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Mountain glaciers shrinking across the West

This map shows the elevation change of Mount Rainier glaciers between 1970 and 2016. The earlier observations are from USGS maps, while the recent data use the satellite stereo imaging technique. Glacier surface elevations have dropped more than 40 meters (130 feet) in some places. Credit: David Shean/University of Washington

Until recently, glaciers in the United States have been measured in two ways: placing stakes in the snow, as federal scientists have done each year since 1957 at South Cascade Glacier in Washington state; or tracking glacier area using photographs from airplanes and satellites.

We now have a third, much more powerful tool. While he was a doctoral student in University of Washington’s Department of Earth and Space Sciences, David Shean devised new ways to use high-resolution satellite images to track elevation changes for massive ice sheets in Antarctica and Greenland. Over the years he wondered: Why aren’t we doing this for mountain glaciers in the United States, like the one visible from his department’s office window?

He has now made that a reality. In 2012, he first asked for satellite time to turn digital eyes on glaciers in the continental U.S., and he has since collected enough data to analyze mass loss for Mount Rainier and almost all the glaciers in the lower 48 states. He will present results from these efforts Oct. 22 at the Geological Society of America’s annual meeting in Seattle.

“I’m interested in the broad picture: What is the state of all of the glaciers, and how has that changed over the last 50 years? How has that changed over the last 10 years? And at this point, how are they changing every year?” said Shean, who is now a research associate with the UW’s Applied Physics Laboratory.

The maps provide a twice-yearly tally of roughly 1,200 mountain glaciers in the lower 48 states, down to a resolution of about 1 foot. Most of those glaciers are in Washington state, with others clustered in the Rocky Mountains of Montana, Wyoming and Colorado, and in California’s Sierra Nevada.

To create the maps, a satellite camera roughly half the size of the Hubble Space Telescope must take two images of a glacier from slightly different angles. As the satellite passes overhead, moving at about 4.6 miles per second, it takes images a few minutes apart. Each pixel of the image covers 30 to 50 centimeters (about 1 foot) and a single image can be tens of miles across.

Shean’s technique uses automated software that matches millions of small features, such as rocks or crevasses, in the two images. It then uses the difference in perspective to create a 3-D model of the surface.

The first such map of a Mount St. Helens glacier was obtained in 2012, and the first for Mount Rainier in 2014. The project has grown steadily since then to include more glaciers every year.

The results confirm stake measurements at South Cascade Glacier, showing significant loss over the past 60 years. Results at Mount Rainier also reflect the broader shrinking trends, with the lower-elevation glaciers being particularly hard hit. Shean estimates cumulative ice loss of about 0.7 cubic kilometers (900 million cubic yards) at Mount Rainier since 1970. Distributed evenly across all of Mount Rainier’s glaciers, that’s equivalent to removing a layer of ice about 25 feet (7 to 8 meters) thick.

“There are some big changes that have happened, as anyone who’s been hiking on Mount Rainier in the last 45 years can attest to,” Shean said. “For the first time we’re able to very precisely quantify exactly how much snow and ice has been lost.”

The glacier loss at Rainier is consistent with trends for glaciers across the U.S. and worldwide. Tracking the status of so many glaciers will allow scientists to further explore patterns in the changes over time, which will help pinpoint the causes — from changes in temperature and precipitation to slope angle and elevation.

“The next step is to integrate our observations with glacier and climate models and say: Based on what we know now, where are these systems headed?” Shean said.

Those predictions could be used to better manage water supplies and flood risks.

“We want to know what the glaciers are doing and how their mass is changing, but it’s important to remember that the meltwater is going somewhere. It ends up in rivers, it ends up in reservoirs, it ends up downstream in the ocean. So there are very real applications for water resource management,” Shean said. “If we know how much snow falls on Mount Rainier every winter, and when and how much ice melts every summer, that can inform water resource managers’ decisions.”

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

Davidsmithite a new Ca-bearing nepheline-group mineral

Restricted access Davidsmithite
Representative Image: Aquamarine Crystal

Davidsmithite, a newly approved feldspathoid mineral (IMA 2016-070), occurs as a rock-forming mineral in the Liset eclogite pod (Norwegian Caledonides).

The approved electron-microprobe analysis gave the crystal–chemical formula: ([Ca0.636◰0.636]◰0.414K0.165Na0.149)Σ2.000Na6.000(Al7.863Fe3+0.019)Σ7.882Si8.192O32 (where ◰ = vacancy)

Davidsmithite completes the compositional space of the nepheline-structure group by providing a new root-composition, (Ca◰)2Na6Al8Si8O32. It is the Ca-analogue of classical nepheline, to which it is related by the heterovalent substitution of K+2 by [Ca2+◰]. Most of the Ca2+ ions are situated in the same atomic position as K+ in nepheline, but some occur in a new and disordered (Ca′) atomic position, whose centre is shifted by 2.18 Å along the 6-fold axis.

The studied samples show some solid-solution towards the other two possible end-members of the nepheline compositional space, so that the channel site contains all of Ca and K in the unit formula, with some Na and â—°. In the Liset eclogite pod, davidsmithite occurs in retrogressed, formerly jadeite-rich zones; it commonly overgrows lisetite and is associated with albitic plagioclase and taramitic amphibole.

This eclogite occurrence is noted for its bulk-rock compositions rich in (Na + Al) and poor in growth of a (K + Mg). The paucity in K prevented the growth of nepheline, and the paucity in Si in precursor jadeite led to the growth of a feldspathoid (davidsmithite) as well as of lisetite; a feldspar (albite or oligoclase) also occurs nearby.

Davidsmithite

Formula: (Caâ—°)2Na6Al8Si8O32
Colour: Colourless
Specific Gravity: 2.597 (Calculated)
Crystal System: Hexagonal

Locality: Liset eclogite pod, Liset, Selje, Sogn og Fjordane, Norway

Physical Properties of Davidsmithite

Transparency: Transparent
Colour: Colourless
Cleavage: None Observed
Density: 2.597 g/cm3

Reference:

  1. Sid-Ali Kechid, Gian Carlo Parodi, Sylvain Pont, Roberta Oberti. Davidsmithite, (Ca,â—°)2Na6Al8Si8O32: a new, Ca-bearing nepheline-group mineral from the Western Gneiss Region, Norway. DOI: 10.1127/ejm/2017/0029-2667 Published on June 2017, First Published on June 28, 2017
  2. Smith, D.C., Kechid, S-A. and Rossi, G. (1986): Occurence and properties of lisetite, CaNa2Al4Si4O16, a new tectosilicate in the system Ca-Na-Al-Si-O. American Mineralogist 71, 1372-1377. [as K-poor, Ca-rich nepheline structure mineral]
  3. Kechid, S.-A., Oberti, R., Rossi, G., Parodi, G., Pont, P. (2016): Davidsmithite, IMA 2016-070. CNMNC Newsletter No. 34, December 2016, page 1317; Mineralogical Magazine: 80: 1315–1321

Research sheds new light on early turquoise mining in Southwest

Turquoise
A turquoise artifact linked to Canyon Creek. Credit: Saul Hedquist

Turquoise is an icon of the desert Southwest, with enduring cultural significance, especially for Native American communities. Yet, relatively little is known about the early history of turquoise procurement and exchange in the region.

University of Arizona researchers are starting to change that by blending archaeology and geochemistry to get a more complete picture of the mineral’s mining and distribution in the region prior to the 16th-century arrival of the Spanish.

In a new paper, published in the November issue of the Journal of Archaeological Science, UA anthropology alumnus Saul Hedquist and his collaborators revisit what once was believed to be a relatively small turquoise mine in eastern Arizona. Their findings suggest that the Canyon Creek mine, located on the White Mountain Apache Indian Reservation, was actually a much more significant source of turquoise than previously thought.

With permission from the White Mountain Apache Tribe, Hedquist and his colleagues visited the now essentially exhausted Canyon Creek source—which has been known to archaeologists since the 1930s—to remap the area and collect new samples. There, they found evidence of previously undocumented mining areas, which suggest the output of the mine may have been 25 percent higher than past surveys indicated.

“Pre-Hispanic workings at Canyon Creek were much larger than previously estimated, so the mine was clearly an important source of turquoise while it was active,” said Hedquist, lead author of the paper, who earned his doctorate from the UA School of Anthropology in the College of Social and Behavioral Sciences in May.

In addition, the researchers measured ratios of lead and strontium isotopes in samples they collected from the mine, and determined that Canyon Creek turquoise has a unique isotopic fingerprint that distinguishes it from other known turquoise sources in the Southwest. The isotopic analysis was conducted in the lab of UA College of Science Dean Joaquin Ruiz in the Department of Geosciences by study co-author and UA geosciences alumna Alyson Thibodeau. Now an assistant professor at Dickinson College in Pennsylvania, Thibodeau did her UA dissertation on isotopic fingerprinting of geological sources of turquoise throughout the Southwest.

