isola, Francesco Mazzarini, Sascha Brune, Derek Keir, Asfaw Erbello, Ameha Muluneh, Finnigan Illsley-Kemp, Anne Glerum. Aborted propagation of the Ethiopian rift caused by linkage with the Kenyan rift. Nature Communications, 2019; 10 (1) DOI: 10.1038/s41467-019-09335-2
The holotype specimen of Daihua sanqiong. Credit: Yang Zhao
One of the ocean’s little known carnivores has been allocated a new place in the evolutionary tree of life after scientists discovered its unmistakable resemblance with other sea-floor dwelling creatures.
Comb jellies occupy a pivotal place in the history of animal evolution with some arguing that they were among the first animals to evolve. Now an international team of palaeontologists have found fossil evidence that proves comb jellies are related to ancestors that sat on the sea floor with polyp-like tentacles.
As reported today in Current Biology, researchers from the University of Bristol, Yunnan University in China and London’s Natural History Museum, compared a 520 million-year-old fossil with fossils of a similar skeletal structure and found that all evolved from the same ancestors.
The fossil, set in a yellow and olive coloured mudstone and resembling a flower, was found in outcrops south of Kunming in the Yunnan Province, South China by Professor Hou Xianguang, co-author of the study.
Several amazingly preserved fossils have been unearthed from outcrops scattered among rice fields and farmlands in this part of tropical China in the last three decades.
It has been named Daihua after the Dai tribe in Yunnan and the Mandarin word for flower ‘Hua’, a cup-shaped organism with 18 tentacles surrounding its mouth. On the tentacles are fine feather-like branches with rows of large ciliary hairs preserved.
“When I first saw the fossil, I immediately noticed some features I had seen in comb jellies,” said Dr Jakob Vinther, a molecular palaeobiologist from the University of Bristol. “You could see these repeated dark stains along each tentacle that resembles how comb jelly combs fossilise. The fossil also preserves rows of cilia, which can be seen because they are huge. Across the Tree of Life, such large ciliary structures are only found in comb jellies.”
In today’s oceans, comb jellies are swimming carnivores. Some of them have become invasive pests. They swim using bands of iridescent, rainbow coloured comb rows along their body composed of densely packed cellular protrusions, known as cilia. Their hair-like structures are the largest seen anywhere in the tree of life.
The researchers noticed that Daihua resembled another fossil, a famous weird wonder from the Burgess Shale (508 million years old) called Dinomischus. This stalked creature also had 18 tentacles and an organic skeleton and was previously assigned to a group called entoprocts.
“We also realised that a fossil, Xianguangia, that we always thought was a sea anemone is actually part of the comb jelly branch,” said co-author Prof Cong Peiyun.
This emerging pattern led researchers to see a perfect transition from their fossils all the way up to comb jellies.
“It was probably one of the most exhilarating moments of my life,” said Dr Vinther. “We pulled out a zoology textbook and tried to wrap our head around the various differences and similarities, and then, bam! — here is another fossil that fills this gap.”
The study shows how comb jellies evolved from ancestors with an organic skeleton, which some still possessed and swam with during the Cambrian. Their combs evolved from tentacles in polyp-like ancestors that were attached to the seafloor. Their mouths then expanded into balloon-like spheres while their original body reduced in size so that the tentacles that used to surround the mouth now emerges from the back-end of the animal.
“With such body transformations, I think we have some of the answers to understand why comb jellies are so hard to figure out. It explains why they have lost so many genes and possess a morphology that we see in other animals,” added co-author Dr Luke Parry.
Until around 150 years ago, zoologists had considered comb jellies and cnidarians to be related. This theory was challenged more recently by new genetic information suggesting comb jellies could be a distant relative to all living animals below the very simple looking sponges.
The authors of this new study believe their findings make a strong case for repositioning the comb jelly back alongside corals, sea anemones and jellyfish.
Reference:
Yang Zhao, Jakob Vinther, Luke A. Parry, Fan Wei, Emily Green, Davide Pisani, Xianguang Hou, Gregory D. Edgecombe, Peiyun Cong. Cambrian Sessile, Suspension Feeding Stem-Group Ctenophores and Evolution of the Comb Jelly Body Plan. Current Biology, 2019; DOI: 10.1016/j.cub.2019.02.036
Volcanic ashes from the Etna eruption and intense cold activated carbon export in the big marine depths of the Mediterranean.
