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New state map from Indiana Geological Survey makes use of high-res imaging

A new state map from the Indiana Geological Survey features the latest digital technology using high-resolution elevation data.

The Indiana Geological Survey has published a new state map that features the latest digital technology using high-resolution elevation data. The map was prepared using lidar data—light detection and ranging—collected by specially equipped aircraft flying over the entire state.

The lidar data were acquired over a three-year period beginning in 2011 and, following a rigorous process of quality control to ensure their accuracy, the digital data were made available to geographic information system technologists in January 2014.

“Maps must be accurate to be useful, but they can also be beautiful,” said Matt Johnson, Indiana Geological Survey head cartographer, who is one of the compilers of the new map.

The shaded-relief map, titled “Indiana,” is printed in full color on high-quality poster paper and measures 28 by 42 inches. It is a 1:500,000-scale map (1 inch on the map equals 7.89 miles) that provides a highly detailed depiction of the diverse landscapes of Indiana.

Included are highways and roads; lakes, rivers and streams; county seats; and population data. Elevations are represented by color, and this, in combination with relief-shading techniques, gives the map a three-dimensional look.

From across the room, one can easily see the incised landscape of the Wabash Valley or, in the northeastern part of the state, the subtle moraines left by retreating glaciers of the Ice Age. Closer up, in the southern part of the state, the details of the uplands and river bottoms become readily apparent.

“Indiana is one of only eight states nationwide that has complete lidar coverage, and it is the only state that has made this information accessible to the public in this format,” said Indiana State Geologist John Steinmetz. “This map contains information to support decision-making where topographic features are of critical importance. It will also facilitate conversations among legislators and stakeholders regarding the importance of timely and high-quality data acquisition.”

Photo

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

Research redefines the properties of faults when rock melts

Photograph of the slip zone in plane view. Credit: University of Liverpool

A new discovery in the study of fault slip seeks to redefine our understanding of how melt-bearing faults behave, say scientists at the University of Liverpool.

Geoscientists have used friction experiments to investigate the processes of fault slip.  Fault slip occurs in many natural environments – including during earthquakes – when large stress build-ups are rapidly released as two sliding tectonic plates grinds together.

In this process a large amount of the energy released can be converted to heat, that leads to frictional melting.  Frictional melts, when cooled, preserve in the rock-record as pseudotachylytes; but their influence is much greater than just this.

As Professor Lavallée and co-workers have demonstrated, the flow properties of the frictional melt helps control fault slip.

Inadequate analyses

The researchers, from the University’s School of Environmental Sciences, warn of the inadequacy of simple Newtonian viscous analyses to describe molten rock along faults, and instead call for the more realistic application of viscoelastic theory.

Melt may be considered a liquid, which is able to undergo a glass transition, as a result of changing temperature and/ or strain-rate. This catastrophic transition allows the melt to either flow or fracture, according to the fault slip conditions.

Professor Lavallée said: “Even once frictional melt forms, slip can continue as if there was no melt; if the slip rate is fast enough the melt behaves as a solid.”

Using slip analysis models, the researchers describe the conditions that result in either viscous remobilisation or fracture of the melt, a description which will be of great use in the understanding of fault slip in melt-bearing slip zones.

Implications

Professor Lavallée added: “This new description of fault slip is not just important for our understanding of earthquake fault rheology, it has far reaching implications for magma transport in volcanic eruptions, for landslide and sector collapse instabilities, and within material sciences; namely for the glass and ceramic industries.”

Reference:
Yan Lavalléea, Takehiro Hirose, Jackie E. Kendrick, Kai-Uwe Hess, and Donald B. Dingwell. Fault rheology beyond frictional melting, Yan Lavallée, PNAS, DOI: 10.1073/pnas.1413608112

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

Earthquakes in western Solomon Islands have long history, study shows

Weathering and moss can make uplifted blend into the background like rocks. Underneath the exterior layer the coral remains a bright white from calcium carbonate, the primary compound of coral skeletons. Credit: Kaustubh Thirumalai

Researchers have found that parts of the western Solomon Islands, a region thought to be free of large earthquakes until an 8.1 magnitude quake devastated the area in 2007, have a long history of big seismic events.

The findings, published online in Nature Communications on Tuesday, suggest that future large earthquakes will occur, but predicting when is difficult because of the complex environment at the interface of the tectonic plates.

The team, led by researchers at The University of Texas Austin, analyzed corals for the study. The coral, in addition to providing a record of when large earthquakes happened during the past 3,000 years, helped provide insight into the relationship between earthquakes and more gradual geological processes, such as tectonic plate convergence and island building through uplift.

“We’re using corals to bridge this gap between earthquakes and long-term deformation, how the land evolves,” said lead researcher Kaustubh Thirumalai, a doctoral student at the University of Texas Institute for Geophysics (UTIG), a research unit within the Jackson School of Geosciences.

The 2007 event was the only large earthquake recorded in 100 years of monitoring the region that started with British colonization in the 1900s. While studying uplifted coral at multiple sites along the eastern coast of the island of Ranongga the researchers found evidence for six earthquakes in the region during the past 3,000 years, with some being as large as or larger than the 2007 earthquake.

“This just shows the importance of paleoseismology and paleogeodesy,” Thirumalai said. “If we have 100 years of instrumental data saying there’s no big earthquakes here, but we have paleo-records that say we’ve had something like five giant ones in the last few thousand years, that gives you a different perspective on hazards and risk assessment.”

During an earthquake, land near its epicenter can be lifted as much as several meters. When the land is shallow-water seafloor, such as it is around the islands, corals can be lifted out of the water with it. The air kills the soft polyps that form coral, leaving behind their network of skeletons and giving the uplifted corals a rock-like appearance.

Uplifted coral make good records for earthquakes because they record the time an earthquake occurs and help estimate how strong it was. The coral’s time of death, which can be deduced through a chemical analysis similar to carbon dating, shows when the earthquake occurred, while the amount of uplift present in the land where the coral was found gives clues about its strength.

“If we have multiple corals going back in time, and we can date them very precisely, we can go from one earthquake, to many earthquakes, to thousands of years of deformation of the land,” Thirumalai said.

The UTIG research team comprised Thirumalai, Frederick Taylor, Luc Lavier, Cliff Frohlich and Laura Wallace. They collaborated with scientists from National Taiwan University, including Chuan-Chou “River” Shen, an expert in coral dating, and researchers from the Chinese Academy of Science; the Department of Mines, Energy and Water Resources in the Solomon Islands; and locals who live on Ranongga Island.

The earthquakes in the region are a result of plate tectonic motion near the island; only four kilometers offshore the Pacific Plate starts to subduct beneath the Australian Plate. A theory of island building says that uplifts during earthquakes are one of the main drivers of land creation and uprising.

However, the earthquake record suggested by the corals was not enough to account for the measured rate of tectonic convergence. This suggests that other geological processes besides those that directly cause earthquakes play an important role in tectonic plate movement and uplift of the islands.

Learning the detailed relationship between earthquakes and these forces will take more research, said Thirumalai. But this study has shown uplifted coral are important geological tools.

Data collected during a rapid-response mission to study uplifted corals in the wake of the 2007 earthquake served an important role in the research, Thirumalai said. The mission, which Taylor led and the Jackson School funded, provided data that served as a benchmark for analyzing the strength of earthquakes that happened before 2007.

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

Spiky monsters: new species of ‘super-armoured’ worm discovered

Collinsium ciliosum, a Collins’ monster-type lobopodian from the early Cambrian Xiaoshiba biota of China. Credit: Jie Yang

A newly-identified species of spike-covered worm with legs, which lived 500 million years ago, was one of the first animals on Earth to develop armour for protection.

A new species of ‘super-armoured’ worm, a bizarre, spike-covered creature which ate by filtering nutrients out of seawater with its feather-like front legs, has been identified by palaeontologists. The creature, which lived about half a billion years ago, was one of the first animals on Earth to develop armour to protect itself from predators and to use such a specialised mode of feeding.

The creature, belonging to a poorly understood group of early animals, is also a prime example of the broad variety of form and function seen in the early evolutionary history of a modern group of animals that, today, are rather homogenous. The results, from researchers at the University of Cambridge and Yunnan University in China, are published today (29 June) in the journal PNAS.

The creature has been named Collinsium ciliosum, or Hairy Collins’ Monster, named for the palaeontologist Desmond Collins, who discovered and first illustrated a similar Canadian fossil in the 1980s. The newly-identified species lived in what is now China during the Cambrian explosion, a period of rapid evolutionary development around half a billion years ago, when most major animal groups first appear in the fossil record.