“If you pick up a piece of turquoise from an archaeological site and say ‘where does it come from?’ you have to have some means of telling the different turquoise deposits apart,” said David Killick, UA professor of anthropology, who co-authored the paper with Hedquist, Thibodeau and John Welch, a UA alumnus now on the faculty at Simon Fraser University. “Alyson’s work shows that the major mining areas can be distinguished by measurement of major lead and strontium isotopic ratios.”

Based on the isotopic analysis, researchers were able to confidently match turquoise samples they collected at Canyon Creek to several archaeological artifacts housed in museums. Their samples matched artifacts that had been uncovered at sites throughout much of east-central Arizona—some more than 100 kilometers from the mine—suggesting that distribution of Canyon Creek turquoise was broader than previously thought, and that the mine was a significant source of turquoise for pre-Hispanic inhabitants of the Mogollon Rim area.

The researchers also were able to pinpoint when the mine was most active. Their samples matched artifacts found at sites occupied between A.D. 1250-1400, suggesting the mine was primarily used in the late 13th and/or 14th centuries.

“Archaeologists have struggled for decades to find reliable means of sourcing archaeological turquoise—linking turquoise artifacts to their geologic origin—and exploring how turquoise was mined and traded throughout the greater pre-Hispanic Southwest,” said Hedquist, who now lives in Tempe, Arizona, and works as an archaeologist and ethnographer for Logan Simpson Inc., a cultural resources consulting firm. “We used both archaeology and geochemistry to document the extent of workings at the mine, estimate the amount of labor spent at the mine and identify turquoise from the mine in archaeological assemblages.”

Research Paves Way for Future Studies

Turquoise is a copper mineral, found only immediately adjacent to copper ore deposits. While detailed documentation of pre-Hispanic turquoise mines is limited, the work at Canyon Creek could pave the way for future investigations.

“I think our study raises the bar a bit by combining archaeological and geochemical analyses to gain a more complete picture of operations at one mine: when it was active, how intensely it was mined and how its product moved about the landscape,” Hedquist said. “Researchers have only recently developed a reliable means of sourcing the mineral, so there’s plenty of potential for future research.”

Similar work involving the UA is already underway to explore the origin of turquoise artifacts found at the Aztec capital of Tenochtitlan in Mexico.

“Canyon Creek is but one of many ancient turquoise mines,” Hedquist said. “This study provides a standard for the detailed documentation of ancient mineral procurement and a framework for linking archaeological turquoise to specific geologic locations. Building on other archaeological patterns—the circulation of pottery and flaked stone artifacts, for example—we can piece together the social networks that facilitated the ancient circulation of turquoise in different times and places.”

A better understanding of the pre-Hispanic history of turquoise is important not only to archaeologists and mining historians but to modern Native Americans, Killick said.

“It’s of great interest to modern-day Apache, Zuni and Hopi, whose ancestors lived in this area, because turquoise continues to be ritually important for them,” he said. “They really have shown a great deal of interest in this work, and they’ve encouraged it.”

Reference:
Saul L. Hedquist et al, Canyon Creek revisited: New investigations of a late prehispanic turquoise mine, Arizona, USA, Journal of Archaeological Science (2017). DOI: 10.1016/j.jas.2017.09.004

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

Dinosaur dung fertilizes planet, New Research

Alamosaurus Dinosaur. Credit: Northern Arizona University

Whether it started with exhibits at the Natural History Museum or fun-terrified screams watching Jurassic Park, humans have always been awestruck by dinosaurs.

But little is known about what, if any, role dinosaurs and other large animals like mammoths or elephants play in ecosystem functioning. What would the world be like if they never existed?

Christopher Doughty, faculty member in the School of Informatics, Computing and Cyber Systems at Northern Arizona University, asks that question often. He has been studying large animals for more than 10 years, specifically how these animals have increased the planet’s fertility.

“Theory suggests that large animals are disproportionately important to the spread of fertility across the planet,” Doughty said. “What better way to test this than to compare fertility in the world during the Cretaceous period — where sauropods, the largest herbivores to exist, roamed freely — to the Carboniferous period — a time in Earth’s history before four-legged erbivores evolved.”

During these two periods, plants were buried faster than they could decompose. As a result, coal was formed. Doughty gathered coal samples from mines throughout the U.S. By measuring the coal elemental concentrations, he found elements needed by plants, like phosphorus, were more abundant and much better distributed during the era of the dinosaurs than the Carboniferous. The data also revealed that elements not needed by plants and animals, such as aluminum, showed no difference, suggesting the herbivores contributed to increased global fertility.

According to Doughty, these large animals are important not for the quantity of dung they produce, but for their ability to move long distances across landscapes, effectively mixing the nutrients. By increasing the abundance and distribution of elements like phosphorus, plants grow faster, meaning large herbivores are responsible for producing their own food and contributing to their lush habitats.

But as today’s large animal populations become more in danger of extinction, the environment too is at risk. Simply put, fewer large animals may mean less plant growth.

“This is important for two reasons,” Doughty said. “First, we are rapidly losing our remaining large animals, like forest elephants, and this loss will critically impair the future functioning of these ecosystems by reducing their fertility. Second, combining the idea that large animals are disproportionately important for the spread of nutrients with the natural rule that animal size increases over time, means the planet may have a Gaia-like mechanism of increasing fertility over time. Life makes the planet easier for more life.”

Note: The above post is reprinted from materials provided by Northern Arizona University. Original written by Carly Banks.

Lost mountains in the Karoo reveal the secrets of massive extinction event

Mountains
Representative Image: Valley of the Ten Peaks and Moraine Lake, Banff National Park, Canada. Mountains from left to right: Tonsa (3057 m), Mount Perren (3051 m), Mount Allen (3310 m), Mount Tuzo (3246 m), Deltaform Mountain (3424 m), Neptuak Mountain (3233 m). Credit: Gorgo/Wikimedia

Fossil records near the lost Gondwanides mountains show that the Permian–Triassic extinction started 1 million years prior to what was previously believed.

Millions of years ago, a mountain range that would have dwarfed the Andes mountains in South America, stretched over what is currently the southern-most tip of Africa.

Remnants of these mountains — called the Gondwanides, after the massive supercontinent, Gondwana over which it stretched — once spanned the southern continents of South America, Antarctica, South Africa and Australia, and parts of it now form the mountains near Cape Town in South Africa.

It is in the shadows of these ancient mountains that Dr Pia Viglietti, a post-doctoral fellow at the Evolutionary Studies Institute (ESI) at Wits University, found the secrets of one of the biggest mass extinction events that Earth has ever seen.

“We’ve established that climatic changes related to the devastating end of the Permian mass extinction event about 250 Million years ago were beginning earlier than previously identified,” says Viglietti.

The Permian-Triassic extinction was one of Earth’s largest extinction events, in which up to 96% of all marine species and 70% of terrestrial vertebrate species became extinct.

For her PhD, Viglietti studied the fossil-rich sediments present in the Karoo, deposited during the tectonic events that created the Gondwanides, and found that the vertebrate animals in the area started to either go extinct or become less common much earlier than what was previously thought. Her research was published in Scientific Reports.

“The Karoo Basin takes up a huge portion of South Africa and most of us who drive through it do not think much of it,” says Viglietti. “But if you know what you’re looking for, the Karoo represents a wealth of knowledge about the story of life on Earth.”

The Karoo tells a 100 million-year long story of the supercontinent Gondwana, and if you can read this rock record you will find the story of the life and death of the animals it supported.

“The Gondwanides not only influenced how and where rivers flowed (depositing sediment), it also had a significant effect on the climate, and thus the ancient fauna of the Karoo Basin,” says Viglietti.

Large mountain ranges put a lot of weight on Earth’s crust, creating a depression in the crust. This can be described by using the analogy of a person standing on the edge of a diving board. The person represents the “load” (or weight) of the mountain while the diving board is Earth’s crust. The depression causes sediment to accumulate around the mountain’s base. It is in this sediment, where rocks and fossils are preserved.

As mountains erode, they put less weight on Earth’s crust, and the depression decreases, just like the diving board would react to the diver jumping off it. This was the effect that the Gondwanides had on the sedimentation in the Karoo Basin over a 100 Million years. The traces of this tectonic dance are preserved by periods of deposition and non-deposition.

“During my PhD, I have identified a new tectonic “loading” event (mountain building event) that kick-started sedimentation in the Latest Permian Karoo Basin,” says Viglietti.

The sediments during this loading event also provided evidence of climatic changes as well as evidence of a previously overlooked “faunal turnover,” that points to the start of the end Permian mass extinction event.

“Within the last million years before this major biotic crisis, the animals had already started to react. I interpret this faunal change as resulting from climatic effects relating to the end-Permian mass extinction event — only occurring much earlier than previously identified,” says Viglietti.

