This is a reconstruction of three ontogenetic (growth) stages of the new pterosaur Caiuajara dobruskii. Credit: Maurilio Oliveira/Museu Nacional-UFRJ; CC-BY
Scientists discovered the bones of nearly 50 winged reptiles from a new species, Caiuajara dobruskii, that lived during the Cretaceous in southern Brazil, according to a study published August 13, 2014 in the open-access journal PLOS ONE by Paulo Manzig from Universidade do Contestado, Brazil, and colleagues.
The authors discovered the bones in a pterosaur bone bed in rocks from the Cretaceous period. They belonged to individuals ranging from young to adult, with wing spans ranging from 0.65-2.35m, allowing scientists to analyze how the bones fit into their clade, but also how the species developed as it matured. After the initial analysis, scientists determined that the bones represent a new pterosaur, Caiuajara dobruskii, which is the southernmost known occurrence of this particular clade.
Several features of the Caiuajara dobruskii head differ from all other members of this clade, including the presence of a bony expansion projecting inside the large opening in the skull in front of the eyes, and the rounded depressions in the outer surface of the jaw. Younger and older reptiles mainly varied in the size and angle of the bony crest on the top of the head. The crest appeared to change from small and inclined in juveniles, to large and steep in adults.
According to the authors, the bone analysis suggests this species was gregarious, lived in colonies and may have been able to fly at a very young age.
Journal Reference:
Manzig PC, Kellner AWA, Weinschutz LC, Fragoso CE, Vega CS, et al. Discovery of a Rare Pterosaur Bone Bed in a Cretaceous Desert with Insights on Ontogeny and Behavior of Flying Reptiles. PLOS ONE, 2014 DOI: 10.1371/journal.pone.0100005
Note : The above story is based on materials provided by PLOS.
A long lasting foreshock series controlled the rupture process of this year’s great earthquake near Iquique in northern Chile. The earthquake was heralded by a three quarter year long foreshock series of ever increasing magnitudes culminating in a Mw 6.7 event two weeks before the mainshock. The mainshock (magnitude 8.1) finally broke on April 1st a central piece out of the most important seismic gap along the South American subduction zone. An international research team under leadership of the GFZ German Research Centre for Geosciences now revealed that the Iquique earthquake occurred in a region where the two colliding tectonic plates where only partly locked.
The Pacific Nazca plate and the South American plate are colliding along South America’s western coast. While the Pacific sea floor submerges in an oceanic trench under the South American coast the plates get stressed until occasionally relieved by earthquakes. In about 150 years time the entire plate margin from Patagonia in the south to Panama in the north breaks once completely through in great earthquakes. This cycle is almost complete with the exception of a last segment — the seismic gap near Iquique in northern Chile. The last great earthquake in this gap occurred back in 1877. On initiative of the GFZ this gap was monitored in an international cooperation (GFZ, Institut de Physique du Globe Paris, Centro Sismologico National — Universidad de Chile, Universidad de Catolica del Norte, Antofagasta, Chile) by the Integrated Plate Boundary Observatory Chile (IPOC), with among other instruments seismographs and cont. GPS. This long and continuous monitoring effort makes the Iquique earthquake the best recorded subduction megathrust earthquake globally. The fact that data of IPOC is distributed to the scientific community in near real time, allowed this timely analysis.
Ruptures in Detail
The mainshock of magnitude 8.1 broke the 150 km long central piece of the seismic gap, leaving, however, two large segments north and south intact. GFZ scientist Bernd Schurr headed the newly published study that appeared in the lastest issue of Nature Advance Online Publication: “The foreshocks skirted around the central rupture patch of the mainshock, forming several clusters that propagated from south to north.” The long-term earthquake catalogue derived from IPOC data revealed that stresses were increasing along the plate boundary in the years before the earthquake. Hence, the plate boundary started to gradually unlock through the foreshock series under increasing stresses, until it finally broke in the Iquique earthquake. Schurr further states: “If we use the from GPS data derived locking map to calculate the convergence deficit assuming the ~6.7 cm/yr convergence rate and subtract the earthquakes known since 1877, this still adds up to a possible M 8.9 earthquake.” This applies if the entire seismic gap would break at once. However, the region of the Iquique earthquake might now form a barrier that makes it more likely that the unbroken regions north and south break in separate, smaller earthquakes.
International Field Campaign
Despite the fact that the IPOC instruments delivered continuous data before, during and after the earthquake, the GFZ HART (Hazard And Risk Team) group went into the field to meet with international colleagues to conduct additional investigations. More than a dozen researchers continue to measure on site deformation and record aftershocks in the aftermath of this great rupture. Because the seismic gap is still not closed, IPOC gets further developed. So far 20 multi-parameter stations have been deployed. These consist of seismic broadband and strong-motion sensors, continuous GPS receivers, magneto-telluric and climate sensors, as well as creepmeters, which transmit data in near real-time to Potsdam. The European Southern astronomical Observatory has also been integrated into the observation network.
Note : The above story is based on materials provided by GFZ GeoForschungsZentrum Potsdam, Helmholtz Centre.
Samples taken from these sites: Top, left to right: Ghab Valley (western Syria), Iron Age settlement of Zincirli, Hatay Province (SE Turkey), and Hittite-era settlement of Nerik (near Samsun,Turkey); Middle, left to right: irrigation channel below Tel Halaf (northern Syria), barley growing near Zincirli, Hatay Province (SE Turkey), and a field in the same place after the harvest; Bottom, left to right: irrigation channel near Zincirli, fields near Zincirli and arid lands with field in Jabroud Region (SW Syria). Credit: Simone Riehl/University of Tübingen
The influence of climate on agriculture is believed to be a key factor in the rise and fall of societies in the Ancient Near East. Dr. Simone Riehl of Tübingen University’s Institute for Archaeological Science and the Senckenberg Center for Human Evolution and Palaeoenvironment has headed an investigation into archaeological finds of grain in order to find out what influence climate had on agriculture in early farming societies. Her findings are published in this week’s PNAS — Proceedings of the National Academy of Sciences.
She and her team analyzed grains of barley up to 12,000 years old from 33 locations across the Fertile Crescent to ascertain if they had had enough water while growing and ripening. Riehl found that periods of drought had had noticeable and widely differing effects on agriculture and societies in the Ancient Near East, with settlements finding a variety of ways to deal with the problem.
The 1,037 ancient samples were between 12,000 and 2,500 years old. They were compared with modern samples from 13 locations in the former Fertile Crescent. Dr. Riehl and her team measured the grains’ content of two stable carbon isotopes. When barley grass gets insufficient water while growing, the proportion of heavier carbon isotopes deposited in its cells will be higher than normal. The two isotopes 12C und 13C remain stable for thousands of years and can be measured precisely — giving Simone Riehl and her colleagues reliable information on the availability of water while the plants were growing.
They found that many settlements were affected by drought linked to major climate fluctuations. “Geographic factors and technologies introduced by humans played a big role and influenced societies’ options for development as well as their particular ways of dealing with drought,” says Riehl. Her findings indicate that harvests in coastal regions of the northern Levant were little affected by drought; but further inland, drought lead to the need for irrigation or, in extreme cases, abandonment of the settlement.
The findings give archaeologists clues as to how early agricultural societies dealt with climate fluctuations and differing local environments. “They can also help evaluate current conditions in regions with a high risk of crop failures,” Riehl adds. The study is part of a German Research Foundation-backed project looking into the conditions under which Ancient Near Eastern societies rose and fell.
Journal Reference:
S. Riehl, K. E. Pustovoytov, H. Weippert, S. Klett, F. Hole. Drought stress variability in ancient Near Eastern agricultural systems evidenced by 13C in barley grain. Proceedings of the National Academy of Sciences, 2014; DOI: 10.1073/pnas.1409516111
Note : The above story is based on materials provided by Universitaet Tübingen.