A detailed analysis of its form and evolutionary relationships indicates that the Chinese Collins’ Monster is a distant early ancestor of modern velvet worms, or onychophorans, a small group of squishy animals resembling legged worms that live primarily in tropical forests around the world.

“Modern velvet worms are all pretty similar in terms of their general body organisation and not that exciting in terms of their lifestyle,” said Dr Javier Ortega-Hernández of Cambridge’s Department of Earth Sciences, one of the paper’s lead authors. “But during the Cambrian, the distant relatives of velvet worms were stunningly diverse and came in a surprising variety of bizarre shapes and sizes.”

The pattern of diverse ancestors leading to relatively unvaried modern relatives has been observed in other groups in the fossil record, including sea lilies (crinoids) and lamp shells (brachiopods). However, this is the first time that this evolutionary pattern has been observed in a mostly soft-bodied group.

Ortega-Hernández and his colleagues identified a remarkably well-preserved fossil from southern China, which included details of the full body organisation, the digestive tract, even down to a delicate coat of hair-like structures on the front end. Their analysis found it to be a new species — an eccentric ancestor of an otherwise straight-laced group.

The Chinese Collins’ Monster had a soft and squishy body, six pairs of feather-like front legs, and nine pairs of rear legs ending in claws. Since the clawed rear legs were not well-suited for walking along the muddy ocean floor, it is likely that Collinsium eked out an existence by clinging onto sponges or other hard substances by its back claws, while sieving out its food with its feathery front legs. Some modern animals, including bamboo shrimp, feed in a similar way, capturing passing nutrients with their fan-like forearms.

Given its sedentary lifestyle and soft body, the Chinese Collins’ Monster would have been a sitting duck for any predators, so it developed an impressive defence mechanism: as many as 72 sharp and pointy spikes of various sizes covering its body, making it one of the earliest soft-bodied animals to develop armour for protection.

The Chinese Collins’ Monster resembles Hallucigenia, another otherworldly Cambrian fossil, albeit one which has been the subject of much more study.

“Both creatures are lobopodians, or legged worms, but the Collins’ Monster sort of looks like Hallucigenia on steroids,” said Ortega-Hernández. “It had much heavier armour protecting its body, with up to five pointy spines per pair of legs, as opposed to Hallucigenia’s two. Unlike Hallucigenia, the limbs at the front of Collins’ Monster’s body were also covered with fine brushes or bristles that were used for a specialised type of feeding from the water column.”

The spines along Collinsium’s back had a cone-in-cone construction, similar to Russian nesting dolls. This same construction has also been observed in the closely-related Hallucigenia and the claws in the legs of velvet worms, making both Collinsium and Hallucigenia distant ancestors of modern onychophorans. According to Ortega-Hernández, “There are at least four more species with close family ties to the Collins’ Monster, which collectively form a group known as Luolishaniidae. Fossils of these creatures are hard to come by and mostly fragmentary, so the discovery of Collinsium greatly improves our understanding of these bizarre organisms.”

The fossil was found in the Xiaoshiba deposit in southern China, a site which is less-explored than the larger Chengjiang deposit nearby, but has turned up fascinating and well-preserved specimens from this key period in Earth’s history.

“Animals during the Cambrian were incredibly diverse, with lots of interesting behaviours and modes of living,” said Ortega-Hernández. “The Chinese Collins’ Monster was one of these evolutionary ‘experiments’ — one which ultimately failed as they have no living direct ancestors — but it’s amazing to see how specialised many animals were hundreds of millions of years ago. At its core, the study of the fossil record seeks answers about the evolution of life on Earth that can only be found in deep time. All the major biological events responsible for shaping the world we inhabit, such as the origin of life, the early diversification of animals, or the establishment of the modern biosphere, are intimately linked to the complex geological history of our planet.”

The research was funded by the National Natural Science Foundation of China, Emmanuel College, Cambridge, and the Templeton World Charity Foundation.

Reference:
Yang, J et al. A super-armoured lobopodian from the Cambrian of China and early disparity in the evolution of Onychophora. PNAS, 2015 DOI: 10.1073/pnas.1505596112

Note: The above post is reprinted from materials provided by University of Cambridge. The original story is licensed under a Creative Commons Licence.

Earthquake not to blame for Indonesian mud volcano

This is a satellite image of the Lusi mud volcano and the buried city of Sidoarjo in March 2007. The image covers approximately 1200 by 600 meters. Credit: Lapindo Brantas

New research led by the University of Adelaide hopes to close the debate on whether a major mud volcano disaster in Indonesia was triggered by an earthquake or had human-made origins.

A mud volcano suddenly opened up in the city of Sidoarjo in East Java, Indonesia, in May 2006. Nine years later the eruption continues — having buried more than 6.5km2 of the city in up to 40m of mud and displacing almost 40,000 people. Costs of the disaster are estimated at over US$2.7 billion.

Results of new research published today in correspondence in the journal Nature Geoscience directly address the ongoing controversy over the cause of the disaster, says lead author Dr Mark Tingay, Adjunct Associate Professor with the University of Adelaide’s Australian School of Petroleum.

“There has been intense debate over the cause of the mud volcano ever since it erupted,” Adjunct Associate Professor Tingay says.

“Some researchers argue that the volcano was human-made and resulted from a drilling accident (a blowout) in a nearby gas well. Others have argued that it was a natural event that was remotely triggered by a large earthquake that occurred 250km away and two days previously. There has been no scientific consensus about this, and it’s a very hot topic politically in Indonesia.

“Our new research essentially disproves all existing earthquake-triggering models and, in my opinion, puts the matter to rest,” he says.

The study by Adjunct Associate Professor Tingay and colleagues in the US (Portland University; University of California, Berkeley) and UK (Newcastle University) is the first to use actual physical data collected in the days before and after the earthquake, rather than models and comparisons.

“The earthquake-trigger theory proposes that seismic shaking induced liquefaction of a clay layer at the disaster location. Clay liquefaction is always associated with extensive gas release, and it is this large gas release that has been argued to have helped the mud flow upwards and erupt on the surface. However, we examined precise and continuous subsurface gas measurements from the adjacent well and show that there was no gas release following the earthquake,” Adjunct Associate Professor Tingay says.

“The rocks showed no response to the earthquake, indicating that the earthquake could not have been responsible for the mud flow disaster. Furthermore, the measurements highlight that the onset of underground activity preceding the mud eruption only started when the drilling ‘kick’ occurred, strongly suggesting that the disaster was initiated by a drilling accident.

“We also use gas signatures from different rocks and the mud eruption itself to ‘fingerprint’ the initial source of erupting fluids. We demonstrate that erupting fluids were initially sourced from a deep formation, which is only predicted to occur in the drilling-trigger hypothesis. Taken together, our data strongly supports a human-made trigger. We hope this closes the debate on whether an earthquake caused this unique disaster,” he says.

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

A deep, dark mystery: New discoveries about the Newport-Inglewood Fault Zone in the Los Angeles Basin

The Newport-Inglewood fault was responsible for the 4.9 magnitude Inglewood earthquake in 1920 and the 6.4 magnitude Long Beach earthquake in 1933. Credit: Sonia Fernandez

UC Santa Barbara geologist Jim Boles has found evidence of helium leakage from Earth’s mantle along a 30-mile stretch of the Newport-Inglewood Fault Zone in the Los Angeles Basin. Using samples of casing gas from two dozen oil wells ranging from LA’s Westside to Newport Beach in Orange County, Boles discovered that more than one-third of the sites — some of the deepest ones — show evidence of high levels of helium-3 (3He).

Considered primordial, 3He is a vestige of the Big Bang. Its only terrestrial source is the mantle. Leakage of 3He suggests that the Newport-Inglewood fault is deeper than scientists previously thought. Boles’s findings appear in Geochemistry, Geophysics, Geosystems (G-Cubed), an electronic journal of the American Geophysical Union and the Geochemical Society.

“The results are unexpected for the area, because the LA Basin is different from where most mantle helium anomalies occur,” said Boles, professor emeritus in UCSB’s Department of Earth Science. “The Newport-Inglewood fault appears to sit on a 30-million-year-old subduction zone, so it is surprising that it maintains a significant pathway through the crust.”

When Boles and his co-authors analyzed the 24 gas samples, they found that high levels of 3He inversely correlate with carbon dioxide (CO2), which Boles noted acts as a carrier gas for 3He. An analysis showed that the CO2 was also from the mantle, confirming leakage from deep inside Earth.

Blueschist found at the bottom of nearby deep wells indicates that the Newport-Inglewood fault is an ancient subduction zone — where two tectonic plates collide — even though its location is more than 40 miles west of the current plate boundary of the San Andreas Fault System. Found 20 miles down, blueschist is a metamorphic rock only revealed when regurgitated to the surface via geologic upheaval.