Reference:
Pia A. Viglietti, Bruce S. Rubidge, Roger M. H. Smith. New Late Permian tectonic model for South Africa’s Karoo Basin: foreland tectonics and climate change before the end-Permian crisis. Scientific Reports, 2017; 7 (1) DOI: 10.1038/s41598-017-09853-3

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

Researcher links salmon sex to geological change

A salmon swims near a redd, or nest, with Mount Shasta in the background. A Washington State University researcher has found that the mating habits of salmon can alter the profile of stream beds, affecting the evolution of an entire watershed. Credit: Photo by Carson Jeffres

It turns out that sex can move mountains.

A Washington State University researcher has found that the mating habits of salmon can alter the profile of stream beds, affecting the evolution of an entire watershed. His study is one of the first to quantitatively show that salmon can influence the shape of the land.

Alex Fremier, lead author of the study and associate professor in the WSU School of the Environment, said female salmon “fluff” soil and gravel on a river bottom as they prepare their nests, or redds. The stream gravel is then more easily removed by flooding, which opens the underlying bedrock to erosion.

“The salmon aren’t just moving sediment,” said Fremier. “They’re changing the character of the stream bed, so when there are floods, the soil and gravel is more mobile.”

The study, “Sex that moves mountains: The influence of spawning fish on river profiles over geologic timescales,” appears in the journal Geomorphology.

Working with colleagues at the University of Idaho and Indiana University, Fremier modeled the changes over 5 million years and saw streams with spawning salmon lowering stream slopes and elevation over time. Land alongside the stream can also get steeper and more prone to erosion.

“Any lowering of the streambed translates upstream to lower the entire landscape,” said Fremier.

Different salmon species can have different effects, Fremier said. Chinook salmon can move bigger pieces of material, while coho tend to move finer material. Over time, this diversification can lead to different erosion rates and changes to the landscape.

The paper is another way of looking at the role of living things in shaping their nonliving surroundings. Trees prevent landslides; beavers build dams that slow water, creating wetlands, flood plains and habitats for different trees and animals.

In 2012, researchers writing in Nature Geoscience described how, before the arrival of trees more than 300 million years ago, landscapes featured broad, shallow rivers and streams with easily eroded banks. But tree roots stabilized river banks and created narrow, fixed channels and vegetated islands, while log jams helped create the formation of new channels. The new landscape in turn led to “an increasingly diverse array of organisms,” the researchers wrote.

Similarly, said Fremier, salmon can be creating new stream habitats that encourage the rise of new salmon species. On the other hand, streams where salmon drop in number or disappear altogether could see significant long-term changes in their profile and ecology.

“The evolution of a watershed can be influenced by the evolution of a species” Fremier said.

Reference:
Sex that moves mountains: The influence of spawning fish on river profiles over geologic timescales. DOI: 10.1016/j.geomorph.2017.09.033

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

Microbes Leave “Fingerprints” on Martian Rocks

Metallosphaera sedula grown on synthetic Martian Regolith. The microbes are specifically stained by Fluorescence-In-Situ-Hybridization (FISH). Credit: Tetyana Milojevic

At the Department of Biophysical Chemistry at the University of Vienna, Tetyana Milojevic and her team have been operating a miniaturized “Mars farm” in order to simulate ancient and probably extinct microbial life – based on gases and synthetically produced Martian regolith of diverse composition. The team investigates interactions between Metallosphaera sedula, a microbe that inhabits extreme environments, and different minerals which contain nutrients in form of metals. Metallosphaera sedula is a chemolithotroph, means being capable of metabolizing inorganic substances like iron, sulphur and uranium as well.

To satisfy microbial nutritional fitness, the research team uses mineral mixtures that mimic the Martian regolith composition from different locations and historical periods of Mars: “JSC 1A” is mainly composed of palagonite – a rock that was created by lava; “P-MRS” is rich in hydrated phyllosilicates; the sulfate containing “S-MRS”, emerging from acidic times on Mars and the highly porous “MRS07/52” that consists of silicate and iron compounds and simulates sediments of the Martian surface.

“We were able to show that due to its metal oxidizing metabolic activity, when given an access to these Martian regolith simulants, M. sedula actively colonizes them, releases soluble metal ions into the leachate solution and alters their mineral surface leaving behind specific signatures of life, a ‘fingerprint’, so to say”, explains Milojevic. The observed metabolic activity of M. sedula coupled to the release of free soluble metals can certainly pave the way to extraterrestrial biomining, a technique which extracts metals from ores, launching the biologically assisted exploitation of raw materials from asteroids, meteors and other celestial bodies.

Using electron microscopy tools combined with analytical spectroscopy techniques, the researchers were able to examine the surface of bioprocessed Martian regolith simulants in detail. Cooperation with the workgroup of chemist Veronika Somoza from the Department of Physiological Chemistry was valuable to achieve these results. “The obtained results expand our knowledge of biogeochemical processes of possible life beyond earth, and provide specific indications for detection of biosignatures on extraterrestrial material – a step further to prove potential extra-terrestrial life”, says Tetyana Milojevic.

Reference:
“Frontiers in Microbiology”, Research Topic “Habitability Beyond Earth”: Kölbl D, Pignitter M, Somoza V, Schimak MP, Strbak O, Blazevic A and Milojevic T (2017) Exploring Fingerprints of the Extreme Thermoacidophile Metallosphaera sedula Grown on Synthetic Martian Regolith Materials as the Sole Energy Sources. Front. Microbiol. 8:1918. DOI: 10.3389/fmicb.2017.01918

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

Scientists determine source of world’s largest mud eruption

mud eruption
On May 29, 2006, mud started erupting from several sites on the Indonesian island of Java and hasn’t stopped since. The eruption became known as Lusi and is the most destructive ongoing mud eruption in history. Credit: Adriano Mazzini/The Lusi Lab Project

On May 29, 2006, mud started erupting from several sites on the Indonesian island of Java. Boiling mud, water, rocks and gas poured from newly-created vents in the ground, burying entire towns and compelling many Indonesians to flee. By September 2006, the largest eruption site reached a peak, and enough mud gushed on the surface to fill 72 Olympic-sized swimming pools daily.

Indonesians frantically built levees to contain the mud and save the surrounding settlements and rice fields from being covered. The eruption, known as Lusi, is still ongoing and has become the most destructive ongoing mud eruption in history. The relentless sea of mud has buried some villages 40 meters (130 feet) deep and forced nearly 60,000 people from their homes. The volcano still periodically spurts jets of rocks and gas into the air like a geyser. It is now oozing around 80,000 cubic meters (3 million cubic feet) of mud each day — enough to fill 32 Olympic-sized pools. Watch a video of the Lusi eruption here: https://www.youtube.com/watch?v=1PXS1OIAD4o&feature=youtu.be

Now, more than 11 years after it first erupted, researchers may have figured out why the mudflows haven’t stopped: deep underground, Lusi is connected to a nearby volcanic system.

In a new study, researchers applied a technique geophysicists use to map Earth’s interior to image the area beneath Lusi. The images show the conduit supplying mud to Lusi is connected to the magma chambers of the nearby Arjuno-Welirang volcanic complex through a system of faults 6 kilometers (4 miles) below the surface.

Volcanoes can be connected to each other deep underground and scientists suspected Lusi and the Arjuno-Welirang volcanic complex were somehow linked, because previous research showed some of the gas Lusi expels is typically found in magma. But no one had yet shown that Lusi is physically connected to Arjuno-Welirang.

The researchers discovered that the scorching magma from the Arjuno-Welirang volcano has essentially been “baking” the organic-rich sediments underneath Lusi. This process builds pressure by generating gas that becomes trapped below the surface. In Lusi’s case, the pressure grew until an earthquake triggered it to erupt.

Studying the connection of these two systems could help scientists to better understand how volcanic systems evolve, whether they erupt magma, mud or hydrothermal fluids.

“We clearly show the evidence that the two systems are connected at depth,” said Adriano Mazzini, a geoscientist at CEED — University of Oslo and lead author of the new study in the Journal of Geophysical Research: Solid Earth, a journal of the American Geophysical Union. “What our new study shows is that the whole system was already existing there — everything was charged and ready to be triggered.”

Finding a connection

Java is part of a volcanic island arc, formed when one tectonic plate subducts below another. As the island rose upward out of the sea, volcanoes formed along its spine, with basins of shallow water between them. Lusi’s mud comes from sediments laid down in those basins while the island was still partially submerged underwater.

Mazzini has been studying Lusi since soon after the eruption began. Two years ago, the study’s authors installed a network of 31 seismometers around Lusi and the neighboring volcanic complex. Researchers typically use seismometers to measure ground shaking during earthquakes, but scientists can also use them to create three-dimensional images of the areas underneath volcanoes.

