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Voyage from Earth’s crust to its mantle and back again

A numerical simulation shows how Earth's crust (blue) is subducted and transported into the mantle (orange). Credit: Graphics: ETH Zurich/ Geophysical Fluid Dynamics
A numerical simulation shows how Earth’s crust (blue) is subducted and transported into the mantle (orange). Credit: Graphics: ETH Zurich/ Geophysical Fluid Dynamics

From the beginning of time, uranium has been part of Earth and, thanks to its long-lived radioactivity, it has proven ideal to date geological processes and deduce Earth’s evolution. Natural uranium consists of two long-lived isotopes uranium-238 and the lighter uranium-235. A new study of the global cycle of these uranium isotopes brings additional perspectives to the debate on how Earth has changed over billions of years as revealed in a recently published study in the journal Nature.

From early Earth history, the continental crust (Earth’s thick solid outer skin that we live on) has accumulated mass from the underlying hot mantle. Most of the newly formed crust, however, is lost again. At mid-ocean ridges at the bottom ocean, where plates drift apart, new oceanic crust is constantly produced as basaltic rocks when hot volcanic lava emerges from the mantle and solidifies. The oceanic crust moves away from the mid-ocean-ridges and ultimately gets transported back into the underlying mantle through “subduction” at ocean trenches.

Uranium is enriched in the rocks of the continental crust; however, at Earth’s surface, different environments over time have influenced its mobility. In an oxygen-free atmosphere, as prevailed on early Earth, uranium stayed immobile in rocks as tetravalent uranium (IV). Only after atmospheric oxygen was formed did uranium become oxidised to its mobile hexavalent uranium (VI). This more mobile uranium may then be released during the weathering and break-down of rocks and transported to the oceans in aqueous form. As the cooling oceanic crust moves away from the mid-ocean-ridges in the oceans, seawater eventually percolates through cracks in its rock and in the process uranium gets incorporated into the oceanic crust, in a similar way that a sponge takes up water.

“The radioactive nature of uranium isotopes has long been key in reconstructing early Earth history, but we now see that they also have another story to tell” explains Morten Andersen, a geochemist in the Department of Earth Sciences at ETH Zurich.

Uranium isotopes form specific signatures

For this work, conducted at the University of Bristol including Morten Andersen (now Earth Science, ETH Zurich) along with researchers from the Durham (UK), Wyoming and Rhode Island (US), used the ‘fingerprint’ carried in the ratio of the two uranium isotopes.

The specific “fingerprint” derived from the ratio of the uranium isotopes, relates to uranium oxidation processes at Earth’s surface. In particular, the researchers found that a higher ratio of uranium-238 to uranium-235 is incorporated into the modern oceanic crust, when compared to the uranium isotope signature found in meteorites. The meteorites represent Earth’s “building blocks” and, thus, yield the original uranium isotope composition of Earth as a whole, and also the undisturbed mantle. This uranium isotope “fingerprint” of the altered oceanic crust provides a way to trace uranium that has moved from the surface and back into Earth’s interior through subduction.

In order to examine the uranium cycle (and the rock cycle), the researchers analysed mid-ocean ridge basalts (MORBs), the hot volcanic lava that is produced from the upper and well-mixed part of the mantle. The ratio of the uranium isotopes in MORBs can be compared with those found in ocean island basalts in places such as Hawaii and the Canary Islands. These islands are so-called “hot-spots” with lava formed from hot mantle plumes that up-well beneath the oceanic crust. Compared to the MORB mantle, the island basalts are made up of material transported to the surface from a much deeper, less well-mixed, mantle sources.

Heavy uranium from surface to the deep

The isotope ratios for uranium-238 to uranium-235 are significantly greater for MORBs than for ocean island basalts. The ratios are also higher than that found in meteorites. This suggests that the MORBs contain a “fingerprint” of the uranium from the oceanic crust, drawn down from the surface and into the upper part of Earth’s mantle through subduction, according to Andersen.

Through convection — slow movements of material in the upper mantle — the material was eventually mixed around and carried to the area of the mid-ocean ridges and transported back to the surface in the lavas that make up MORBs.

A drill core of altered oceanic crust near a mid-ocean ridge with uranium-bearing in-fillings (rust-brown areas) (Photo: IODP)

In contrast, the island basalts’ ratios of uranium-238 to uranium-235 correspond to those of the meteorites used in the study and showed that these rocks could not have the same mantle source as the MORBs. The researchers explain that ocean island lavas comes from a deeper, less mixed, mantle source and therefore any uranium added from the surface originates from a much earlier time in Earth’s history, when the surface environment was very different from today.

Study co-author Heye Freymuth of the University of Bristol explains: “Although uranium was incorporated into the oceanic crust since the initial rise in atmospheric oxygen about 2.4 billion years ago, the ocean crust did not incorporate higher amounts of uranium-238 as the oceans did not yet have adequate supplies of oxygen.”

Only during the second marked increase in atmospheric oxygen content 600 million years ago did the deep ocean become fully oxidised, which allowed the oceanic crust to gain the “fingerprint” of high uranium-238. So, despite the oceanic crust having been transported into Earth’s mantle for a long time, the uranium isotope ratio of the subducted oceanic crust first differed from Earth’s mantle only after the full oxidation of the oceans.

“An important result of this study is how changing conditions on Earth’s surface and the increase of oxygen in the atmosphere influenced the composition of deep Earth. Our results suggest that due to changes over the past 600 million years, uranium was mobilised from the surface, transported into Earth’s interior and distributed within the mantle,” says Andersen.

Hot debate about Earth’s early days

The study of uranium and the crust’s cycle brings new perspectives to the debate about how the face of Earth has changed over billions of years. “This is currently one of the hottest research topics for Earth scientists,” Andersen points out. Particularly lively debates take place on how the concentration of oxygen in the atmosphere evolved; after all, it is associated with many other geological weathering processes, including the fate of uranium. The current study is mainly fundamental research in a relatively young research area. The identified uranium isotope signatures could in future be used commercially to detect unknown uranium deposits and help understand processes of uranium mobility. The first basic scientific work pointing to the potential of uranium-238 to uranium-235 variation on Earth was published in 2007. The study by Andersen and his colleagues is the first to use the uranium isotope ratio for the examination of igneous rock and apply it to the recycling process in deep Earth.

Reference:
Morten B. Andersen, Tim Elliott, Heye Freymuth, Kenneth W. W. Sims, Yaoling Niu, Katherine A. Kelley. The terrestrial uranium isotope cycle. Nature, 2015; 517 (7534): 356 DOI: 10.1038/nature14062

Note : The above story is based on materials provided by ETH Zürich. The original article was written by Peter Rüegg.

Fossil ankles indicate Earth’s earliest primates lived in trees

Fossil ankles show that Purgatorius, an early primate, lived in trees. Credit: Patrick Lynch/Yale University

Earth’s earliest primates have taken a step up in the world, now that researchers have gotten a good look at their ankles.

A new study has found that Purgatorius, a small mammal that lived on a diet of fruit and insects, was a tree dweller. Paleontologists made the discovery by analyzing 65-million-year-old ankle bones collected from sites in northeastern Montana.

Purgatorius, part of an extinct group of primates called plesiadapiforms, first appears in the fossil record shortly after the extinction of non-avian dinosaurs. Some researchers have speculated over the years that primitive plesiadapiforms were terrestrial, and that primates moved into the tree canopy later. These ideas can still be found in some textbooks today.

“The textbook that I am currently using in my biological anthropology courses still has an illustration of Purgatorius walking on the ground. Hopefully this study will change what students are learning about earliest primate evolution and will place Purgatorius in the trees where it rightfully belongs,” said Stephen Chester, the paper’s lead author. Chester, who conducted much of the research while at Yale University studying for his Ph.D., is an assistant professor at Brooklyn College, City University of New York. Chester is also a curatorial affiliate at the Yale Peabody Museum of Natural History.

