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The living, breathing ocean

Light levels are shown as colored shading: magenta lines mark out low-nutrient regions and black lines show regions affected by sea-ice formation. Credit: Image courtesy of University of California – Santa Barbara

The ocean is a complex ecosystem. The ocean carbon cycle is governed by the relationship among carbon, nutrients and oxygen, and the ratio between certain elements is key to understanding ocean respiration.
Phytoplankton — photosynthesizing microscopic organisms inhabiting the upper sunlit layer of the ocean — play an important role in governing carbon, nutrients and oxygen cycles. A new study by UC Santa Barbara’s Timothy DeVries and Curtis Deutsch of the University of Washington reveals a threefold variation across latitudes in the ratio of oxygen consumed to phosphorus released during organic matter respiration. The findings, which appear today in the journal Nature Geoscience, demonstrate how climate change might affect the ratio of carbon, oxygen and nutrients in the subsurface ocean.

Just like trees and plants on Earth’s surface, phytoplankton take up nutrients and carbon, which are processed and released as organic matter that sinks to the ocean’s subsurface. In this study, DeVries and Deutsch focused primarily on the depth of 200 meters, which is below the photic zone. With no light no photosynthesis can occur. Once again mimicking the biological processes that take place on Earth’s surface, marine microbes in the ocean consume the organic matter and use oxygen to respire it.

The scientists estimated how much oxygen the microbes used per unit of phosphorus they have consumed, expressed as a ratio, O2:P. “The interesting thing we see is that this ratio varies a great deal,” said DeVries, a newly appointed assistant professor in UCSB’s Department of Geography and at the campus’s Earth Research Institute.

DeVries and Deutsch mapped out the O2:P ratio of microbial respiration at a 200-meter depth in the ocean. Credit: Image courtesy of University of California – Santa Barbara

“We’re not able to determine what varies the ratio, but just based on basic chemistry and biology, we know that it’s probably in large part due to variations in the carbon-to-phosphorus ratio of the organic matter that the microbes are consuming,” DeVries added. “So a high C:P ratio would correlate with a high O2:P ratio of respiration. The more carbon there is in the organic matter, the more oxygen it takes to respire it.

We’re quite confident that the O2:P ratio of microbial respiration that we’re seeing correlates with the C:P ratio of the phytoplankton. There have been measurements of this in the surface ocean and those measurements correlate to what we’re seeing in the subsurface.”

Such ratios, known as stoichiometry, describe the relative quantities of reactants and products in chemical reactions. The ocean circulation model and global climatologies of oxygen and phosphate used by DeVries and Deutsch allowed them to detect strong regional variabilities in the ratios of respired oxygen and phosphorus in the subsurface ocean. Previous analyses were unable to detect these variations because of the highly simplified ways they represented ocean mixing processes. In addition, the researchers said that ratio variations show close correlation with environmental conditions in the surface ocean.

Central to the team’s modeling results is how these spatial variations correlate with different ocean surface biomes or ecosystems. According to DeVries, some surface areas of the ocean contain few nutrients but an abundance of sunlight; other areas manifest the opposite combination: low light and plenty of nutrients.

“One of the reasons this is important is that in an ocean growing warmer under climate change, we expect an increase in regions of the ocean that have more light and are nutrient poor,” DeVries said. “Based on these patterns, we expect that will shift the phytoplankton community to a higher C:P ratio. If there is a shift toward this regime, there’s going to be more carbon stored in the ocean than the corresponding situation in which there is no shift.”

That is actually a good thing, DeVries noted. Phytoplankton taking up more carbon because they are exposed to more light and fewer nutrients could help offset the predicted slowdown of the ocean’s uptake of carbon dioxide from the atmosphere. “As the Earth’s climate warms, it will cause the oceans to stratify and reduce their capacity to take up CO2, causing warming to accelerate even faster,” DeVries continued. “This shift in C:P ratios that we predict could slow the acceleration slightly, but not halt it entirely.”

A related issue is how oceanic oxygen levels will change in the future. “As the ocean warms and the water holds less oxygen, low-oxygen regions are going to expand, and this will put a great deal of stress on marine animals,” DeVries concluded. “How much they expand and whether we can predict the extent is going to depend on the types of stoichiometric variability we see in this study.”

Reference:
Tim DeVries, Curtis Deutsch. Large-scale variations in the stoichiometry of marine organic matter respiration. Nature Geoscience, 2014; DOI: 10.1038/ngeo2300

Note : The above story is based on materials provided by University of California – Santa Barbara. The original article was written by Julie Cohen.

Investigators research the Laguna del Maule Volcanic Field, Chile

View southwest across Laguna del Maule, Chile, from near the summit of the vent for the Holocene rhyolite flows of Cari Launa at 3030 meters above sea level. The 1.2 cubic kilometers of brown glassy lava comprising the central lakeshore in the middle of the photo is the late Holocene rhyolite coulée of Las Nieblas, whose vent is 12.7 kilometers away. The center of maximum uplift measured using InSAR geodesy is in the bay just to the right (north) of the Nieblas rhyolite. Nathan Andersen is collecting pumice blocks for geochemical and geochronological study. Credit: Brad Singer, 6 April 2013.

The Laguna del Maule Volcanic Field, Chile, includes a record of unusually large and recent concentration of silicic eruptions. Since 2007, the crust there has been inflating at an astonishing rate of 25 centimeters per year. This unique opportunity to investigate the dynamics of a large rhyolitic system while magma migration, reservoir growth, and crustal deformation are actively under way is stimulating a new international collaboration.

Explosive eruptions of large-volume rhyolitic magma systems are common in the geologic record and pose a major potential threat to society. Unlike other natural hazards, such as earthquakes and tsunamis, a large rhyolitic volcano may provide warning signs long before a caldera-forming eruption occurs. Yet, these signs—and what they imply about magma-crust dynamics—are not well known.

This is because we have learned how these systems form, grow, and erupt mainly from the study of ash-flow tuffs deposited tens to hundreds of thousands of years ago or more, or from the geophysical imaging of the unerupted portions of the reservoirs beneath the associated calderas.

Research findings thus far lead to the hypothesis that the silicic vents have tapped an extensive layer of crystal-poor, rhyolitic melt that began to form atop a magmatic mush zone that was established by about 20,000 years ago, with a renewed phase of rhyolite eruptions during the Holocene. Modeling of surface deformation, magnetotelluric data, and gravity changes suggest that magma is currently intruding at a depth of approx. 5 km. The next phase of this investigation seeks to enlarge the sets of geophysical and geochemical data and to use these observations in numerical models of system dynamics.

Reference:
“Dynamics of a large, restless, rhyolitic magma system at Laguna del Maule, southern Andes, Chile.” B.S. Singer et al., University of Wisconsin–Madison, Dept. of Geoscience, Madison, Wisconsin 53706, USA, Pages 4–10; DOI: 10.1130/GSATG216A.1.

Note : The above story is based on materials provided by Geological Society of America

Turtles and dinosaurs: Scientists solve reptile mysteries with landmark study on the evolution of turtles

Turtles — like this alligator snapping turtle Macrochelys temminckii — are a diverse group of animals with a hotly contested evolutionary history. Researchers from the California Academy of Sciences used a next-generation genetic sequencing technique to reconstruct a robust turtle ‘tree of life’ and fill-in existing knowledge gaps. Credit: The California Academy of Sciences

A team of scientists, including researchers from the California Academy of Sciences, has reconstructed a detailed “tree of life” for turtles. The specifics of how turtles are related — to one another, to other reptiles, and even to dinosaurs — have been hotly debated for decades. Next generation sequencing technologies in Academy labs have generated unprecedented amounts of genetic information for a thrilling new look at turtles’ evolutionary history. These high-tech lab methods revolutionize the way scientists explore species origins and evolutionary relationships, and provide a strong foundation for future looks into Earth’s fossil record.

Research results, appearing in Molecular Phylogenetics and Evolution, describe how a new genetic sequencing technique called Ultra Conserved Elements (UCE) reveal turtles’ closest relatives across the animal kingdom. The new genetic tree uses an enormous amount of data to refute the notion that turtles are most closely related to lizards and snakes. Instead, authors place turtles in the newly named group “Archelosauria” with their closest relatives: birds, crocodiles, and dinosaurs. Scientists suspect the new group will be the largest group of vertebrates to ever receive a new scientific name.