Using 10 months of data recorded by the seismometers, Mazzini and his colleagues imaged the area below Lusi and the surrounding volcanoes. The images showed a tunnel protruding from the northernmost of Arjuno-Welirang’s magma chambers into the sedimentary basin where Lusi is located. This allows magma and hydrothermal fluids originating in the mantle to intrude into Lusi’s sediments, which triggers massive reactions and creates gas that generates high pressure below Earth’s surface. Any perturbation — like an earthquake — can then trigger this system to erupt.

“It’s just a matter of reactivating or opening these faults and whatever overpressure you have gathered in the subsurface will inevitably want to escape and come to the surface, and you have a manifestation on the surface, and that is Lusi,” Mazzini said.

Triggering an eruption

Mazzini and other researchers suspect a magnitude 6.3 earthquake that struck Java two days before the mud started flowing was what triggered the Lusi eruption, by reactivating the fault system that connects it to Arjuno-Welirang.

By allowing magma to flow into Lusi’s sedimentary basin, the fault system could be an avenue for moving the entire volcanic system northward, said Stephen Miller, a professor of geodynamics at the University of Neuchâtel in Neuchâtel, Switzerland who was not connected to the study.

“It looks like this might be the initial stages of this march forward of this volcanic arc,” Miller said. “Ultimately, it’s bringing all this heat over toward Lusi, which is driving that continuous system.”

Mazzini and other scientists are unsure how much longer Lusi will continue to erupt. While mud volcanoes are fairly common on Java, Lusi is a hybrid between a mud volcano and a hydrothermal vent, and its connection to the nearby volcano will keep sediments cooking for years to come.

“So what it means to me is that Lusi’s not going to stop anytime soon,” Miller said.

Reference:
Mohammad Javad Fallahi, Anne Obermann, Matteo Lupi, Karyono Karyono, Adriano Mazzini. The plumbing system feeding the Lusi eruption revealed by ambient noise tomography. Journal of Geophysical Research: Solid Earth, 2017; DOI: 10.1002/2017JB014592

Note: The above post is reprinted from materials provided by American Geophysical Union.

Keratin, proteins from 54-million-year-old sea turtle show survival trait evolution

Fossil (left) and modern sea turtle hatchlings. Credit: Johan Lindgren

Researchers from North Carolina State University, Lund University in Sweden and the University of Hyogo in Japan have retrieved original pigment, beta-keratin and muscle proteins from a 54 million-year-old sea turtle hatchling. The work adds to the growing body of evidence supporting persistence of original molecules over millions of years and also provides direct evidence that a pigment-based survival trait common to modern sea turtles evolved at least 54 million years ago.

Tasbacka danica is a species of sea turtle that lived during the Eocene period, between 56 and 34 million years ago. In 2008 an extremely well-preserved T. danica hatchling was recovered from the Für formation in Jutland, Denmark. The specimen was less than 3 inches (74 millimeters) long. In 2013 paleontologist Johan Lindgren of Lund University uncovered soft tissue residues from an area located near the sea turtle’s left “shoulder.” He collected five small samples for biomolecular analysis.

The shells of modern sea turtle hatchlings are dark colored — this pigmentation gives them protection from aerial predators (such as seagulls) as they float on the ocean surface to breathe. Since turtles are reptiles, and therefore cold-blooded, the dark coloration also allows them to absorb heat from sunlight and regulate their body temperature. This elevated body temperature also allows more rapid growth, reducing the time they are vulnerable at the ocean surface.

The T. danica hatchling specimen appeared to share this coloration with its living counterparts. The researchers observed round organelles in the fossil that could be melanosomes, pigment-containing structures in the skin (or epidermis) that give turtle shells their dark color.

To determine the structural and chemical composition of the soft tissues Lindgren collected and see if the fossil sea turtle did have a dark colored shell, the researchers subjected the sample to a selection of high-resolution analytical techniques, including field emission gun scanning electron microscopy (FEG-SEM), transmission electron microscopy (TEM), in situ immunohistochemistry, time-of-flight secondary ion mass spectrometry (ToF-SIMS), and infrared (IR) microspectroscopy.

Lindgren performed ToF-SIMS on the samples to confirm the presence of heme, eumelanin and proteinaceous molecules — the components of blood, pigment and protein.

Co-author Mary Schweitzer, professor of biological sciences at NC State with a joint appointment at the North Carolina Museum of Natural Sciences, performed histochemical analyses of the sample, finding that it tested positive against antibodies for both alpha and beta-keratin, hemoglobin and tropomyosin, a muscle protein. TEM, performed by University of Hyogo evolutionary biologist Takeo Kuriyama, and Schweitzer’s immunogold testing further confirmed the findings.

In the end, the evidence pointed to these molecules as being original to the specimen, confirming that these ancient turtles shared a pigmentation-based survival trait with their modern-day brethren.

“The presence of eukaryotic melanin within a melanosome embedded in a keratin matrix rules out contamination by microbes, because microbes cannot make eukaryotic melanin or keratin,” Schweitzer says. “So we know that these hatchlings had the dark coloration common to modern sea turtles.

“The data not only support the preservation of multiple proteins, but also suggest that coloration was used for physiology as far back as the Eocene, in the same manner as it is today.”

Reference:
Johan Lindgren, Takeo Kuriyama, Henrik Madsen, Peter Sjövall, Wenxia Zheng, Per Uvdal, Anders Engdahl, Alison E. Moyer, Johan A. Gren, Naoki Kamezaki, Shintaro Ueno, Mary H. Schweitzer. Biochemistry and adaptive colouration of an exceptionally preserved juvenile fossil sea turtle. Scientific Reports, 2017; 7 (1) DOI: 10.1038/s41598-017-13187-5

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

Study shows how water could have flowed on ‘cold and icy’ ancient Mars

Extensive valley networks spidering through the southern highlands of Mars suggest that the planet was once warmer and wetter, but new research shows that water could still have flowed intermittently on a cold and icy early Mars. Credit: NASA/JPL-Caltech/Arizona State University

For scientists trying to understand what ancient Mars might have been like, the red planet sends some mixed signals. Water-carved valleys and lakebeds leave little doubt that water once flowed on the surface. But climate models for early Mars suggest average temperatures around the globe stayed well below freezing.

A recent study led by Brown University geologists offers a potential bridge between the “warm and wet” story told by Martian geology and the “cold and icy” past suggested by atmospheric models. The study shows that it’s plausible, even if Mars was generally frozen over, that peak daily temperatures in summer might sneak above freezing just enough to cause melting at the edges of glaciers. That meltwater, produced in relatively small amounts year after year, could have been enough to carve the features observed on the planet today, the researchers conclude.

The study is published online in the journal Icarus. Ashley Palumbo, a Ph.D. student at Brown, led the work with Jim Head, a professor in Brown’s Department of Earth, Environmental and Planetary Science, and Robin Wordsworth, a professor in Harvard’s School of Engineering and Applied Sciences.

Palumbo says the research was inspired by climate dynamics found here on Earth.

“We see this in the Antarctic Dry Valleys, where seasonal temperature variation is sufficient to form and sustain lakes even though mean annual temperature is well below freezing,” Palumbo said. “We wanted to see if something similar might be possible for ancient Mars.”

The researchers started with a state-of-the-art climate model for Mars — one that assumes an ancient atmosphere composed largely of carbon dioxide (as it is today). The model generally produces a cold and icy early Mars, partly because the sun’s energy output is thought to have been much weaker early in solar system history. The researchers ran the model for a broad parameter space for variables that may have been important around 4 billion years ago when the iconic valley networks on the planet’s southern highlands were formed.

While scientists generally agree that the Martian atmosphere was thicker in the past, it’s not clear just how thick it actually was. Likewise, while most researchers agree that the atmosphere was mostly carbon dioxide, there may have been small amounts of other greenhouse gases present. So Palumbo and her colleagues ran the model with various plausible atmospheric thicknesses and extra amounts of greenhouse warming.

It’s also not known exactly what the variations in Mars’ orbit might have been like 4 billion years ago, so the researchers tested a range of plausible orbital scenarios. They tested different degrees of axis tilt, which influences how much sunlight the planet’s upper and lower latitudes receive, as well as different degrees of eccentricity — the extent to which the planet’s orbit around the sun deviates from a circle, which can amplify seasonal temperature changes.

The model produced scenarios in which ice covered the region near the location of the valley networks. And while the planet’s mean annual temperature in those scenarios stayed well below freezing, the model produced peak summertime temperatures in the southern highlands that rose above freezing.