Until now, paleontologists had only the animal’s teeth and jaws to examine, which left much of its appearance and behavior a mystery. The identification of Purgatorius ankle bones, found in the same area as the teeth, gave researchers a better sense of how it lived.

“The ankle bones have diagnostic features for mobility that are only present in those of primates and their close relatives today,” Chester said. “These unique features would have allowed an animal such as Purgatorius to rotate and adjust its feet accordingly to grab branches while moving through trees. In contrast, ground-dwelling mammals lack these features and are better suited for propelling themselves forward in a more restricted, fore-and-aft motion.”

The research provides the oldest fossil evidence to date that arboreality played a key role in primate evolution. In essence, said the researchers, it implies that the divergence of primates from other mammals was not a dramatic event. Rather, primates developed subtle changes that made for easier navigation and better access to food in the trees.

The research appears in the Jan. 19 online edition of the Proceedings of the National Academy of Sciences.

Reference:
Stephen Gregory Benson Chester, Jonathan I. Bloch, Doug M. Boyer, William A. Clemens. Oldest known euarchontan tarsals and affinities of Paleocene Purgatorius to Primates. Proceedings of the National Academy of Sciences, 2015;

Note :The above story is based on materials provided by Yale University. The original article was written by Jim Shelton.

Ten years after the disaster: Tsunami-Early Warning System for the Indian Ocean

Technical concept of GITEWS. Credit: Image courtesy of Helmholtz Centre Potsdam – GFZ German Research Centre for Geoscience

The day after Christmas this year will mark the 10 anniversary of the tsunami disaster in the Indian Ocean. On 26 December 2004, a quarter of a million people lost their lives, five million required immediate aid and 1.8 million citizens were rendered homeless. The natural disaster, which caused extreme devastation over huge areas and the accompanying grief and anxiety, especially in Indonesia, Thailand and Sri Lanka exceeded the imaginable and reached such drastic dimensions, mainly due to the lack of a warning facility and a disaster management plan for the entire Indian Ocean region at this time.

Germany and the international community of states reacted with immediate support. Within the framework of the German Flood Victim Aid the Federal Government commissioned the Helmholtz Association of German Research Centres under the direction of the GFZ German Research Centre for Geosciences with the development of an Early Warning System for the Indian Ocean. From 2005 to 2011, with the large-scale project GITEWS (German-Indonesian Tsunami Early Warning System), the core of an integrated, modern, and effective Tsunami Early Warning System in Indonesia was established.

With the follow-up project PROTECTS (Project for Training, Education and Consulting for Tsunami Early Warning Systems, 2011-2014) the personnel of the participating Indonesian institutions were trained to proceed independently and to take over responsibility for the operation of the Early Warning System as well as for the diverse technical and organizational components. In this ways PROTECTS which started in June 2011 and comprised a total of 192 training courses, internships, and hands-on-practice courses, covering all aspects of operation and maintenance of the Tsunami-Early Warning System contributed significantly to the sustainability of InaTEWS.

Under the auspices of the IntergovernmentalOceanographicCommission of UNESCO and with the collaboration of international partner institutes from Germany, the USA, China and Japan, GITEWS was integrated into a Tsunami Early Warning System for Indonesia. GITEWS was positively reviewed by a commission of international experts in 2010 and handed over to Indonesia in March 2011. Since then it has been providing its services under the name InaTEWS — Indonesian Tsunami Early Warning System and is operated by the Indonesian Service for Meteorology, Climatology and Geophysics BMKG.

On 12 October 2011 the exercise drill “IOWAVE11” was carried out in the Indian Ocean. With this drill, InaTEWS successfully demonstrated that it could, furthermore, take over the role of a Regional Tsunami Service Provider (RTSP). Since then Indonesia, in addition to Australia und India, performs the double function as a National Tsunami Warning Center (NTWC) and also as a RTSP and takes over the responsibility for the timely warning of 28 states around the Indian Ocean in the event of a threatening Tsunami. With the on-going step-by-step development, a comprehensive all-encompassing InaTEWS could be successfully realized.

Indonesia now avails of one of the most modern Tsunami Early Warning Systems. On the basis of data from approx. 300 measuring stations a warning can be issued at a maximum of five minutes after an earthquake. These measuring stations include e.g. seismometers, GPS stations und coastal tide gauges. With the data gained from the sensors and using the most modern evaluation systems such as SeisComP3 which was developed by GFZ scientists for the analyses of earthquake data and a Tsunami simulation system in the Warning Centre it is possible to compile a comprehensive picture of the situation.

With the aid of a decision support system respectively classified warnings for the affected coastal areas can then be issued. A total of 70 people are involved the operation of the Warning Centre in Jakarta, with 30 employees working solely in a full shift system. According to information provided by the BMKG a total of 1700 earthquakes with a magnitude of more than M= 5 and 11 quakes with a magnitude of 7 and higher have been evaluated and six Tsunami Warnings have been issued to the public by the Earthquake Monitoring and Tsunami Early Warning Centre since the hand over in March 2011.

Schooling, training and disaster precautions (capacity development) for the local community and Town and District councils have received special emphasis. This Capacity Development has been carried out since 2006 in three “typical” regions: Padang (Sumatra), Chilacap (South-Java) and Denpassar (Bali, tourist stronghold). Here particular emphasis was placed on understanding both the warnings issued and the planned evacuation measures.

Local disaster management structures are established with local decision-makers and Disaster Risk Reduction Strategies are developed. Specifically, the education of trainers who are, in turn, responsible for the further spreading of the developed concepts plays a significant role.

Another key element is the determination of hazard and risk maps as a basis for the local evacuation planning as well as for future town and land-use planning. In Bali communication with the hotel industry was an additional factor.

No Early Warning System will ever be able to prevent a strong earthquake and a resulting tsunami and also, in the future, there will be loss of life and material damage. However, through the existence of an Early Warning System and the integration of organizational measures together with comprehensive capacity building the adverse effects of such a natural disaster can certainly be reduced.

Note : The above story is based on materials provided by Helmholtz Centre Potsdam – GFZ German Research Centre for Geosciences.

Melting glaciers have big carbon impact

Scientists have done field work in Tibet and Alaska, among other places as part of this study. Credit: Robert Spencer/Florida State

As Earth warms and glaciers all over the world begin to melt, researchers and public policy experts have focused largely on how all of that extra water will contribute to sea level rise.

But another impact lurking in that inevitable scenario is carbon.

More specifically, what happens to all of the organic carbon found in those glaciers when they melt?

That’s the focus of a new paper by a research team that includes Florida State University assistant professor Robert Spencer. The study, published in Nature Geoscience, is the first global estimate by scientists at what happens when major ice sheets break down.

“This is the first attempt to figure out how much organic carbon is in glaciers and how much will be released when they melt,” Spencer said. “It could change the whole food web. We do not know how different ecological systems will react to a new influx of carbon.”

Glaciers and ice sheets contain about 70 percent of Earth’s freshwater and ongoing melting is a major contributor to sea level rise. But, glaciers also store organic carbon derived from both primary production on the glaciers and deposition of materials such as soot or other fossil fuel combustion byproducts.

Spencer, along with colleagues from Alaska and Switzerland, studied measurements from ice sheets in mountain glaciers globally, the Greenland ice sheet and the Antarctic ice sheet to measure the total amount of organic carbon stored in the global ice reservoir.

It’s a lot.

Specifically, as glaciers melt, the amount of organic carbon exported in glacier outflow will increase 50 percent over the next 35 years. To put that in context, that’s about the amount of organic carbon in half of the Mississippi River being added each year to the ocean from melting glaciers.

“This research makes it clear that glaciers represent a substantial reservoir of organic carbon,” said Eran Hood, the lead author on the paper and a scientist with the University of Alaska Southeast. “As a result, the loss of glacier mass worldwide, along with the corresponding release of carbon, will affect high-latitude marine ecosystems, particularly those surrounding the major ice sheets that now receive fairly limited land-to-ocean fluxes of organic carbon.”