The UCE technique used in high-tech labs allowed scientists to move beyond years of speculation and place the Archelosauria group in its rightful place on the reptile tree of life. UCE has been available since 2012, yet scientists are just beginning to tap its potential for generating enormous amounts of genetic data across vertebrates.

“Calling this is an exciting new era of sequencing technology is an understatement,” says Brian Simison, PhD, Director of the Academy’s Center for Comparative Genomics (CCG) that analyzed the study’s massive amount of data. The CCG is a state-of-the-art facility composed of a sequencing lab, frozen DNA collection, and computing resources that serves as the Academy’s core genetic center. Established in the summer of 2008, the CCG continues to refine Academy research — including new turtle findings — on a global, evolutionary scale.

“In the space of just five years, reasonably affordable studies using DNA sequencing have advanced from using only a handful of genetic markers to more than 2,000 — an unbelievable amount of DNA,” adds Simison. “New techniques like UCE dramatically improve our ability to help resolve decades-long evolutionary mysteries, giving us a clear picture of how animals like turtles evolved on our constantly-changing planet.”

Major findings also resolve an evolutionary mystery surrounding softshell turtles — a bizarre group of scale-less turtles with snorkel-like snouts. Until now, studies linked softshell turtles with a smaller semi-aquatic group called mud turtles, despite the fact that softshells appear in the fossil record long before their mud-loving counterparts. The Academy’s study places softshells in a league of their own on the evolutionary tree, quite far removed from any turtle relatives. Their long independent history helps explain their striking looks as well as their ancient presence in the fossil record.

Study coauthor James Parham, PhD — Academy Research Associate, Assistant Professor of Geological Sciences at Cal State Fullerton, and turtle expert — says cutting-edge testing techniques bring a new level of clarity to more than two decades of his turtle research. With large amounts of data backing up each evolutionary branch on the turtle tree of life, scientists are able to compare their evolution not only across species, but also across each continent’s corresponding fossil records.

“I have been working on the evolutionary relationships of turtles for over 20 years using a variety of methods,” says Parham. “Fossils are essential for showing us what extinct turtles looked like, but also in letting us know when and where they lived in the past.”

Parham notes that studying turtle fossils — particularly the physical features of their bones — hasn’t always painted an accurate evolutionary picture of turtle relationships across continents and through time. “The turtle tree of life based on fossil turtle anatomy didn’t match up with the timing of their appearance in the fossil record, as well as their geography,” Parham says. “But the tree of life generated at the Academy’s CCG is consistent with time and space patterns we’ve gathered from the fossil record. These new testing techniques help reconcile the information from DNA and fossils, making us confident that we’ve found the right tree.”

Reference:
Nicholas G. Crawford, James F. Parham, Anna B. Sellas, Brant C. Faircloth, Travis C. Glenn, Theodore J. Papenfuss, James B. Henderson, Madison H. Hansen, W. Brian Simison. A phylogenomic analysis of turtles. Molecular Phylogenetics and Evolution, 2014; DOI: 10.1016/j.ympev.2014.10.021

Note : The above story is based on materials provided by California Academy of Sciences.

New volume documents the science at the legendary snowmastodon fossil site in Colorado

Excavation of the initial Columbian mammoth remains found at the Ziegler Reservoir site. Snomass Village, CO, USA Photographer: Paul Carrara “U.S. Geological Survey “

DENVER-Four years ago, a bulldozer operator turned over some bones during construction at Ziegler Reservoir near Snowmass Village, Colorado. Scientists from the Denver Museum of Nature & Science were called to the scene and confirmed the bones were those of a juvenile Columbian mammoth, setting off a frenzy of excavation, scientific analysis, and international media attention. This dramatic and unexpected discovery culminates this month with the publication of the Snowmastodon Project Science Volume in the international journal Quaternary Research.
Fourteen papers by 47 authors from the United States and abroad collectively represent “a new benchmark for understanding climate change in the American West,” said paleontologist Dr. Ian Miller, Snowmastodon Project co-leader and chair of the Museum’s Earth Sciences Department.

Project co-leader and former DMNS chief curator, Dr. Kirk Johnson, and several scientists from the U.S. Geological Survey and academic institutions around the world contributed articles to the journal.

“Nothing beats pulling fossils out of the ground,” said project scientist Dr. Jeff Pigati of the U.S. Geological Survey, “but the site also lets us see what the Colorado Rockies were like during a period of time that we simply couldn’t reach before the discovery.”

The Snowmastodon site was an ancient lake that filled with sediment between 140,000 and 55,000 years ago preserving a series of Ice Age fossil ecosystems. Particularly fortuitous is the high-elevation locale, providing first-time documentation of alpine ecosystems during the last interglacial period between about 130,000 and 110,000 years ago. Because scientists were able to collect and study such a wide range of fauna and flora–from tiny specks of pollen to the bones of giant mastodons–the site emerged as a trove of information that Miller said will inspire future research for years to come.

“This project was unprecedented in its size, speed, and depth of collaboration. The science volume now moves beyond the pure excitement of the discovery to the presentation of its hard science and its implications for understanding the biological and climate history of the Rocky Mountain region,” said Johnson, now the Sant Director of the Smithsonian’s National Museum of Natural History.

Papers in the special edition focus on impacts of climate change, then and now. The site’s ecosystems–plants, insects, and animals combined–varied dramatically in response to climate change.

“In other words, turn the climate dial a little and the ecosystems change considerably. We were also surprised to find that certain periods in the record that seem to be cool elsewhere in North America were quite warm in the central Rockies,” said Miller. “The implication is that alpine ecosystems respond differently to climate change than other, lower elevation ecosystems. These new results have huge implications for predicting present-day climate change in Colorado and beyond.”

Usually fossil sites preserve only snapshots in time, which are then pieced together to understand past time periods. By contrast, the Snowmastodon site captures a nearly continuous 85,000-year time span. As a result, the site provides the best-known record of life and climate at high elevation anywhere in North America.

During a total of 69 days in 2010 and 2011, the Museum mobilized one of the largest fossil excavation efforts ever, recovering more than 5,000 large bones and 22,000 small bones representing roughly 50 different species. The site is most notable for containing the remains of at least 35 American mastodons, representing both genders as well as a variety of ages, from calves to full-grown adults.

“We had no idea that the high Rockies were filled with American mastodons during the last interglacial period,” Miller noted.

While the spectacular array of Ice Age animals initially drew scientists to the site, the opportunity to understand the world that they inhabited proved to be a powerful draw as well. “Scientists from around the world donated countless hours and resources toward the project,” said Pigati. “For so many of them to come together and reconstruct a world that no longer exists in such incredible detail, well that’s just a dream come true.”

Reference:
Kirk R. Johnson, Ian M. Miller, Jeffrey S. Pigati. Introduction to the Snowmastodon Project Special Volume. Quaternary Research, 2014; DOI: 10.1016/j.yqres.2013.12.010

Note : The above story is based on materials provided by Denver Museum of Nature & Science.

Zambezi River

The Zambezi is the fourth-longest river in Africa, and the largest flowing into the Indian Ocean from Africa. The area of its basin is 1,390,000 square kilometres (540,000 sq mi), slightly less than half that of the Nile. The 2,574-kilometre-long river (1,599 mi) rises in Zambia and flows through eastern Angola, along the eastern border of Namibia and the northern border of Botswana, then along the border between Zambia and Zimbabwe to Mozambique, where it crosses that country to empty into the Indian Ocean.

The Zambezi’s most noted feature is Victoria Falls. Other notable falls include the Chavuma Falls at the border between Zambia and Angola, and Ngonye Falls, near Sioma in Western Zambia.

There are two main sources of hydroelectric power on the river, the Kariba Dam, which provides power to Zambia and Zimbabwe, and the Cahora Bassa Dam in Mozambique, which provides power to Mozambique and South Africa. There is also a smaller power station at Victoria Falls.

Course of the river

Sources

The Zambezi and its river basin

The Zambezi and its river basinThe river rises in a black marshy dambo in north-west Zambia, in dense undulating miombo woodland, about 1,524 m (4,900 ft) above sea level. Eastward of the source, the watershed between the Congo and Zambezi basins is a well-marked belt of high ground, running nearly east-west and falling abruptly to the north and south. This distinctly cuts off the basin of the Lualaba (the main branch of the upper Congo) from that of the Zambezi. In the neighborhood of the source the watershed is not as clearly defined, but the two river systems do not connect.