To understand earthquakes, scientists have hatched an audacious plan – go straight to the source.
That means drilling miles-deep into the earth, directly through faults where two plates of the earth’s crust come into contact.
Geologists at the University of Wisconsin-Madison are doing just that, as part of two experiments located at dangerous faults in New Zealand and Japan – faults that could rupture at any moment, causing massive earthquakes.
“These are the natural disasters that kill the most people on the planet. So we need to know as well as we can how they work and whether there are ways to mitigate their effects by early warning or detection,” said Harold Tobin, a professor in the department of geoscience at UW-Madison.
To understand the processes that trigger such massive quakes, the scientists will take samples of rock from the faults they drill, record the conditions in the borehole and, if they’re lucky, catch a quake in action.
Earthquakes are some of the most destructive and deadly natural disasters on the planet. They also are some of the least predictable. Scientists can say how likely a fault is to experience a quake, but only over the span of decades – not very helpful for people living in the area who need to take cover in the moments before.
Scientists don’t know how – or even if – it might be possible to predict earthquakes. Part of the problem is they know so little about how earthquakes start. The phenomenon begins deep below the surface of the earth, inaccessible to researchers.
Typically, earthquakes are studied by measuring the seismic waves that emanate from tremors within the earth. This information is useful, but it’s indirect. It’s sort of like trying to figure out what’s inside your Christmas present by shaking the box around – you’d know much more if you could unwrap it and look directly at what was inside.
This is why the scientists want to drill down to the fault. They will take cores as they drill, bringing up intact samples of rock in order to study their properties. And they will place instruments in the borehole to measure seismic tremors and other important characteristics of the fault zone, like the pressure, temperature, and stresses and strains on the rocks, as well as properties of groundwater in the area.
“If we want to understand earthquakes, it’s one of the few kind of direct ways we can get evidence about what faults are like,” said Clifford Thurber, a professor in the department of geoscience at UW-Madison.
Thurber and Tobin are part of an international group of scientists working on the Deep Fault Drilling Project, an experiment studying the Alpine Fault in New Zealand.
Fault due for quake
This fault has lain dormant since 1717, and it typically produces a major quake every 300 or 400 years. Scientists therefore think the fault is due, estimating a 28 percent chance of a quake in the next 50 years. Beginning in October, experimenters will drill nearly a mile deep into the Alpine Fault.
Drilling such holes, however, is no easy task – especially for faults that are underwater, as many of the most dangerous, tsunami-generating faults are.
As co-chief scientist of the Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE) in Japan, Tobin spent seven weeks at sea last winter on a scientific drilling ship called the Chikyu, drilling into the Nankai Fault off the coast of southern Japan.
At times braving harsh winds and waves as high as 30 feet, Tobin and his fellow scientists took round-the-clock shifts analyzing the data and cores of rock that came out of the borehole. The hole is currently more than halfway to its planned depth of three miles below the seabed.
Instruments will remain in the boreholes of both experiments for decades, quietly collecting data, waiting for a quake that could strike at any time.
The UW researchers also were involved in an earlier experiment, the San Andreas Fault Observatory at Depth (SAFOD), completed in 2007. Scientists drilled a two-mile-deep hole that pierced the infamous San Andreas Fault in California.
The experiment recovered some of the first samples of rock from a fault at the depth where small earthquakes can originate.
However, scientists encountered many setbacks. Drilling was more expensive than expected, due to rising oil prices. And instruments placed in the borehole failed shortly after they were installed, due to the corrosive gases, crushing pressures and high temperatures they encountered at that depth.
“The whole thing is just like a cauldron down there,” Thurber said.
The lessons scientists learned through their struggles with SAFOD will be applied to the experiments in New Zealand and Japan.
These experiments won’t quite reach the depth where major quakes are initiated, but they will gain valuable information about how faults behave close to the source, and how earthquakes travel along the fault when it ruptures.
“We’re seeing rocks much closer to what they are like down where earthquakes do their thing,” Thurber said.
Foam sent through a microfluidic model created at Rice University shows its ability to remove oil (pink) from low-permeability formations. Rice scientists conducted experiments to see how foam would compare with water, gas or combinations of the two for use in enhanced oil recovery. (Credit: Biswal Lab/Rice University)
HOUSTON – (Aug. 12, 2014) – A Rice University laboratory has provided proof that foam may be the right stuff to maximize enhanced oil recovery (EOR).
In tests, foam pumped into an experimental rig that mimicked the flow paths deep underground proved better at removing oil from formations with low permeability than common techniques involving water, gas, surfactants or combinations of the three.
The open-access paper led by Rice scientists Sibani Lisa Biswal and George Hirasaki was published online today by the Royal Society of Chemistry journal Lab on a Chip.
Oil rarely sits in a pool underground waiting to be pumped out to energy-hungry surface dwellers. Often, it lives in formations of rock and sand and hides in small cracks and crevices that have proved devilishly difficult to tap. Drillers pump various substances downhole to loosen and either push or carry oil to the surface.
Biswal’s lab has learned a great deal about how foam forms. Now, with an eye toward EOR, she and her colleagues created microfluidic models of formations — they look something like children’s ant farms — to see how well foam stacks up against other materials in removing as much oil as possible.
The formations are not much bigger than a postage stamp and include wide channels, large cracks and small cracks. By pushing various fluids, including foam, into test formations, the researchers can visualize the ways by which foam is able to remove oil from hard-to-reach places. They can also measure the fluid’s pressure gradient to see how it changes as it navigates the landscape.
The team determined the numbers are strongly in foam’s favor. Foam dislodged all but 25.1 percent of oil from low-permeability regions after four minutes of pushing it through a test rig, versus 53 percent for water and gas and 98.3 percent for water flooding; this demonstrated efficient use of injected fluid with foam to recover oil.
The less-viscous fluids appear to displace oil in high-permeability regions while blowing right by the smaller cracks that retain their treasure. But foam offers mobility control, which means a higher resistance to flow near large pores.
“The foam’s lamellae (the borders between individual bubbles) add extra resistance to the flow,” said Biswal, an associate professor of chemical and biomolecular engineering. “Water and gas don’t have that ability, so it’s easy for them to find paths of least resistance and move straight through. Because foam acts like a more viscous fluid, it’s better able to plug high-permeable regions and penetrate into less-permeable regions.”
Charles Conn, a Rice graduate student and lead author of the paper, said foam tends to dry out as it progresses through the model. “The bubbles don’t actually break. It’s more that the liquid drains away and leaves them behind,” he said.
Drying has two effects: It slows the progress of the foam even further and allows surfactant from the lamellae to drain into low-permeability zones, where it forces oil out. Foam may also cut the sheer amount of material that may have to be sent downhole.
One of the challenges will always be to get the foam to the underground formation intact. “It’s nice to know that foam can do these things, but if you can’t generate foam in the reservoir, then it’s not going to be useful,” Conn said. “If you lose the foam, it collapses into slugs of gas and liquid. You really want foam that can regenerate as it moves through the pores.”
The lab plans to test foam on core samples that more closely mimic the environment underground, Biswal said.
Kun Ma, a Rice alumnus, co-authored the paper. The Department of Energy, the Abu Dhabi National Oil Co., the Abu Dhabi Oil R&D Sub-Committee, the Abu Dhabi Co. for Onshore Oil Operations, the Zakum Development Co., the Abu Dhabi Marine Operating Co. and the Petroleum Institute of the United Arab Emirates supported the research.