Spencer said he and his colleagues are continuing on this line of research and will do additional studies to try to determine exactly what the impact will be when that carbon is released into existing bodies of water.

“The thing people have to think about is what this means for Earth,” Spencer said. “We know we’re losing glaciers, but what does that mean for marine life, fisheries, things downstream that we care about? There’s a whole host of issues besides the water issue.”

Reference:
Eran Hood, Tom J. Battin, Jason Fellman, Shad O’Neel, Robert G. M. Spencer. Storage and release of organic carbon from glaciers and ice sheets. Nature Geoscience, 2015; DOI: 10.1038/ngeo2331

Note : The above story is based on materials provided by Florida State University.

Underwater volcano erupts off Tonga

An underwater volcano off Tonga was spewing ash high into the air on Tuesday ” 13 January, 2015, causing several carriers to suspend air travel to the South Pacific island nation and turning the surrounding ocean blood red, residents and officials said.

The Hunga Tonga-Hunga Ha’apai underwater volcano, about 65km north of the capital Nuku’alofa, was sending volcanic ash up to 4,500m into the air, the Wellington Volcanic Ash Advisory Centre (VAAC) said.

Volcanic eruption on Cape Verde Island

Eruption of the Fogo volcano/Cape Verde Islands, January 2015. Credit: Judith Levy, GFZ

A new volcanic eruption commenced on Fogo, one of the Cape Verde Islands, on November 23rd, 2014. This eruption continues to date, and is considered to be the largest eruption by volume, and in terms of damage, on the archipelago for over 60 years. Most damage was caused by lava flows advancing into populated regions, so that numerous buildings, homes and roads were destroyed. In total, three villages have been abandoned and thousands of residents have had to be evacuated.

A team from the GFZ German Research Centre for Geosciences is currently conducting research to support local partners and to better assess the evolution of the eruption and associated hazards. Stimulated by a contact point for the European CECIS (Common Emergency Communication and Information System), the GFZ has started to observe the volcano eruption and to provide support on data acquisition and interpretation. “Our team, the GFZ Hazard and Risk Team HART, works in close collaboration with the University of Cape Verde, the Volcano Observatory of the Canary Islands, and the German Aerospace Centre,” says GFZ-volcanologist Dr. Thomas Walter. “On one hand, we are analysing data from the newest remote sensing satellites to develop models of the magma ascent path. On the other, we are collecting data on the lava flows directly in the field by installing volcano monitoring instruments.”

Three dimensional view on the Fogo volcanic island, Cape Verdes. The radar satellite Sentinel-1 enables a recording of movements of the ground. The figure shows a movement towards the satellite in blue, and a movement away from the satellite in red. By means of computer simulations, GFZ researchers could compute the likely position and dimension of a magma-filled crack at depth, through which magma has ascended to the eruption site. The eruption did not occur at the volcano summit Pico do Fogo, but just above the magma filled crack. (Graphics: Thomas Walter, Mehdi Nikkhoo und Pau Prats).

The satellite data, which is acquired by the European Space Agency’s Sentinel-1 satellite, enables the measurement of ground movements associated with the volcano eruption. The GFZ scientists have succeeded in locating and following the path of the magma from depth to its point of eruption. As a result, the location of the ascent paths at depth explains well why the eruption site is off-centered with respect to the volcano summit. The Sentinel-1 satellite acquires new imagery about once per week, which allows for regular updates on the ground movement and the magma ascent path beneath.

This remote sensing data is complemented by an expedition team that is making different types of measurements. Infrared recordings allow for monitoring temperature changes. A laser scanner, in addition, provides topographic measurements at millions of points. GFZ scientist Walter explains: “This data allows us to quantify the erupted lava volumes and also to better assess the hazard associated with lava flows to come.” The remaining duration of the eruption is not known. The magma’s eruption rate has decreased, but concerns have arisen about a recent increase of the explosive character of the eruption and related ash dispersion. These developments are currently being investigated, although they mean that an all-too-close approach to the eruption site remains dangerous.

Note : The above story is based on materials provided by Helmholtz Centre Potsdam – GFZ German Research Centre for Geosciences.

NASA mountaintop sensor finds high methane over Los Angeles

The Los Angeles basin from Mt. Wilson. Credit: NASA/JPL-Caltech

A NASA study using two years of observations from a novel mountaintop instrument finds that Los Angeles’ annual emissions of methane, an important greenhouse gas, are 18 to 61 percent higher than widely used estimates. The study is the first to demonstrate the feasibility of long-term mapping of greenhouse gases across an urban area from an elevated — but still earthbound — site.

“For the first time, we’ve been able to provide an accurate estimate of total methane emissions from the Los Angeles basin, whatever their sources,” said senior research scientist Stanley Sander of NASA’s Jet Propulsion Laboratory, Pasadena, California, the new instrument’s principal investigator. “Altogether, it’s a very significant increase in the estimate.”

Methane is extremely efficient at trapping heat and warming the planet. Its urban sources include gas pipeline leaks, landfills, wastewater treatment plants and transportation.

The study used observations by an instrument called a spectrometer, which measures the effect of methane and other gases on the spectrum of sunlight, allowing it to “count” the number of molecules in the air above LA. The instrument is part of the California Laboratory for Atmospheric Remote Sensing (CLARS), located about 5,700 feet (1,700 meters) above Los Angeles atop Mt. Wilson. Because of regional air patterns, virtually none of LA’s pollution drifts as high as the CLARS site, but all of it is within view. “The instrument is like a stationary satellite,” said Clare Wong, a NASA postdoctoral fellow at JPL and lead author of a paper on the new study in the journal Atmospheric Chemistry and Physics.

Every 90 minutes during daylight hours, the CLARS spectrometer points at one after another of 28 flat, unobstructed sites throughout the Los Angeles basin, including Angels Stadium in Anaheim and the Santa Anita racetrack in Arcadia. The spectrometer measures how much methane, carbon dioxide and other pollutants are in the air between it and each site. It also takes a measurement in the clean air above the mountain. The difference between the clean-air and ground-site measurements gives the amount of methane in the LA basin.

Over the sprawling 30-by-70-mile LA basin (50 by 110 kilometers), methane emissions were estimated to be 430,000 U.S. tons (0.39 teragrams) per year. This is significantly larger than the value obtained by the common method of adding up estimated emissions from all known methane sources.

Although the study was not specifically designed to find out where the methane is coming from, “certain areas seem to be more significant emitters than others,” Sander said. “The ones we have been able to identify are — perhaps coincidentally, but perhaps not — located near large landfills. That is consistent with our understanding that landfills have the potential to be methane sources under certain conditions.” The highest concentrations were recorded at ground sites in eastern Los Angeles County and near the Rose Bowl in Pasadena.

The mountaintop instrument is part of the pilot Megacities Carbon Project to monitor emissions from urban areas with populations of more than 10 million. Cities are the source of about 70 percent of the world’s carbon emissions, and Earth’s 22 megacities are responsible for about half of that 70 percent. Sander noted that a setup like CLARS would work equally well in other megacities that are overlooked by mountains, such as Rio de Janeiro, Seoul and Mexico City.

The Megacities Carbon Project LA site is funded by NASA; the National Institute of Standards and Technology; the National Oceanic and Atmospheric Administration; the Keck Institute for Space Studies, Pasadena, California; and the California Air Resources Board, Sacramento, California. To learn more about the initiative, visit:

http://megacities.jpl.nasa.gov

Why Is Methane Important?

Methane is a greenhouse gas that traps heat in Earth’s atmosphere and warms it. It is the third most abundant greenhouse gas, behind water vapor and carbon dioxide.

While methane is much less prevalent in Earth’s atmosphere than carbon dioxide, molecule for molecule, it packs a much bigger punch, particularly on short timescales. Because of its potency and potential to contribute to climate change, scientists are interested in how its concentrations may be changing.