“About 30 million years ago, the Pacific plate was colliding with the North American plate, which created a subduction zone at the Newport-Inglewood fault,” Boles explained. “Then somehow that intersection jumped clear over to the present San Andreas Fault, although how this occurred is really not known. This paper shows that the mantle is leaking more at the Newport-Inglewood fault zone than at the San Andreas Fault, which is a new discovery.”

The study’s findings contradict a scientific hypothesis that supports the existence of a major décollement — a low-angle thrust fault — below the surface of the LA Basin. “We show that the Newport-Inglewood fault is not only deep-seated but also directly or indirectly connected with the mantle,” Boles said.

“If the décollement existed, it would have to cross the Newport-Inglewood fault zone, which isn’t likely,” he added. “Our findings indicate that the Newport-Inglewood fault is a lot more important than previously thought, but time will tell what the true importance of all this is.”

Study co-authors include Grant Garven of Tufts University; Hilario Camacho of Occidental Oil and Gas Corp.; and John Lupton of the National Oceanic and Atmospheric Administration’s Pacific Marine Environmental Laboratory.

This research was supported by the U.S. Department of Energy’s Office of Science and Office of Basic Energy Sciences and by the NOAA Pacific Marine Environmental Laboratory.

Reference:
J. R. Boles, G. Garven, H. Camacho, J. E. Lupton. Mantle helium along the Newport-Inglewood fault zone, Los Angeles basin, California-A leaking paleo-subduction zone. Geochemistry, Geophysics, Geosystems, 2015; DOI: 10.1002/2015GC005951

Note: The above post is reprinted from materials provided by University of California – Santa Barbara. The original item was written by Julie Cohen.

Extreme makeover: Humankind’s unprecedented transformation of Earth

Japanese Garden in Kyoto, a very visible way in which humans ‘Anthropocize’ the biosphere. Credit: University of Leicester

Human beings are pushing the planet in an entirely new direction with revolutionary implications for its life, a new study by researchers at the University of Leicester has suggested.

The research team led by Professor Mark Williams from the University of Leicester’s Department of Geology has published their findings in a new paper entitled ‘The Anthropocene Biosphere’ in The Anthropocene Review.

Professor Jan Zalasiewicz from the University of Leicester’s Department of Geology who was involved in the study explained the research: “We are used to seeing headlines daily about environmental crises: global warming, ocean acidification, pollution of all kinds, looming extinctions. These changes are advancing so rapidly, that the concept that we are living in a new geological period of time, the Anthropocene Epoch — proposed by the Nobel Prize-winning atmospheric chemist Paul Crutzen — is now in wide currency, with new and distinctive rock strata being formed that will persist far into the future.

“But what is really new about this chapter in Earth history, the one we’re living through? Episodes of global warming, ocean acidification and mass extinction have all happened before, well before humans arrived on the planet. We wanted to see if there was something different about what is happening now.”

The team examined what makes the Anthropocene special and different from previous crises in Earth’s history. They identified four key changes:

  • The homogenization of species around the world through mass, human-instigated species invasions — nothing on this global scale has happened before
  • One species, Homo sapiens, is now in effect the top predator on land and in the sea, and has commandeered for its use over a quarter of global biological productivity. There has never been a single species of such reach and power previously
  • There is growing direction of evolution of other species by Homo sapiens
  • There is growing interaction of the biosphere with the ‘technosphere’ — a concept pioneered by one of the team members, Professor Peter Haff of Duke University — the sum total of all human-made manufactured machines and objects, and the systems that control them

In total, the team suggests that these changes represent a planetary transformation as fundamental as the one that saw the evolution of the photosynthetic microbes which oxygenated the planet 2.4 billion years ago, or that saw the transition from a microbial Earth to one dominated by multicellular organisms half a billion years ago.

Professor Williams added: “We think of major changes to the biosphere as the big extinction events, like that which finished off the dinosaurs at the end of the Cretaceous Period. But the changes happening to the biosphere today may be much more significant, and uniquely are driven by the actions of one species, humans.”

Reference:
M. Williams, J. Zalasiewicz, P. Haff, C. Schwagerl, A. D. Barnosky, E. C. Ellis. The Anthropocene biosphere. The Anthropocene Review, 2015; DOI: 10.1177/2053019615591020

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

A ‘hydrothermal siphon’ drives water circulation through the seafloor

Studies by Andrew Fisher and colleagues have shown that seamounts provide conduits through which enormous quantities of water flow between the ocean and the rocks beneath the seafloor. Credit: Courtesy of Nicolle Rager

Vast quantities of ocean water circulate through the seafloor, flowing through the volcanic rock of the upper oceanic crust. A new study by scientists at UC Santa Cruz, published June 26 in Nature Communications, explains what drives this global process and how the flow is sustained.

About 25 percent of the heat that flows out of the Earth’s interior is transferred to the oceans through this process, according to Andrew Fisher, professor of Earth and planetary sciences at UC Santa Cruz and coauthor of the study. Much of the fluid flow and heat transfer occurs through thousands of extinct underwater volcanoes (called seamounts) and other locations where porous volcanic rock is exposed at the seafloor.

Fisher led an international team of scientists that in the early 2000s discovered the first field site where this process could be tracked from fluid inflow to outflow, in the northeastern Pacific Ocean. In a 2003 paper published in Nature, Fisher and others reported that bottom seawater entered into one seamount, traveled horizontally through the crust, gaining heat and reacting with crustal rocks, then discharged into the ocean through another seamount more than 50 kilometers away.

‘Ever since we discovered a place where these processes occur, we have been trying to understand what drives the fluid flow, what it looks like, and what determines the flow direction,’ Fisher said.

For the new study, first author Dustin Winslow, a UCSC Ph.D. candidate who graduated this month, developed the first three-dimensional computer models showing how the process works. The models reveal a ‘hydrothermal siphon’ driven by heat loss from deep in the Earth and the flow of cold seawater down into the crust and of warmed water up out of the crust.

‘Dustin’s models provide the best, most realistic view of these systems to date, opening a window into a hidden realm of water, rock, and life,’ Fisher said.

The models show that water tends to enter the crust (‘recharge’) through seamounts where fluid flow is easiest due to favorable rock properties and larger seamount size. Water tends to discharge where fluid flow is more difficult due to less favorable rock properties or smaller seamount size. This finding is consistent with field observations suggesting that smaller seamounts are favored as sites of hydrothermal discharge.

‘This modeling result was surprising initially, and we had to run many simulations to convince ourselves that it made sense,’ Winslow said. ‘We also found that models set up to flow in the opposite direction would spontaneously flip so that discharge occurred through less transmissive seamounts. This seems to be fundamental to explaining how these systems are sustained.’

Winslow’s project was funded by the U.S. National Science Foundation through a graduate fellowship and as part of the Center for Dark Energy Biosphere Investigations (C-DEBI). UCSC is a partner in C-DEBI, which is headquartered at the University of Southern California.

Reference:
Dustin M. Winslow, Andrew T. Fisher. Sustainability and dynamics of outcrop-to-outcrop hydrothermal circulation. Nature Communications, 2015; 6: 7567 DOI: 10.1038/ncomms8567

Note: The above post is reprinted from materials provided by University of California – Santa Cruz. The original item was written by Tim Stephens.

The ashes of Mt. St. Helens

Mount St. Helen Credit: USGS Cascades Volcano Observatory

The massive eruption of Mt. St. Helens 35 years ago is one of the largest ever seen in North America. LMU volcanologists now report a retrospective analysis of salts leached from the ash deposited by the volcano on that occasion.

As a consequence of the 1980 eruption of Mt. St. Helens, in the state of Washington, USA, a large area of the Pacific Northwest was covered in volcanic ash. Volcanologists of the LMU group of Professor Donald Dingwell have now carried out a comprehensive review of data reported in several studies of the salt content on this ash. The results, which appear in the “Bulletin of Volcanology” reveal that the range of salt concentrations is more complex than hitherto assumed.

Due to interactions between the ash and the gases released during the eruption, salt crystals formed on the surfaces of the ash particles in the plume. In order to assess the impact of these salts on vegetation and groundwater, the amounts and composition of the salts must be determined. Direct measurements on the salts themselves are difficult but, since the salts are water-soluble, they can be leached from the ash and analyzed in solution. “Several published studies have described the spatial and temporal variability of the salt composition of volcanic deposits around Mt. St. Helens and proposed mechanisms for the interactions between gas and ash in the plume that can account for it,” says Dr. Paul Ayris, first author on the new paper. “The 1980 blast at Mt. St. Helens is the best characterized volcanic eruption in history. Studies of this eruption have laid the foundation for our current understanding of the chemical reactions that occurred in the plume. But now, 35 years later, we wanted to view the eruption from our modern perspective.”