Volcanic ash is hazardous to many aspects of our lives. When airborne, it can damage aircraft: its particles abrade aeroplane surfaces and can even cause failure to critical instruments. Once the ash falls, it can harm our health and damage infrastructure, agriculture and the environment. To protect itself from these hazards, society needs to develop effective forecasting methods.
To this end scientists supported by the EU-funded projects AVAST and SLIM have been researching how ash particles are affected by different volcanic eruptions. The idea is that if researchers can estimate the size shape and composition of volcanic ash then they can more accurately predict the hazards of various eruptions without even sampling the ash. To achieve the goal the project team has used a novel analytical method to grasp how varied eruptive activity affects a range of hazards. Their new technique is based on quantitative mineral analysis conducted under a scanning electron microscope enabling them to link the surface composition of volcanic ash particles to activity during eruptions. The research results have been published in the journal Scientific Reports.
The researchers obtained their ash samples from the Guatemalan volcanic complex Santiaguito that has been growing since 1922. The most recent of its four vents, Caliente, has been actively erupting for more than 40 years, with regular explosions of ash and rock fragments, and a near-continuous lava discharge. The volcanic ash studied was selected from two sources. One source was a vulcanian explosion consisting of gas and ash clouds ejected high up in the air. The other was a pyroclastic flow – a fast-moving current of hot gas and volcanic matter sweeping down the sides of a volcano – caused by a dome collapse at the Santiaguito complex.
Volcanic activity affects magma fragmentation
Volcanic ash particles are less than 2 mm in diameter and are usually made up of crystal and volcanic glass formed in magma and sometimes also rock fragments. In their study the project team introduced a system called QEMSCAN (Quantitative Evaluation of Minerals by Scanning Electron Microscopy) Particle Mineralogical Analysis. They used this new system to examine their Santiaguito ash samples and to investigate the fragmentation mechanisms. “How magma fragments depends on the type of volcanic activity involved in its production and this also changes the mineralogy that is found at the surfaces of the ash particles” explained lead author Dr Adrian Hornby in a news item posted on Phys.org.
The ash samples obtained from the vulcanian explosion had an even distribution of plagioclase – a form of feldspar – and glass, enriched with other minerals at the particles’ surfaces. However, the ash generated from the dome collapse had more glass and less feldspar at the surfaces. “Our findings make a significant contribution to a better understanding of the origin and composition of volcanic ash – which is necessary to enable the risks associated with eruptions to be assessed,” stated Dr Hornby.
The research supported by AVAST (Advanced Volcanic Ash characteriSaTion) and SLIM (Strain Localisation in Magma) highlights the need for further investigation into fragmentation mechanisms. SLIM ended in June 2018, while AVAST continues until August 2019.
A. J. Hornby et al. Phase partitioning during fragmentation revealed by QEMSCAN Particle Mineralogical Analysis of volcanic ash, Scientific Reports (2019). DOI: 10.1038/s41598-018-36857-4
Note: The above post is reprinted from materials provided by CORDIS.
There are two geysers on the Fly Ranch property. The first was created nearly 100 years ago as part of an effort to make a part of the desert usable for farming. A well was drilled, and geothermal boiling water (200 degrees) was hit. Obviously not suitable for irrigation water, this geyser was left alone and a 10 to 12-foot calcium carbonate cone formed.
In 1964 a geothermic energy company drilled a test well at the same site. The water they struck was that same 200 degrees. Hot, but not hot enough for their purposes. The well was supposedly re-sealed, but apparently, it did not hold. The new geyser, a few hundred feet north of the original, robbed the first of its water pressure, and the cone now lies dry.
This second geyser, known as Fly Geyser, has grown substantially in the last 40 years as minerals from the geothermal water pocket deposit on the desert surface. Because there are multiple geyser spouts, this geyser has not created a cone as large as the first, but instead an ever-growing alien looking mound. The geyser is covered with thermophilic algae, which flourishes in moist, hot environments, resulting in the multiple hues of green and red that add to its out-of-this-world appearance.
Fly Geyser
Fly Geyser, also known as Fly Ranch Geyser is a small geothermal geyser located on private land in Washoe County, Nevada, about 20 miles (32 km) north of Gerlach. Fly Geyser is located near the edge of Fly Reservoir in the Hualapai Geothermal Flats and is approximately 5 feet (1.5 m) high by 12 feet (3.7 m) wide, counting the mound on which it sits.