The region drained by the Zambezi is a vast broken-edged plateau 900–1200 m high, composed in the remote interior of metamorphic beds and fringed with the igneous rocks of the Victoria Falls. At Shupanga, on the lower Zambezi, thin strata of grey and yellow sandstones, with an occasional band of limestone, crop out on the bed of the river in the dry season, and these persist beyond Tete, where they are associated with extensive seams of coal. Coal is also found in the district just below Victoria Falls. Gold-bearing rocks occur in several places.

Upper Zambezi

The river flows to the south-west into Angola for about 240 kilometres (150 mi), then is joined by sizeable tributaries such as the Luena and the Chifumage flowing from highlands to the north-west. It turns south and develops a floodplain, with extreme width variation between the dry and rainy seasons. It enters dense evergreen Cryptosepalum dry forest, though on its western side, Western Zambezian grasslands also occur. Where it re-enters Zambia it is nearly 400 metres (1,300 ft) wide in the rainy season and flows rapidly, with rapids ending in the Chavuma Falls, where the river flows through a rocky fissure. The river drops about 400 metres (1,300 ft) in elevation from its source at 1,500 metres (4,900 ft) to the Chavuma Falls at 1,100 metres (3,600 ft), in a distance of about 400 kilometres (250 mi). From this point to the Victoria Falls, the level of the basin is very uniform, dropping only by another 180 metres (590 ft) in a distance of around 800 kilometres (500 mi).

The first of its large tributaries to enter the Zambezi is the Kabompo River in the north-western province of Zambia. The savanna through which the river has flowed gives way to a wide floodplain, studded with Borassus fan palms. A little farther south is the confluence with the Lungwebungu River. This is the beginning of the Barotse Floodplain, the most notable feature of the upper Zambezi, but this northern part does not flood so much and includes islands of higher land in the middle.

Thirty kilometres below the confluence of the Lungwebungu the country becomes very flat, and the typical Barotse Floodplain landscape unfolds, with the flood reaching a width of 25 km in the rainy season. For more than 200 km downstream the annual flood cycle dominates the natural environment and human life, society and culture.

Eighty kilometres further down, the Luanginga, which with its tributaries drains a large area to the west, joins the Zambezi. A few kilometres higher up on the east the main stream is joined in the rainy season by overflow of the Luampa/Luena system.

A short distance downstream of the confluence with the Luanginga is Lealui, one of the capitals of the Lozi people who populate the Zambian region of Barotseland in Western Province. The chief of the Lozi maintains one of his two compounds at Lealui; the other is at Limulunga, which is on high ground and serves as the capital during the rainy season. The annual move from Lealui to Limulunga is a major event, celebrated as one of Zambia’s best known festivals, the Kuomboka.

After Lealui, the river turns to south-south-east. From the east it continues to receive numerous small streams, but on the west is without major tributaries for 240 km. Before this, the Ngonye Falls and subsequent rapids interrupt navigation. South of Ngonye Falls, the river briefly borders Namibia’s Caprivi Strip. The strip projects from the main body of Namibia, and results from the colonial era: it was added to German South-West Africa expressly to give Germany access to the Zambezi.

Below the junction of the Cuando River and the Zambezi the river bends almost due east. Here, the river is broad and shallow, and flows slowly, but as it flows eastward towards the border of the great central plateau of Africa it reaches a chasm into which the Victoria Falls plunge.

Middle Zambezi

The Victoria Falls are considered the boundary between the upper and middle Zambezi. Below them the river continues to flow due east for about 200 kilometres (120 mi), cutting through perpendicular walls of basalt 20 to 60 metres (66 to 200 ft) apart in hills 200 to 250 metres (660 to 820 ft) high. The river flows swiftly through the Batoka Gorge, the current being continually interrupted by reefs. It has been described as one of the world’s most spectacular whitewater trips, a tremendous challenge for kayakers and rafters alike. Beyond the gorge are a succession of rapids which end 240 km (150 mi) below Victoria Falls. Over this distance, the river drops 250 metres (820 ft).

At this point, the river enters Lake Kariba, created in 1959 following the completion of the Kariba Dam. The lake is one of the largest man-made lakes in the world, and the hydroelectric power-generating facilities at the dam provide electricity to much of Zambia and Zimbabwe.

The Luangwa and the Kafue are the two largest left-hand tributaries of the Zambezi. The Kafue joins the main river in a quiet deep stream about 180 metres (590 ft) wide. From this point the northward bend of the Zambezi is checked and the stream continues due east. At the confluence of the Luangwa (15°37′ S) it enters Mozambique.

The middle Zambezi ends where the river enters Lake Cahora Bassa (also spelled Cabora Bassa). Formerly the site of dangerous rapids known as Kebrabassa, the lake was created in 1974 by the construction of the Cahora Bassa Dam.

Lower Zambezi

The lower Zambezi’s 650 km from Cahora Bassa to the Indian Ocean is navigable, although the river is shallow in many places during the dry season. This shallowness arises as the river enters a broad valley and spreads out over a large area. Only at one point, the Lupata Gorge, 320 km from its mouth, is the river confined between high hills. Here it is scarcely 200 m wide. Elsewhere it is from 5 to 8 km wide, flowing gently in many streams. The river bed is sandy, and the banks are low and reed-fringed. At places, however, and especially in the rainy season, the streams unite into one broad fast-flowing river.

About 160 km from the sea the Zambezi receives the drainage of Lake Malawi through the Shire River. On approaching the Indian Ocean, the river splits up into a delta. Each of the four prime tributaries, Kongone, Luabo and Timbwe, is obstructed by a sand bar. A more northerly branch, called the Chinde mouth, has a minimum depth at low water of 2 m at the entrance and 4 m further in, and is the branch used for navigation. 100 km further north is a river called the Quelimane, after the town at its mouth. This stream, which is silting up, receives the overflow of the Zambezi in the rainy season.

Geological changes to the course

More than two million years ago, the Upper Zambezi river used to flow south through what is now the Makgadikgadi Pan to the Limpopo River. The land around the pan experienced tectonic uplift (perhaps as part of the African superswell) and a large lake formed, and extended east.

Meanwhile, 1,000 kilometres (620 mi) east, a western tributary of the Shire River in the East African Rift’s southern extension through Malawi eroded a deep valley on its western escarpment. At the rate of a few cm per year, this river, the Middle Zambezi, started cutting back the bed of its river towards the west, aided by grabens (rift valleys) forming along its course in an east-west axis. As it did so it captured a number of south-flowing rivers such as the Luangwa and Kafue.

Eventually the large lake trapped at Makgadikgadi (or a tributary of it) was captured by the Middle Zambezi cutting back towards it, and emptied eastwards. The Upper Zambezi was captured as well. The Middle Zambezi was about 300 metres (980 ft) lower than the Upper Zambezi, and a high waterfall formed at the edge of the basalt plateau across which the upper river flows. This was the first Victoria Falls, somewhere down the Batoka Gorge near where Lake Kariba is now.

Note : The above story is based on materials provided by Wikipedia

Massive river system buried under today’s Goldfields

WA researchers are learning more about the rivers that flowed in the Goldfields 35–45 million years ago, thanks to small, iron-rich stones left in the sediment. Credit: Robert Thorne,Ravi Anand and Alexandra Suvorova

A CSIRO geologist has been studying the way small, iron-rich stones formed in the deeply buried river systems that once drained much of what is now southern WA.

In so doing, Dr Robert Thorne paints a picture of what the present-day Goldfields and Great Southern may have looked like 35–45 million years ago.
He says about 45 million years ago, wetter conditions caused open channels to form, creating river systems that mostly drained into the Eucla Basin.

These rivers and creeks had kaolinitic clay beds, and seasonal rains successively wet and dried them, providing the conditions needed for evolution of the small stones, known as pisoliths.

Dr Thorne says pisoliths began to form when tiny particles in the river bed acted as nuclei around which iron salts could precipitate.

By studying the formation of pisoliths, shown here as circular stones still embedded in clay, researchers are learning more about Western Australia’s ancient environment. Credit: Robert Thorne, Ravi Anand and Alexandra Suvorova

“You get precipitation of goethite, which is a hydrated iron oxide, around a nucleus which might be ferruginised clays, or in some places wood fragments,” he says.