Currently, more than half of atmospheric methane comes from human-related sources, such as livestock, landfills and leaks of natural gas into the atmosphere during its extraction, storage, transportation and distribution. Natural gas is primarily composed of methane.

Natural sources of methane include wetlands and termite mounds.

Reference:
K. W. Wong, D. Fu, T. J. Pongetti, S. Newman, E. A. Kort, R. Duren, Y.-K. Hsu, C. E. Miller, Y. L. Yung, S. P. Sander. Mapping CH4: CO2 ratios in Los Angeles with CLARS-FTS from Mount Wilson, California. Atmospheric Chemistry and Physics, 2015; 15 (1): 241 DOI: 10.5194/acp-15-241-2015

Note : The above story is based on materials provided by NASA/Jet Propulsion Laboratory.

New model illustrates similarities between landslides and earthquakes

Credit: IRD / P. Lacroix

Landslides are responsible for nearly 10,000 victims every year. Nearly 60% of all landslides are triggered by earthquakes. Researchers from IRD and INGEMMET in Peru have produced the first series measurements of this kind of landslide reactivated by an earthquake. The quake that occurred in the region of Maca in south Peru in July 2013 led to ground subsidence, a phenomenon observed for more than a month.

This new data and the resulting model also reveal the analogy between the mechanics of ground movements and tectonic faults, opening up new avenues for research into the dynamics of these faults.

During earthquakes in mountainous areas, nearly a third of victims can be attributed to landslides triggered by the quake. However, the mechanisms of these ground movements under seismic forcing are little known because there is limited data recorded in situ during earthquakes.

Triple displacement after the quake

Researchers from IRD and the Instituto Geológico Minero y Metalúrgico (INGEMMET) in Peru have just provided the first observations from a landslide reactivated by an earthquake that occurred in July 2013 in southern Peru. GPS measurements show that the response of the landslide is both concomitant with the earthquake, with a simultaneous displacement of 2cm, but also post-seismic. In fact, the slip continued for five weeks, during which the extent of displacement tripled, reaching 6cm. This study has been published in the Geophysical Research Letters.

A miniature tectonic response

This new data also made it possible to model the mechanics of the landslide and reveal ground movement analogous with that of creeping tectonic faults in response to significant earthquakes. In other words, this study illustrates the similarities between the mechanics of landslides and those of creeping tectonic faults. This will be valuable in preventing the risks related to landslides, but it also opens up new avenues for research into these faults. Due to their smaller dimensions, more superficial nature and their greater kinematics, landslides may serve as models to develop better understanding of the friction parameters of faults, on an intermediary level between the laboratory and the real-life situation.

A sensitive zone under threat

The Maca landslide, the effects of which are ongoing, covers a surface area of almost 1 km². It affects a village of around 900 inhabitants, located in the Colca valley 70km north of Arequipa. It has also provoked the subsidence of a road used by a high number of tourists (160,000 visitors a year) and is threatening the pre-Inca terraces.  Since this zone is highly sensitive to earthquakes, the phenomenon has been tracked by GPS since 2011, as part of the partnership between IRD and INGEMMET. Falling mainly between December to April, rain is another factor contributing to the slip. This led the regional government of Arequipa asking for the relocation of Maca inhabitants in May 2013.

Reference:
Lacroix Pascal, Perfettini Hugo, Taipe Edu, Guillier Bertrand,” Coseismic and postseismic motion of a landslide: Observations, modeling, and analogy with tectonic faults,” Geophysical Research Letters, 2014, 41, DOI: 10.1002/2014GL061170

Note : The above story is based on materials provided by Institut de Recherche pour le Développement.

Tongan volcano creates new island

Smoke rises from a volcano some 65 km south-west of the South Pacific nation Tonga’s capital Nuku’alofa, as seen in this image from New Zealand’s Ministry of Foreign Affairs and Trade, released on January 15, 2015

A Tongan volcano has created a substantial new island since it began erupting last month, spewing out huge volumes of rock and dense ash that has killed nearby vegetation, officials said on Friday.

The volcano, about 65 kilometres (40 miles) northwest of the South Pacific nation’s capital Nuku’alofa, rumbled to life on December 20 for the first time in five years, the Lands and Natural Resources Ministry said.

It said the volcano was erupting from two vents, one on the uninhabited island of Hunga Ha’apai and the other underwater about 100 metres offshore.

The ministry said experts took a boat trip to view the eruption on Thursday and confirmed it had transformed the local landscape.

“The new island is more than one kilometre wide, two kilometres long and about 100 metres high,” it said in a statement.

“During our observations the volcano was erupting about every five minutes to a height of about 400 metres, accompanied by some large rocks… as the ash is very wet, most is being deposited close to the vent, building up the new island.”

It said ash and acidic rain was deluging an area 10 kilometres around the volcano, adding: “Leaves on trees on Hunga Tonga and Hunga Ha’apai have died, probably caused by volcanic ash and gases.”

A number of international flights were cancelled earlier this week amid concerns about the volcano’s ash plume but they resumed on Wednesday, with authorities saying debris from the eruption was not being thrown high into the atmosphere.

Tonga, which is almost 2,000 kilometres northeast of New Zealand, lies on the so-called Pacific “Ring of Fire”, where continental plates collide causing frequent volcanic and seismic activity.

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

Tiny plant fossils a window into Earth’s landscape millions of years ago

This is a 49 million-year-old epidermal phytolith from a fossil soil horizon of the Las Flores Formation. Its curvy and large shape indicate the plant it came from grew in shady conditions. Scale bar = 10 micrometers. Credit: Regan Dunn, U of Washington

Minuscule, fossilized pieces of plants could tell a detailed story of what the Earth looked like 50 million years ago.

An international team led by the University of Washington has discovered a way to determine the tree cover and density of trees, shrubs and bushes in locations over time based on clues in the cells of plant fossils preserved in rocks and soil. Tree density directly affects precipitation, erosion, animal behavior and a host of other factors in the natural world. Quantifying vegetation structure throughout time could shed light on how the Earth’s ecosystems changed over millions of years.

“Knowing an area’s vegetation structure and the arrangement of leaves on the Earth’s surface is key for understanding the terrestrial ecosystem. It’s the context in which all land-based organisms live, but we didn’t have a way to measure it until now,” said lead author Regan Dunn, a paleontologist at the UW’s Burke Museum of Natural History and Culture. Dunn completed this work as a UW doctoral student in the lab of Caroline Strömberg, the Estella B. Leopold associate professor in biology and curator of paleobotany at the Burke Museum.

The findings are published Jan. 16 in the journal Science.

The team focused its fieldwork on several sites in Patagonia, Argentina, which have some of the best-preserved fossils in the world and together represent 38 million years of ecosystem history (49-11 million years ago). Paleontologists have for years painstakingly collected fossils from these sites, and worked to precisely determine their ages using radiometric dating. The new study builds on this growing body of knowledge.

In Patagonia and other places, scientists have some idea based on ancient plant remains such as fossilized pollen and leaves what species of plants were alive at given periods in Earth’s history. For example, the team’s previous work documented vegetation composition for this area of Patagonia. But there hasn’t been a way to precisely quantify vegetation openness, aside from general speculations of open or bare habitats, as opposed to closed or tree-covered habitats.

“Now we have a tool to go and look at a lot of different important intervals in our history where we don’t know what happened to the structure of vegetation,” said Dunn, citing the period just after the mass extinction that killed off the dinosaurs.

“The significance of this work cannot be understated,” said co-author Strömberg. “Vegetation structure links all aspects of modern ecosystems, from soil moisture to primary productivity to global climate. Using this method, we can finally quantify in detail how Earth’s plant and animal communities have responded to climate change over millions of years, which is vital for forecasting how ecosystems will change under predicted future climate scenarios.”