In June 2016, the non-profit Burning Man Project purchased the 3,800 acres (1,500 ha) Fly Ranch, including the geyser, for $6.5 million. The Burning Man Project began offering limited public access to the property in May 2018. The geyser contains thermophilic algae, which flourishes in moist, hot environments, resulting in multiple hues of green and red coloring the rocks.
Location
Fly Geyser is located on the Fly Ranch in Hualapai Flat, about 0.3 miles (0.48 km) from State Route 34 and about 25 miles (40 km) north of Gerlach, Nevada. It is due east of Black Rock Desert.
Formation of Fly Geyser
The source of the Fly Geyser field’s heat is attributed to a very deep pool of hot rock where tectonic rifting and faulting are common.
The first geyser at the site was formed in 1916 when a well was drilled seeking irrigation water. When geothermal water at close to boiling point was found, the well was abandoned, and a 10–12-foot (3.0–3.7 m) calcium carbonate cone formed.
In 1964 a geothermic energy company drilled a second well near the site of the first well. The water was not hot enough for energy purposes. They reportedly capped the well, but the seal failed. The discharge from the second well released sufficient pressure that the original geyser dried up. Dissolved minerals in the water, including calcium carbonate and silica, accumulated, creating the cones and travertine pools.
The geyser has multiple conic openings sitting on a mound: the cones are about 6 feet (1.8 m), and the entire mound is 25 to 30 feet (7.6 to 9.1 m) tall.
A map of Japan showing locations for the epicenter of the 2011 Tohoku earthquake (✩),Kamioka (K), Matsushiro (M) and seismic survey instruments used (△ and ●). Credit: 2019 Kimura Masaya
Every year earthquakes worldwide claim hundreds or even thousands of lives. Forewarning allows people to head for safety and a matter of seconds could spell the difference between life and death. UTokyo researchers demonstrate a new earthquake detection method — their technique exploits subtle telltale gravitational signals traveling ahead of the tremors. Future research could boost early warning systems.
The shock of the 2011 Tohoku earthquake in eastern Japan still resonates for many. It caused unimaginable devastation, but also generated vast amounts of seismic and other kinds of data. Years later researchers still mine this data to improve models and find novel ways to use it, which could help people in the future. A team of researchers from the University of Tokyo’s Earthquake Research Institute (ERI) found something in this data which could help the field of research and might someday even save lives.
It all started when ERI Associate Professor Shingo Watada read an interesting physics paper on an unrelated topic by J. Harms from Istituto Nazionale di Fisica Nucleare in Italy. The paper suggests gravimeters — sensors which measure the strength of local gravity — could theoretically detect earthquakes.
“This got me thinking,” said Watada. “If we have enough seismic and gravitational data from the time and place a big earthquake hit, we could learn to detect earthquakes with gravimeters as well as seismometers. This could be an important tool for future research of seismic phenomena.”
The idea works like this. Earthquakes occur when a point along the edge of a tectonic plate comprising the earth’s surface makes a sudden movement. This generates seismic waves which radiate from that point at 6-8 kilometers per second. These waves transmit energy through the earth and rapidly alter the density of the subsurface material they pass through. Dense material imparts a slightly greater gravitational attraction than less dense material. As gravity propagates at light speed, sensitive gravimeters can pick up these changes in density ahead of the seismic waves’ arrival.
“This is the first time anyone has shown definitive earthquake signals with such a method. Others have investigated the idea, yet not found reliable signals,” elaborated ERI postgraduate Masaya Kimura. “Our approach is unique as we examined a broader range of sensors active during the 2011 earthquake. And we used special processing methods to isolate quiet gravitational signals from the noisy data.”
Japan is famously very seismically active so it’s no surprise there are extensive networks of seismic instruments on land and at sea in the region. The researchers used a range of seismic data from these and also superconducting gravimeters (SGs) in Kamioka, Gifu Prefecture, and Matsushiro, Nagano Prefecture, in central Japan.
The signal analysis they performed was extremely reliable scoring what scientists term a 7-sigma accuracy, meaning there is only a one-in-a-trillion chance a result is incorrect. This fact greatly helps to prove the concept and will be useful in calibration of future instruments built specifically to help detect earthquakes. Associate Professor Masaki Ando from the Department of Physics invented a novel kind of gravimeter — the torsion bar antenna (TOBA) — which aims to be the first of such instruments.