In examining the chemistry behind the process, Dr Thorne says his team is learning more about how these river systems formed in what are now WA’s arid goldfields.

The presence of wood, for example, provides clues about the river environment.

“We learn a little more about the drainage system… It’s a bit wetter, a bit hotter, with woody plants growing on the banks,” Dr Thorne says.

Bacterial helpers

Dr Thorne’s team examined the pisoliths under electron microscopes, finding evidence of microorganisms that may also have helped form them.

Dr Thorne says the bacteria could have played an active role in the precipitation of iron oxide, which was formed in their metabolic processes, or they could have acted as passive precipitation sites.

“[Bacteria] cell walls are generally negatively charged, and they attract the iron [and other] positively charged elements,” he says.

“[These positively charged ions] nucleate on the cell walls, then that reduces the activation energy for continued precipitation of iron oxide on these cell walls.”

Dr Thorne says the pisoliths formed and reformed many times.

“The river dries out, and [later] you get a bit more water coming, then movement and breaking and erosion on the outer layers of the pisolith, and then reformation and that process begins again.”

His team obtained most of the pisoliths used in this study from the walls of open pit mines.

Reference:
Robert Thorne, Ravi Anand, Alexandra Suvorova, “The formation of fluvio-lacustrine ferruginous pisoliths in the extensive palaeochannels of the Yilgarn Craton, Western Australia,” Sedimentary Geology, Volume 313, November 2014, Pages 32-44, ISSN 0037-0738, dx.doi.org/10.1016/j.sedgeo.2014.08.004.

Note : The above story is based on materials provided by Science Network WA

Researchers find wreck of sunken barge in Monterey Canyon

The red dot indicates the location of the wreck of the Umpqua II barge in this bathymetric map of Monterey Bay. Credit: MBARI.

During a recent expedition to map earthquake faults in Monterey Bay, MBARI researchers discovered the wreck of a barge on the muddy seafloor in Monterey Canyon. The barge Umpqua II was about 1,700 meters (one mile) below the ocean surface.
Researchers first spotted the barge in sonar data from MBARI’s autonomous underwater vehicle (AUV) D. Allen B., which is specially designed to map the seafloor. Cruising as low as 50 meters above the seafloor, the AUV can detect objects just a few centimeters across. This has allowed MBARI geologists to discover many new geological features, including two hydrothermal vent areas in the Gulf of California. The AUV has also proven useful in mapping wrecks such as the Montebello, an oil tanker that sank off Central California during World War II.

In this latest discovery, the research team did not set out to find shipwrecks. Led by MBARI geologist Charlie Paull, they were on a week-long research cruise to study the San Gregorio Fault, an active earthquake fault that crosses Monterey Bay. As a first step in their research, the geologists used MBARI’s mapping AUV to create detailed maps of the seafloor in the area where they believed that the fault crossed Monterey Canyon.

Katie Maier, a geologist with the U.S. Geological Survey, was examining sonar images from the AUV when she noticed a strange, rectangular object on the floor of Monterey Canyon. A closer look at the sonar data suggested that the object was man made.

After the seafloor maps were completed, the research team used MBARI’s remotely operated vehicle (ROV) Doc Ricketts to dive down into Monterey Canyon and examine the seafloor for traces of the fault. Curious about what they had seen on the sonar maps, the researchers began one dive by sending the ROV down to take a close look at the object.

As the ROV approached the mysterious object, the entire science team gathered in the ROV control room to watch the video from the ROV. One of the first things they saw was the stern of the wrecked vessel, where its name, Umpqua II, and its home port of Reedsport, Oregon, were clearly visible.

A quick search on the internet showed that this barge had been built in 1960, and was used primarily to carry dredge spoils. According to the web site “wrecksite.eu” the barge ran ground near Moss Landing in 1982 and was subsequently towed offshore and intentionally sunk in Monterey Canyon. (This would probably not be allowed today, since the wreck site is within the Monterey Bay National Marine Sanctuary).

The researchers flew the ROV around the wreck several times, shooting video to document the condition of the vessel. Aside from a little rust, and damage that probably occurred during the grounding or sinking, the barge was in surprisingly good shape. It had been colonized by a few sea stars, anemones, and fish, but was not heavily overgrown with marine life. The researchers speculate that low oxygen concentrations in this deep part of the canyon could have slowed down both the decomposition of the metal barge and its colonization by marine life.

Although MBARI has no immediate plans to return to the sunken barge, the wreck may prove useful to researchers studying the long-term effects of the deep sea on man-made objects, as well as the effects of these objects on the marine environment. Since 2004, MBARI has been collaborating with researchers at the Monterey Bay National Sanctuary to study the slow decomposition and environmental effects of a sunken shipping container that ended up on the seafloor of Monterey Bay. The shipping container is in slightly shallower water only a few miles away from the wreck of the Umpqua II, and has been submerged about one third as long. Thus, researchers may be interested in comparing the two sites.

Even though MBARI researchers have been diving in Monterey Canyon since 1989, this discovery reminds us how little of the deep seafloor we have actually observed first hand. As MBARI develops more research tools such as the mapping AUV, additional discoveries are bound to come.

Note : The above story is based on materials provided by Monterey Bay Aquarium Research Institute

40,000-year-old blood brings mammoth cloning closer

Dr Tori Herridge with the mammoth. Credit: Channel 4 Television

Mammoth cloning is closer to becoming a reality following the discovery of blood in the best-preserved specimen ever found.

An autopsy on a 40,000-year-old mammoth has yielded blood that could contain enough intact DNA to make cloning possible, galvanising scientists who have been working for years to bring back the extinct elephant relative.
Tests are still being conducted on the blood to see if it will yield a complete genome – the genetic code necessary to build an organism.

Blood and guts

The mammoth (nicknamed Buttercup) was discovered in 2013 on Maly Lyakhovsky Island in northern Siberia and excavated from the permafrost. The flesh was remarkably well-preserved, and oozed a dark red liquid when scientists cut into it.

That liquid has now been confirmed as blood, following an autopsy conducted by scientists including Museum palaeobiologist Dr Tori Herridge.

‘As a palaeontologist, you normally have to imagine the extinct animals you work on,’ said Dr Herridge.

‘So actually coming face-to-face with a mammoth in the flesh, and being up to my elbows in slippery, wet, and frankly rather smelly mammoth liver, counts as one of the most incredible experiences of my life.’

The full results of the autopsy will be shown in the Channel 4 documentary Woolly Mammoth – The Autopsy, on Sunday 23 November at 20.00.

The South Korean firm Sooam Biotech Research Foundation is leading the research project.

Life and death of a mammoth

The blood was not the only remarkable finding of the autopsy. Analysis of the mammoth’s tusks revealed it was a female who had been through at least eight successful calving events.

Rates of tusk growth depend on whether the female is pregnant or lactating, and from Buttercup’s tusks the team were able to tell that at least one of her calves had died.

Analysis of her teeth show that Buttercup died in her fifties. The molar teeth of mammoths and elephants, which are closely related, are replaced six times throughout their lives. Once the last set wears down, the animal generally starves and dies.

However, it was determined that Buttercup met her end by becoming trapped in a peat bog and getting eaten alive by predators. Despite her brutal death she was incredibly well-preserved, thanks oxygen-free environment of the peat bog and the freezing process.

‘The information gleaned from Buttercup’s autopsy about her life and death, and the future discoveries that will come from analyses of her muscles and internal organs, will add to our understanding of these magnificent Ice Age beasts,’ said Dr Herridge.

If we can clone – should we?

The information learnt about the lives of mammoths is exciting in itself, but it is the potential for cloning that has captured the most attention.

However, while we are now closer to the reality of creating a living mammoth than ever before, Dr Herridge thinks that it may not be a good idea.

‘I doubt that there are many people in the world who would like to see a real-life woolly mammoth as much as I do. And yet I think cloning one would be ethically flawed,’ she wrote in an opinion piece for the Guardian this week.

A major objection to mammoth cloning is the fact that endangered Asian elephant surrogates would be required to birth a live mammoth baby. It is likely that many surrogates would be needed before the first successful birth.

‘Does the potential benefit to humanity of cloning a mammoth outweigh the suffering an Asian elephant surrogate mother might experience? I’ve yet to hear a convincing argument that it does,’ wrote Dr Herridge.

‘So, why should we clone a mammoth? Because it would be cool to see one? That’s not going to cut it, I’m afraid.’