Work by other scientists has shown that the cells found in a plant’s outermost layer, called the epidermis, change in size and shape depending on how much sun the plant is exposed to while its leaves develop. For example, the cells of a leaf that grow in deeper shade will be larger and curvier than the cells of leaves that develop in less covered areas.

Dunn and collaborators found that these cell patterns, indicating growth in shade or sun, similarly show up in some plant fossils. When a plant’s leaves fall to the ground and decompose, tiny silica particles inside the plants called phytoliths remain as part of the soil layer. The phytoliths were found to perfectly mimic the cell shapes and sizes that indicate whether or not the plant grew in a shady or open area.

The researchers decided to check their hypothesis that fossilized cells could tell a more complete story of vegetation structure by testing it in a modern setting: Costa Rica.

Dunn took soil samples from sites in Costa Rica that varied from covered rainforests to grassy savannahs to woody shrub lands. She also took photos looking directly up at the tree canopy (or lack thereof) at each site, noting the total vegetation coverage.

Back in the lab, she extracted the phytoliths from each soil sample and measured them under the microscope. When compared with tree coverage estimated from the corresponding photos, Dunn and co-authors found that the curves and sizes of the cells directly related to the amount of shade in their environments. The researchers characterized the amount of shade as “leaf area index,” which is a standard way of measuring vegetation over a specific area.

Testing this relationship between leaf area index and plant cell structures in modern environments allowed the team to develop an equation that can be used to predict vegetation openness at any time in the past, provided there are preserved plant fossils.

“Leaf area index is a well-known variable for ecologists, climate scientists and modelers, but no one’s ever been able to imagine how you could reconstruct tree coverage in the past — and now we can,” said co-author Richard Madden of the University of Chicago. “We should be able to reconstruct leaf area index by using all kinds of fossil plant preservation, not just phytoliths. Once that is demonstrated, then the places in the world where we can reconstruct this will increase.”

When Dunn and co-authors applied their method to 40-million-year-old phytoliths from Patagonia, they found something surprising — habitats lost dense tree cover and opened up much earlier than previously thought based on other paleobotanic studies. This is significant because the decline in vegetation cover occurred during the same period as cooling ocean temperatures and the evolution of animals with the type of teeth that feed in open, dusty habitats.

The research team plans to test the relationship between vegetation coverage and plant cell structure in other regions around the world. They also hope to find other types of plant fossils that hold the same information at the cellular level as do phytoliths.

Reference:
R. E. Dunn, C. A. E. Stromberg, R. H. Madden, M. J. Kohn, A. A. Carlini. Linked canopy, climate, and faunal change in the Cenozoic of Patagonia. Science, 2015; 347 (6219): 258 DOI: 10.1126/science.1260947

Note: The above story is based on materials provided by University of Washington. The original article was written by Michelle Ma.

Out of the pouch: ancient DNA from extinct giant roos

Dr Bastien Llamas with a skull of an extinct short-faced kangaroo (Simosthenurus occidentalis). Credit: Mike Lee / SA Museum

Scientists have finally managed to extract DNA from Australia’s extinct giant kangaroos ─ the mysterious marsupial megafauna that roamed Australia over 40,000 years ago.

A team of scientists led by Dr Bastien Llamas and Professor Alan Cooper from the University of Adelaide’s Australian Centre for Ancient DNA (ACAD) have extracted DNA sequences from two species: a giant short-faced kangaroo (Simosthenurus occidentalis) and a giant wallaby (Protemnodon anak). These specimens died around 45,000 years ago and their remains were discovered in a cold and dry cave in Tasmania.

Relatively good preservation conditions in the cave allowed enough short pieces of DNA to survive so researchers could reconstruct partial “mitochondrial genomes”─genetic material transmitted from mother to offspring and widely used to infer evolutionary relationships.

“The ancient DNA reveals that extinct giant wallabies are very close relatives of large living kangaroos, such as the red and western grey kangaroos,” says lead author Dr Bastien Llamas, ACAD senior research associate. “Their skeletons had suggested they were quite primitive macropods─a group that includes kangaroos, wallabies, pademelons and quokkas─but now we can place giant wallaby much higher up the kangaroo family tree.”

The research has also confirmed that short-faced kangaroos are a highly distinct lineage of macropods, which had been predicted on their unusual anatomy.

Generally poor preservation conditions and the age of Australian megafaunal remains has prevented retrieval of its DNA until now, although complete nuclear or mitochondrial genomes have been previously obtained from extinct megafauna from Eurasia, the Americas, and New Zealand. Scientists attempting to decipher the evolutionary relationships of the Australian megafauna were previously restricted to using information from bones.

“In addition to poor DNA preservation, most of the extinct Australian megafauna do not have very close relatives roaming around today, which makes it more difficult to retrieve and interpret the genetic data,” says Dr Llamas. “Together with my colleagues Alan Cooper and Paul Brotherton, we had to think hard about experimental and bioinformatics approaches to overcome more than 10 million years of divergent evolution between the extinct and living species.”

Although ancient DNA confirms that the short-faced kangaroos left no descendants, it also shows their closest living cousin could be the banded hare-wallaby (Lagostrophus fasciatus), which is now restricted to small isolated islands off the coast of Western Australia.

“Our results suggest the banded hare-wallaby is the last living representative of a previously diverse lineage of kangaroos. It will hopefully further encourage and justify conservation efforts for this endangered species,” says co-author Professor Mike Lee of the South Australian Museum and the University’s School of Biological Sciences.

The research is published online (ahead of print) in Molecular Biology and Evolution.

Reference:
B. Llamas, P. Brotherton, K. J. Mitchell, J. E. L. Templeton, V. A. Thomson, J. L. Metcalf, K. N. Armstrong, M. Kasper, S. M. Richards, A. B. Camens, M. S. Y. Lee, A. Cooper. Late Pleistocene Australian Marsupial DNA Clarifies the Affinities of Extinct Megafaunal Kangaroos and Wallabies. Molecular Biology and Evolution, 2014; DOI: 10.1093/molbev/msu338

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

Seismic experiment in Alaska could shed light on slow earthquakes

Abhijit Ghosh, seen here near a seismic station he helped set up in Alaska. Credit: GHOSH LAB, UC RIVERSID

An earthquake expert at the University of California, Riverside is leading a team of seismologists and volcanologists to conduct an experiment in Alaska that will record a variety of seismic events in that state. The experiment will also help better describe the characteristics of the Alaska-Aleutian subduction zone, one of the most seismically active regions in the world that is also home to many active volcanoes.

“In spite of being a hot-spot of earthquake and volcanic hazard, this area is poorly studied because of its inaccessibility, remoteness and rugged terrain,” said Abhijit Ghosh, an assistant professor of geophysics in UC Riverside’s Department of Earth Sciences and the research project’s principal investigator.

Called the “Aleutian Array of Arrays,” the project began collaboratively between UCR, the University of Wisconsin-Madison, the Alaska Volcano Observatory and the U.S. Geological Survey. It was launched last year when the researchers set up 19 seismic stations within a 1 kilometer-square area on one of the Aleutian Islands. This seismic array of stations acts like a mini-radar that continuously scans for earthquakes and fault movements beneath the ground. Eventually, more arrays will be set up.

“The carefully designed array we started with is placed in a strategic location so that it can simultaneously image the subduction fault and the volcanic system,” Ghosh said. “Our experiment aims at studying the active Alaska-Aleutian subduction zone using multiple seismic arrays – an array of arrays – that will eventually span a larger area. This is the largest seismic experiment in this part of the Aleutian Islands. This is also the first time that the array of arrays approach is being used in this region.”

Ghosh explained that the Alaska-Aleutian subduction zone experiences frequent damaging earthquakes, a notable example being the magnitude 9.2 Good Friday earthquake in 1964. Ground shaking due to this earthquake and the resulting tsunami caused severe damage in the entire region, including Anchorage, Alaska’s capital.