Many of the studies devoted to these salts were based on relatively modest datasets and, as the new study highlights, could not capture the range of natural variability and the full complexity of the ash deposited over a wide region. The authors of the new study have therefore collated data from many studies and reanalyzed them, with a view to characterize the spatial distribution and relative abundances of sulphate and chloride salts in the ash deposits around the volcano. The findings reveal that the spatial distribution of salts is considerably more complex than previously thought. “This more detailed picture of the variation in the salts found in these deposits is compatible with the known chemical and physical properties of the ash deposits, and helps us validate our present understanding of the plume,” says Ayris. “The study therefore represents a significant contribution, and provides a basis for the development of theoretical models that enable us to forecast the impact of ash falls on the environment more accurately, on the scale of forests, farmland or gardens.”

Reference:
“Spatial analysis of Mount St. Helens tephra leachate compositions: implications for future sampling strategies.” Bulletin of Volcanology. DOI: 10.1007/s00445-015-0945-8

Note: The above post is reprinted from materials provided by Ludwig Maximilian University of Munich.

Research shows how Spanish colonists changed life in the Middle Rio Grande Valley

Study sites in Middle Rio Grande Valley

Spanish settlement of the Middle Rio Grande Valley in New Mexico changed the way people lived, but a new paper in the journal “The Holocene” by UNM Assistant Professor of Anthropology Emily Jones, suggests the change did not come quickly.

“The Columbian Exchange and landscapes of the Middle Rio Grande Valley, AD 1300-1900” is an examination of the impact of Spanish colonization including what people were eating, and an indication of what animals and plants were abundant in the area.

When the Spanish expeditions came to the Middle Rio Grande Valley in 1598 to establish residence, they found inhabited villages and long standing agricultural practices. The Spanish colonists brought seeds, plant cuttings and domestic livestock with them and use of the plants and animals were readily adopted by the Native Americans.

But Jones says animal bones from archeological sites suggest no immediate major impact on the landscape.

Jones’ research focuses on the “Columbian Exchange” or the transformation of landscapes that came with contact between the old and new world. For this paper she examined archeological faunal materials from a number of historic pueblos, missions and villages – essentially the bones left if the trash heaps to determine the animal portion of historic people’s diets.

Jones found significant amounts of wild game (pronghorn, deer and rabbits) alongside domestic animals up through the late 19th century, suggesting hunting was a major part of life through that time.

“I was expecting to see a turnover in the mammals people ate – a change from wild mammals to introduced domesticates, like sheep, goats and cattle – relatively early in the 17th or early 18th century. You would start with wild fauna which would then be mostly replaced by things like sheep, and goats and cattle,” she said. “What I actually found was that this change doesn’t seem to occur until very late in the game in the late 19th and early 20th century.”

The date on mammals have implications about how vegetation may have changed with Spanish colonization. There has been some debate as to when overgrazing became a problem in the Middle Rio Grande Valley – whether it occurred soon after Spanish colonists brought sheet and cattle in 1598 or if livestock populations took some time to make an impact.

Jones’ data may suggest that widespread overgrazing of the landscape did not occur until the time that rail travel brought many more people into the Middle Rio Grande Valley in the late 19th century – a time when other invasive species such as tumbleweeds also became a problem.

“To me the Columbian exchange was an incredible event. It shaped the world we live in now, causing environments in very different parts of the world to look more similar to each other,” Jones said. “This research project is situated in the larger question of when did that change take place and how – was it gradual or quick? To me, this question is really cool.”

Reference:
“The ‘Columbian Exchange’ and landscapes of the Middle Rio Grande Valley, AD 1300–1900.” The Holocene 0959683615588375, first published on June 3, 2015 DOI: 10.1177/0959683615588375

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

NASA explains why June 30 will get extra second

The day will officially be a bit longer than usual on Tuesday, June 30, 2015, because an extra second, or “leap” second, will be added.

“Earth’s rotation is gradually slowing down a bit, so leap seconds are a way to account for that,” said Daniel MacMillan of NASA’s Goddard Space Flight Center in Greenbelt, Md.

Strictly speaking, a day lasts 86,400 seconds. That is the case, according to the time standard that people use in their daily lives — Coordinated Universal Time, or UTC. UTC is “atomic time” — the duration of one second is based on extremely predictable electromagnetic transitions in atoms of cesium. These transitions are so reliable that the cesium clock is accurate to one second in 1,400,000 years.

However, the mean solar day — the average length of a day, based on how long it takes Earth to rotate — is about 86,400.002 seconds long. That’s because Earth’s rotation is gradually slowing down a bit, due to a kind of braking force caused by the gravitational tug of war between Earth, the moon and the sun. Scientists estimate that the mean solar day hasn’t been 86,400 seconds long since the year 1820 or so.

This difference of 2 milliseconds, or two thousandths of a second — far less than the blink of an eye — hardly seems noticeable at first. But if this small discrepancy were repeated every day for an entire year, it would add up to almost a second. In reality, that’s not quite what happens. Although Earth’s rotation is slowing down on average, the length of each individual day varies in an unpredictable way.

The length of day is influenced by many factors, mainly the atmosphere over periods less than a year. Our seasonal and daily weather variations can affect the length of day by a few milliseconds over a year. Other contributors to this variation include dynamics of the Earth’s inner core (over long time periods), variations in the atmosphere and oceans, groundwater, and ice storage (over time periods of months to decades), and oceanic and atmospheric tides. Atmospheric variations due to El Niño can cause Earth’s rotation to slow down, increasing the length of day by as much as 1 millisecond, or a thousandth of a second.

Scientists monitor how long it takes Earth to complete a full rotation using an extremely precise technique called Very Long Baseline Interferometry (VLBI). These measurements are conducted by a worldwide network of stations, with Goddard providing essential coordination of VLBI, as well as analyzing and archiving the data collected.

The time standard called Universal Time 1, or UT1, is based on VLBI measurements of Earth’s rotation. UT1 isn’t as uniform as the cesium clock, so UT1 and UTC tend to drift apart. Leap seconds are added, when needed, to keep the two time standards within 0.9 seconds of each other. The decision to add leap seconds is made by a unit within the International Earth Rotation and Reference Systems Service.

Typically, a leap second is inserted either on June 30 or December 31. Normally, the clock would move from 23:59:59 to 00:00:00 the next day. But with the leap second on June 30, UTC will move from 23:59:59 to 23:59:60, and then to 00:00:00 on July 1. In practice, many systems are instead turned off for one second.

Previous leap seconds have created challenges for some computer systems and generated some calls to abandon them altogether. One reason is that the need to add a leap second cannot be anticipated far in advance.

“In the short term, leap seconds are not as predictable as everyone would like,” said Chopo Ma, a geophysicist at Goddard and a member of the directing board of the International Earth Rotation and Reference Systems Service. “The modeling of the Earth predicts that more and more leap seconds will be called for in the long-term, but we can’t say that one will be needed every year.”

From 1972, when leap seconds were first implemented, through 1999, leap seconds were added at a rate averaging close to one per year. Since then, leap seconds have become less frequent. This June’s leap second will be only the fourth to be added since 2000. (Before 1972, adjustments were made in a different way.)

Scientists don’t know exactly why fewer leap seconds have been needed lately. Sometimes, sudden geological events, such as earthquakes and volcanic eruptions, can affect Earth’s rotation in the short-term, but the big picture is more complex.

VLBI tracks these short- and long-term variations by using global networks of stations to observe astronomical objects called quasars. The quasars serve as reference points that are essentially motionless because they are located billions of light years from Earth. Because the observing stations are spread out across the globe, the signal from a quasar will take longer to reach some stations than others. Scientists can use the small differences in arrival time to determine detailed information about the exact positions of the observing stations, Earth’s rotation rate, and our planet’s orientation in space.

Current VLBI measurements are accurate to at least 3 microseconds, or 3 millionths of a second. A new system is being developed by NASA’s Space Geodesy Project in coordination with international partners. Through advances in hardware, the participation of more stations, and a different distribution of stations around the globe, future VLBI UT1 measurements are expected to have a precision better than 0.5 microseconds, or 0.5 millionths of a second.

“The next-generation system is designed to meet the needs of the most demanding scientific applications now and in the near future,” says Goddard’s Stephen Merkowitz, the Space Geodesy Project manager.

NASA manages many activities of the International VLBI Service for Geodesy and Astrometry including day-to-day and long-term operations, coordination and performance of the global network of VLBI antennas, and coordination of data analysis. NASA also directly supports the operation of six global VLBI stations.