“SGs and seismometers are not ideal as the sensors within them move together with the instrument, which almost cancels subtle signals from earthquakes,” explained ERI Associate Professor Nobuki Kame. “This is known as an Einstein’s elevator, or the equivalence principle. However, the TOBA will overcome this problem. It senses changes in gravity gradient despite motion. It was originally designed to detect gravitational waves from the big bang, like earthquakes in space, but our purpose is more down-to-earth.”
The team dreams of a network of TOBA distributed around seismically active regions, an early warning system that could alert people 10 seconds before the first ground shaking waves arrive from an epicenter 100 km away. Many earthquake deaths occur as people are caught off-guard inside buildings that collapse on them. Imagine the difference 10 seconds could make. This will take time but the researchers continually refine models to improve accuracy of the method for eventual use in the field.
Reference:
Earthquake-induced prompt gravity signals identified in dense array data in Japan. DOI: 10.1186/s40623-019-1006-x
Note: The above post is reprinted from materials provided by University of Tokyo.
This is Emerald Bay, Lake Tahoe, USA. Credit: R.A. Schweickert et al.
Emerald Bay, California, a beautiful location on the southwestern shore of Lake Tahoe, is surrounded by rugged landscape, including rocky cliffs and remnants of mountain glaciers. Scenic as it may be, the area is also a complex structural puzzle. Understanding the history of fault movement in the Lake Tahoe basin is important to assessing earthquake hazards for regional policy planners.
The Lake Tahoe region is rife with active faults, many of which have created the dramatic and rugged landscapes. The Lake Tahoe region lies between the Sierra Nevada microplate to the west and the Basin and Range Province to the east. Northwestward movement of the Sierra Nevada microplate creates stresses that may produce both strike slip (horizontal) and vertical movement on faults. For years, geologists have traversed the forbidding terrain around Emerald Bay, noting where faults cut the landscape, but a detailed picture of the faults was still missing.
Two of these faults — the Tahoe-Sierra frontal fault zone (TSFFZ) and the West Tahoe-Dollar Point fault zone (WTDPFZ) — stretch along the western side of Lake Tahoe, but their continuity across landscapes and the nature of their movement has been debated for nearly two decades. Richard Schweickert, of the University of Nevada-Reno (UNR), part of a team of geologists and engineers from UNR, the U.S. Geological Survey, and Santa Clara University, said, “We found plenty of evidence for scarps (i.e., faults) that cut the glacial moraines all along the west side of Lake Tahoe, in particular around Emerald Bay.”
But it was what they couldn’t hike across that most interested them. “We were desperate to see what’s actually going on the bottom [of Emerald Bay].” The research team decided to examine the faults both “by land and by sea.”
In a new paper in Geosphere, Schweickert and colleagues describe a number of deep dives that uncovered evidence for major faults on the floor of Emerald Bay. Using a remotely operated vehicle, or ROV, and previously published multibeam echo sounder imagery, the team created a detailed map of the bathymetry (depth and shape) and geology in Emerald Bay.
The high-resolution bathymetry survey showed clear evidence of scarps cutting across submerged glacial deposits and lake sediments, along with landslide deposits that toppled into the bay after the glaciers melted. Based on the age of nearby moraines, Schweickert says the scarps in most cases are younger than about 20,000 years old.
The faults scarps in the Bay are very sharp, with steep faces sloping between 30 and 60 degrees — surprisingly steep for scarps that could be thousands of years old. “You would only see that steep angle on land exposures for faults that had just moved within the last few hundred years,” Schweickert says, but noted the scarps were likely preserved by being underwater instead of being repeatedly exposed to running water on land.
Schweickert says that the bathymetric data paired with direct underwater observations with the ROV show conclusively that the scarps are related to faults. “We’ve been able to produce the highest resolution maps with the greatest amount of detail of anywhere in the Lake Tahoe Basin,” he added.
After studying the ROV, bathymetry, and LiDAR data, the team noted that over the past 20,000 years, the TSFFZ and WTDPFZ were moving vertically, with no strike slip motion. Schweickert says their discovery was a bit of a paradox to what might be expected in the Lake Tahoe basin. Ten to 15 years of satellite GPS measurements show a northwest movement for the Lake Tahoe region, relative to the interior of North America. But the TSFFZ and WTDPFZ don’t reflect that direction of movement — at least not recently.