Note : The above story is based on materials provided by Natural History Museum

Principles of sequence stratigraphy

Book Name : Principles of sequence stratigraphy
By : OCTAVIAN CATUNEANU
Department of Earth and Atmospheric Sciences
University Of Alberta
Edmonton , Alberta , Canada

First edition 2006
Copyright © 2006 Elsevier B.V. All rights reserved

Download : https://www.mediafire.com/?s99evd5exa94maq

Paleontologists name new armoured dinosaur

Life restoration of Zaraapelta nomadis by Danielle Dufault

The Gobi Desert of Late Cretaceous Mongolia was the place to be if you were one of the armoured dinosaurs called ankylosaurs. Besides the badlands of southern Alberta, the Gobi Desert has the highest number of ankylosaur species that lived together at the same time—and now a new family member has just been identified.
The new species, Zaraapelta nomadis, was discovered in 2000 by a team led by Phil Currie, and is named today in a paper by Victoria Arbour, Demchig Badamgarav and Philip Currie published in the Zoological Journal of the Linnean Society. The name Zaraapelta is a combination of the Mongolian and Greek works for “hedgehog” and “shield” in reference to its spiky appearance, and “nomadis” in honour of the Mongolian company Nomadic Expeditions, which has facilitated paleontological fieldwork in the Gobi Desert for almost two decades.

Zaraapelta is known from a well-preserved skull that is missing the front of the snout. Like some of the other ankylosaurs from the Gobi Desert, the top of its skull was bumpy and spiky. Zaraapelta is even more ostentatious than the other Mongolian ankylosaurs, with an elaborate pattern of bumps and grooves behind the eye. At the back of its skull there are distinctive horns with a prominent ridge along the top. The skull is part of the collections of the Mongolian Paleontological Center in Ulaanbaatar.

Arbour says the elaborate and distinctive ornamentation on the skulls of Saichania, Tarchia and Zaraapelta may have evolved as a way to show off to members of the opposite sex. It has long been thought that other kinds of dinosaurs, like the crested hadrosaurs or ceratopsians with their horns and frills, used these ornaments during sexual displays, but the idea hasn’t been applied to ankylosaurs.

The skull of Zaraapelta nomadis. Credit: Jessica Tansey

“You can think of bone as being an expensive item for your body to maintain,” she explains. “Bone requires a lot of nutrients and metabolic energy to create, and so that investment needs to pay off in some way. Maybe ankylosaurs had this bumpy ornamentation for protection, but another good explanation is that the horns and bumps on their skulls showed that they were a good mate to choose, in the same way that male peacocks use their tail feathers.”

Arbour’s history-making PhD research on ankylosaurs has earned her a reputation as the go-to person on the intricacies of their anatomy, lifestyle and growing family tree. She has studied the armoured, club-tailed plant-eaters for the last eight years and has taught paleobiology to students around the globe as one of the instructors for Dino 101, the U of A’s first massive open online course.

Resurrecting a discarded dinosaur

In addition to naming the new ankylosaur Zaraapelta, this study also re-examined previously named ankylosaurs from Mongolia and found support for “resurrecting” a species that had been discarded by earlier workers. The science of naming organisms, called taxonomy, is more fluid than many people might realize, Arbour notes. Sometimes, researchers might determine that two species names represent only one actual species, in which case the name that was created first has priority. This was the case for an ankylosaur called Tarchia kielanae, which was eventually thought to be the same kind of ankylosaur as Tarchia gigantea. But new information from recent dinosaur discoveries, including this study, suggests that Tarchia kielanae might be a separate species after all, so the name has been brought back into use.

Note : The above story is based on materials provided by University of Alberta

Geologists shed light on formation of Alaska Range

Syracuse University Professor Paul Fitzgerald and a group of students have been studying the Alaska Range. Credit: Syracuse University

Geologists in Syracuse University’s College of Arts and Sciences have recently figured out what has caused the Alaska Range to form the way it has and why the range boasts such an enigmatic topographic signature. The narrow mountain range is home to some of the world’s most dramatic topography, including 20,320-foot Mount McKinley, North America’s highest mountain.

Professor Paul Fitzgerald and a team of students and fellow scientists have been studying the Alaska Range along the Denali fault. They think they know why the fault is located where it is and what accounts for the alternating asymmetrical, mountain-scale topography along the fault.

Their findings were the subject of a recent paper in the journal Tectonics (American Geophysical Union, 2014).

In 2002, the Denali fault, which cuts across south-central Alaska, was the site of a magnitude-7.9 earthquake and was felt as far away as Texas and Louisiana. It was the largest earthquake of its kind in more than 150 years.

“Following the earthquake, researchers flocked to the area to examine the effects,” says Fitzgerald, who serves as professor of Earth Sciences and an associate dean for the College. “They were fascinated by how the frozen ground behaved; the many landslides [the earthquake] caused; how bridges responded; and how the Trans-Alaska oil pipeline survived, as it was engineered to do so.”

Geologists were also surprised by how the earthquake began on a previously unknown thrust-fault; then propagated eastward, along the Denali fault, and finally jumped onto another fault, hundreds of kilometers away.

“From our perspective, the earthquake has motivated analyses of why the highest mountains in the central Alaska Range occur south of the Denali fault and the highest mountains in the eastern Alaska Range occur north of the fault—something that has puzzled us for years,” Fitzgerald adds. “It’s been an enigma staring us in the face.”

He attributes the Alaska Range’s alternating topographic signatures to a myriad of factors: contrasting lithospheric strength between large terranes (i.e., distinctly different rock units); the location of the curved Denali fault; the transfer of strain inland from southern Alaska’s active plate margin; and the shape of the controlling former continental margin against weaker suture-zone rocks.

It’s no secret that Alaska is one of the most geologically active areas on the planet. For instance, scientists know that the North American Plate is currently overriding the Pacific Plate at the latter’s southern coast, while the Yakutat microplate is colliding with North America.

As a result of plate tectonics, Alaska is an amalgamation of terranes that have collided with the North American craton and have accreted to become part of North America.

Cratons are pieces of continents that have been largely stable for hundreds of millions of years.

Terranes often originate as volcanic islands (like those of Hawaii) and, after colliding with one another or a continent, are separated by large discrete faults. When terranes collide and accrete, they form a suture, also known as a collision zone, which is made up of weak, crushed rock. During deformation, suture-zone rocks usually deform first, especially if they are adjacent to a strong rock body.

“Technically, the Denali fault is what we’d call an ‘intercontinental right-lateral strike-slip fault system,'” says Fitzgerald, adding that a strike-slip fault occurs when rocks move horizontally past one another, usually on a vertical fault. “This motion includes a component of slip along the fault and a component of normal motion against the fault that creates mountains. Hence, the shape of the fault determines which of the two components is predominant and where mountains form.”

In Alaska, the shape of the accreted terranes generally controls the location of the Denali fault and the mountains that form along it, especially at the bends in the trace of the fault.

Fitzgerald: “Mount McKinley and the central Alaska Range lie within the concave curve of the Denali fault. There, higher topography and greater exhumation [uplift of rock] occur south of the Denali fault, exactly where you’d expect a mountain range to form, given the regional tectonics. In the eastern Alaska Range, higher topography and greater exhumation are found north of the fault, on its convex side—not an expected pattern at all and very puzzling.”

Using mapped surface geology, geophysical data, and thermochronology (i.e., time-temperature history of the rocks), Fitzgerald and colleagues have determined that much of Alaska’s uplift and deformation began some 25 million years ago, when the Yakutat microplate first started colliding with North America. The bold, glacier-clad peaks comprising the Alaska Range actually derive from within the aforementioned “weak suture-zone rocks” between the terranes.

While mountains are high and give the impression of strength, they are built largely from previously fractured rock units. Rock movement along the Denali fault drives the uplift of the mountains, which form at bends in the fault, where previously fractured suture-zone rocks are pinned against the stronger former North American continental margin.

“The patterns of deformation help us understand regional tectonics and the formation of the Alaska Range, which is fascinating to geologists and non-geologists alike,” says Fitzgerald. “Being able to determine patterns or how to reveal them, while others see chaos, is often the key to finding the answer to complex problems. … To us scientists, the real significance of this work is that it helps us understand the evolution of our planet, how faults and mountain belts form, and why earthquakes happen. It also provides a number of hypotheses about Alaskan tectonics and rock deformation that we can test, using the Alaska Range as our laboratory.”