Faults release stress in the form of earthquakes, which are caused by a sudden slip along faults. Recently, it has been discovered that faults also slip slowly. These so-called “slow earthquakes” occur over days and months, and release significant amount of stress.

Results from a 2012 pilot study done by Ghosh and his colleagues in Alaska showed that the Alaska-Aleutian subduction zone experiences high tremor activity, a signature of slow earthquakes.

“We identified low-frequency earthquakes, which are a specific type of earthquakes characterized by slow movement on the subduction fault,” said Ghosh, who presented the pilot study results in a meeting of the American Geophysical Union in 2013.

He explained that although California’s San Andreas Fault is characterized by a completely different tectonic setting (strike-slip as opposed to subduction), it shows tremor and low-frequency earthquake activity, which are signatures of slow earthquakes.

“We expect the Aleutian Array of Arrays experiment will shed new light on the details of slow earthquakes, physics of fault movement and associated seismic hazards,” Ghosh said. “There are lessons for California in this research.”

His team plans to go back to the Aleutian Islands this summer to install at least two more seismic arrays. These arrays, combined with the one installed this year, will work together to complete the array of arrays.

“They will simultaneously image the subduction megathrust and volcanic system with very high resolution,” Ghosh said.

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

Fossil find sheds new light on evolution of reptiles

The new ancient reptile has been named Erpetonyx arsenaultorum. Credit: Sean Modesto, CBU

A lucky find by a young boy on a Prince Edward Island beach has revealed important information about the early evolution of reptiles, according to new research from the University of Toronto Mississauga.

In 1995, father and son Ed and Mike Arsenault were exploring the beach at Cape Egmont, Prince Edward Island, when they spotted a fossil embedded in the red sandstone. They pried the rock from the earth to discover a nearly complete fossil of a small animal. After unsuccessful attempts to sell the find, Mike stashed the fossil under his bed where it stayed until years later when an endowment allowed the Royal Ontario Museum to acquire it in 2004.

In a new study published in the January edition of the Proceedings of Royal Society B: Biological Sciences, study co-author and UTM professor Robert Reisz and his team describe the Arsenault find, Erpetonyx arsenaultorum, which turns out to be an entirely new genus and species of reptile that lived millions of years ago, and the first new species from the Canadian Maritimes in over four decades.

Early reptiles evolved during the Carboniferous era when much of this part of the world was covered in swampy forests. Previous data showed that parareptiles (from which turtles originate) had one ancestor that survived the Carboniferous era, however a dearth of specimens leaves large gaps in our understanding of this period.

The Arsenault fossil is the only specimen from this part of the Carboniferous era, and the only reptile specimen from that time. Named in honour of its discoverers, Erpetonyx arsenaultorum adds new branches to the early reptilian family tree, increasing the number of reptiles known to be living at the time.

“Our analysis of the interrelationships of early reptiles reveals that our new species is the closest relative of a enigmatic group called bolosaurid parareptiles,” says Reisz, who adds that the find sheds new light on the diversity of reptiles at the end of the Carboniferous period. “It suggests reptiles were 80 per cent more diverse than previously thought,” he says.

Erpetonyx arsenaultorum has no living relatives, Reisz says, adding that that the 25-com-long lizard would have looked very similar to a modern-day desert iguana. It had clawed feet and small peg-like teeth. “We presume that it was a carnivore and insectivore, eating arthropods and small vertebrates,” he says.

It’s a lucky find. “Small fossils like these are easily overlooked. They are also less likely to be preserved in the fossil record than those of larger species,” Reisz says of the fossil. “This is one of the nicest looking, most complete reptiles of the Carboniferous period.”

Reference:
“The oldest parareptile and the early diversification of reptiles.” Proc. R. Soc. B:2015282 20141912; ” Published 14 January 2015 ” DOI: 10.1098/rspb.2014.1912.

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

Did the Anthropocene begin with the nuclear age?

This is Dr. Jan Zalasiewicz of the University of Leicester Department of Geology. Credit: University of Leicester

Scientists identify July 16 1945 as key time boundary in Earth history.

An international group of scientists has proposed a start date for the dawn of the Anthropocene — a new chapter in the Earth’s geological history.

Humans are having such a marked impact on the Earth that they are changing its geology, creating new and distinctive strata that will persist far into the future. This is the idea behind the Anthropocene, a new epoch in Earth history proposed by the Nobel Prize-winning atmospheric chemist Paul Crutzen just 15 years ago. Since then the idea has spread widely through both the sciences and humanities.

But if the Anthropocene is to be a geological epoch — when should it begin? Humans have long affected the environment, and ideas as to when the Anthropocene might start range from the thousands of years ago with the dawn of agriculture, to the Industrial Revolution — and even to the future (for the greatest human-made changes could still be to come).

Now, members of the international working group formally analysing the Anthropocene suggest that the key turning point happened in the mid-twentieth century. This was when humans did not just leave traces of their actions, but began to alter the whole Earth system. There was a ‘Great Acceleration’ of population, of carbon emissions, of species invasions and extinctions, of earth moving, of the production of concrete, plastics and metals.

It included the start, too, of the nuclear age, when artificial radionuclides were scattered across the Earth, from the poles to the Equator, to be leave a detectable signal in modern strata virtually everywhere.

The proposal, signed up to by 26 members of the working group, including lead author Dr Jan Zalasiewicz, who also chairs the working group, and Professor Mark Williams, both of the University of Leicester’s Department of Geology, is that the beginning of the Anthropocene could be considered to be drawn at the moment of detonation of the world’s first nuclear test: on July 16th 1945. The beginning of the nuclear age, it marks the historic turning point when humans first accessed an enormous new energy source — and is also a time level that can be effectively tracked within geological strata, using a variety of geological clues.

Dr Zalasiewicz said: “Like any geological boundary, it is not a perfect marker — levels of global radiation really rose in the early 1950s, as salvoes of bomb tests took place. But it may be the optimal way to resolve the multiple lines of evidence on human-driven planetary change. Time — and much more discussion — will tell.”

This year, the Anthropocene Working Group will put together more evidence on the Anthropocene, including discussion of possible alternative time boundaries. In 2016, the group aims to make recommendations on whether this new time unit should be formalized and, if so, how it might be defined and characterised.

Reference:
Jan Zalasiewicz, Colin N. Waters, Mark Williams, Anthony D. Barnosky, Alejandro Cearreta, Paul Crutzen, Erle Ellis, Michael A. Ellis, Ian J. Fairchild, Jacques Grinevald, Peter K. Haff, Irka Hajdas, Reinhold Leinfelder, John McNeill, Eric O. Odada, Clément Poirier, Daniel Richter, Will Steffen, Colin Summerhayes, James P.M. Syvitski, Davor Vidas, Michael Wagreich, Scott L. Wing, Alexander P. Wolfe, Zhisheng An, Naomi Oreskes. When did the Anthropocene begin? A mid-twentieth century boundary level is stratigraphically optimal. Quaternary International, 2015; DOI: 10.1016/j.quaint.2014.11.045

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

New sulfate-breathing species discovered beneath ocean crust

C-DEBI researchers deply the ROV Jason to collect samples. Credit: Courtesy of Alberto Robado / USC

Two miles below the surface of the ocean, researchers have discovered new microbes that “breathe” sulfate.

The microbes, which have yet to be classified and named, exist in massive undersea aquifers — networks of channels in porous rock beneath the ocean where water continually churns. About one-third of Earth’s biomass is thought to exist in this largely uncharted environment.

“It was surprising to find new bugs, but when we go to warmer, relatively old and isolated fluids, we find a unique microbial community,” said Alberto Robador, postdoctoral researcher at the USC Dornsife College of Letters, Arts and Sciences and lead author of a paper on the new findings that will be published by the open-access journal Frontiers in Microbiology on Jan. 14.