Video:
Note : The above story is based on materials provided by David Ruth , Mike Williams ” Copyright Rice University News & Media. “
The Wilson cycle begins in Stage A with a
stable continental craton. A hot spot (not present in the drawings) rises up under the craton, heating it, causing it to swell upward, stretch and thin like taffy, crack, and finally split into two pieces. This process not only splits a continent in two it also creates a new divergent plate boundary.
Continental collision is a phenomenon of the plate tectonics of Earth that occurs at convergent boundaries. Continental collision is a variation on the fundamental process of subduction, whereby the subduction zone is destroyed, mountains produced, and two continents sutured together. Continental collision is known only from this planet and is an interesting example of how our different crusts, oceanic and continental, behave during subduction.
Way back. A cliffside in Guam shows lava made during the formation of the Mariana Trench. On the left, a close-up of the cliff shows the same lavas in distinct pillowlike shapes. Credit: Dr. Mark Reagan
A journey to the Mariana Trench, the deepest crevice on Earth’s surface, reveals the great Pacific tectonic plate descending deep into the planet where it recycles back into mantle rock. This recycling of old tectonic plate, called subduction, drives plate tectonics and is nothing new to scientists, but exactly when the process got started is a hot debate. A new study may put that to rest by unmasking a sequence of 4.4-billion-year-old lavas as the remnants of the first subduction zone on Earth. If correct, the discovery marks the dawn of plate tectonics and thus several geological processes critical to Earth’s environment and perhaps even its life.
In 2008, scientists studying ancient lavas in northern Quebec, known to geologists as the Nuvvuagittuq greenstone belt, saw that they had the same geochemical signature as lavas from modern subduction zones like the Mariana. This meant that they must have mixed with briny fluids squeezed up through subduction zones and only there. The geochemistry of those rocks could be used as a sort of fingerprint to help identify subduction zone lavas.
Geologists Tracy Rushmer and Simon Turner of Macquarie University in Sydney, Australia, decided to take a closer look. They and their colleagues noticed a distinct chemical pattern to the layers in the lava, creating a unique sequence of rocks. The team thought this sequence could be similar to lava sequences made by modern subduction zones like the Mariana Trench. Mark Reagan, a geologist at the University of Iowa who has taken submersibles into the trench five times as deep as 6500 meters, confirmed Rushmer and Turner’s suspicions. “The whole sequence,” Rushmer says, “linked in with what Mark was seeing in the Mariana Trench.” The team says each rock layer in the sequences at the Mariana lavas and the Nuvvuagittuq lavas describes a step in the birth of a subduction zone.
The key is in how rocks and their chemistry change with each successive layer. As the oceanic slab descends, lavas begin rising up and erupt on the surface in layers atop one another, creating a rising sequence of igneous rocks. With increasing depth, heat and pressure begin squeezing different elements out of the slab in fluids. Over time, these fluids change the chemical composition of the lavas so that they become rich in rare earth elements like ytterbium, but poor in the element niobium. The first layer in the sequence erupts before the fluids can escape the slab, but the next layer in the sequence gets just enough fluid to make a partial signature. The final layer carries huge amounts of rare earth elements and very little niobium, together making the clarion mark of subduction zone lava.
The team realized not only do both rocks carry the same geochemical signature, but in comparing the Mariana and the Nuvvuagittuq, they also discovered the rocks and the geochemistry of both sequences change in the exact same way, they report in the current issue of Geology. This finding bolstered the theory that the Nuvvuagittuq sequence is an ancient subduction zone. “Seeing the evolving chemical signature,” Turner says, “was much more robust than just saying there is or isn’t niobium.”
Geochemist Julian Pearce of Cardiff University in the United Kingdom still isn’t completely convinced, though. He says the Nuvvuagittuq greenstone belt might just be too old and warped to have a reliable signal from 4.4 billion years ago. “The evidence would be compelling if the rocks were young, undeformed, and fresh,” Pearce says. As they are now, the Nuvvuagittuq rocks have been modified by intense heat and pressure “which can mask and modify geochemical signals” through contamination from nearby rocks. Furthermore, while Pearce believes a subduction zone is one place these geochemical signatures can be made, “it is not the only location.”
While those are legitimate concerns, geoscientist Norman Sleep of Stanford University in Palo Alto, California, isn’t too bothered. “It’s not fully sorted out yet,” Sleep says, but the Nuvvuagittuq rocks “really seem like modern arclike lavas” found at the Mariana. When it comes to the geochemical signature of subduction, Turner and the members of the team say that heat and pressure don’t alter the geochemical fingerprint much, and Sleep says this is reasonable. Despite all of the difficulties of studying such timeworn rocks, he says “the work done in this paper is very valuable.”
For one, everyone agrees subduction zones could sculpt ideal sanctuaries for the origin of life. Fluids released from subducting crust also transform mantle rocks into a mineral called serpentine. Those fluids go on to form hot springs on the ocean floor. “The serpentine provides an energy source,” Sleep says, which is one of three requirements for early life. The molecule RNA can satisfy the other two requirements by acting as both a catalyst helping other molecules form and a way to self-replicate. But RNA will fall apart without something to stabilize it. As luck would have it, these serpentine vents are bursting with boron, which acts as a stabilizing agent for RNA. This makes what could be the most ancient subduction zone on Earth, Pearce says, “a likely setting for life to start.”
Note : The above story is based on materials provided by Angus Chen “American Association for the Advancement of Science”
Palaeontological reconstruction of rangeomorph fronds from the Ediacaran Period (635-541 million years ago) built using computer models of rangeomorph growth and development. Credit: Jennifer Hoyal Cuthill
New three-dimensional reconstructions show how some of the earliest animals on Earth developed, and provide some answers as to why they went extinct.
A bizarre group of uniquely-shaped organisms known as rangeomorphs may have been some of the earliest animals to appear on Earth, uniquely suited to ocean conditions 575 million years ago.
A new model devised by researchers at the University of Cambridge has resolved many of the mysteries around the structure, evolution and extinction of these ‘proto animals’. The findings are reported today (11 August) in the journal Proceedings of the National Academy of Sciences.
Rangeomorphs were some of the earliest large organisms on Earth, existing during a time when most other forms of life were microscopic in size. Most rangeomorphs were about 10 centimetres high, although some were up to two metres in height.
These creatures were ocean dwellers which lived during the Ediacaran period, between 635 and 541 million years ago. Their bodies were made up of soft branches, each with many smaller side branches, forming a geometric shape known as a fractal, which can be seen in many familiar branching shapes such as fern leaves and even river networks.
Rangeomorphs were unlike any modern organism, which has made it difficult to determine how they fed, grew or reproduced, and therefore difficult to link them to any particular modern group. However, despite the fact that they looked like plants, evidence points to the fact that rangeomorphs were actually some of the earliest animals.
“We know that rangeomorphs lived too deep in the ocean for them to get their energy through photosynthesis as plants do,” said Dr Jennifer Hoyal Cuthill of Cambridge’s Department of Earth Sciences, who led the research. “It’s more likely that they absorbed nutrients directly from the sea water through the surface of their body. It would be difficult in the modern world for such large animals to survive only on dissolved nutrients.”
“The oceans during the Ediacaran period were more like a weak soup — full of nutrients such as organic carbon, whereas today suspended food particles are swiftly harvested by a myriad of animals,” said co-author Professor Simon Conway Morris.
Starting 541 million years ago, the conditions in the oceans changed quickly with the start of the Cambrian Explosion — a period of rapid evolution when most major animal groups first emerge in the fossil record and competition for nutrients increased dramatically.
Rangeomorphs have often been considered a ‘failed experiment’ of evolution as they died out so quickly once the Cambrian Explosion began in earnest, but this new analysis shows just how successful they once were.