Proposals have been made to abolish the leap second. No decision about this is expected until late 2015 at the earliest, by the International Telecommunication Union, a specialized agency of the United Nations that addresses issues in information and communication technologies.

Note: The above post is reprinted from materials provided by NASA/Goddard Space Flight Center.

Iron: A biological element?

By studying iron extracted from cores drilled in rocks similar to these in Karijini National Park, Western Australia, UW-Madison researchers determined that half of the iron atoms had originated in shallow oceans after being processed by microbes 2.5 billion years ago. Credit: Clark Johnson

Think of an object made of iron: An I-beam, a car frame, a nail. Now imagine that half of the iron in that object owes its existence to bacteria living two and a half billion years ago.

That’s the upshot of a study published this week in the Proceedings of the National Academy of Sciences (PNAS). The findings have meaning for fields as diverse as mining and the search for life in space.

Clark Johnson, a professor of geoscience at the University of Wisconsin-Madison, and former postdoctoral researcher Weiqiang Li examined samples from the banded iron formation in Western Australia. Banded iron is the iron-rich rock found in ore deposits worldwide, from the proposed iron mine in Northern Wisconsin to the enormous mines of Western Australia.

These ancient deposits, up to 150 meters deep, were begging for explanation, says Johnson.

Scientists thought the iron had entered the ocean from hot, mineral-rich water released at mid-ocean vents that then precipitated to the ocean floor. Now Johnson and Li, who is currently at Nanjing University in China, show that half of the iron in banded iron was metabolized by ancient bacteria living along the continental shelves.

The banding was thought to represent some sort of seasonal changes. The UW-Madison researchers found long-term swings in the composition, but not variations on shorter periods like decades or centuries.

The study began with precise measurements of isotopes of iron and neodymium using one of the world’s fastest lasers, housed in the UW-Madison geoscience department. (Isotopes, forms of an atom that differ only by weight, are often used to “fingerprint” the source of various samples.)

Bursts of light less than one-trillionth of a second long vaporized thin sections of the sample without heating the sample itself. “It’s like taking an ice cream scoop and quickly pulling out material before it gets heated,” Johnson explains.

“Heating with traditional lasers gave spurious results.”

It took three years to perfect the working of the laser and associated mass spectrometry instruments, Li says.

Banded iron formations are the primary source of iron ore worldwide. These rocks, at Soudan Underground Mine State Park, Minnesota. Credit: Clark Johnson

Previous probes of the source of banded iron had focused on iron isotopes. “There has been debate about what the iron isotopes were telling us about the source,” Li says. “Adding neodymium changed that picture and gave us an independent measure of the amount coming from shallow continental waters that carried an isotopic signature of life.”

The idea that an organism could metabolize iron may seem strange today, but Earth was very different 2.5 billion years ago. With little oxygen in the atmosphere, many organisms derived energy by metabolizing iron instead of oxygen.

Biologists say this process “is really deep in the tree of life, but we’ve had little evidence from the rock record until now,” Johnson says. “These ancient microbes were respiring iron just like we respire oxygen. It’s a hard thing to wrap your head around, I admit.”

The current study is important in several ways, Johnson says. “If you are an exploration geologist, you want to know the source of the minerals so you know where to explore.”

The research also clarifies the evolution of our planet—and of life itself—during the “iron-rich” era 2.5 billion years ago. “What vestiges of the iron-rich world remain in our metabolism?” Johnson asks. “It’s no accident that iron is an important part of life, that early biological molecules may have been iron-based.”

NASA has made the search for life in space a major focus and sponsors the UW-Madison Astrobiology Institute, which Johnson directs. Recognizing unfamiliar forms of life is a priority for the space agency.

The study reinforces the importance of microbes in geology. “This represents a huge change,” Johnson says. “In my introductory geochemistry textbook from 1980, there is no mention of biology, and so every diagram showing what minerals are stable at what conditions on the surface of the Earth is absolutely wrong.”

Research results like these affect how classes are taught, Johnson says. “If I only taught the same thing, I would be teaching things that are absolutely wrong. If you ever wonder why we combine teaching and research at this university, geomicrobiology gives you the answer. It has completely turned geoscience on its ear.”

Reference:
Biologically recycled continental iron is a major component in banded iron formations, DOI: 10.1073/pnas.1505515112

Note: The above post is reprinted from materials provided by University of Wisconsin-Madison.

Backward-moving glacier helps scientists explain glacial earthquakes

One of the 20 GPS sensors deployed on Helheim Glacier’s chaotic surface. Credit: Alistair Everett, Swansea University; (courtesy of University of Michigan)

The relentless flow of a glacier may seem unstoppable, but a team of researchers from the United Kingdom and the U.S. has shown that during some calving events — when an iceberg breaks off into the ocean — the glacier moves rapidly backward and downward, causing the characteristic glacial earthquakes which until now have been poorly understood.This new insight into glacier behavior, gained by combining field observations in Greenland with laboratory calving experiments, should enable scientists to measure glacier calving remotely and will improve the reliability of models that predict future sea-level rise in a warming climate.

The research is scheduled for publication in Science Express on June 25. The lead author is Tavi Murray of Swansea University. Co-authors include U-M’s L. Mac Cathles, an assistant professor in the Department of Earth and Environmental Sciences and the Department of Atmospheric, Oceanic and Space Sciences and a postdoctoral fellow in the Michigan Society of Fellows.

The Greenland ice sheet is an important contributor to global sea level, and nearly half of the ice sheet’s annual mass loss occurs through the calving of icebergs to the ocean. Glacial earthquakes have increased sevenfold in the last two decades and have been migrating north, suggesting an increase in rates of mass loss from the ice sheet through calving.

“Our new understanding is a crucial step toward developing tools to remotely measure the mass loss that occurs when icebergs break off ice sheets,” Cathles said. “Combining field observations with laboratory measurements from scaled-model calving experiments provided insights into the dynamics of calving and glacial earthquakes that would not have otherwise been possible.”

Helheim Glacier is one of the largest glaciers in southeast Greenland. At 6 kilometers (3.7 miles) wide and more than 200 kilometers (124.3 miles) long, it can flow as fast as 30 meters (98 feet) a day. Icebergs calving from Helheim Glacier have been measured at up to 4 kilometers (2.5 miles) across, with a volume of about 1.25 cubic kilometers (0.3 cubic miles).

During summer 2013, researchers from Swansea, Newcastle and Sheffield universities installed a robust wireless network of Global Positioning System devices on the chaotic surface of Helheim to measure velocity and displacement of the glacier surface.

With U.S. collaborators from U-M, Columbia University and Emory University, earthquake data from the Global Seismographic Network and scaled-down models in water tanks were used to explain the unexpected movements of the glacier in the minutes surrounding the calving events.

“We were really surprised to see the glacier flowing backward in our GPS data. The motion happens every time a large iceberg is calved and a glacial earthquake is produced,” said Swansea’s Murray. “A theoretical model for the earthquakes and the laboratory experiments has allowed us to explain the backward and downward movement.”

U-M’s Cathles helped design and run the laboratory experiments of iceberg calving presented in the paper. The international collaboration grew out of a conversation that Cathles and Murray had at an International Glaciological Society meeting in Chamonix, France, last summer.

“We both presented in the same session and realized that I was measuring in the lab a very similar signal to what Professor Murray was observing in the field,” Cathles said. “That started a year-long collaboration in which the paper’s co-authors talked regularly and collectively developed a model to explain the GPS observations and a deeper understanding of how glacial earthquakes are generated during an iceberg calving event.”

Understanding this glacier behavior and the associated glacial earthquakes is a crucial step toward remote measurement of calving events and their contribution to sea-level change. This tool has the potential to provide unprecedented global, near-real-time estimates of iceberg loss from the ice sheet.

The research was supported by the U.K. Natural Environment Research Council, the U.S. National Science Foundation and the Climate Change Consortium of Wales and Thales U.K.

Video

Reference:
T. Murray, M. Nettles, N. Selmes, L. M. Cathles, J. C. Burton, T. D. James, S. Edwards, I. Martin, T. O’farrell, R. Aspey, I. Rutt, T. Baug. Reverse glacier motion during iceberg calving and the cause of glacial earthquakes. Science, 2015 DOI: 10.1126/science.aab0460

Note: The above post is reprinted from materials provided by University of Michigan. The original item was written by L. Mac Cathles.

Earth’s daily rotation period encoded in an atomic-level protein structure

This image shows Earth and the circadian clock protein KaiC. Credit: IMS/NINS

A collaborative group of Japanese researchers has demonstrated that the Earth’s daily rotation period (24 hours) is encoded in the KaiC protein at the atomic level, a small, 10 nm-diameter biomolecule expressed in cyanobacterial cells.