Sulfate is a compound of sulfur and oxygen that occurs naturally in seawater. It is used commercially in everything from car batteries to bath salts and can be aerosolized by the burning of fossil fuels, increasing the acidity of the atmosphere.

Microbes that breathe sulfate — that is, gain energy by reacting sulfate with organic (carbon-containing) compounds — are thought to be some of the oldest types of organisms on Earth. Other species of sulfate-breathing microbes can be found in marshes and hydrothermal vents.

Microbes beneath the ocean’s crust, however, are incredibly tricky to sample.

Researchers from USC and the University of Hawaii took their samples from the Juan de Fuca Ridge (off the coast of Washington state), where previous teams had placed underwater laboratories, drilled into the ocean floor. To place the labs, they lowered a drill through two miles of ocean and bored through several hundred feet of ocean sediment and into the rock where the aquifer flows.

“Trying to take a sample of aquifer water without contaminating it with regular ocean water presented a huge challenge,” said Jan Amend, professor at USC Dornsife and director of the Center for Dark Energy Biosphere Investigations (C-DEBI), which helped fund the research.

To solve this problem, C-DEBI created Circulation Obviation Retrofit Kit (CORK) observatories. The moniker was basically dreamed up to fit the term “CORK” because these devices create a seal at the seafloor, like a cork in a bottle, allowing scientists to deploy instruments and sampling devices down a borehole while keeping ocean water out.

Samples were then shuttled to the surface by remote-controlled undersea vehicles or “elevators” — balloons that drop ballast and float samples gently up to the waiting scientists.

Like the microbes on the forest floor that break down leaf litter and dead organisms, the microbes in the ocean also break down organic — that is, carbon-based — material like dead fish and algae. Unlike their counterparts, however, the microbes beneath the ocean crust often lack the oxygen that is used on land to effect the necessary chemical reaction.

Instead, these microbes can use sulfate to break down carbon from decaying biological material that sinks to the sea bottom and makes its way into the crustal aquifer, producing carbon dioxide.

Learning how these new microbes function will be important to getting a more accurate, quantified understanding of the overall global carbon cycle — a natural cycling of carbon through the environment in which it is consumed by plants, exhaled by animals and enters the ocean via the atmosphere. This cycle is currently being disrupted by human-made carbon dioxide emissions.

“This is the first direct account of microbial activity in these type of environments,” Robador said, “and shows the potential of these organisms to respire organic carbon.”

The research was funded by the National Science Foundation (C-DEBI award OCE0939564, MCB0604014, 1207880 and 1207874) and the NASA Astrobiology Institute.

Reference:
Alberto Robador, Sean P. Jungbluth, Douglas E. LaRowe, Robert M. Bowers, Michael S. Rappé, Jan P. Amend, James P. Cowen. Activity and phylogenetic diversity of sulfate-reducing microorganisms in low-temperature subsurface fluids within the upper oceanic crust. Frontiers in Microbiology, 2015; 5 DOI: 10.3389/fmicb.2014.00748

Note : The above story is based on materials provided by University of Southern California.

Silurian Scorpion from Ontario – Out of the water

Palaeontology Departmental Associate, Janet Waddington shows us a Silurian Scorpion specimen found in Ontario and explains a recent discovery that allows us to suggest these creatures lived in the sea but also walked on land!

Video Source : Royal Ontario Museum
Read More : Research Reveals Spectacular 430-Million Year Old Ontario Scorpion!

Research Reveals Spectacular 430-Million Year Old Ontario Scorpion!

A specimen of the new scorpion species Eramoscorpius brucensis, which lived about 430 million years ago, making it among the earliest scorpions. The species probably lived in water, but it had feet that would have allowed it to scuttle about on land. Credit: © David Rudkin, Royal Ontario Museum

New research on extraordinarily complete and well-preserved fossil aquatic scorpions from the 430 million year old Eramosa Formation Konservat-Lagerstätte in Ontario demonstrates that a key prerequisite for living on land – the ability to walk unsupported by water – appeared surprisingly early in the fossil record. The findings, co-authored by the ROM’s Janet Waddington and David Rudkin, and the Museum für Naturkunde’s Jason Dunlop, will be published online 14 January 2015 GMT/Tuesday 13 January EST in the Royal Society journal Biology Letters.

Credit: © David Rudkin, Royal Ontario Museum.

Assigned to the species Eramoscorpius brucensis, these new Ontario specimens are the oldest known scorpions from North America and among the oldest in the world. Their legs, intriguingly similar to those of a modern scorpion, end in a short foot that could have been placed flat on the ground, providing a weight-bearing surface which, combined with the legs’ sturdy attachment to the body, would have allowed the animal to support its own weight without the buoyancy of water. The presence of other fossils of animals that lived only in the sea indicates that these new scorpions must have spent most of their time under water; however the fossils occur on rock surfaces that show ripples suggestive of brief exposure to air. The scorpions are preserved in a splayed posture suggesting that they represent empty moulted exoskeletons rather than carcasses of an animal that died. A possible explanation is that the scorpions took advantage of this leg structure to venture briefly into a temporarily exposed area in order to moult, where they would be safe from predators such as large eurypterids and cephalopods, and then returned to deeper water.

The fossil scorpions range in size from about 29 to 165 mm long, representing several different age classes.

The specimens all originated from the Bruce Peninsula and came to the ROM in a variety of ways: one was found in a quarry spoil heap by a young fossil hunter, others were spotted by quarry workers, and several other were discovered in quarried stone delivered to landscaping projects far from their origin.

“This extraordinary find contributes to our understanding of how scorpions moved from the sea onto land,” says Janet Waddington, Departmental Associate in the ROM’s Department of Natural History.  “It is the enthusiasm and generosity of amateur fossil collectors that allows us to study and publish these findings, which are vital to the ROM’s collections and research.”

Reference :
A new mid-Silurian aquatic scorpion—one step closer to land? Biology Letters, Published 14 January 2015. DOI: 10.1098/rsbl.2014.0815

Note : The above story is based on materials provided by Royal Ontario Museum.

Isotopic memory of atmospheric persistence

Rocks of the Ujaraaluk unit of the Nuvvuagittuq Greenstone Belt. Credit: Boswell Wing, McGill University

Chemical analysis of some of the world’s oldest rocks, by an international team led by McGill University researchers, has provided the earliest record yet of Earth’s atmosphere. The results show that the air 4 billion years ago was very similar to that more than a billion years later, when the atmosphere — though it likely would have been lethal to oxygen-dependent humans — supported a thriving microbial biosphere that ultimately gave rise to the diversity of life on Earth today.

The findings, published last week in the Proceedings of the National Academy of Sciences, could help scientists better understand how life originated and evolved on the planet. Until now, researchers have had to rely on widely varying computer models of the earliest atmosphere’s characteristics.

The new study builds on previous work by former McGill PhD student Jonathan O’Neil (now an assistant professor at Ottawa University) and McGill emeritus professor Don Francis, who reported in 2008 that rocks along the Hudson Bay coast in northern Quebec, in an area known as the Nuvvuagittuq Greenstone Belt, were deposited as sediments as many as 4.3 billion years ago — a couple of hundred million years after Earth formed.

In the new study, a team led by researchers from McGill’s Earth and Planetary Sciences Department, used mass spectrometry to measure the amounts of different isotopes of sulfur in rocks from the Nuvvuagittuq belt. The results enabled the scientists to determine that the sulfur in these rocks, which are at least 3.8 billion years old and possibly 500 million years older, had been cycled through Earth’s early atmosphere, showing the air at the time was extremely oxygen-poor compared to today, and may have had more methane and carbon dioxide.

“We found that the isotopic fingerprint of this atmospheric cycling looks just like similar fingerprints from rocks that are a billion to 2 billion years younger,” said Emilie Thomassot, a former postdoctoral researcher at McGill and lead author of the paper. Emilie Thomassot is now with the Centre de Recherches Pétrographiques et Géochimiques (CRPG) in Nancy France.