Rangeomorphs almost completely filled the space surrounding them, with a massive total surface area. This made them very efficient feeders that were able to extract the maximum amount of nutrients from the ocean water.
“These creatures were remarkably well-adapted to their environment, as the oceans at the time were high in nutrients and low in competition,” said Dr Hoyal Cuthill. “Mathematically speaking, they filled their space in a nearly perfect way.”
Dr Hoyal Cuthill examined rangeomorph fossils from a number of locations worldwide, and used them to make the first computer reconstructions of the development and three-dimensional structure of these organisms, showing just how well-suited they were to their Ediacaran environment.
As the Cambrian Explosion began however, the rangeomorphs became ‘sitting ducks’, as they had no known means of defence from predators which were starting to evolve, and the changing chemical composition of the ocean meant that they could no longer get the nutrients they required to feed.
“As the Cambrian began, these Ediacaran specialists could no longer survive, and nothing quite like them has been seen again,” said Dr Hoyal Cuthill.
Note : The above story is based on materials provided by University of Cambridge. The original story is licensed under a Creative Commons Licence.
A fisherman walks toward open water in the Antarctic ice sheet. Conflicting research on the heating and cooling of Earth has led to a global temperature conundrum, which climate scientists plan to address further this fall. Photo: iStock Photo
When the Intergovernmental Panel on Climate Change recently requested a figure for its annual report, to show global temperature trends over the last 10,000 years, the University of Wisconsin-Madison’s Zhengyu Liu knew that was going to be a problem.
“We have been building models and there are now robust contradictions,” says Liu, a professor in the UW-Madison Center for Climatic Research. “Data from observation says global cooling. The physical model says it has to be warming.”
Writing in the journal Proceedings of the National Academy of Sciences today, Liu and colleagues from Rutgers University, the National Center for Atmospheric Research, the Alfred Wegener Institute for Polar and Marine Research, the University of Hawaii, the University of Reading, the Chinese Academy of Sciences, and the University of Albany describe a consistent global warming trend over the course of the Holocene, our current geological epoch, counter to a study published last year that described a period of global cooling before human influence.
The scientists call this problem the Holocene temperature conundrum. It has important implications for understanding climate change and evaluating climate models, as well as for the benchmarks used to create climate models for the future. It does not, the authors emphasize, change the evidence of human impact on global climate beginning in the 20th century.
“The question is, ‘Who is right?'” says Liu. “Or, maybe none of us is completely right. It could be partly a data problem, since some of the data in last year’s study contradicts itself. It could partly be a model problem because of some missing physical mechanisms.”
Over the last 10,000 years, Liu says, we know atmospheric carbon dioxide rose by 20 parts per million before the 20th century, and the massive ice sheet of the Last Glacial Maximum has been retreating. These physical changes suggest that, globally, the annual mean global temperature should have continued to warm, even as regions of the world experienced cooling, such as during the Little Ice Age in Europe between the 16th and 19th centuries.
The three models Liu and colleagues generated took two years to complete. They ran simulations of climate influences that spanned from the intensity of sunlight on Earth to global greenhouse gases, ice sheet cover and meltwater changes. Each shows global warming over the last 10,000 years.
Yet, the bio- and geo-thermometers used last year in a study in the journal Science suggest a period of global cooling beginning about 7,000 years ago and continuing until humans began to leave a mark, the so-called “hockey stick” on the current climate model graph, which reflects a profound global warming trend.
In that study, the authors looked at data collected by other scientists from ice core samples, phytoplankton sediments and more at 73 sites around the world. The data they gathered sometimes conflicted, particularly in the Northern Hemisphere.
Because interpretation of these proxies is complicated, Liu and colleagues believe they may not adequately address the bigger picture. For instance, biological samples taken from a core deposited in the summer may be different from samples at the exact same site had they been taken from a winter sediment. It’s a limitation the authors of last year’s study recognize.
“In the Northern Atlantic, there is cooling and warming data the (climate change) community hasn’t been able to figure out,” says Liu.
With their current knowledge, Liu and colleagues don’t believe any physical forces over the last 10,000 years could have been strong enough to overwhelm the warming indicated by the increase in global greenhouse gases and the melting ice sheet, nor do the physical models in the study show that it’s possible.
“The fundamental laws of physics say that as the temperature goes up, it has to get warmer,” Liu says.
Caveats in the latest study include a lack of influence from volcanic activity in the models, which could lead to cooling — though the authors point out there is no evidence to suggest significant volcanic activity during the Holocene — and no dust or vegetation contributions, which could also cause cooling.
Liu says climate scientists plan to meet this fall to discuss the conundrum.
“Both communities have to look back critically and see what is missing,” he says. “I think it is a puzzle.”
The study was supported by grants from the (U.S.) National Science Foundation, the Chinese National Science Foundation, the U.S. Department of Energy, and the Chinese Ministry of Science and Technology.
Note : The above story is based on materials provided by University of Wisconsin-Madison. The original article was written by Kelly April Tyrrell.
Still searing from the formation of the solar system, the core of Earth is a nuclear reactor generating heat from the breakdown of radioactive elements like uranium, thorium, and potassium. Scientists have been harnessing that heat for decades by drilling deep wells to power turbines. But now researchers have been able to tap into even greater energy by drilling into volcanoes and exploiting the heat of molten rock. If current geothermal wells are replaced with the new technology, it could provide 30% more power than current renewable energy sources.
The idea of tapping the energy of magma came from a pair of accidents. In 1985, workers drilling for a geothermal well in Iceland ran into a sudden and uncontrollable blast of high-pressure steam. Scientists think the steam originated from a reservoir of water that’s under such pressure that as it begins to boil, the water cannot expand enough to become vapor and remains in a liquidlike state. Water in such a “supercritical state” contains enormous amounts of energy. Water reaches this state once it reaches 222 bars of pressure and 374°C or above, and flashes into steam when the pressure drops as the water rises to the surface.
For the next 2 decades, researchers dreamed of capturing superhot steam from supercritical fluids and turning it into electricity. Whereas a typical geothermal well produces 5 to 10 MW of electricity, geologist Wilfred Elders, an emeritus professor at the University of California, Riverside, says supercritical wells could potentially yield 10 times that much.
The second unexpected event happened in 2009. The Icelandic Deep Drilling Project (IDDP), a consortium of energy companies and scientists, including Elders, had begun drilling for the theorized supercritical fluid wells when they hit a pocket of magma. The molten rock ruined their equipment, but the team realized that the intense heat could actually boost the production capability of the well. The higher the temperature, the easier it becomes for water to enter a supercritical state, and the magma pouring into their well was hotter than 900°C. “There is an enormous energy potential, orders of magnitude greater than can be produced from conventional geothermal systems at 200 to 300°C,” Elders says.
To use the magma for energy, workers wouldn’t drill directly into it. Instead, they could either tap into superhot water in nearby magma-heated rock and use its steam to turn turbines, or make artificial steam by injecting water from the surface. In 2011, the researchers finished the well just above the magma, where the temperature didn’t quite reach 900°C. Even so, the well generated superheated steam and 35 MW of electricity at 500°C, Elders and his colleagues report in the current issue of Geothermics. For the first time, researchers proved it was possible to create supercritical geothermal wells enhanced by magma.
It isn’t so simple though. IDDP’s 2011 well suffered from mechanical failure after only 2 years of use, and tools are still being developed to withstand such extreme conditions. Location is a problem, too: Magma-heated systems require active volcanoes, and even there it’s exceedingly hard to find magma to drill into. It’s “a bit like finding a needle in a haystack,” says Bruce Marsh, a professor at Johns Hopkins University’s Department of Earth and Planetary Sciences, who wasn’t involved in the work. These types of wells won’t be easily replicable, but Marsh is hopeful. “Maybe after we find a few of these things, we’ll know how to look for them,” he says.