In order for this mechanism to possibly explain the valley networks, it must produce the correct volume of water in the time duration of valley network formation, and the water must run off on the surface at rates comparable to those required for valley network incision. A few years ago, Head and Eliot Rosenberg, an undergraduate at Brown at the time who has since graduated, published an estimate of the minimum amount of water required to carve the largest of the valleys. Using that as a guide, along with estimates of necessary runoff rates and the duration of valley network formation from other studies, Palumbo showed that model runs in which the Martian orbit was highly eccentric did indeed meet these criteria. That degree of eccentricity required is well within the range of possible orbits for Mars 4 billion years ago, Palumbo says.

Taken together, Palumbo says, the results offer a potential means of reconciling the geological evidence for flowing water on early Mars with the atmospheric evidence for a cold and icy planet.

“This work adds a plausible hypothesis to explain the way in which liquid water could have formed on early Mars, in a manner similar to the seasonal melting that produces the streams and lakes we observe during our field work in the Antarctic McMurdo Dry Valleys,” Head said. “We are currently exploring additional candidate warming mechanisms, including volcanism and impact cratering, that might also contribute to melting of a cold and icy early Mars.”

So while the work doesn’t close the “cold and icy” versus “warm and wet” debate, it does make the case that a mostly frozen early Mars was a distinct possibility.

Reference:
Ashley M. Palumbo, James W. Head, Robin D. Wordsworth. Late Noachian Icy Highlands climate model: Exploring the possibility of transient melting and fluvial/lacustrine activity through peak annual and seasonal temperatures. Icarus, 2018; 300: 261 DOI: 10.1016/j.icarus.2017.09.007

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

Study reshapes understanding of climate change’s impact on early societies

Credit: Department of Papyrology, Institute of Archaeology, University of Warsaw

A new study linking paleoclimatology — the reconstruction of past global climates — with historical analysis by researchers at Yale and other institutions shows a link between environmental stress and its impact on the economy, political stability, and war-fighting capacity of ancient Egypt.

The team of researchers examined the hydroclimatic and societal impacts in Egypt of a sequence of tropical and high-latitude volcanic eruptions spanning the past 2,500 years, as known from modern ice-core records. The team focused on the Ptolemaic dynasty of ancient Egypt (305-30 B.C.E.) — a state formed in the aftermath of the campaigns of Alexander the Great, and famed for rulers such as Cleopatra — as well as material and cultural achievements including the great Library and Lighthouse of Alexandria.

Using an interdisciplinary approach that combined evidence from climate modelling of large 20th-century eruptions, annual measurements of Nile summer flood heights from the Islamic Nilometer — the longest-known human record of environmental variability — between 622 and 1902, as well as descriptions of Nile flood quality in ancient papyri and inscriptions from the Ptolemaic era, the authors show how large volcanic eruptions impacted on Nile river flow, reducing the height of the agriculturally-critical summer flood.

The findings, published in the journal Nature Communications, show that integrating evidence from historical writings with paleoclimate data can advance both our understanding of how the climate system functions, and how climatic changes impacted past human societies.

“Ancient Egyptians depended almost exclusively on Nile summer flooding brought by the summer monsoon in east Africa to grow their crops. In years influenced by volcanic eruptions, Nile flooding was generally diminished, leading to social stress that could trigger unrest and have other political and economic consequences,” says Joseph Manning, lead author on the paper and the William K. & Marilyn Milton Simpson Professor of History and Classics at Yale.

The reason for reduced flooding of the Nile is because volcanic eruptions can disrupt the climate by injecting sulfurous gases into the stratosphere, says Francis Ludlow, the study’s corresponding author. Ludlow is a climate historian who began collaborating with Manning as a postdoctoral fellow at Yale, and is now based in history in Trinity College, Dublin. These gases react to form aerosols that remain in the atmosphere in decreasing concentrations for one or two years, reflecting incoming solar radiation back to space. These volcanic aerosols can influence global hydroclimate. The reduction in surface temperatures can lead to reduced evaporation over waterbodies, and hence lessen rainfall. If the aerosols are dispersed primarily in the Northern Hemisphere, the greater cooling in this hemisphere can also diminish the summertime heating that drives the northward migration of monsoon winds over Africa up to the Ethiopian highlands where the Blue Nile is supplied with its summer floodwaters.

Because the Ptolemaic era is one of ancient Egypt’s most well-documented periods, the dates of major political events are known with some confidence, note the researchers, adding that what is often less clear from the ancient writings is what specific factors triggered events like revolts. The researchers were able to show a recurring close timing between such events and the dates of major volcanic eruptions. Knowledge of the historical context is essential to fully understanding how shocks from diminished Nile flooding acted to trigger revolts and constrain Ptolemaic war making, say the researchers, explaining that the shocks from poor Nile flooding would have occurred against a background of multiple socioeconomic and political difficulties that would have compounded the impacts of Nile variability.

“Egypt and the Nile are very sensitive instruments for climate change, and Egypt provides a unique historical laboratory in which to study social vulnerability and response to abrupt volcanic shocks,” says Manning. “Nile flood suppression from historical eruptions has been little studied, despite well documented Nile failures with severe social impacts coinciding with eruptions in 939, in 1783-1784 in Iceland, and 1912 in Alaska,” he adds.

“With volcanic eruption dates fixed precisely in time, we can see society in motion around them. This is the first time for ancient history that we can begin to talk about a dynamic understanding of society,” says Manning.

According to Manning, this research not only alters the perception of climatic changes on various scales, from short-term shocks to slower-moving, long-term changes, but it is also revolutionizing the understanding of human societies and how the forces of nature shaped them in the past. “The study is of particular importance for the current debate about climate change,” says Manning.

“It is very rare in science and history to have such strong and detailed evidence documenting how societies responded to climatic shocks in the past,” says Jennifer Marlon, research scientist in the Yale School of Forestry & Environmental Studies, and a co-author on the study.

The study reflects a significant advance in the integration of research among scientists and historians, and points to the need for more interdisciplinary scholarship to better document and analyze how humans have related and responded to past environmental changes, says Marlon.

The researchers note that the study provides historical context for what is happening today and what may happen in the future and demonstrates that there is need for further investigation into the effects of climate change on modern societies worldwide.

“There hasn’t been a large eruption affecting the global climate system since Mount Pinatubo in the Philippines in 1991,” says Manning. “We are living in a period where we are fairly quiescent in terms of large volcanic eruptions that are affecting climate. A lot of volcanoes erupt each year but they are not affecting the climate system on the scale of some past eruptions. Sooner or later we will experience a large volcanic eruption, and perhaps a cluster of them, that will act to exacerbate drought in sensitive parts of the world.”

Other authors on the study are Alexander R. Stine, San Francisco State University; William R. Boos, University of California-Berkeley; and Michael Sigl, Paul Scherrer Institute.

Reference:
Joseph G. Manning, Francis Ludlow, Alexander R. Stine, William R. Boos, Michael Sigl, Jennifer R. Marlon. Volcanic suppression of Nile summer flooding triggers revolt and constrains interstate conflict in ancient Egypt. Nature Communications, 2017; 8 (1) DOI: 10.1038/s41467-017-00957-y

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

Fault Types : What are the three main types of faults?

What is a fault?

A fault is a fracture or zone of fractures between two blocks of rock. Faults allow the blocks to move relative to each other. This movement may occur rapidly, in the form of an earthquake – or may occur slowly, in the form of creep. Faults may range in length from a few millimeters to thousands of kilometers. Most faults produce repeated displacements over geologic time. During an earthquake, the rock on one side of the fault suddenly slips with respect to the other. The fault surface can be horizontal or vertical or some arbitrary angle in between.

A fault plane is the plane that represents the fracture surface of a fault. A fault trace or fault line is the intersection of a fault plane with the ground surface. A fault trace is also the line commonly plotted on geologic maps to represent a fault.

Fault Types

Three main types of faults

Faults are subdivided according to the movement of the two blocks. There are three or four primary fault types:

Normal fault

Normal Fault

A dip-slip fault in which the block above the fault has moved downward relative to the block below. This type of faulting occurs in response to extension. “Occurs when the “hanging wall” moves down relative to the “foot wall””

Reverse fault

A dip-slip fault in which the upper block, above the fault plane, moves up and over the lower block. This type of faulting is common in areas of compression, When the dip angle is shallow, a reverse fault is often described as a thrust fault. “Occurs where the “hanging wall” moves up or is thrust over the “foot wall””

Strike-slip fault

strike slip fault

A fault on which the two blocks slide past one another. The San Andreas Fault is an example of a right lateral fault.

Types of Strike-slip fault movement

A left-lateral strike-slip fault

Left-lateral strike-slip fault

If you were to stand on the fault and look along its length, this is a type of strike-slip fault where the left block moves toward you and the right block moves away

A right-lateral strike-slip fault

Right-lateral strike-slip fault

If you were to stand on the fault and look along its length, this is a type of strike-slip fault where the right block moves toward you and the left block moves away.