This research group included: Dr. Jun Abe, Assistant Prof. Atsushi Mukaiyama, and Prof. Shuji Akiyama of the Institute for Molecular Science (IMS) Research Center of Integrative Molecular Systems (CIMoS); Assistant Prof. Toshifumi Mori and Prof. Shinji Saito of the Department of Theoretical and Computational Molecular Science at IMS; Designated Prof. Takao Kondo of Nagoya University; and Assistant Prof. Eiki Yamashita of the Osaka University Institute for Protein Research.

The results of this joint research will help elucidate a longstanding question in chronobiology: How is the circadian period of biological clocks determined? The results will also help understand the basic molecular mechanism of the biological clock. This knowledge might contribute to the development of therapies for disorders associated with abnormal circadian rhythms.

In accordance with diurnal changes in the environment (notably light intensity and temperature) resulting from the Earth’s daily rotation around its axis, many organisms regulate their biological activities to ensure optimal fitness and efficiency. The biological clock refers to the mechanism whereby organisms adjust the timing of their biological activities. The period of this clock is set to approximately 24 hours. A wide range of studies have investigated the biological clock in organisms ranging from bacteria to mammals. Consequently, the relationship between the biological clock and multiple diseases has been clarified. However, it remains unclear how 24-hour circadian rhythms are implemented.

The research group mentioned above addressed this question using cyanobacteria. The cyanobacterial circadian clock can be reconstructed by mixing three clock proteins (KaiA, KaiB, and KaiC) and ATP. A study published in 2007 showed that KaiC ATPase activity, which mediates the ATP hydrolysis reaction, is strongly associated with circadian periodicity. The results of that study indicated that the functional structure of KaiC could be responsible for determining the circadian rhythm.

KaiC ATPase activity exhibits a robust circadian oscillation in the presence of KaiA and KaiB proteins. In the study reported here, the temporal profile of KaiC ATPase activity exhibited an attenuating and oscillating component even in the absence of KaiA and KaiB. A close analysis revealed that this signal had a frequency of 0.91 day-1, which approximately coincided with the 24-hour period. Thus, KaiC is the source of a steady cycle that is in tune with the Earth’s daily rotation.

To identify causal structural factors, the N-terminal domain of KaiC was analyzed using high-resolution crystallography. The resultant atomic structures revealed the underlying cause of KaiC’s slowness relative to other ATPases. “A water molecule is prevented from attacking into the ideal position for the ATP hydrolysis by a steric hindrance near ATP phosphoryl groups. In addition, this hindrance is surely anchored to a spring-like structure derived from polypeptide isomerization,” elaborates Dr. Jun Abe. “The ATP hydrolysis, which involves access of a water molecule to the bound ATP and reverse isomerization of the polypeptide, is expected to require a significantly larger amount of free energy than for typical ATP hydrolysis. Thus, the three-dimensional atomic structure discovered in this study explains why the ATPase activity of KaiC is so much lower (by 100- to 1,000,000-fold) than that of typical ATPase molecules.”

The circadian clock’s period is independent of ambient temperature, a phenomenon known as temperature compensation. One KaiC molecule is composed of six identical subunits, each containing duplicated domains with a series of ATPase motifs. The asymmetric atomic-scale regulation by the aforementioned mechanism dictates a feedback mechanism that maintains the ATPase activity at a constant low level. The authors of this study discovered that the Earth’s daily rotation period (24 hours) is implemented as the time constant of the feedback mechanism mediated in this protein structure.

Technological Implications

KaiC and other protein molecules are capable of moving on short time scales, on the order of 10-12 to 10-1 seconds. This study provides the first atomic-level demonstration that small protein molecules can generate 24-hour rhythms by regulating molecular structure and reactivity. Lab head and CIMoS Director Porf. Shuji Akiyama sees, “The fact that a water molecule, ATP, the polypeptide chain, and other universal biological components are involved in this regulation suggests that humans and other complex organisms may also share a similar molecular machinery. In the crowded intracellular environment that contains a myriad of molecular signals, KaiC demonstrates long-paced oscillations using a small amount of energy generated through ATP consumption. This clever mechanism for timekeeping in a noisy environment may inspire development of highly efficient and sustainable chemical reaction processes and molecular-system-based information processing.”

Glossary

1) Clock protein: A clock protein plays an essential role in the circadian pacemaker. Mutations and deficiencies in clock proteins can alter the intrinsic characteristics of circadian rhythm.

2) ATP: Adenosine triphosphate is a source of energy required for muscle contraction and many other biological activities. ATP, a nucleotide that mediates the storage and consumption of energy, is sometimes referred to as the “currency of biological energy” due to its universality and importance in metabolism. ATP consists of an adenosine molecule bound to three phosphate groups. Upon hydrolysis, the ATPase releases one phosphate molecule plus approximately 8 kcal/mol of energy.

3) Polypeptide isomerization: Protein polypeptide main chains undergo isomerization on a time scale of seconds or longer; therefore, protein isomerization is one of the slowest biological reactions. Most functional protein main chains have a trans conformation, and a few proteins have a functional cis conformation.

Reference:
Jun Abe, Takuya B. Hiyama, Atsushi Mukaiyama, Seyoung Son, Toshifumi Mori, Shinji Saito, Masato Osako, Julie Wolanin, Eiki Yamashita, Takao Kondo, and Shuji Akiyama. Atomic-scale origins of slowness in the cyanobacterial circadian clock. Science, 25 June 2015 DOI: 10.1126/science.1261040

Note: The above post is reprinted from materials provided by National Institutes of Natural Sciences.

Ordovician Carbon Isotope Curve

By Bergstrom, S.M., Xu Chen, Gutierrez-Marco, J.C., and Dronov, A., 2008, Lethaia, DOI: 10.1111/j.1502-3931.2008.00136.x

Click HERE to download a better version (higher resolution)

Copyright © 2013-2014 International Commission on Stratigraphy – ALL RIGHTS RESERVED

Newly found ring of teeth uncovers what common ancestor of molting animals looked like

Left: Hallucigenia sparsa from the Burgess Shale (Royal Ontario Museum 61513) The fossil is 15 mm long. Right: Colour reconstruction of Hallucigenia sparsa. Credit: Left: Jean-Bernard Caron; Right: Danielle Dufault

A new study of an otherworldly creature from half a billion years ago — a worm-like animal with legs, spikes and a head difficult to distinguish from its tail — has definitively identified its head for the first time, and revealed a previously unknown ring of teeth and a pair of simple eyes. The results, published today in the journal Nature, have helped scientists reconstruct what the common ancestor of everything from tiny roundworms to huge lobsters might have looked like.

Researchers from the University of Cambridge, the Royal Ontario Museum and the University of Toronto have found that the creature, known as Hallucigenia due to its strange appearance, had a throat lined with needle-like teeth, a previously unidentified feature which could help connect the dots between it, modern velvet worms and arthropods — the group which contains modern insects, spiders and crustaceans.

Arthropods, velvet worms (onychophorans) and water bears (tardigrades) all belong to the massive group of animals that moult, known as ecdysozoans. Though Hallucigenia is not the common ancestor of all ecdysozoans, it is a precursor to velvet worms. Finding this mouth arrangement in Hallucigenia helped scientists determine that velvet worms originally had the same configuration — but it was eventually lost through evolution.

“The early evolutionary history of this huge group is pretty much uncharted,” said Dr Martin Smith, a postdoctoral researcher in Cambridge’s Department of Earth Sciences, and the paper’s lead author. “While we know that the animals in this group are united by the fact that they moult, we haven’t been able to find many physical characteristics that unite them.”

“It turns out that the ancestors of moulting animals were much more anatomically advanced than we ever could have imagined: ring-like, plate-bearing worms with an armoured throat and a mouth surrounded by spines,” said Dr Jean-Bernard Caron, Curator of Invertebrate Palaeontology at the Royal Ontario Museum and Associate Professor in the Departments of Earth Sciences and Ecology & Evolutionary Biology at the University of Toronto. “We previously thought that neither velvet worms nor their ancestors had teeth. But Hallucigenia tells us that actually, velvet worm ancestors had them, and living forms just lost their teeth over time.”

Hallucigenia was just one of the weird creatures that lived during the Cambrian Explosion, a period of rapid evolutionary development starting about half a billion years ago, when most major animal groups first emerge in the fossil record.

At first, Hallucigenia threw palaeontologists for a bit of a loop. When it was identified in the 1970s, it was reconstructed both backwards and upside down: the spines along its back were originally thought to be legs, its legs were thought to be tentacles along its back, and its head was mistaken for its tail.