Power aside, Marsh says he is excited about the wells’ scientific value. Magma is hard to study, he notes. Researchers usually analyze it as solid rock that has come to the surface or as solid drill cores. But now scientists might be able to study it from where it is inside the crust and begin understanding what drives systems in Earth’s interior. “We’ve got a tiger by the tail,” Marsh says. “It’s the difference between studying something in the zoo and studying it in the wild.”
IDDP, meanwhile, is moving forward with other supercritical geothermal wells in Iceland soon, and similar projects are under way in New Zealand and Japan. “There’s enormous potential out there,” Marsh says.
Note : The above story is based on materials provided by Angus Chen ” American Association for the Advancement of Science. “
Pele. Her name brings visions of fire, lightning, wind—and volcanoes. Of the ancient Hawaiian goddesses, Pele, the “lady in the red dress,” is the best known.
Locals believe that her powers formed Hawaii’s chain of volcanic islands. The word pele means molten lava in Hawaiian. Volcanic eruptions, or Pele’s tears, it’s said, are her way of expressing red-hot emotions.
Science may offer another explanation.
The island volcanoes of Hawaii are the most recent evidence, researchers say, of an ancient process that created the 3,700-mile-long Hawaiian-Emperor Seamount Chain.
It’s what goes on at the base of that chain, hidden in the depths of the Pacific Ocean, that interests marine ecologists David Emerson of the Bigelow Laboratory for Ocean Sciences in East Boothbay, Maine, Craig Moyer of Western Washington University, and Clara Chan of the University of Delaware.
What the scientists found there is “Pele red” in color: Iron oxide, or rust, come to life.
Villages of rust in the sea’s depths
Along the Hawaiian-Emperor Seamount Chain at Loihi Seamount—an active submarine volcano 22 miles off the coast of the island of Hawaii and 3,000 feet below sea level—the biologists are conducting research on Zetaproteobacteria, life forms that use iron as an energy source. Zetaproteobacteria form iron-rich microbial mats on Loihi’s flanks.
Hydrothermal vents, seafloor geysers that support microbial oases, line Loihi’s summit. The hot fluids spewing from the vents contain high levels of iron, turning Loihi’s underwater slopes an unusual, and characteristic, orange-red.
This iron-rich cauldron is a perfect environment for Zetaproteobacteria.
“Iron is the fourth most abundant element in Earth’s crust,” says Emerson, “and is essential for life. For example, iron is the oxygen-carrying component of hemoglobin in blood.”
What’s less known about iron, he says, “is that it can support the growth of an array of microbes.”
Zetaproteobacteria are the dominant bacteria in Loihi’s iron-rich microbial mats. They’re rarely found in other deep-sea or marine habitats, suggesting that they might be restricted to niches where iron is abundant.
Recent discoveries have expanded their range, however, and that of their distant relatives to deep within the ocean crust, iron deposits in salt marshes, and to the corrosion on steel. “They’re more cosmopolitan than anyone realized,” says Emerson.
In freshwater, their kin are found in roadside ditches, slow-moving streams, wetlands, and on the roots of submerged plants.
“One indicator of their presence is a metallic sheen on the water, which is sometimes mistaken for an oil slick,” says Emerson.
A closer look reveals a mat of iron-oxidizing bacteria with linking, filament-like structures. They form an intricate miniature ecosystem, Emerson says.
It takes a village… of bacteria
“We don’t usually think of bacteria as villages,” he maintains. “For the Zetaproteobacteria that live at Loihi, that might be a good analogy, though. What they do with rust is remarkable.”
These undersea designers fashion “skyscrapers,” spires and highways of iron oxide filaments woven together.
“Zetaproteobacteria are the ultimate in sustainable architects,” says Chan. “They recycle rusty minerals into building blocks.”
With funding from the National Science Foundation (NSF), Emerson, Chan and Moyer are exploring the rust villages to learn the roles of their bacterial builders.
“These bacteria are a rare life form that derives energy out of iron oxidation, that is, they sustain themselves by turning iron into rust,” says Anton Post, program director in NSF’s Division of Ocean Sciences.
The scientists are also interested in other species that may live side-by-side with Zetaproteobacteria, how the inhabitants all work together, and how the interaction of life and minerals contributes to a rust village.
“One of the fates of the microbial mat ecosystems,” Emerson says, “is that they eventually turn into iron-rich stone.”
Another is that the iron oxides the bacteria produce are widely dispersed in the ocean, where they’re an iron source for plankton and other marine life.
Stalk-like structures unique to Zetaproteobacteria
The ability of Zetaproteobacteria to form iron oxide structures in sheaths or stalks is unique. These hallmarks, scientists say, are easily recognized under a microscope.
“Electron microscopy shows subtle differences that may be diagnostic of different populations of the bacteria,” says Emerson.
“Zetas” can produce huge amounts of iron oxides connected by sheaths; 100 cells might crank out as much as three feet of sheath in one day. This complex matrix shunts water and nutrient flow in the villages.
The microbes may also influence geochemical cycling and mineral deposition on larger scales.
Zetas to the rescue?
Zetaproteobacteria colonize steel exposed to seawater, where they foster the release of iron from the steel’s surface.
Water treatment managers view the bacteria’s relatives as nuisances that clog wells, foul and corrode pipelines, and lead to unsightly red water.
But now the Zetas’ and their freshwater cousins’ beneficial sides are coming to light.
The iron oxides they produce can act as filters, removing toxic metals like arsenic, lead and cadmium. The rust Zetas form also gets rid of organic pollutants such as pesticides, as well as nutrients like phosphorus that lead to overgrowth of algae in waterways, fast becoming a major problem in the Great Lakes and elsewhere.
The influence of Zetaproteobacteria and their clan may be far-reaching, spilling well beyond ocean depths.
Not so different from another architect who builds elaborate structures in shades of red: Pele herself.
Note : The above story is based on materials provided by National Science Foundation
The HOWD Polenet seismic station is located near the northwest corner of the Antarctica’s Ellsworth Mountains. It was the station that showed the clearest indication of high-frequency signals following the 2010 Chilean earthquake. Credit: Eric Kendrick/Ohio State University
Seismic events aren’t rare occurrences on Antarctica, where sections of the frozen desert can experience hundreds of micro-earthquakes an hour due to ice deformation. Some scientists call them icequakes. But in March of 2010, the ice sheets in Antarctica vibrated a bit more than usual because of something more than 3,000 miles away: the 8.8-magnitude Chilean earthquake. A new Georgia Institute of Technology study published in Nature Geoscience is the first to indicate that Antarctica’s frozen ground is sensitive to seismic waves from distant earthquakes.
To study the quake’s impact on Antarctica, the Georgia Tech team looked at seismic data from 42 stations in the six hours before and after the 3:34 a.m. event. The researchers used the same technology that allowed them to “hear” the seismic response at large distances for the devastating 2011 magnitude 9 Japan earthquake as it rumbled through the earth. In other words, they simply removed the longer-period signals as the seismic waves spread from the distant epicenter to identify high-frequency signals from nearby sources. Nearly 30 percent (12 of the 42 stations) showed clear evidence of high-frequency seismic signals as the surface-wave arrived on Antarctica.
“We interpret these events as small icequakes, most of which were triggered during or immediately after the passing of long-period Rayleigh waves generated from the Chilean mainshock,” said Zhigang Peng, an associate professor in the School of Earth and Atmospheric Sciences who led the study. “This is somewhat different from the micro-earthquakes and tremor caused by both Love and Rayleigh-type surface waves that traditionally occur in other tectonically active regions thousands of miles from large earthquakes.