Note : The above story is based on materials provided by Syracuse University

Danube River

Map of the Danube River

The Danube is a river in Central and Eastern Europe, the European Union’s longest and the continent’s second longest (after the Volga).
Classified as an international waterway, it originates in the town of Donaueschingen—which is in the Black Forest of Germany—at the confluence of the rivers Brigach and Breg. The Danube then flows southeast for 2,872 km (1,785 mi), passing through four capital cities before emptying into the Black Sea via the Danube Delta in Romania and Ukraine.

Once a long-standing frontier of the Roman Empire, the river passes through or touches the borders of ten countries: Romania (29.0% of basin area), Hungary (11.6%), Serbia (10.2%), Austria (10.0%), Germany (7.0%), Bulgaria (5.9%), Slovakia (5.9%), Croatia (4.4%), Ukraine (3.8%), and Moldova (1.6%). Its drainage basin extends into nine more.

Names and etymology

The name Dānuvius is presumably a loan from a Scythian language, or possibly Gaulish. It is one of a number of river names derived from a Proto-Indo-European language word *dānu, apparently a term for “river”, but possibly also of a primeval cosmic river, and of a Vedic river goddess (see Danu), perhaps from a root *dā “to flow/swift, rapid, violent, undisciplined.” Other river names with the same etymology include Don, Donets, Dnieper and Dniestr. Dniepr (pre-Slavic Danapir by Gothic historian Jordanes) and Dniestr, from Danapris and Danastius, are presumed from Scythian Iranian *Dānu apara “river afar” and *Dānu nazdya- “river near”, respectively.

The Danube was known in Latin as Danubius, Danuvius, Ister, in Ancient Greek as Ἴστρος (Istros). The Dacian/Thracian name was Donaris/Donaris (Τάναις in Greek, upper Danube) and Istros (lower Danube). Its Thraco-Phrygian name was Matoas, “the bringer of luck”. The Ancient Greek Istros was a borrowing from Thracian/Dacian meaning “strong, swift”, akin to Sanskrit iṣiras “swift”.

Since the Norman conquest of England, the English language has used the Latin-derived word Danube.

Geology

Although the headwaters of the Danube are relatively small today, geologically, the Danube is much older than the Rhine, with which its catchment area competes in today’s southern Germany. This has a few interesting geological complications. Since the Rhine is the only river rising in the Alps mountains which flows north towards the North Sea, an invisible line beginning at Piz Lunghin divides large parts of southern Germany, which is sometimes referred to as the European Watershed.

Before the last ice age in the Pleistocene, the Rhine started at the southwestern tip of the Black Forest, while the waters from the Alps that today feed the Rhine were carried east by the so-called Urdonau (original Danube). Parts of this ancient river’s bed, which was much larger than today’s Danube, can still be seen in (now waterless) canyons in today’s landscape of the Swabian Alb. After the Upper Rhine valley had been eroded, most waters from the Alps changed their direction and began feeding the Rhine. Today’s upper Danube is but a meek reflection of the ancient one.
The Iron Gate, on the Serbian-Romanian border (Iron Gates natural park and Đerdap national park)

Since the Swabian Alb is largely shaped of porous limestone, and since the Rhine’s level is much lower than the Danube’s, today subsurface rivers carry much water from the Danube to the Rhine. On many days in the summer, when the Danube carries little water, it completely oozes away noisily into these underground channels at two locations in the Swabian Alp, which are referred to as the Donauversickerung (Danube Sink). Most of this water resurfaces only 12 km south at the Aachtopf, Germany’s wellspring with the highest flow, an average of 8500 liters per second, north of Lake Constance—thus feeding the Rhine. The European Water Divide applies only for those waters that pass beyond this point, and only during the days of the year when the Danube carries enough water to survive the sink holes in the Donauversickerung.

Since such large volumes of underground water erode much of the surrounding limestone, it is estimated that the Danube upper course will one day disappear entirely in favor of the Rhine, an event called stream capturing.

The hydrological parameters of Danube are regularly monitored in Croatia at Batina, Dalj, Vukovar and Ilok.

 Note : The above story is based on materials provided by Wikipedia

Iceland volcano spewing smoke

The alert warning for the area surrounding Iceland’s Bardarbunga volcano was kept at orange on Tuesday, indicating increased unrest with greater potential for an eruption. Smoke is spewing from the volcano, and lava is spouting nearby. (Sept. 2)

Video provided by AP

Deep-Earth carbon offers clues on origin of life

Diamond on coal (stock image). Credit: © RTimages / Fotolia

New findings by a Johns Hopkins University-led team reveal long unknown details about carbon deep beneath Earth’s surface and suggest ways this subterranean carbon might have influenced the history of life on the planet.
The team also developed a new, related theory about how diamonds form in Earth’s mantle.

For decades scientists have had little understanding of how carbon behaved deep below Earth’s surface even as they learned more and more about the element’s vital role at the planet’s crust. Using a model created by Johns Hopkins geochemist Dimitri Sverjensky, he, Vincenzo Stagno of the Carnegie Institution of Washington and Fang Huang, a Johns Hopkins graduate student, have become the first to calculate how much carbon and what types exist in fluids at 100 miles below Earth’s surface at temperatures up to 2,100 degrees F.

In an article published this week in the journal Nature Geoscience, Sverjensky and his team demonstrate that in addition to the carbon dioxide and methane already documented deep in subduction zones, there exists a rich variety of organic carbon species that could spark the formation of diamonds and perhaps even become food for microbial life.

“It is a very exciting possibility that these deep fluids might transport building blocks for life into the shallow Earth,” said Sverjensky, a professor in the Department of Earth and Planetary Sciences. “This may be a key to the origin of life itself.”

Sverjensky’s theoretical model, called the Deep Earth Water model, allowed the team to determine the chemical makeup of fluids in Earth’s mantle, expelled from descending tectonic plates. Some of the fluids, those in equilibrium with mantle peridotite minerals, contained the expected carbon dioxide and methane. But others, those in equilibrium with diamonds and eclogitic minerals, contained dissolved organic carbon species including a vinegar-like acetic acid.

These high concentrations of dissolved carbon species, previously unknown at great depth in Earth, suggest they are helping to ferry large amounts of carbon from the subduction zone into the overlying mantle wedge where they are likely to alter the mantle and affect the cycling of elements back into Earth’s atmosphere.

The team also suggested that these mantle fluids with dissolved organic carbon species could be creating diamonds in a previously unknown way. Scientists have long believed diamond formation resulted through chemical reactions starting with either carbon dioxide or methane. The organic species offer a range of different starting materials, and an entirely new take on the creation of the gemstones.

The research is part of a 10-year global project to further understanding of carbon on Earth called the Deep Carbon Observatory. The work is funded by the Alfred P. Sloan Foundation.

Reference:
Dimitri A. Sverjensky, Vincenzo Stagno, Fang Huang. Important role for organic carbon in subduction-zone fluids in the deep carbon cycle. Nature Geoscience, 2014; DOI: 10.1038/ngeo2291

Note: The above story is based on materials provided by Johns Hopkins University.

Volcanic ash clouds can cross Atlantic Ocean

Queen’s University Belfast scientists found volcanic ash had travelled from Alaska to Northern Ireland. It is the first evidence that suggest ash clouds (stock image shown) can cross the Atlantic. This could mean airways are more susceptible to volcanoes than first thought

Scientists at Queen’s University Belfast have led the discovery of a volcanic ash cloud that travelled from Alaska to Northern Ireland and beyond — overturning previously held assumptions about how far ash deposits can drift, with major implications for the airline industry.
The discovery, which was made in partnership with an international team of academics and has been published in the journal Geology, is the first evidence that ash clouds can travel across the Atlantic Ocean, confirming Queen’s as a global leader in research. This particular ash, found in sites across Europe, including Sluggan Bog near Randalstown, Co Antrim, has been traced to an eruption from Mount Bona-Churchill in Alaska, around AD 847.

The discovery has significant implications for the aviation industry as well as environmental science, illustrating Queen’s impact on a global scale. The plumes spewed out by the volcano Eyjafjallajokull, in Iceland in 2010, caused major disruption and grounded over 100,000 international flights, costing airlines more than £2 billion.