“I think this shows us that the GPS data really doesn’t tell us what the faults themselves are doing on a local scale,” says Schweickert. “They do their own thing.” He adds that scientists studying other faults in the Lake Tahoe area have reached similar conclusions.
However, Schweickert notes that landforms around Emerald Bay, thought to be roughly 100,000 years old, look like they experienced right lateral, strike slip movement sometime in the past. “Faults can move in different directions over long periods of time,” he says. “Just because we see some them doing something right now doesn’t mean that they didn’t have a more complex history in the not too distant past.”
“There’s more to this story that still needs to be known,” says Schweickert, and notes that studies like theirs have value for policy and planning.
Reference:
R.A. Schweickert, J.G. Moore, M.M. Lahren, W. Kortemeier, C. Kitts, T. Adamek. The Tahoe-Sierra frontal fault zone, Emerald Bay area, Lake Tahoe, California: History, displacements, and rates. Geosphere, 2019 DOI: 10.1130/GES02022.1
California’s Central Valley aquifer, the major source of groundwater in the region, suffered permanent loss of capacity during the drought experienced in the area from 2012 to 2015.
California has been afflicted by a number of droughts in recent decades, including one between 2007 and 2009, and the millennium drought that plagued the state from 2012 to 2015. Due to lack of water resources, the state drew heavily on its underground aquifer reserves during these periods.
According to new research, the San Joaquin Valley aquifer in the Central Valley shrank permanently by up to 3 percent due to excess pumping during the sustained dry spell. Combined with the loss from the 2007 to 2009 drought, the aquifer may have lost up to 5 percent of its storage capacity during the first two decades of the 21st Century, according to Manoochehr Shirzaei, an assistant professor of earth sciences at Arizona State University in Tempe and one of the co-authors of a new study published in AGU’s Journal of Geophysical Research: Solid Earth.
Groundwater exists in the pore spaces between grains of soil and rocks. When fluids are extracted from aquifers, the pore spaces close. There is a range for which these spaces can shrink and expand elastically. But if the pore spaces close too much, they start to collapse, causing the land to shrink irreversibly.
Figuring out how much the aquifer shrank permanently could help water managers prepare for future droughts, according to the study’s authors. The San Joaquin Valley aquifer supplies freshwater to the Central Valley – a major hub that produces more than 250 different crops valued at $17 billion per year, according to the U.S. Geological Survey.
“If we have even one drought per decade, our aquifers could shrink a bit more each time and permanently lose more than a quarter of their storage capacity this century,” said Susanna Werth, a research assistant professor of earth sciences at Arizona State University, and a co-author of the new study.
The new study could also help scientists understand how other areas might be affected by drought.
“That was a curiosity for us to understand how much groundwater has been lost in those particular regions and will give us a picture of what we can expect for arid areas around the globe if groundwater practices are not sustainable,” said Chandrakanta Ojha, a post-doctoral researcher at Arizona State and the lead author of the new study.
Underground water from space
The researchers measured water volume changes due to groundwater variation in the aquifer using data from the Gravity Recovery and Climate Experiment (GRACE), a twin satellite mission that has been measuring the Earth’s gravity field every month from April 2002 until June 2017. The study’s authors compared the groundwater losses based on GRACE measurements with those calculated from vertical land motion measurements obtained by GPS. Land depressions were also measured by a radar technique called InSAR and multiple extensometers, devices which are installed in a borehole of a groundwater observation well. They also examined groundwater level records.
The study’s authors found that from 2012 to 2015, the aquifer of the San Joaquin Valley lost a total volume of about 30 cubic kilometers (7.2 cubic miles) of groundwater. The aquifer also shrank permanently by 0.4 percent to 3.25 percent, according to the new study.
Previous research found the 2007 to 2009 drought caused the San Joaquin aquifer to permanently lose between 0.5 percent to 2 percent of its capacity. Cumulatively, the authors said both drought periods – 2007 to 2009 and 2012 to 2015—caused the San Joaquin aquifer to shrink permanently by as much as 5.25 percent.
Forecasting future drought effects
Shirzaei said the information they have gathered is important for future planning—particularly since the loss of permanent storage capacity is unsustainable in the long-run.
By using this type of calculation, Shirzaei said land and water resource managers can predict the effect of droughts on the aquifer system. This can help to make better regulations for groundwater conservation during those periods and prevent permanent loss of aquifer storage capacity.