“Those younger rocks contain clear signs of microbial life and there are a couple of possible interpretations of our results,” says Boswell Wing, an associate professor at McGill and co-author of the new study. “One interpretation is that biology controlled the composition of the atmosphere on early Earth, with similar microbial biospheres producing the same atmospheric gases from Earth’s infancy to adolescence. We can’t rule out, however, the possibility that the biosphere was decoupled from the atmosphere. In this case geology could have been the major player in setting the composition of ancient air, with massive volcanic eruptions producing gases that recurrently swamped out weak biological gas production.”

The research team is now extending its work to try to tell whether the evidence supports the “biological” or the “geological” hypothesis — or some combination of both. In either case Emilie Thomassot says, the current study “demonstrates that the Nuvvuagittuq sediments record a memory of Earth’s surface environment at the very dawn of our planet. And surprisingly, this memory seems compatible with a welcoming terrestrial surface for life.” The team is now extending their investigation to early Archean sediments from other localities in Canada, such as the Labrador coast.

The research was supported by the Natural Sciences and Engineering Research Council of Canada and the Canadian Space Agency, and by France’s Lorraine region and the Centre National de la Recherche Scientifique.

Reference:
E. Thomassot, J. O’Neil, D. Francis, P. Cartigny, B. A. Wing. Atmospheric record in the Hadean Eon from multiple sulfur isotope measurements in Nuvvuagittuq Greenstone Belt (Nunavik, Quebec). Proceedings of the National Academy of Sciences, Jan. 5, 2015 DOI: 10.1073/pnas.1419681112

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

Jaw mechanics of a shell-crushing Jurassic fish revealed

This image shows a perfectly preserved example of the Lower Jurassic fish Dapedium from Lyme Regis, Dorset. Perfectly preserved specimens such as this allow us to calculate the biomechanical function of anatomical features, thus giving us an insight into the ecologies of long extinct animals. Credit : Fiann Smithwick

The feeding habits of an unusual 200-million-year-old fish have been uncovered by a University of Bristol undergraduate in a groundbreaking study which has been published in Palaeontology, a leading scientific journal, this week – a rare achievement for an undergraduate student.

The Jurassic fish, Dapedium, known from the Lower Lias rocks of the Dorset coast around Lyme Regis, was one of many new groups of fishes that came on the scene 200 million years ago. These included ancestors of the modern teleost fishes – the group of 30,000 species of salmon, cod, seahorses, and perch – that dominate the waters today.

This distinctive fish was also one of a number of ancient animals first discovered by the pioneering nineteenth century fossil collector Mary Anning, and fascinated early palaeontologists such as Henry De la Beche and Louis Agassiz.

Dapedium was a deep-bodied fish, shaped like a dinner plate in side view, which could grow to over half a metre in length. It had a tiny mouth with jutting front teeth and masses of pebble-shaped teeth further back.

In his research, Bristol undergraduate Fiann Smithwick applied a new lever-based mechanical model, developed to understand the jaw mechanics of modern fishes, to reconstruct the feeding behaviour of this extraordinary ancient fish.

“My work indicates that Dapedium was well adapted to crush shells,” said Fiann, “feeding on bivalves and other hard-shelled creatures that it could scrape from the sea floor.”

He examined 89 specimens of Dapedium in the Natural History Museum, Bristol City Museum, and the Philpot Museum in Lyme Regis, and measured the positions and lengths of the jaw bones. He calculated the positions and orientations of jaw muscles and varied these to include all possible models.

“Every time he ran the model, the result was the same,” explained Professor Mike Benton, Fiann’s supervisor. “The outputs showed that Dapedium was a shell crusher. Its jaws moved slowly, but strongly, and so it could work on the hard shells of its prey. Other fishes have fast-moving, but weaker jaws, and those are adapted for feeding on speedy, slippery fish prey.”

In comparisons with modern fishes, Dapedium matches closely the modern sea breams. These fishes are also flat-sided and deep-bodied, and they crush shells in their small mouths, armed with blunt-topped teeth.

Dapedium lived side-by-side with the great sea reptiles of the Jurassic, such as the dolphin-shaped ichthyosaurs, long-necked plesiosaurs, and even some marine crocodilians. Dapedium probably escaped being caught by these reptiles because it was so thin-bodied it might be hard to see head-on, and it probably lurked close to reefs and the seabed.

“We are delighted to see such an excellent piece of work carried out by an undergraduate,” said Professor Benton. “Fiann was funded by a Summer Research Bursary from the Palaeontological Association, and he devised the project himself, learned the numerical techniques, and wrote it up himself. It’s rare for an undergraduate to be able to do all this and pass the scrutiny of one of the world’s leading scientific journals.”

Reference :
‘Feeding ecology of the deep-bodied fish Dapedium (Actinopterygii Neopterygii)) from the Sinemurian of Dorset, England’ by Smithwick, F. M. in Palaeontology, published online ahead of print (doi: 10.1111/pala.12145).

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

Predicting coral reef futures under climate change

This is a macroalgae dominated reef in the Seychelles. Credit Image: Nicholas Graham

Researchers examining the impact of climate change on coral reefs have found a way to predict which reefs are likely to recover following bleaching episodes and which won’t.

Coral bleaching is the most immediate threat to reefs from climate change; it’s caused when ocean temperatures become warmer than normal maximum summer temperatures, and can lead to widespread coral death.

A key unanswered question has been what dictates whether reefs can bounce back after such events, or if they become permanently degraded.

An international team of scientists found that five factors could predict if a reef was likely to recover after a bleaching event.

“Water depth, the physical structure of the reef before disturbance, nutrient levels, the amount of grazing by fish and survival of juvenile corals could help predict reef recovery,”says study lead author, Dr Nicholas Graham from the ARC Centre of Excellence for Coral Reef Studies at James Cook University in Australia.

“Remarkably, the two most easily measured variables, water depth and the physical structure of the reef before disturbance, predicted recovery with 98% confidence,” Dr Graham says.

As part of the research, published in the journal Nature, researchers from Australia, the United Kingdom and France examined nearly 20 years of coral reef data gathered from the Seychelles.

Data was collected before and after an unprecedented coral bleaching event in 1998, in which 90 per cent of the country’s corals across 21 reefs were lost.

Of the reefs affected by the episode, twelve recovered while nine did not. The event had a significant impact on the biodiversity of local fish populations, which changed substantially when reefs did not recover.

From their data the researchers identified thresholds for the factors that dictated whether reefs would recover.

“Putting numbers on the threshold points at which reefs either recover or degrade helps predict reef futures under climate change,” Dr Graham says.

Study co-author, Dr Shaun Wilson from the Department of Parks and Wildlife, Western Australia adds that the findings are important for predicting reef futures under climate change.

“The beauty of this study is that easily acquired measures of reef complexity and depth provide a means of predicting long term consequences of ocean warming events,” Dr Wilson says.

“The ability to predict which reefs have the capacity to recover is really important for mapping of winners and losers, and risk analysis”

Co-author Dr Aaron MacNeil from the Australian Institute of Marine Science says the insights can be applied to studies and management aimed at improving the outlook of coral reefs around the world.

“This gives reef management a major boost in the face of the threats posed by climate change and, encouragingly, suggests people can take tangible steps to improve the outlook for reefs,” Dr MacNeil says.

“By carefully managing reefs with conditions that are more likely to recover from climate-induced bleaching, we give them the best possible chance of surviving over the long term, while reduction of local pressures that damage corals and diminish water quality will help to increase the proportion of reefs that can bounce back.”

Reference:
The paper, Predicting climate-driven regime shifts versus rebound potential in coral reefs by Nicholas AJ Graham, Simon Jennings, M Aaron MacNeil, David Mouillot and Shaun K Wilson is published in the journal Nature. Doi:10.1038/nature14140

Note : The above story is based on materials provided by ARC CENTRE OF EXCELLENCE FOR CORAL REEF STUDIES.

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