With volcanoes like Mount Bona-Churchill — much more volatile than Eyjafjallajokull — scheduled to erupt on average every 100 years, another ash-cloud drama could be imminent, this time with consequences for trans-Atlantic as well as European travel.

Lead researcher Dr Britta Jensen from the School of Geography, Archaeology and Paleoecology at Queen’s University, said: “The ash, or tephra, is from Mount Bona-Churchill where it is called the White River Ash and occurs as a thick white layer spreading eastwards into Canada. Using chemical ‘fingerprinting’, the team has matched it to a tephra layer which occurs in Ireland, Norway, Germany and Greenland, where it is called the AD860B. For the past 20 years or so, European researchers assumed that AD860B came from a relatively nearby volcano in Iceland, which is the source of most ash in Europe, including that from Eyjafjallajokull in 2010. However, the AD860B never quite fitted with what researchers knew of volcanoes in Iceland.”

Co-researcher Dr Sean Pyne-O’Donnell, from School of Geography, Archaeology and Paleoecology at Queen’s University, said the discovery was also significant in advancing knowledge across other disciplines, particularly in the area of climate change: “The layer was deposited very quickly after eruption, probably within a matter of days and can be used to precisely date and compare the relative timing of any environmental or archaeological events associated with it by tephro-chronology. This makes the layer very useful for researchers wanting to link together how climate behaved in distant parts of the world at this time. Such information is vital for climate scientists attempting to explain how climate worked in the past compared with the present. The team also speculates that other tephra layers from similar trans-Atlantic eruptions may yet be uncovered in other Irish sites.”

Reference:
B. J. L. Jensen, S. Pyne-O’Donnell, G. Plunkett, D. G. Froese, P. D. M. Hughes, M. Sigl, J. R. McConnell, M. J. Amesbury, P. G. Blackwell, C. van den Bogaard, C. E. Buck, D. J. Charman, J. J. Clague, V. A. Hall, J. Koch, H. Mackay, G. Mallon, L. McColl, J. R. Pilcher. Transatlantic distribution of the Alaskan White River Ash. Geology, 2014; 42 (10): 875 DOI: 10.1130/G35945.1

Note : The above story is based on materials provided by Queen’s University Belfast.

Erosion may trigger earthquakes

A natural arch produced by erosion of differentially weathered rock in Jebel Kharaz (Jordan) Photo Copyright © Etan J. Tal

Researchers from laboratories at Géosciences Rennes (CNRS/Université de Rennes 1)*, Géosciences Montpellier (CNRS/Université de Montpellier 2) and Institut de Physique du Globe de Paris (CNRS/IPGP/Université Paris Diderot), in collaboration with a scientist in Taiwan, have shown that surface processes, i.e. erosion and sedimentation, may trigger shallow earthquakes (less than five kilometers deep) and favor the rupture of large deep earthquakes up to the surface. Although plate tectonics was generally thought to be the only persistent mechanism able to influence fault activity, it appears that surface processes also increase stresses on active faults, such as those in Taiwan, one of the world’s most seismic regions.

The work is published in Nature Communications on 21 November 2014.

Over the last few decades, many studies have focused on the evolution of mountain range landscapes over geological time (1 to 100 million years). The aim is to better understand the dynamics and interactions between erosion, sedimentation and tectonic deformation processes. Recent work has shown that Earth’s surface can undergo major changes in just a few days, months or years, for instance during extreme events such as typhoons or high magnitude earthquakes. Such events cause many landslides and an increase in sedimentary transport into rivers, as was the case in 2009 when typhoon Morakot struck Taiwan, leading to abrupt erosion of landscapes. Such rapid changes to the shape of Earth’s surface alter the balance of forces at the site of deep active faults.

In Taiwan, where erosion and deformation rates are among the highest in the world, the researchers showed that erosion rates of the order of 0.1 to 20 millimeters per year can cause an increase of the order of 0.1 to 10 bar in stresses on faults located nearby. Such forces are probably enough to trigger shallow earthquakes (less than five kilometers deep) or to favor the rupture of deep earthquakes up to the surface, especially if they are amplified by extreme erosion events caused by typhoons and high magnitude earthquakes. The researchers have thus shown that plate tectonics is not the only persistent mechanism able to influence the activity of seismic faults, and that surface processes such as erosion and sedimentation can increase stresses on active faults sufficiently to cause shallow earthquakes.

Thanks to an analysis of the relationships between surface processes and active deformation of Earth in near real-time, this study provides new perspectives for understanding the mechanisms that trigger earthquakes.

*The Géosciences Rennes laboratory is part of the Observatoire des Sciences de l’Univers de Rennes.

Reference:
Philippe Steer, Martine Simoes, Rodolphe Cattin, J. Bruce H. Shyu. Erosion influences the seismicity of active thrust faults. Nature Communications, 2014; 5: 5564 DOI: 10.1038/ncomms6564

Note : The above story is based on materials provided by CNRS.

Mexico’s Volcano of Fire blows huge ash cloud

General view of the Volcano of fire projecting a fumarole on June 10, 2005, in Yerbabuena, Mexico

An explosion on western Mexico’s Volcano of Fire blew out a giant column of ash on Friday that rained down on some towns in two states.

The ash cloud rose five kilometers (three miles) above the volcano in the state of Colima, but it did not pose an immediate threat to the population, the interior ministry said in a statement.

The volcano spewed hot, dry rock and gases two kilometers from the crater.

The ash cloud traveled a distance of 25 kilometers, and a “light ash fall” was reported in the town of Queseria, Colima, and the towns of Tonila and Zapotiltic in the neighboring state of Jalisco, the statement said.

“We recommend that people cover their nose and mouth, protect sources of potable water, and avoid dumping ash in drainage systems because it hardens with the moisture,” national civil protection coordinator Luis Felipe Puente told Foro television.

An explosion had been expected ever since a dome formed inside the crater in January 2013, and the formation needed to break, Puente said.

The explosion was weaker than in March 2005, when the crater registered its biggest volcanic activity in almost a quarter century, he added.

Note : The above story is based on materials provided by © 2014 AFP

Himalaya tectonic dam with a discharge

Yarlung Zangbo river

The Himalaya features some of the most impressive gorges on Earth that have been formed by rivers. The geologic history of the famous Tsangpo Gorge, in the eastern Himalaya, now needs to be rewritten.

A team of German, Chinese, and American geoscientists have namely discovered a canyon, filled with more than 500 m of sediments beneath the bed of the present-day Yarlung Tsangpo River upstream from the gorge. Using drill cores, the scientists were able to reconstruct the former valley floor of this river, which allowed them to reconstruct the geological history of the Tsangpo Gorge (Science, 21.11.2014). They discovered that the gorge obtained its steep form in response to rapid tectonic uplift in the Himalaya, two to three million years ago. “Because of its high gradient, the river incises its bed very rapidly”, explains Dirk Scherler from the GFZ German Research Centre for Geosciences. “The rocks here are eroded at annual rates of up to one centimeter per year which is matched by tectonic uplift of the same rate.” The collision of India with the Eurasian continent has created a tectonic dam here.

This barrier caused a lower flow velocity of the Yarlung Tsangpoupstream. Previously, the river had deeply incised into the Tibetan Plateau. Due to the reduced flow rate the sediments which the Yarlung Tsangpo River and its tributaries eroded from the highlands were deposited in the river bed along hundreds of kilometers.

The scientists estimated that these deposits are up to 1000 m thick. “Five drillings have been conducted over a distance of 300 km upstream of the gorge”, says Dirk Scherler. “One of the drillings encountered bedrock after 540 meters of sediments. From the drill cores, we were able to infer the reduction in stream flow velocity and date the initiation of sedimentation using cosmogenic nuclides. These are rare isotopes that are produced by cosmic rays near the Earth’s surface. Three Million years ago, the river was still incising into Himalayan bedrock.” But today the once huge canyon is buried by sediments.

The Yarlung Tsangpo is the largest high mountain river on Earth. It flows along a distance of 1700 km across the Tibetan Plateau, at an elevation of around 4000 meters and follows the boundary between India and Eurasia. In the eastern Himalaya, the river leaves the high plateau and breaks through the world famous, horseshoe-shaped Tsangpo Gorge for the plains of India.

The new findings show that rapid incision of the Yarlung Tsangpo and the development of the Tsangpo Gorge occurred in response to tectonic uplift, and not, as previously thought, the other way round. In addition, these observations refute existing hypotheses that relate the origin of the Tsangpo Gorge to river capture of the Yarlung Tsangpo by the Brahmaputra River.