Peng says the subtle difference is that micro-earthquakes respond to both shearing and volumetric deformation from distant events. The newly found icequakes respond only to volumetric deformation.
“Such differences may be subtle, but they tell us that the mechanism of these triggered icequakes and small earthquakes are different,” Peng added. “One is more like cracking, while the other is like a shear slip event. It’s similar to two hands passing each other.”
Some of the icequakes were quick bursts and over in less than one second. Others were long duration, tremor-like signals up to 10 seconds. They occurred in various parts of the continent, including seismic stations along the coast and near the South Pole.
The researchers found the clearest indication of induced high-frequency signals at station HOWD near the northwest corner of the Ellsworth Mountains. Short bursts occurred when the P wave hit the station, then continued again when the Rayleigh wave arrived. The triggered icequakes had very similar high waveform patterns, which indicates repeated failure at a single location, possibly by the opening of cracks.
Peng says the source locations of the icequakes are difficult to determine because there isn’t an extensive seismic network coverage in Antarctica.
“But at least some of the icequakes themselves create surface waves, so they are probably formed very close to the ice surface,” he added. “While we cannot be certain, we suspect they simply reflect fracturing of ice in the near surface due to alternating volumetric compressions and expansions as the Rayleigh waves passed through Antarctica’s frozen ice.”
Antarctica was originally not on the research team’s target list. While examining seismic stations in the Southern Hemisphere, Peng “accidently” found the triggered icequakes at a few openly available stations. He and former Georgia Tech postdoctoral student Jake Walter (now a research scientist at the Institute for Geophysics at UT Austin) then reached out to other seismologists (the paper’s four co-authors) who were in charge of deploying more broadband seismometers in Antarctica.
Video :
High-frequency icequakes are shown at station HOWD in Antarctica during the distant waves of the 2010 magnitude 8.8 Chile earthquake. The triggered icequakes are indicated by the narrow vertical bands in the middle and lower sections of the graphic. They begin when the P wave arrives approximately 8 minutes (480 seconds) after the Chilean quake and continue through the arrival of the Rayleigh waves. The sound is generated by speeding up the HOWD’s seismic data 100 times. Credit: Georgia Tech
High-frequency icequakes are shown at station AGO (near the South Pole) in Antarctica during the distant waves of the 2010 magnitude 8.8 Chile earthquake. The triggered icequakes are indicated by the narrow vertical bands in the middle and lower sections of the graphic. They begin when the P wave arrives approximately 10 minutes (600 seconds) after the Chilean quake and continue through the arrival of the Rayleigh waves. The sound is generated by speeding up the AGO’s seismic data 100 times. Credit: Georgia Tech
The forerunner of dinosaurs like three-horned Triceratops was a bird-hipped creature the size of a turkey that lived in herds in South America and liked to munch on ferns, scientists said Wednesday.
Laquintasaura venezuelae, named after the country in which it was discovered, lived 201 million years ago in the earliest Jurassic period, soon after a major extinction at the end of the Triassic, said a paper in the journal Proceedings of the Royal Society B.
The early history of bird-hipped, beaked, plant-eating dinosaurs called Ornithischia, of which the newly-discovered lizard is a very old example, has thus far been sketchy, as so few have been found.
Ornithischia gave rise to famous beasts like Iguanodon, Stegosaurus and Triceratops, which have inspired childrens’ toys and cartoons.
The discovery of the remains of at least four Laquintasaura in Venezuela showed that dinosaurs bounced back quickly after the Triassic species wipeout, said study author Paul Barrett, a palaeontologist at the Natural History Museum in London.
Also, “it is fascinating and unexpected to see they lived in herds, something we have little evidence of so far in dinosaurs from this time,” he said in a statement.
“The fact that it is from a completely new and early taxon means we can fill in some of the gaps in our understanding of when different groups of dinosaurs evolved.”
The remains were found in the La Quinta geological formation in the Venezuelan Andes, an area previously thought to have been far too inhospitable for dinosaurs.
The fossilised evidence revealed that Laquintasaura walked on two hind legs, and was about a metre (3.3 feet) long with its tail, and about a quarter of that wide at the hips.
It is thought to have been largely a plant-eater, favouring ferns, but curved tips on some of its teeth suggest it may have also eaten insects and other small prey.
“It is always exciting to discover a new dinosaur species but there are many surprising firsts with Laquintasaura,” said Barrett.
“Not only does it expand the distribution of early dinosaurs, its age makes it important for understanding their early evolution and behaviour.”
It is the first new dinosaur species found in the north of South America.
The fossils’ age was determined with techniques that included analysing residual radioactivity of tiny crystals within the rock containing the ancient bones.
This is an artist’s conception of internal structure of the Moon based on this science result. Credit: Image courtesy of National Astronomical Observatory of Japan
An international research team, led by Dr. Yuji Harada from Planetary Science institute, China University of Geosciences, has found that there is an extremely soft layer deep inside the Moon and that heat is effectively generated in the layer by the gravity of Earth. These results were derived by comparing the deformation of the Moon as precisely measured by Kaguya (SELENE, Selenological and Engineering Explorer) and other probes with theoretically calculated estimates. These findings suggest that the interior of the Moon has not yet cooled and hardened, and also that it is still being warmed by the effect of Earth on the Moon. This research provides a chance to reconsider how both Earth and the Moon have been evolving since their births through mutual influence until now.
When it comes to clarifying how a celestial body like a planet or a natural satellite is born and grows, it is necessary to know as precisely as possible its internal structure and thermal state. How can we know the internal structure of a celestial body far away from us? We can get clues about its internal structure and state by thoroughly investigating how its shape changes due to external forces. The shape of a celestial body being changes by the gravitational force of another body is called tide. For example, the ocean tide on Earth is one tidal phenomenon caused by the gravitational force between the Moon and the Sun, and Earth. Sea water is so deformable that its desplacement can be easily observed. How much a celestial body can be deformed by tidal force, in this way, depends on its internal structure, and especially on the hardness of its interior. Conversely, it means that observing the degree of deformation enables us to learn about the interior, which is normally not directly visible to the naked eye.
The Moon is no exception; we can learn about the interior of our natural satellite from its deformation caused by the tidal force of Earth. The deformation has already been well known through several geodetic observations (*1). However, models of the internal structure of the Moon as derived from past research could not account for the deformation precisely observed by the above lunar exploration programs.
Therefore, the research team performed theoretical calculations to understand what type of internal structure of the Moon leads to the observed change of the lunar shape.
What the research team focused on is the structure deep inside the Moon. During the Apollo program, seismic observations (*2) were carried out on the Moon. One of the analysis results concerning the internal structure of the Moon based upon the seismic data indicates that the satellite is considered to consist mainly of two parts: the “core,” the inner portion made up of metal, and the “mantle,” the outer portion made up of rock. The research team has found that the observed tidal deformation of the Moon can be well explained if it is assumed that there is an extremely soft layer in the deepest part of the lunar mantle. The previous studies indicated that there is the possibility that a part of the rock at the deepest part inside the lunar mantle may be molten. This research result supports the above possibility since partially molten rock becomes softer. This research has proven for the first time that the deepest part of the lunar mantle is soft, based upon the agreement between observation results and the theoretical calculations.