Shirzaei said the compaction of the aquifer may also cause fissures and cracks on the surface as the land subsides. This could affect roads, power lines, railroads or other infrastructure, but more research is needed to understand the details of these effects.
Reference:
Chandrakanta Ojha et al. Groundwater loss and aquifer-system compaction in San Joaquin Valley during 2012-2015 drought, Journal of Geophysical Research: Solid Earth (2019). DOI: 10.1029/2018JB016083
This story is republished courtesy of AGU Blogs (http://blogs.agu.org), a community of Earth and space science blogs, hosted by the American Geophysical Union.
Thrinaxodon, a therapsid animal related to today’s mammals. The therapsids are the group where mammal relatives began developing diverse forelimbs. Credit: April I. Neander
Bats fly, whales swim, gibbons swing from tree to tree, horses gallop, and humans swipe on their phones — the different habitats and lifestyles of mammals rely on our unique forelimbs. No other group of vertebrate animals has evolved so many different kinds of arms: in contrast, all birds have wings, and pretty much all lizards walk on all fours. Our forelimbs are a big part of what makes mammals special, and in a new study in the Proceedings of the National Academy of Sciences, scientists have discovered that our early relatives started evolving diverse forelimbs 270 million years ago — a good 30 million years before the earliest dinosaurs existed.
“Aside from fur, diverse forelimb shape is one of the most iconic characteristics of mammals,” says the paper’s lead author Jacqueline Lungmus, a research assistant at Chicago’s Field Museum and a doctoral candidate at the University of Chicago. “We were trying to understand where that comes from, if it’s a recent trait or if this has been something special about the group of animals that we belong to from the beginning.”
To determine the origins of mammals’ arms today, Lungmus and her co-author, Field Museum curator Ken Angielczyk, examined the fossils of mammals’ ancient relatives. About 312 million years ago, land-dwelling vertebrates split into two groups — the sauropsids, which went on to include dinosaurs, birds, crocodiles, and lizards, and the synapsids, the group that mammals are part of. A key difference between sauropsids and synapsids is the pattern of openings in the skull where jaw muscles attach. While the earliest synapsids, called pelycosaurs, were more closely related to humans than to dinosaurs, they looked like hulking reptiles. Angielczyk notes, “If you saw a pelycosaur walking down the street, you wouldn’t think it looked like a mammal — you’d say, ‘That’s a weird-looking crocodile.'”
About 270 million years ago, though, a more diverse (and sometimes furry) line of our family tree emerged: the therapsids. “Modern mammals are the only surviving therapsids — this is the group that we’re part of today,” explains Lungmus. Therapsids were the first members of our family to really branch out — instead of just croc-like pelycosaurs, the therapsids included lithe carnivores, burly-armed burrowers, and tree-dwelling plant-eaters.
Lungmus and Angielczyk set out to see if this explosion of diversity came with a corresponding explosion in different forelimb shapes. “This is the first study to quantify forelimb shape across a big sample of these animals,” says Lungmus. The team examined the upper arm bones of hundreds of fossil specimens representing 73 kinds of pelycosaurs and therapsids, taking measurements near where the bones joined the shoulder and the elbow. They then analyzed the shapes of the bones using a technique called geometric morphometrics.
When they compared the shapes of arm bones, the researchers found a lot more variation in the bones of the therapsids than the pelycosaurs. They also noted that the upper part of the arm, near the shoulder, was especially varied in therapsids — a feature that might have let them move more freely than the pelycosaurs, whose bulky and tightly-fitting shoulder bones likely gave them a more limited range of motion.
Lungmus and Angielczyk found that a wide variety of different forelimb shapes evolved within the therapsids 270 million years ago. “The therapsids are the first synapsids to increase the variability of their forelimbs — this study dramatically pushes that trait back in time,” says Lungmus. Prior to this study, the earliest that paleontologists had been able to definitively trace back mammals’ diverse forelimbs was 160 million years ago. With Lungmus and Angielczyk’s work, that’s been pushed back by more than a hundred million years.
The researchers note that the study helps explain how mammals evolved traits that have made us what we are today. “So much of what we do every day is related to the way our forelimbs evolved — even simple things like holding a phone,” says Angielczyk.
“This is something that’s so cool about our evolutionary lineage,” says Lungmus. “These animals are in the same group as us — part of what makes this research compelling is that these are our relatives.”