Right side up and right way round, Hallucigenia still looks pretty strange: it had pairs of lengthy spines along its back, seven pairs of legs ending in claws, and three pairs of tentacles along its neck. The animals were between 10 and 50 millimetres in length and lived on the floor of the Cambrian oceans.

More significantly, Hallucigenia’s unearthly appearance has made it difficult to link it to modern animal groups and to find its home in the Tree of Life. In 2014, research from Cambridge partially solved this problem by studying the structure of Hallucigenia’s claws, which helped definitively link it to modern velvet worms.

In the new work, researchers used electron microscopy to examine fossils from the collections of the Royal Ontario Museum and the Smithsonian Institution, definitively sorting Hallucigenia’s front from back, and making some surprising observations.

“Prior to our study there was still some uncertainty as to which end of the animal represented the head, and which the tail,” said Smith. “A large balloon-like orb at one end of the specimen was originally thought to be the head, but we can now demonstrate that this actually wasn’t part of the body at all, but a dark stain representing decay fluids or gut contents that oozed out as the animal was flattened during burial.”

Identifying this end as the tail led Caron to revisit the fossils and dig away the sediment that was covering the head: the animals died as they were buried in a mudslide, and their floppy head often ended up pointing down into the mud. “This let us get the new images of the head,” said Caron. “When we put the fossils in the electron microscope, we were initially hoping that we might find eyes, and were astonished when we also found the teeth smiling back at us!”

The new images show an elongated head with a pair of simple eyes, which sat above a mouth with a ring of teeth. In addition, Hallucigenia’s throat was lined with needle-shaped teeth. The fossils originated in the Burgess Shale of Yoho National Park in western Canada, one of the world’s richest sources of fossils from the Cambrian period.

The ring of teeth that surrounded Hallucigenia’s mouth probably helped to generate suction, flexing in and out, like a valve or a plunger, in order to suck its food into its throat. The researchers speculate that the teeth in the throat worked like a ratchet, keeping food from slipping out of the mouth each time it took another ‘suck’ at its food.

“These teeth resemble those we see in many early moulting animals, suggesting that a tooth-lined throat was present in a common ancestor,” said Caron. “So where previously there was little reason to think that arthropod mouths had much in common with the mouths of animals such as penis worms, Hallucigenia tells us that arthropods and velvet worms did ancestrally have round-the-mouth plates and down-the-throat teeth — they just lost or simplified them later.”

The material for this study was collected between 1992 and 2000 and represents more than 165 additional Hallucigenia specimens — including many rare orientations and well-preserved specimens.

Parks Canada, which holds jurisdiction over the Burgess Shale sites located in Yoho and Kootenay national parks, is thrilled by this discovery and eager to share this exciting new piece of the ever-unfolding Burgess Shale story with their visitors.

The research was funded by Clare College, Cambridge, the Natural Sciences and Engineering Research Council of Canada, and the Royal Ontario Museum.

Video

Reference:
Martin R. Smith, Jean-Bernard Caron. Hallucigenia’s head and the pharyngeal armature of early ecdysozoans. Nature, 2015; DOI: 10.1038/nature14573

Note: The above post is reprinted from materials provided by University of Cambridge. The original story is licensed under a Creative Commons Licence.

Researchers Reconstruct Dinosaur Tracks

Recent photograph of DFMMh/FV 648, the best preserved footprint, photographed at a low angle. The arrow shows the strongly inclined digit impression IV.

Paleontologists from the University of Bonn use photos to create a digital, three-dimensional model of the discovery site

Twelve years ago, footprints of carnivorous dinosaurs were discovered and excavated in a quarry near Goslar. Paleontologists from the University of Bonn, working with Dinosaur Park Münchehagen and the State Museum of Hanover, have now created a three-dimensional digital model based on photographs of the excavation. The reconstruction of the discovery site suggests that carnivorous dinosaurs hunted herbivorous island-dwelling dinosaurs about 154 million years ago. They believe the predators could have immigrated via a land bridge as sea levels dropped. The findings have now been published in the geoscience journal “Palaeontologia Electronica”.

In 2003, a private fossil collector made a surprising discovery in a limestone quarry near Goslar in Lower Saxony: a total of 20 dinosaur footprints imprinted on a stone slab. Nils Knötschke, from Dinosaur Park Münchehagen, was able to salvage five of the tracks and kept them from being destroyed by the quarry work. Now, about a dozen years later, paleontologists from the University of Bonn, led by Prof. Dr. Martin Sander, have worked with Nils Knötschke and Dr. Oliver Wings from the State Museum of Hanover to reconstruct the tracks in a three-dimensional model, using digital methods. The project was based on photos of the tracks taken at the time when they were excavated.

“Even five years ago, it wouldn’t have been technically possible to do this kind of reconstruction,” says first author Jens N. Lallensack of the Steinmann Institute for Geology, Mineralogy and Paleontology at the University of Bonn. Based on the 3D model, the researchers were able to gain crucial information about the dinosaurs that left the footprints behind, and about their habitat at the time. The tracks, measuring between 36 and 47 centimeters in length, probably represent two different species of predatory dinosaurs from the Theropoda group.

Glimpses of the habitat 154 million years ago

Based on the digital model, we can now see how the individual footprints are positioned in relation to one another. “That allowed us to reconstruct the moving direction, and how fast the animals were traveling. Based on the length of the footprints, we can estimate that the largest animals had a body length of about eight meters. In some places, the carnivorous dinosaurs also left much deeper tracks in the sediment than elsewhere. “Where the ground was soft, the dinosaurs sank in much deeper than where it was dry,” reports Lallensack.

About 154 million years ago, during the Late Jurassic Era, there was a shallow sea throughout this region, with small islands jutting up out of it. Bones found in the Langenberg Quarry confirm that the islands were inhabited by a species of small dinosaurs, Europasaurus holgeri. These herbivores belonged to the group of gigantic, long-necked dinosaurs called sauropods. However, a full-grown Europasaurus only measured six to eight meters – about one-fourth the length of its nearest relative, Camarasaurus. “The dinosaur probably had to shrink down to dwarf size in order to survive, given the limited food available on these small islands in the shallow Central European sea,” says Lallensack.

Theropods probably immigrated via a land bridge

The theropods that originally made the reconstructed dinosaur tracks came on the scene about 35,000 years later. “It’s possible that the sea level dropped during this period – a relatively short time from a geological perspective – and that the mainland carnivorous dinosaurs immigrated at that point,” surmises Dr. Wings, who is heading a research project funded by VolkswagenStiftung at the State Museum of Hanover on the overall Jurassic habitats of the region. The theropod tracks come from a dried-up ocean floor bed very close to one of the islands.

As a result, the researchers suspect that the predatory theropods came from the mainland in order to hunt the herbivorous Europasaurus. All of the limestone in the quarry formed in a shallow sea basin, as evidenced by the large number of marine fossils such as snails, mussels and sea urchins. To date, the tracks are the only indication that the region was temporarily dry, and that large mainland-based carnivorous dinosaurs were present on the former Europasaurus island. “We suspect that is what sealed the fate of these specialized island-dwelling dwarves,” says Lallensack.

Reference:
Jens N. Lallensack, P. Martin Sander, Nils Knötschke, and Oliver Wings. Dinosaur tracks from the Langenberg Quarry (Late Jurassic, Germany) reconstructed with historical photogrammetry: Evidence for large theropods soon after insular dwarfism. Palaeontologia Electronica, 2015: http://palaeo-electronica.org/content/2015/1166-langenberg-tracks

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

Scientists persuade volcanoes to tell their stories

Laser compositional image in 3D of a volcanic crystal. Different crystal zones are shown with different colors. Credit: Courtesy of Teresa Ubide, Trinity College Dublin

Every volcano has a story, but, until now, most of these stories were shrouded in mystery.

However, scientists from Trinity College Dublin have just discovered how to prise volcanic secrets from magma crystals, which means they are better able to piece together the history of global geography and to predict future eruptions of active volcanoes.

Their method will help to understand the reasons for past eruptions, and thus allow more accurate predictions for eruptions yet to occur.

Research fellow in geology in the School of Natural Sciences at Trinity, Dr. Teresa Ubide, was among those who worked out how to persuade volcanoes to tell their stories.

She said: ‘Volcanoes are fascinating, but also dangerous. We need to understand how they work to be better prepared for volcanic eruptions, such as the 2010 Eyjafjallajökull eruption in Iceland, which collapsed air traffic across Europe and caused huge economic, political and cultural problems for huge numbers of people.’

The volcanic cones and lava flows we see on the surface of Earth are fed by magma from great depth. It is thought that the injection of fresh magma into deep reservoirs is the key trigger in volcanic eruptions.