Reference:
USGS: What is a fault and what are the different types?
USGS: Fault
University of Saskatchewan: Fault Types
University of Wisconsin System: Types of Earthquakes & Faults

What Is a Geologic Fault?

Quarry face showing 2 normal fault surfaces in the Upper Carboniferous sandstone and shale sequence of Round O Quarry, Lancashire, UK. Credit: University College Dublin

A fault is a planar fracture or discontinuity in a volume of rock, across which there has been significant displacement as a result of rock-mass movement.

Not every crack in the ground is a fault. What defines a fault is the movement of the rock on either side. When that movement is sudden, the released energy causes an earthquake. Some faults are tiny, but others are part of great fault systems along which rocks have slid past each other for hundreds of miles.

Large faults within the Earth’s crust result from the action of plate tectonic forces, with the largest forming the boundaries between the plates, such as subduction zones or transform faults. Energy release associated with rapid movement on active faults is the cause of most earthquakes.

A fault plane is the plane that represents the fracture surface of a fault. A fault trace or fault line is the intersection of a fault plane with the ground surface. A fault trace is also the line commonly plotted on geologic maps to represent a fault.

Since faults do not usually consist of a single, clean fracture, geologists use the term fault zone when referring to the zone of complex deformation associated with the fault plane.

Different types of Faults

1- Normal Faulting
2- Reverse Faulting
3- Strike-slip Faulting
4- Dip-slip faulting
5- Oblique-slip faulting
6- Listric faulting

Three main types of faults

Reference:
– Wikipedia: Fault (geology)
– USGS: What is a Fault?
– University College Dublin: Fault Analysis

Is it gonna blow? Measuring volcanic emissions from space

Simon Carn measures gas emissions from Mount Yasur in the island nation of Vanuatu in 2014. Credit: Simon Carn

Late last month, a stratovolcano in Bali named Mount Agung began to smoke. Little earthquakes trembled beneath the mountain. Officials have since evacuated thousands of people to prevent what happened when Agung erupted in 1963, killing more than 1,000 people.

Before volcanoes erupt, there are often warning signs. Tiny earthquakes rarely felt by humans but sensed by seismographs emanate from the volcano. Plumes of water vapor rise from the crater. When the volcano begins to emit gases like carbon dioxide and sulfur dioxide, eruption may be imminent.

But getting close to the top of a volcano is dangerous work. Using remote sensing to detect rising carbon dioxide and sulfur dioxide emissions without endangering people or equipment would greatly increase human understanding of volcanoes. Remote sensing emissions could prevent humanitarian disasters—and false alarms.

Mount Agung hasn’t erupted yet (at the time this article was written), but seismic activity remains intense. Balinese officials are beginning to wonder if an eruption truly is imminent; the people who were evacuated from the area want to return to their homes and tourism is down.

Researchers including Michigan Technological University volcanologist Simon Carn have published a collection of papers including “Spaceborne detection of localized carbon dioxide sources” in the journal Science; the article details the first-known measurement of localized anthropogenic and natural carbon dioxide sources from a satellite in low-Earth orbit.

The five papers in the OCO-2 Science Special Collection showcase the abilities of NASA’s Orbiting Carbon Observatory-2 (OCO-2) satellite; measurements from the satellite’s sensors provide insights into how carbon links everything on Earth. The research is supported by NASA’s Jet Propulsion Laboratory.

Monitoring CO2 Emissions From Space

The paper Carn co-authored discusses how the research team has taken high-resolution, sensitive spaceborne measurements of atmospheric carbon dioxide at the kilometer scale. This data reveals that the satellite’s sensors are able to pinpoint localized sources of carbon dioxide in the atmosphere—a difficult task considering the sheer amount of background carbon dioxide in the atmosphere to begin with.

The satellite uses spectrometry; the sensors onboard the satellite measure reflected sunlight—radiation—in high-spectral resolution using wavelengths undetectable to the human eye. When light passes through carbon dioxide, some is absorbed by the gas. The remaining light bounces off the ocean and the Earth. The OCO-2 sensors measure the light that bounces back to quantify what was absorbed by carbon dioxide, allowing scientists to isolate emission sources, whether human or natural.

“The main focus of the article is detecting localized, point-source emissions of carbon dioxide as opposed to measuring the broad-scale concentration in the atmosphere,” says Carn, an associate professor in the Department of Geological and Mining Engineering and Sciences. “Volcanoes can be strong, localized sources of carbon dioxide. But on a global basis, all available evidence indicates that human activities are emitting much more carbon dioxide than volcanoes.”

The OCO-2 satellite’s spatial resolution—2.25 kilometers—is high enough that chemical signals are not diluted. However, while OCO-2’s measurements are unprecedented, the satellite cannot be used as a routine volcano monitoring tool because it does not pass over the same place on the Earth frequently enough.

“This is a demonstration that the technique does work, but we need better sensors before it becomes a routine monitoring tool, especially for volcanoes where we expect rapid changes in gas emissions,” Carn says. “If we could measure volcanic carbon dioxide from space routinely, it would be a very powerful addition to the techniques we use. That kind of observation would be useful (for Agung) right now.”

Carn combed through satellite data to find detectable spaceborne carbon dioxide measurements from three volcanoes in the Pacific island nation of Vanuatu. One of these, Mount Yasur, has been erupting since at least the 1700s, and on the day of the OCO-2 measurement was emitting carbon dioxide about 3.4 parts per million above background atmospheric levels, equal to about 42 kilotons of emissions. In comparison, human emissions average 100,000 kilotons a day.

OCO-2’s sensors also measured carbon dioxide emissions over the Los Angeles basin, detecting a sort of carbon dioxide “dome”. Urban areas account for more than 70 percent of anthropogenic emissions.

“Natural processes on Earth are currently able to absorb about half of human fossil fuel emissions,” says Annmarie Eldering, OCO-2 deputy project scientist at NASA’s Jet Propulsion Laboratory in Pasadena, California, and lead author of an overview paper in Science on the state of OCO-2 science. “If those natural processes falter, slowing down the helpful removal of carbon dioxide, greenhouse-gas-induced warming would accelerate and intensify. These data begin to give us a better view of how climate affects the carbon cycle, reducing the huge uncertainty around how both might change in the future.”

The OCO-2 measurements across Los Angeles were detailed enough to capture differences in concentrations within the city resulting from localized sources. They also tracked diminishing carbon dioxide concentrations as the spacecraft passed from over the crowded city to the suburbs and out to the sparsely populated desert to the north.

Reference:
Florian M. Schwandner et al, Spaceborne detection of localized carbon dioxide sources, Science (2017). DOI: 10.1126/science.aam5782

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

Fanged kangaroo research could shed light on extinction

Credit: University of Queensland

Fanged kangaroos – an extinct family of small fanged Australian kangaroos – might have survived at least five million years longer than previously thought.

A University of Queensland-led study has found the species might have competed for resources with ancestors of modern kangaroos.

Research into species diversity, body size and the timing of extinction found that fanged kangaroos, previously thought to have become extinct about 15 million years ago, persisted to at least 10 million years ago.

The fanged kangaroos, including the species Balbaroo fangaroo, were about the size of a small wallaby.

UQ School of Earth and Environmental Sciences PhD student Kaylene Butler said the research involved Queensland Museum holdings of ancient fossil deposits from the Riversleigh World Heritage Area, where kangaroo fossil evidence goes back as far as 25 million years.

“Fanged kangaroos and the potential ancestors of modern kangaroos are both browsers – meaning they ate leaves – and they scurried, but did not hop,” Ms Butler said.

“Northern Queensland was predominantly covered in rainforest when these fanged kangaroos first appear in the fossil record.

“There is a lot of research to be done before we can be sure what their canine teeth were used for but some have suggested they were used to attract potential mates. We do know that despite their large canines they were herbivorous (plant eaters).

“We found that fanged kangaroos increased in body size right up until their extinction.”

Ms Butler said the research aimed to fill significant gaps in the understanding of kangaroo evolution, and new fossil finds were helping to bring ancient lineages into focus.

“Currently 21 macropod species are listed as vulnerable or endangered on the International Union for the Conservation of Nature Red List of Threatened Species,” she said.

She said understanding when and why kangaroos went extinct in the past could help with understanding what drove extinction of such animals.

“Currently, we can only hypothesise as to why balbarids became extinct – the original hypothesis related to events during a change in climate 15 million years ago but the balbarids persisted past that,” she said.

“This new finding of their persistence until 10 million years ago means something else must have been at play, such as being outcompeted by other species.”

Ms Butler last year discovered two new ancient species of kangaroo, Cookeroo bulwidarri and Cookeroo hortusensis.