Furthermore, the research team also clarified that heat is efficiently generated by the tides in the soft part, deepest in the mantle. In general, a part of the energy stored inside a celestial body by tidal deformation is changed to heat. The heat generation depends on the softness of the interior. Interestingly, the heat generated in the layer is expected to be nearly at the maximum when the softness of the layer is comparable to that which the team estimated from the above comparison of the calculations and the observations. This may not be a coincidence. Rather, the layer itself is considered to be maintained as the amount of the heat generated inside the soft layer is exquisitely well balanced with that of the heat escaping from the layer. Whereas previous research also suggests that some part of the energy inside the Moon due to the tidal deformation is changed to heat, the present research indicates that this type of energy conversion does not uniformly occur in the entire Moon, but only intensively in the soft layer. The research team believes that the soft layer is now warming the core of the Moon as the core seems to be wrapped by the layer, which is located in the deepest part of the mantle, and which efficiently generates heat. They also expect that a soft layer like this may efficiently have warmed the core in the past as well.
Concerning the future outlook for this research, Dr. Yuji Harada, the principle investigator of the research team, said, “I believe that our research results have brought about new questions. For example, how can the bottom of the lunar mantle maintain its softer state for a long time? To answer this question, we would like to further investigate the internal structure and heat-generating mechanism inside the Moon in detail. In addition, another question has come up: how has the conversion from the tidal energy to the heat energy in the soft layer affected the motion of the Moon relative to the Earth, and also the cooling of the Moon? We would like to resolve those problems as well so that we can thoroughly understand how the Moon was born and has evolved.”
Another investigator, Prof. Junichi Haruyama of Institute of Space and Aeronautical Science, Japan Aerospace Exploration Agency, mentioned the significance of this research, saying, “A smaller celestial body like the Moon cools faster than a larger one like the Earth does. In fact, we had thought that volcanic activities on the Moon had already come to a halt. Therefore, the Moon had been believed to be cool and hard, even in its deeper parts. However, this research tells us that the Moon has not yet cooled and hardened, but is still warm. It even implies that we have to reconsider the question as follows: How have the Earth and the Moon influenced each other since their births? That means this research not only shows us the actual state of the deep interior of the Moon, but also gives us a clue for learning about the history of the system including both the Earth and the Moon.”
The scientific paper on which this article is based appears in the Nature Geoscience.
Strong tidal heating in an ultralow-viscosity zone at the core-mantle boundary of the Moon.
Note:
*1: Geodetic observation. (This is also called “selenodetic” observation as it is for the Moon.)
Observational results on gravity and rotation of the Moon are used in this research. Precise measurements of the lunar gravity and rotation enable us to know how our natural satellite is deformed by tidal forces.
The gravity of the Moon can be measured by tracking the motion of a satellite orbiting the Moon. This is because the motion of the satellite is influenced by lunar gravity. The motion of the satellite orbiting the Moon can be determined by using radio waves between the Earth and the satellite, and between multiple satellites around the Moon. The gravity of the Moon changes when it deforms due to tidal forces. The change in gravity caused by the lunar deformation due to the tidal force is extremely small, but when the change in location of the orbiter can be determined precisely enough, it is possible to accurately detect the change in lunar gravity caused by the deformation due to the tidal force. During the last several years, the degree of the lunar deformation caused by the tidal forces has been determined by several orbiters, for example, Kaguya from Japan, Chang’e-1 from China, and Lunar Reconnaissance Orbiter (LRO) and Gravity Recovery and Interior Laboratory (GRAIL) from the USA.
The rotation of the Moon can be observed by monitoring the change in position of a kind of mirror placed in several locations on the lunar surface. The same side of the Moon is almost always facing the Earth, but strictly speaking, it changes by a slight amount according to the lunar orbit around the Earth. This means that the locations of the mirrors with respect to the Earth also changes over time. If this change in position is precisely measured, it can also be determined how the direction of the lunar axis changes. This slight change of direction also depends on the deformation caused by the tidal force. It can be seen, therefore, how the Moon deforms due to the tidal force once the change in the axis is measured precisely. Some of the above-mentioned mirrors have been left on the surface of the Moon in the framework of the lunar exploration programs led by the USA or the former USSR several decades ago, such as the Apollo program. The degree of change in the location of each mirror on the Moon can be determined by using laser beams emitted from the Earth. This experiment still continues to be carried out even today.
*2: Seismic observation. (Quakes on the Moon are also called “moonquakes.” )
There are seismic activities not only on the Earth, but also on the Moon. As part of the Apollo program in the past, seismometers were placed on the lunar surface for seismological measurements. Waves induced by quakes measured with seismometers suggest what the internal structure of a celestial body is like. The behavior of the seismic waves is very important for understanding how the hardness inside the celestial body will change in accordance with the depth. In particular, the present research considered the following two previous analysis results in order to theoretically calculate the lunar deformation caused by the tidal force.
The first one is the existence of the area deep inside the Moon where the seismic waves become drastically weaker. It is generally known that the energy of the seismic waves tends to reduce more in softer solids, especially when they contain liquids. Therefore, the deepest part of the lunar mantle is softer than the shallower part. Also, a portion of the rocks is thought to be melted.
The second one is the existence of areas deep inside the Moon whose interfaces reflect the seismic waves. Three boundaries are considered to exist. Two of them are like the ones in the Earth: one separating the solid inner core and the liquid outer core, and the other one separating the outer core and the mantle. The last boundary is considered to correspond to the one in the mantle separating the solid area and the partially molten area mentioned above.
Note : The above story is based on materials provided by National Astronomical Observatory of Japan.
The middens are ancient dumping sites that typically contain a mix of mollusk shells, fish and bird bones, ceramics, cloth, charcoal, maize and other plants. Credit: M. Carré / Univ. of Montpellier
The planet’s largest and most powerful driver of climate changes from one year to the next, the El Niño Southern Oscillation in the tropical Pacific Ocean, was widely thought to have been weaker in ancient times because of a different configuration of the Earth’s orbit. But scientists analyzing 25-foot piles of ancient shells have found that the El Niños 10,000 years ago were as strong and frequent as the ones we experience today.
The results, from the University of Washington and University of Montpellier, question how well computer models can reproduce historical El Niño cycles, or predict how they could change under future climates. The paper is now online and will appear in an upcoming issue of Science.
“We thought we understood what influences the El Niño mode of climate variation, and we’ve been able to show that we actually don’t understand it very well,” said Julian Sachs, a UW professor of oceanography.
The ancient shellfish feasts also upend a widely held interpretation of past climate.
“Our data contradicts the hypothesis that El Niño activity was very reduced 10,000 years ago, and then slowly increased since then,” said first author Matthieu Carré, who did the research as a UW postdoctoral researcher and now holds a faculty position at the University of Montpellier in France.
In 2007, while at the UW-based Joint Institute for the Study of the Atmosphere and Ocean, Carré accompanied archaeologists to seven sites in coastal Peru. Together they sampled 25-foot-tall piles of shells from Mesodesma donacium clams eaten and then discarded over centuries into piles that archaeologists call middens.
While in graduate school, Carré had developed a technique to analyze shell layers to get ocean temperatures, using carbon dating of charcoal from fires to get the year, and the ratio of oxygen isotopes in the growth layers to get the water temperatures as the shell was forming.
The shells provide 1- to 3-year-long records of monthly temperature of the Pacific Ocean along the coast of Peru. Combining layers of shells from each site gives water temperatures for intervals spanning 100 to 1,000 years during the past 10,000 years.
The new record shows that 10,000 years ago the El Niño cycles were strong, contradicting the current leading interpretations. Roughly 7,000 years ago the shells show a shift to the central Pacific of the most severe El Niño impacts, followed by a lull in the strength and occurrence of El Niño from about 6,000 to 4,000 years ago.
One possible explanation for the surprising finding of a strong El Niño 10,000 years ago was that some other factor was compensating for the dampening effect expected from cyclical changes in Earth’s orbit around the sun during that period.
“The best candidate is the polar ice sheet, which was melting very fast in this period and may have increased El Niño activity by changing ocean currents,” Carré said.