Reference:
Jacqueline K. Lungmus, Kenneth D. Angielczyk. Antiquity of forelimb ecomorphological diversity in the mammalian stem lineage (Synapsida). Proceedings of the National Academy of Sciences, 2019; 201802543 DOI: 10.1073/pnas.1802543116
A 3D model of the mandible of Alophia rendered from high resolution CT scans. It is dated to 22 million years in age, and measures 3.7 cm (1.45 inches) in length. Credit: The University of Texas at Austin
The teeth of a new fossil monkey, unearthed in the badlands of northwest Kenya, help fill a 6-million-year void in Old World monkey evolution, according to a study by U.S. and Kenyan scientists published in the Proceedings of the National Academy of Sciences.
The discovery of 22-million-year-old fossilized monkey teeth — described as belonging to a new species, Alophia metios — fills a void between a previously discovered 19-million-year-old fossil tooth in Uganda and a 25-million-year-old fossil tooth found in Tanzania. The finding also sheds light on how their diet may have changed the course of their evolution.
“For a group as highly successful as the monkeys of Africa and Asia, it would seem that scientists would have already figured out their evolutionary history,” said the study’s corresponding author John Kappelman, an anthropology and geology professor at The University of Texas at Austin. “Although the isolated tooth from Tanzania is important for documenting the earliest occurrence of monkeys, the next 6 million years of the group’s existence are one big blank. This new monkey importantly reveals what happened during the group’s later evolution.”
Since the time interval from 19 to 25 million years ago is represented by a small number of African fossil sites, the team targeted the famous fossil-rich region of West Turkana to try to fill in that blank.
“Today, this region is very arid,” said Benson Kyongo, a collections manager at the National Museums of Kenya. “But millions of years ago, it was a forest and woodland landscape crisscrossed by rivers and streams. These ancient monkeys were living the good life.”
While in the field, the team uncovered hundreds of mammal and reptile jaws, limbs and teeth ranging from 21 million to more than 24 million years old, including remains of early elephants. The newly discovered monkey teeth are more primitive than geologically younger monkey fossils, lacking what researchers referred to as “lophs,” or a pair of molar crests, thus earning the new species its name, Alophia, meaning “without lophs.”
“These teeth are so primitive that when we first showed them to other scientists, they told us, “Oh no, that isn’t a monkey. It’s a pig,” said Ellen Miller, an anthropology professor at Wake Forest University. “But because of other dental features, we are able to convince them that yes, it is in fact a monkey.”
The success of Old World monkeys appears to be closely tied to their unique dentition, researchers said. Today, the configuration of cusps and lophs on the molar teeth enable them to process the wide range of plant and animal foods encountered in the diverse environments of Africa and Asia.
“You can think of the modern-day monkey molar as the uber food processor, able to slice, dice, mince and crush all sorts of foods,” said Mercedes Gutierrez, an anatomy professor at the University of Minnesota.
“How and when this unique dentition evolved is one of the unanswered questions in primate evolution,” said James Rossie, an anthropology professor at Stony Brook University. The researchers speculated that Alophia’s primitive dentition was adapted to a diet that consisted of hard fruits, seeds and nuts, and not leaves, which are more efficiently processed by the more evolved dentition of fossil monkeys dating from after 19 million years ago.
“It is usually assumed that the trait responsible for a group’s success evolved when the group originated, but Alophia shows us this is not the case for Old World monkeys,” said Samuel Muteti, a researcher at the National Museums of Kenya. “Instead, the characteristic dentition of modern monkeys evolved long after the group first appeared.”
The researchers hypothesized that the inclusion of leaves in the diet is what later drove monkey dental evolution.
Monkeys originated at a time when Africa and Arabia were joined as an island continent, with its animals evolving in isolation until docking with Eurasia sometime between 20 million and 24 million years ago. It was only after docking that the mammals today typically considered “African” — antelope, pigs, lions, rhinos, etc. — made their entry onto the continent. So, researchers asked: Could this event and possible competition between the residents and the newly arrived Eurasian species have driven monkeys to exploit leaves, or did changing climates serve to make leaves a more attractive menu entrée?
“The way to test between these hypotheses is to collect more fossils,” Kappelman said. “Establishing when, exactly, the Eurasian fauna entered Afro-Arabia remains one of the most important questions in paleontology, and West Turkana is one of the only places we know of to find that answer.”
The team intends to be back in the field later this year.