Reference:
Kaylene Butler et al. Species abundance, richness and body size evolution of kangaroos (Marsupialia: Macropodiformes) throughout the Oligo-Miocene of Australia, Palaeogeography, Palaeoclimatology, Palaeoecology (2017). DOI: 10.1016/j.palaeo.2017.08.016

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

Fossil discovery in Tanzania reveals ancient bobcat-sized carnivore

A closer look at the bobcat-like fossil animal uncovered in Tanzania. Credit: Matthew Borths

Paleontologists working in Tanzania have identified a new species of hyaenodont, a type of extinct meat-eating mammal. The study is published today, National Fossil Day, in the journal PLOS ONE and funded by the National Science Foundation (NSF).

After the extinction of the non-avian dinosaurs 66 million years ago, hyaenodonts were the main predators on the African continent. The newly discovered animal is called Pakakali rukwaensis, the name derived from the Swahili term “pakakali,” meaning “fierce cat,” and “rukwaensis,” the word for the Rukwa Rift region of the Great Rift Valley in southwestern Tanzania.

Between 23 and 25 million years ago, newcomers arrived in Africa—the first relatives of modern dogs, cats and hyenas—where they coexisted with hyaenodonts for millions of years. But eventually, hyaenodonts went extinct.

“The shift from hyaenodonts to modern carnivores in Africa is like a controlled experiment,” says study co-author Matthew Borths of Ohio University.

“We start with only hyaenodonts. Then the relatives of cats and dogs arrive. They coexist for a few million years, then the hyaenodonts are driven to extinction and we’re left with ‘The Lion King.’ With Pakakali, we can start to unravel that extinction. Were the lineages competing? Were they adapting differently to a drier, more open landscape?”

The new fossil helps researchers unravel extinction dynamics for predatory mammals stalking African ecosystems of that long-ago time.

“This new carnivore, discovered in Tanzania sediment deposits dating from 25 million years ago, provides new information about the transition of carnivores in older ecosystem types to carnivores in today’s African ecosystems,” says Judy Skog, program director in NSF’s Division of Earth Sciences, which funded the research.

The new hyaenodont species was discovered in the same 25 million-year-old rocks as the oldest fossil evidence of the split between Old World monkeys and apes. At that time, the ecosystem was undergoing dramatic climate and tectonic upheavals as Africa collided with Eurasia and the modern East African Rift System formed.

The fossil gives paleontologists a glimpse of hyaenodont anatomy before modern carnivores invaded the continent, revealing that Pakakali was about the size of a bobcat.

Based on the findings of the study, hyaenodonts may have been pushed to become more specialized meat-eaters due to competition from other species. That dietary specialization may have made hyaenodonts more vulnerable to extinction in the changing African ecosystem by leaving them with fewer food choices.

Pakakali was discovered by an international team of scientists from the United States, Australia and Tanzania as part of the Rukwa Rift Basin Project (RRBP), an interdisciplinary collaboration examining the development of the modern African ecosystem. In more than a decade of exploration, RRBP researchers have described the habitat Pakakali called home along with many other animals that occupied the ecosystem.

“The environment containing Pakakali reveals a fascinating window into extinction,” says Nancy Stevens, co-author of the study and a paleontologist at Ohio University. “It highlights the vulnerability of carnivorous species to rapid environmental change, a topic we are grappling with on the African continent today.”

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

Geologic evidence is the forerunner of ominous prospects for a warming Earth

The image on the left shows eolian (lower) and runup bedding (upper) exposed in a roadcut on Old Land Road on Great Exuma Island (road elevation +23 meters). On the right are thick beds with fenestral porosity, or ‘beach bubbles,’ showing that massive waves ran up over older dunes exposed in a roadcut on Suzy Turn Road along the Atlantic Ocean east side of Providenciales, Turks and Caicos Islands, BWI. Credit: Marine Geology

While strong seasonal hurricanes have devastated many of the Caribbean and Bahamian islands this year, geologic studies on several of these islands illustrate that more extreme conditions existed in the past. A new analysis published in Marine Geology shows that the limestone islands of the Bahamas and Bermuda experienced climate changes that were even more extreme than historical events. In the interest of our future world, scientists must seek to understand the complexities of linked natural events and field observations that are revealed in the geologic record of past warmer climates.

In Bermuda and the Bahamas, the geology of the last interglacial (LIG; approximately 120,000 years ago) is exquisitely preserved in nearly pure carbonate sedimentary rocks. A record of superstorms and changing sea levels is exposed in subtidal, beach, storm, and dune deposits on multiple islands. Extensive studies by the authors over the past decades on these islands have documented stratigraphic, sedimentologic, and geomorphic evidence of major oceanic and climatic disruptions at the close of the last interglacial.

Dr. Paul J. Hearty, a retired Associate Professor at the University of North Carolina at Wilmington, and Dr. Blair. R. Tormey, a Coastal Research Scientist at Western Carolina University conducted an invited review of published findings. It demonstrates that during a global climate transition in the late last interglacial, also known as marine isotope substage 5e (MIS 5e), abrupt multi-meter sea-level changes occurred. Concurrently, coastlines of the Bahamas and Bermuda were impacted by massive storms generated in the North Atlantic Ocean, resulting in a unique trilogy of wave-transported deposits: megaboulders, chevron-shaped, storm-beach ridges, and runup deposits on high dune ridges.

While perhaps more mundane than the megaboulders (found only locally on Eleuthera), the sedimentological structures found within chevron ridge and runup deposits across islands throughout the Bahamas and Bermuda point to frequent and repeated inundation by powerful storm waves, in some locations leaving storm deposits tens of meters above sea level.

During the last interglacial, sea levels were about 3-9 meters higher than they are now. The geologic evidence indicates that the higher sea-levels were accompanied by intense “superstorms,” which deposited giant wave-transported boulders at the top of cliffed coastlines, formed chevron-shaped, storm beach ridges in lowland areas, and left wave runup deposits on older dunes more than 30 meters above sea level. These events occurred at a time of only slightly warmer global climate and CO2 (about 275 ppm) was much lower than today.

The authors emphasize “the LIG record reveals that strong climate forcing is not required to yield major impacts on the ocean and ice caps.” In our industrial world, rapidly increasing atmospheric CO2 has surpassed 400 ppm, levels not achieved since the Pliocene era about 3 million years ago, while global temperature has increased nearly 1 °C since the 1870s. Today, ice sheets are melting, sea level is rising, oceans are warming, and weather events are becoming more extreme.

Drs. Hearty and Tormey conclude that with the greatly increased anthropogenic CO2 forcing at rates unmatched in nature, except perhaps during global extinction events, dramatic change is certain. They caution that, “Our global society is producing a climate system that is racing forward out of humanity’s control into an uncertain future. If we seek to understand the non-anthropogenic events of the last interglaciation, some of the consequences of our unchecked forward speed may come more clearly into focus…a message from the past; a glimpse into the future.”

Reference:
P.J. Hearty, B.R. Tormey. Sea-level change and superstorms; geologic evidence from the last interglacial (MIS 5e) in the Bahamas and Bermuda offers ominous prospects for a warming Earth. Marine Geology, 2017; 390: 347 DOI: 10.1016/j.margeo.2017.05.009

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

Scientists describe ‘enigmatic’ species that lived in Utah some 500 million years ago

This is the only example of a species that lived in Utah during the mid Cambrian. Researchers believe the specimen probably drifted away from a community of similar stalked filter feeders. Credit: Julien Kimmig | KU News Service

To the untrained eye, it looks like a flower crudely etched into rock — as if a child had scratched a picture of a bloom. But to the late fossil hunter Lloyd Gunther, the tulip shape he unearthed at Antimony Canyon in northern Utah looked like the remnant of an ancient marine animal.

Years ago, Gunther collected the rock and later gave it to researchers at the University of Kansas’ Biodiversity Institute — just one among thousands of such fossils he donated to the institute over the years.

But this find was the only fossilized specimen of a species previously unknown to science — an “obscure” stalked filter feeder. It has just been detailed for the first time in a paper appearing in the Journal of Paleontology.

“This was the earliest specimen of a stalked filter feeder that has been found in North America,” said lead author Julien Kimmig, collections manager for Invertebrate Paleontology at the Biodiversity Institute. “This animal lived in soft sediment and anchored into the sediment. The upper part of the tulip was the organism itself. It had a stem attached to the ground and an upper part, called the calyx, that had everything from the digestive tract to the feeding mechanism. It was fairly primitive and weird.”

Kimmig researches the taxonomy, stratigraphy and paleoecology of the Cambrian Spence Shale found in Utah and Idaho, where Gunther found the obscure filter feeder.

“The Spence Shale gives us soft-tissue preservation, so we get a much more complete biota in these environments,” he said. “This gives us a better idea of what the early world was like in the Cambrian. It’s amazing to see what groups of animals had already appeared over 500 million years ago, like arthropods, worms, the first vertebrate animals — nearly every animal that we have around today has a relative that already lived during those times in the Cambrian.”