Reference:
P. Wang, D. Scherler et al.: „Tectonic Control of Yarlung Tsangpo Gorge Revealed by a Buried Canyon in Southern Tibet”, Science Nr. 6212, Vol. 346, pp. 978-980, 21.11.2014, DOI: 10.1126/science.1259041

Note : The above story is based on materials provided by GFZ GeoForschungsZentrum Potsdam, Helmholtz Centre

Secrets of dinosaur ecology found in fragile amber

Inclusions in Canadian Cretaceous amber from Grassy Lake amber, a 78-79 million year old amber in the Late Cretaceous of southern Alberta. Credit: University of Alberta Strickland Entomology Museum (UASM) specimen, R.C. McKellar

Ryan McKellar’s research sounds like it was plucked from Jurassic Park: he studies pieces of amber found buried with dinosaur skeletons. But rather than re-creating dinosaurs, McKellar uses the tiny pieces of fossilized tree resin to study the world in which the now-extinct behemoths lived.

New techniques for investigating very tiny pieces of fragile amber buried in dinosaur bonebeds could close the gaps in knowledge about the ecology of the dinosaurs, said McKellar, who is a research scientist at the Royal Saskatchewan Museum in Saskatchewan, Canada.

“Basically it puts a backdrop to these dinosaur digs, it tells us a bit about the habitat,” said McKellar. The amber can show what kinds of plants were abundant, and what the atmosphere was like at the time the amber was formed, he explained. Scientists can then put together details regarding what kind of habitat the dinosaur lived in and how the bonebed formed.

The preliminary findings about dinosaur ecology, habitat, and other results from four different fossil deposits from the Late Cretaceous in Alberta and Saskatchewan, Canada, will be presented on Monday, October 20 at the Geological Society of America Annual Meeting in Vancouver, Canada.

“Just a few of these little pieces among the bones can show a lot of information,” McKellar said.

The type of amber that the scientists work with is not like the jewelry grade variety that can be made into a necklace or earrings.

“This type of amber hasn’t been pursued in the past. It is like working with a shattered candy cane,” he said. It is called friable amber, which is crumbly and fragile.

McKellar and his colleagues work with very small pieces of amber, just millimeters wide. But even samples at such a small scale can hold enormous clues to the past.

Before it hardened into amber, the sticky tree resin would often collect animal and plant material, like leaves and feathers. Scientists call these contents “inclusions,” which they study along with the surrounding amber, to look at environmental conditions, surrounding water sources, temperature, and even oxygen levels in the ancient environment.

Insects can also be included in the amber, which can be even more helpful to scientists. One example is the discovery of an aphid, stuck directly to a duck-billed dinosaur with some amber. With a find like this, scientists can track insect evolution, find their modern relatives, and see how they might have interacted with dinosaurs, said McKellar.

“When you get insects, it is like frosting on the cake—you can really round out the view of the ecosystem.”

Improvements in processing friable amber have made this research possible. Instead of the past technique of screening amber in a glycerin bath, the scientists reduce crumbling by vacuum-injecting the amber with epoxy, said McKellar.

Friable amber is widespread across the North American Continent in association with coals, and in the uncovered bonebeds, which means this area of research has expanded with the new techniques. It means scientists can sample at a finer scale, and still close some gaps in the past, especially regarding insect evolution, said McKellar.

Some of the early results of this method will be presented from amber pieces found with the skeleton of ‘Scotty’ the Tyrannosaurus rex, in Saskatchewan, Canada. McKellar will also be including case studies from three other bonebeds: the Danek Bonebed near Edmonton, Alberta; Dinosaur Provincial Park, Alberta; and the Pipestone Creek Pachyrhinosaurus Bonebed near Grande Prairie, Alberta.

Reference:
Amber associated with late cretaceous dinosaur bonebeds in western Canada, gsa.confex.com/gsa/2014AM/webp… ram/Paper249774.html

Note : The above story is based on materials provided by Geological Society of America

Permafrost soil is possible source of abrupt rise in greenhouse gases at end of last ice age

Pleistocene Ice Complex cliff: 35 meters high Pleistocene Ice Complex cliff at Sobo Sise Island (Lena Delta), Siberian Arctic. Credit: Alfred-Wegener-Institut / Thomas Opel

Scientists from the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI) have identified a possible source of carbon dioxide (CO2) and other greenhouse gases that were abruptly released to the atmosphere in large quantities around 14,600 years ago. According to this new interpretation, the CO2 — released during the onset of the Bølling/Allerød warm period — presumably had their origin in thawing Arctic permafrost soil and amplified the initial warming through positive feedback. The study now appears online in the journal Nature Communications.

One of the most abrupt rises in the carbon dioxide concentration in the atmosphere at the end of the last ice age took place about 14,600 years ago. Ice core data show that the CO2 concentration at that time increased by more than 10 ppm (parts per million, unit of measure for the composition of gases) within 200 years. This CO2 increase, i.e. approx. 0.05 ppm per year, was significantly less than the current rise in atmospheric CO2 of 2-3 ppm in the last decade caused by fossil fuels. These data describe an abrupt change in the global carbon cycle during the transition from the last ice age to the present-day warm interglacial and allow conclusions to be drawn about similar processes that could play a role in the future.

To determine the origin of the greenhouse gas, a team around by the geoscientists and climate researchers Dr. Peter Köhler and Dr. Gregor Knorr from the Alfred Wegener Institute has carried out computer simulations focusing on the new interpretation of these CO2 data. These calculations were motivated by new radiocarbon data (14C) that provide information on the age of the CO2 released to the atmosphere. The age of the carbon then allows conclusions to be drawn about the carbon source.

“The virtual lack of radiocarbon in the CO2 that was released into the atmosphere shows us that the carbon must have been very old,” says Köhler. The carbon therefore cannot be originated from the deep ocean, Köhler adds: “The carbon stored in the deep ocean has been subject to exchange with the atmosphere over a period of millennia. In the atmosphere 14C has its only source. It is produced through the impact of galactic cosmic rays on molecules in the atmosphere.” However, radiocarbon is unstable and decays with a half-life of around 5,700 years. The atmospheric data of CO2 and 14C can only be explained if a carbon source is assumed that contains virtually no 14C any more — thus the greenhouse gases must have had another source than the deep ocean.

Permafrost soil contains, to some extent, very old organic material, which is released in the form of the greenhouse gases CO2 and methane when the soil thaws. Permafrost soil thus might be a possible source of old carbon. The thawing of Arctic permafrost soil might have been caused by a sudden resumption of large-scale Atlantic heat transport in the ocean that initiated the Bølling/Allerød warm period in the high northern hemisphere.

The scientists were able to estimate the amount of the carbon dioxide released to the atmosphere by applying a computer model that simulates the global carbon cycle. The simulation results indicate that the input of more than half a gigaton of carbon per year (1 gigaton = 1 petagram) over a period of two centuries is necessary to explain the observed data. This corresponds to a total amount of more than 100 gigatons of carbon. Present-day anthropogenic CO2 emissions due to fossil fuels, at approx. ten gigatons of carbon a year, are greater than the release rates of this natural process by a factor of at least ten.

According to the study, the proposed thawing of large areas of permafrost, followed by the rise in greenhouse gases, occurred at the same time as the warming in the northern hemisphere at the beginning of the Bølling warm period. The released greenhouse gases may amplify the initial warming through feedback effects.

A similar effect is also predicted for the future in the current IPCC report. Warming in Siberia, for instance, is already leading to thawing of permafrost soil: outgassing of CO2 and methane takes place. The same processes observed today — and are expected to an even greater extent in the coming decades — presumably occurred in a similar manner 14,600 years ago. “However, the state of the climate on Earth today has already been changed by anthropogenically emitted greenhouse gases. Future CO2 release due to the proposed thawing of permafrost will be substantially less than the input due to fossil fuels. However, these emissions from permafrost soil are additional greenhouse gas sources that further amplify the anthropogenically induced effect,” says Köhler.

Reference:
Peter Köhler, Gregor Knorr, Edouard Bard. Permafrost thawing as a possible source of abrupt carbon release at the onset of the Bølling/Allerød. Nature Communications, 2014; 5: 5520 DOI: 10.1038/ncomms6520

Note : The above story is based on materials provided by Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research.

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