But how is it possible to reconstruct what is going on many kilometres below the surface, at temperatures greater than 1000 degrees Celsius?

Ubide added: ‘Just as investigators reconstruct events to learn the truth, we prise magma injections from the crystals that are transported to the surface by erupted magmas to do the same thing. This method helps us form a detailed picture of the magma history.’

Magmatic crystals typically grow from the center outwards, like tree rings. The microscopic growth rings or zones of crystals record the history of magmatic processes occurring during crystallization, which can be read by expert eyes. The chemical composition of successive growth zones is a particularly valuable source of information about magma history.

The Trinity scientists are funded by SFI to improve the method by which a laser beam, similar to that used for eye surgery, removes a thin film from the surface of the crystals. This produces a group of particles than are analyzed to visualize the precise pattern of growth zones of the crystal.

Importantly, the method works even for chemical elements present at very low concentrations, some of which are particularly useful for unveiling magma history with unprecedented detail.

The article presenting the methodology and its optimization for magmatic crystals has just been published in the journal Chemical Geology.

The paper includes results for crystals from magmas related to the opening of the North Atlantic Ocean, where the separation of tectonic plates made the crust thinner and weaker, allowing the ascent of magmas.

That particular magmatic system developed 79 million years ago in northeast Spain, where the Costa Brava is located today, and where tourists enjoy its warm weather and selected cuisine unaware of the many secrets hidden in the rocks and crystals just next to their beach umbrellas!

Video

Reference:
Teresa Ubide, Cora A. McKenna, David M. Chew, Balz S. Kamber. High-resolution LA-ICP-MS trace element mapping of igneous minerals: In search of magma histories. Chemical Geology, 2015; 409: 157 DOI: 10.1016/j.chemgeo.2015.05.020

Note: The above post is reprinted from materials provided by Trinity College Dublin.

Sefapanosaurus: New Sesotho-named dinosaur from South Africa

South African and Argentinian palaeontologists have discovered a new 200 million year old dinosaur from South Africa, and named it Sefapanosaurus, from the Sesotho word “sefapano”.

The researchers from South Africa’s University of Cape Town (UCT) and the University of the Witwatersrand (Wits University), and from the Argentinian Museo de La Plata and Museo Paleontológico Egidio Feruglio made the announcement in the scientific journal, Zoological Journal of the Linnaean Society. The paper, titled: A new basal sauropodiform from South Africa and the phylogenetic relationships of basal sauropodomorphs, was published online on Tuesday, 23 June 2015.

The specimen was found in the late 1930s in the Zastron area of South Africa’s Free State province, about 30km from the Lesotho border. For many years it remained hidden among the largest fossil collection in South Africa at the Evolutionary Studies Institute (ESI) at Wits University.

A few years ago it was studied and considered to represent the remains of another South African dinosaur, Aardonyx. However, upon further study, close scrutiny of the fossilised bones has revealed that it is a completely new dinosaur.

One of the most distinctive features is that one of its ankle bones, the astragalus, is shaped like a cross. Considering the area where the fossil was discovered, the researchers aptly named the new dinosaur, Sefapanosaurus, after the Sesotho word “sefapano”, meaning “cross”.

Anusuya Chinsamy-Turan, co-author and Professor in the Department of Biological Sciences at UCT, says: “The discovery of Sefapanosaurus shows that there were several of these transitional early sauropodomorph dinosaurs roaming around southern Africa about 200 million years ago.”

Dr Alejandro Otero, Argentinian palaeontologist and lead author, says Sefapanosaurus helps to fill the gap between the earliest sauropodomorphs and the gigantic sauropods. “Sefapanosaurus constitutes a member of the growing list of transitional sauropodomorph dinosaurs from Argentina and South Africa that are increasingly telling us about how they diversified.”

Says Dr Jonah Choiniere, co-author and Senior Researcher in Dinosaur Palaeobiology at the ESI at Wits University: “This new animal shines a spotlight on southern Africa and shows us just how much more we have to learn about the ecosystems of the past, even here in our own ‘backyard’. And it also gives us hope that this is the start of many such collaborative palaeo-research projects between South Africa and Argentina that could yield more such remarkable discoveries.”

Argentinian co-author, Dr Diego Pol, says Sefapanosaurus and other recent dinosaur discoveries in the two countries reveal that the diversity of herbivorous dinosaurs in Africa and South America was remarkably high back in the Jurassic, about 190 million years ago when the southern hemisphere continents were a single supercontinent known as Gondwana.

Finding a new dinosaur among old bones

Otero and Emil Krupandan, PhD-student from UCT, were visiting the ESI collections to look at early sauropodomorph dinosaurs when they noticed bones that were distinctive from the other dinosaurs they were studying.

Krupandan was working on a dinosaur from Lesotho as part of his studies when he realised the material he was looking at was different to Aardonyx. “This find indicates the importance of relooking at old material that has only been cursorily studied in the past, in order to re-evaluate past preconceptions about sauropodomorph diversity in light of new data.”

The remains of the Sefapanosaurus include limb bones, foot bones, and several vertebrae. Sefapanosaurus is represented by the remains of at least four individuals in the ESI collections at Wits University. It is considered to be a medium-sized sauropodomorph dinosaur – among the early members of the group that gave rise to the later long necked giants of the Mesozoic.

Reference:
The researchers are from South Africa’s University of Cape Town (UCT) and the University of the Witwatersrand (Wits University), and from the Argentinian Museo de La Plata and Museo Paleontológico Egidio Feruglio. They made the announcement in a paper, titled: A new basal sauropodiform from South Africa and the phylogenetic relationships of basal sauropodomorphs, published online in the journal, Zoological Journal of the Linnaean Society, on Tuesday, 23 June 2015. DOI: 10.1111/zoj.12247

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

Sudden shift in ‘forcing’ led to demise of Laurentide ice sheet

A study of the demise of the Laurentide Ice Sheet that once covered Canada may help scientists better understand shrinking ice fields today — like this melting ice margin in Greenland. Credit: Courtesy of Oregon State University 

A new study has found that the massive Laurentide ice sheet that covered Canada during the last ice age initially began shrinking through calving of icebergs, and then abruptly shifted into a new regime where melting on the continent took precedence, ultimately leading to the sheet’s demise.

Researchers say a shift in ‘radiative forcing’ began prior to 9,000 years ago and kicked the deglaciation into overdrive. The results are important, scientists say, because they may provide a clue to how ice sheets on Greenland and Antarctica may respond to a warming climate.

Results of the study, which was funded by the National Science Foundation with support from the National Aeronautics and Space Administration (NASA), are being published this week in Nature Geoscience.

David Ullman, a postdoctoral researcher at Oregon State University and lead author on the study, said there are two mechanisms through which ice sheets diminish — dynamically, from the jettisoning of icebergs at the fringes, or by a negative ‘surface mass balance,’ which compares the amount of snow accumulation relative to melting. When more snow accumulates than melts, the surface mass balance is positive.

When melting outpaces snow accumulation, as happened after the last glacial maximum, the surface mass balance is negative.

‘What we found was that during most of the deglaciation, the surface mass balance of the Laurentide Ice Sheet was generally positive,’ Ullman said. ‘We know that the ice sheet was disappearing, so the cause must have been dynamic. But there was a shift before 9,000 years ago and the deck became stacked, as sunlight levels were high because of Earth’s orbit and CO2 increased.

‘There was a switch to a new state, and the ice sheet began to melt away,’ he added. ‘Coincidentally, when melting took off, the ice sheet began pulling back from the coast and the calving of icebergs diminished. The ice sheet got hammered by surface melt, and that’s what drove final deglaciation.’

Ullman said the level of CO2 that helped trigger the melting of the Laurentide ice sheet was near the top of pre-industrial measurements — though much less than it is today. The solar intensity then was higher than today, he added.

‘What is most interesting is that there are big shifts in the surface mass balance that occur from only very small changes in radiative forcing,’ said Ullman, who is in OSU’s College of Earth, Ocean, and Atmospheric Sciences. ‘It shows just how sensitive the system is to forcing, when it might be solar radiation or greenhouse gases.’

Scientists have examined ice cores dating back some 800,000 years and have documented numerous times when increases in summer insolation took place, but not all of them resulted in deglaciation to present-day ice volumes. The reason, they say, is that there likely is a climatic threshold at which severe surface melting is triggered.

‘It just might be that the ice sheet needed an added kick from something like elevated CO2 levels to get things going,’ Ullman said.

Reference:
David J. Ullman, Anders E. Carlson, Faron S. Anslow, Allegra N. LeGrande, Joseph M. Licciardi. Laurentide ice-sheet instability during the last deglaciation. Nature Geoscience, 2015; DOI: 10.1038/ngeo2463

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

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