In honor of fossil hunter Gunther, a preeminent collector who performed fieldwork from the 1930s to the 2000s, Kimmig and Biodiversity Institute colleagues Luke Strotz and Bruce Lieberman named the newly described species Siphusauctum lloydguntheri.

The stalked filter feeder is just the second animal placed within its genus, and the first Siphusauctum to be discovered outside the Burgess Shale, a fossil-rich deposit in the Canadian Rockies.

“What these animals were doing was filtering water to get food, like micro-plankton,” Kimmig said. “The thing is, where this one was located we only found a single specimen over a period of 60 years of collecting in the area.”

Kimmig said it isn’t yet known if the newly discovered stalked filter feeder lived a highly solitary life or if it drifted off from a community of similar animals.

“It’s hard to tell from a single specimen,” he said. “There were algae found right next to it, so it likely was transported there. The algae found with it were planktonic algae that were floating themselves. It could have fallen just next to it — but that would be a big coincidence — so that’s why we’re thinking it came loose from somewhere else and got mixed in with the algae.”

Kimmig and his KU colleagues say the newly described specimen varies in key areas from similar known species of stalked filter feeders from the Cambrian.

“There are several differences in how the animal looked,” Kimmig said. “If you look at the digestive tract preserved in this specimen, the lower digestive tract is closer to the base of the animal compared to other animals. The calyx is very slim — it looks like a white wine glass, whereas in other species it looks like a big goblet. What we don’t have in this specimen that the others have are big branches for filter feeding. We don’t know if those weren’t preserved or if this one didn’t have them.”

According to the researchers, there are no species alive today that claim lineage to Siphusauctum lloydguntheri. But Kimmig said there were a few contemporary examples that share similarities.

“The closest thing to the lifestyle — but not a relative — would be crinoids, commonly called sea lilies,” he said. “Unfortunately, there’s likely not a relative of Siphusauctum in the world anymore. We have thousands of similar fossil specimens in the Burgess Shale, but it’s hard to identify what these animals actually were. It might be possibly related to contemporary entoprocts, which are a lot smaller than this one — but it’s hard to tell if they’re related at all.”

Ultimately, the mysterious stalked filter feeder is a reminder of the strange and vast arc of evolution where species continuously come and go, according to Kimmig.

“It is enigmatic because we don’t have anything living that is exactly like it,” he said. “What is fascinating about this animal is we can clearly relate it to animals existing in the Cambrian and then we just don’t find it anymore. It’s just fascinating to see how evolution works. Sometimes it creates something — and it just doesn’t work out. We have some lineages like worms that lived long before the Cambrian and haven’t changed in appearance or behavior, then we have things that were around for a couple of million years and just disappeared because they were chance victims of mass extinctions.”

Reference:
Julien Kimmig, Luke C. Strotz, Bruce S. Lieberman. The stalked filter feeder Siphusauctum lloydguntheri n. sp. from the middle Cambrian (Series 3, Stage 5) Spence Shale of Utah: its biological affinities and taphonomy. Journal of Paleontology, 2017; 91 (05): 902 DOI: 10.1017/jpa.2017.57

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

Risk of tsunamis in Mediterranean Sea has been overstated

The boulders on the Tipaza coast of Algeria that would have been deposited in a high-energy event. Credit: C. Morhange

A review of geological evidence for tsunamis during the past 4500 years in the Mediterranean Sea has revealed that as many as 90 per cent of these inundation events may have been misinterpreted by scientists and were due to storm activity instead.

“Understanding the true incidence of devastating tsunamis is vital for assessing the current risk and introducing appropriate protective strategies for densely populated coastal cities,” says study senior author and UNSW Sydney scientist Honorary Professor James Goff.

“Yet discriminating between tsunamis and storm deposits is one of the most challenging and hotly debated areas of coastal geoscience.

“Following intense media coverage of events like the devastating 2004 Indian Ocean tsunami, there has been a marked increase in geological research reporting evidence for past tsunamis in the Mediterranean.

“Our provocative and timely study suggests that up to 90 per cent of the claims for tsunamis having occurred in the Mediterranean in the past 4500 years need to be reconsidered. The risk from this hazard could have been significantly overstated in this region,” Professor Goff says.

The study, by an international team of scientists from UNSW, the French National Centre for Scientific Research, and the universities of Toulouse, Aix-Marseille and Exeter, is published in the journal Science Advances.

About 130 million people live around the Mediterranean Sea and it is one of the world’s leading tourist destinations, with more than 230 million visitors a year.

Geological evidence for past tsunamis includes the presence of large boulders on rocky coastlines, coarse sedimentary deposits in coastal lagoons, and high-energy marine deposits a long way inland.

The team studied 135 past events in eight Mediterranean countries that had been identified in the scientific literature as tsunamis on the basis of geological evidence, and which had been dated using a variety of scientific techniques.

“We compared these events with storm records for the same period,” says study first author Dr Nick Marriner of the French National Centre for Scientific Research.

“We found the dates for the tsunamis peaked every 1500 years – at about 200, 1600 and 3100 years ago. This matched well with 1500-year climate cycles of cooling in the Mediterranean and North Atlantic and heightened storm activity.

“This suggests most of the geological evidence is related to periods of severe storms, rather than tsunamis.”

The Mediterranean is famous for one of the most catastrophic tsunamis of all time – the tsunami caused by the Santorini eruption almost 3500 years ago that devastated the civilisation of Crete, leading to the legend of the lost city of Atlantis.

Reference:
N. Marriner el al., “Tsunamis in the geological record: Making waves with a cautionary tale from the Mediterranean,” Science Advances (2017). DOI: 10.1126/sciadv.1700485

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

‘Fake fin’ discovery reveals new ichthyosaur species

This is a skeleton of new species Protoichthyosaurus applebyi at University of Nottingham. Credit: Copyright University of Nottingham & Dean R. Lomax

An ichthyosaur first discovered in the 1970s but then dismissed and consigned to museum storerooms across the country has been re-examined and found to be a new species.

In 1979, after inspecting several ichthyosaurs from the UK, palaeontologist Dr Robert Appleby announced a new type of ichthyosaur called Protoichthyosaurus. He also named two species, P. prostaxalis and P. prosostealis. Other scientists, however, dismissed the discovery of Protoichthyosaurus and suggested that it was identical with Ichthyosaurus, a very common UK ichthyosaur.

Now a detailed study led by palaeontologists Dean Lomax (The University of Manchester) and Professor Judy Massare (State University of New York), has re-examined and compared Protoichthyosaurus and Ichthyosaurus. It found major differences in the number of bones in the front fin, or forefin, of both species. This fundamental difference probably reflects the way both species used them to manoeuvre whilst swimming. Differences were also found in the skulls. But it was another discovery about the fins that also got the team’s attention.

Lomax explains: “This unusual forefin structure was originally identified by Robert Appleby in 1979, but some of the historic specimens he examined had been ‘faked’, and this fakery had been missed until now. In some instances, an isolated fin of an Ichthyosaurus had been added to a Protoichthyosaurus skeleton to make it appear more complete, which led to the genuine differences being missed. This has been a major problem because it stopped science from progressing. We also found some pathological fins, including Ichthyosaurus fins with pathologies that mimic the Protoichthyosaurus forefin structure.”

Lomax and Massare also teamed up with former undergraduate student Rashmi Mistry (University of Reading), who had been studying an unusual ichthyosaur in the collections of the Cole Museum of Zoology, University of Reading, for her undergraduate dissertation.

“Whilst doing my dissertation in 2016, I studied several ichthyosaurs in the collections, including a very small skeleton. It had an unusual forefin that matched Protoichthyosaurus, which I understood to be a widely unrecognised genus. However, when I contacted Dean, he was very excited. He told me that this little skeleton is the only known small juvenile Protoichthyosaurus,” added Rashmi.

Over 20 specimens of Protoichthyosaurus were identified as part of this study. This is significant as each specimen (with a forefin) has the same structure. The specimens are from the Jurassic Period, between 200 — 190 million years old, and come from Somerset, Dorset, Leicestershire, Warwickshire, Nottinghamshire, England, and Glamorgan, Wales.

Whilst searching through collections, Dean also came across a skeleton at The University of Nottingham. This specimen is different to all other known examples of Protoichthyosaurus in the skull and humerus and it has been identified as a new species, which the team have called Protoichthyosaurus applebyi, in honour of Robert Appleby. It is currently on display as part of the ‘Dinosaurs of China’ exhibition at Lakeside Arts, University of Nottingham.

Reference:
Dean R. Lomax, Judy A. Massare, Rashmiben T. Mistry. The taxonomic utility of forefin morphology in Lower Jurassic ichthyosaurs: Protoichthyosaurus and Ichthyosaurus. Journal of Vertebrate Paleontology, 2017; e1361433 DOI: 10.1080/02724634.2017.1361433

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

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