Reference:
D. Tab Rasmussen, Anthony R. Friscia, Mercedes Gutierrez, John Kappelman, Ellen R. Miller, Samuel Muteti, Dawn Reynoso, James B. Rossie, Terry L. Spell, Neil J. Tabor, Elizabeth Gierlowski-Kordesch, Bonnie F. Jacobs, Benson Kyongo, Mathew Macharwas, and Francis Muchemi. Primitive Old World monkey from the earliest Miocene of Kenya and the evolution of cercopithecoid bilophodonty. Proceedings of the National Academy of Sciences, March 11, 2019; DOI: 10.1073/pnas.1815423116
Scientists are peeking into ancient oceans to unravel the complexities of mass extinctions, past and future. A new examination of Earth’s largest extinction by scientists at the California Academy of Sciences and the University of Wisconsin-Milwaukee sheds light on how ecosystems are changed by such transformative events.
The study, published today in Biology Letters, suggests that the extinction survivors shared many of the same ecological roles as their predecessors, with one catch — there was a surge in the number of individuals with modern traits like greater mobility, higher metabolism, and more diverse feeding habits. These hardy stand-outs did a better job of driving recovery, making ecological interactions more intense in the process: fish were more agile, diverse predators and marine invertebrates like mussels became more defensive. Insights into this system and its occupants can help guide modern conservation in identifying Earth’s most resilient and best equipped species in the face of environmental stress.
“We’re interested in understanding why certain species and communities survived and recovered better than others,” says Dr. Ashley Dineen, a former Academy postdoctoral researcher and current Museum Scientist of Invertebrate Paleontology at the UC Museum of Paleontology at Berkeley. “For a long time biology has focused on the number of species that survive extinction events, but we need to also ask what those species did and how they reacted to stresses — these insights are important as we push our planet into an increasingly uncertain future.”
The massive extinction event, often referred to as the “Great Dying,” took place 252 million years ago and frequently serves as a proxy for the modern era. Similar to today, the climate regime was transitioning from a cooler period to a warmer period. This climatic fluctuation, driven by massive volcanic eruptions that spewed noxious gases, increased the temperature and acidity of the oceans, decreased oxygen concentrations, interrupted mighty ocean currents, and turned the ocean system on its head.
The researchers examined fossils of ocean-dwelling invertebrate creatures like clams, snails, corals, and sponges from Utah, Nevada, and Texas. This region once comprised the shallow outskirts of the ancient and vast Panthalassa Ocean. Using numerical methods, the team grouped marine survivor species into functional groups with similar traits, like mobile bottom-dwelling omnivores such as sea urchins, to better understand the ecological transformation in the wake of the Great Dying.
“We learned from our analysis that beyond documenting the number of species that arise during an ecological recovery, we need to know what they were actually doing — what scientists call their functional diversity,” says Dr. Peter Roopnarine, Academy Curator of Geology. “This helps us understand if the system has shifted toward favoring species with a variety of responses to stress.”
One surprising revelation: the study results showed significant ecological continuity among species — where species that were wiped out during the extinction event shared the same traits as those that originated in its aftermath. During recovery, however, there was a significant shift in numbers toward bigger and more active survivors that are strikingly similar to the inhabitants of our modern oceans. This shift in functional emphasis may be the the hallmark of an ecosystem set on the road to recovery.
“Our next step is to determine what kinds of species you want on the frontlines of recovery,” says Dineen. “For example, if you have a reef with twenty different species of corals but they all react the same to stressors, then they will all be similarly impacted when hit with a disturbance. But on a separate reef, if you have twenty coral species and each reacts differently to stress, the chance of losing the entire reef is lower. Having diverse coping mechanisms is critical for a future marked by increasing environmental stressors.”
The study team hopes their findings about species survivors will help scientists identify our modern — and urgently needed — conservation priorities.
“We’re often focused on estimating the number of species in an ecosystem, but we should also be learning about how — and how well — these species survive, and concentrate conservation efforts accordingly,” says Dineen. “When you consider the mass extinction we face today, it’s clear we have to take entire systems into account before it’s too late to correct course.”
Reference:
Ashley A. Dineen, Peter D. Roopnarine, Margaret L. Fraiser. Ecological continuity and transformation after the Permo-Triassic mass extinction in northeastern Panthalassa. Biology Letters, 2019; 15 (3): 20180902 DOI: 10.1098/rsbl.2018.0902