Around 6,000 years ago most of the ice age floes would have finished melting, so the effect of Earth’s orbital geometry might have taken over then to cause the period of weak El Niños.
In previous studies, warm-water shells and evidence of flooding in Andean lakes had been interpreted as signs of a much weaker El Niño around 10,000 years ago.
The new data is more reliable, Carré said, for three reasons: the Peruvian coast is strongly affected by El Niño; the shells record ocean temperature, which is the most important parameter for the El Niño cycles; and the ability to record seasonal changes, the timescale at which El Niño can be observed.
“Climate models and a variety of datasets had concluded that El Niños were essentially nonexistent, did not occur, before 6,000 to 8,000 years ago,” Sachs said. “Our results very clearly show that this is not the case, and suggest that current understanding of the El Niño system is incomplete.”
The research was funded by the U.S. National Science Foundation, the U.S. National Oceanic and Atmospheric Administration and the French National Research Agency.
Other co-authors are Sara Purca at the Marine Institute of Peru; Andrew Schauer, a UW research scientist in Earth and space sciences; Pascale Braconnot at France’s Climate and Environment Sciences Laboratory; Rommel Angeles Falcón at Peru’s Minister of Culture; and Michèle Julien and Danièle Lavallée at France’s René Ginouvès Institute for Archaeology and Anthropology.
InSAR image showing volcanic uplift in the Great Rift Valley
Little known volcanoes in one of Africa’s most stunning locations are to be explored in a bid to understand the threat they pose to life, livelihood and the landscape. Researchers are to assess largely uncharted volcanoes in the East African Rift Valley, home to vast mammal migrations, mountain gorillas, spectacular peaks and fertile plains.
The region’s volcanoes, numbering more than 100, are shrouded in mystery. Dates of their last eruptions are mostly unknown and very few have detectors in place to highlight early signs of activity.
The human and financial cost could be huge if any of the volcanoes in the densely-populated and economically crucial area of Ethiopia’s main rift become active.
Researchers aim to understand past volcanic behaviour, search for signs of current activity and make a long-range eruptive forecast for the region. A recent report for the World Bank ranked 49 of Ethiopia’s 65 volcanoes in the highest category of hazard uncertainty.
The eruption of Nabro volcano on the Ethiopia-Eritrea border in 2011 was a reminder of the potential threat to the region. Despite lying in a remote and sparsely populated location and with no historical record of eruption, it claimed the lives of 32 people and displaced 5,000 more. Prior to its eruption, the volcano was believed to be dormant.
The five-year project, focusing on the volcanoes of the Main Ethiopian Rift, will be led by researchers from the Universities of Edinburgh and Bristol, in collaboration with the Universities of Cambridge, Leeds, Oxford and Southampton, the British Geological Survey, Addis Ababa University and the Geological Survey of Ethiopia. Overseas partners include Reykjavik Geothermal, which is part of a multi-billion dollar investment to develop the infrastructure to exploit this rich source of geothermal power.
The multi-disciplinary team will collect samples, map the geological record of previous eruptions and deploy geophysical instruments before analysing the data and creating models of the eruptive history, current states of unrest, and computing the likelihood of future eruptions. The team will also work on the best way of communicating their results to the relevant authorities and communities.
The £3.7million project, known as RiftVolc, is funded by the Natural Environment Research Council and begins in September. It will build on previous successful studies collaborating with Addis Ababa University and the Geological Survey of Ethiopia in the region.
RiftVolc co-leader Dr Juliet Biggs, of the University of Bristol’s School of Earth Sciences said; “The East African Rift is a fascinating place, full of exciting scientific challenges. We’re thrilled to establish a major project to study the past, present and future behaviour of these little-known volcanoes, and to be able work with our Ethiopian partners on such a societally relevant project.”
Note : The above story is based on materials provided by University of Bristol
A site at Pitch Lake where liquid oil ascends to the surface. Credit: Rainer Meckenstock
An international team of researchers has found extremely small habitats that increase the potential for life on other planets while offering a way to clean up oil spills on our own.
Looking at samples from the world’s largest natural asphalt lake, they found active microbes in droplets as small as a microliter, which is about 1/50th of a drop of water.
“We saw a huge diversity of bacteria and archaea,” said Dirk Schulze-Makuch, a professor in Washington State University’s School of the Environment and the only U.S. researcher on the team. “That’s why we speak of an ‘ecosystem,’ because we have so much diversity in the water droplets.”
Writing in the journal Science, the researchers report they also found the microbes were actively degrading oil in the asphalt, suggesting a similar phenomenon could be used to clean up oil spills.
“For me, the cool thing is I got into it from an astrobiology viewpoint, as an analog to Saturn’s moon, Titan, where we have hydrocarbon lakes on the surface,” said Schulze-Makuch. “But this shows astrobiology has also great environmental applications, because of the biodegradation of oil compounds.”
Schulze-Makuch and his colleagues in 2011 found that the 100-acre Pitch Lake, on the Caribbean island of Trinidad, was teeming with microbial life, which is also thought to increase the likelihood of life on Titan.
The new paper adds a new, microscopic level of detail to how life can exist in such a harsh environment.
“We discovered that there are additional habitats where we have not looked at where life can occur and thrive,” said Schulze-Makuch.
Analyzing the droplets’ isotopic signatures and salt content, the researchers determined that they were not coming from rain or groundwater, but ancient sea water or a brine deep underground.
Eat dirt. Ancient seafloor diggers, like the extinct worm Ancalagon minor depicted here, may have altered planetary chemistry. Obsidian Soul/Creative Commons
You can credit your existence to tiny wormlike creatures that lived 500 million years ago, a new study suggests. By tunneling through the sea floor, scientists say, these creatures kept oxygen concentrations at just the right level to allow animals and other complex life to evolve. The finding may help answer an enduring mystery of Earth’s past.
At the dawn of the Cambrian period about 570 million years ago, multicellular organisms were just beginning to appear, largely in the oceans. But for animals to evolve, the concentration of oxygen in the ocean and atmosphere had to be just right. Too little oxygen, and nascent animals would have suffocated. Too much, and lightning strikes would have created catastrophic fires, torching the primordial land vegetation. “How come oxygen levels didn’t crash or double?” says Tais Dahl, a geochemist at the University of Southern Denmark (SDU), Odense. “Something [regulated] oxygen in relatively narrow limits.”
A key moment in the evolution of the new study was when Dahl met Richard Boyle, a geochemical modeler who was then at the University of Exeter in the United Kingdom. Dahl was puzzled by data he and others had collected from rock outcroppings that were once on the floor of the ocean. For 30 million years, beginning 530 million years ago, the oxygen levels of the ocean dropped steadily, four different sets of chemical measurements suggested.
Boyle, now at SDU, had developed a hypothesis that might explain why. By burrowing, he reasoned, seafloor creepy-crawlies that lived at the start of the Cambrian kick-started a complex chain of events that altered the chemical composition of Earth. In the new study, the two scientists and their colleagues use a simple model to spell out their proposed mechanism. The idea is that as they dug and wiggled, these early multicellular creatures—some were likely worms as long as 40 cm—exposed new layers of seafloor sediment to the ocean’s water. Each new batch of sediment that settles onto the sea floor contains bacteria; as those bacteria were exposed to the oxygen in the water, they began storing a chemical called phosphate in their cells. So as the creatures churned up more sediment layers, more phosphate built up in ocean sediments and less was found in seawater.
Because algae and other photosynthetic ocean life require phosphate to grow, removing phosphate from seawater reduced their growth. Less photosynthesis, in turn, meant less oxygen released into the ocean. In this way, the system formed a negative feedback loop that automatically slowed the rise in oxygen levels as the levels increased. What kept the oxygen levels from getting too low? Less oxygen in the water also meant fewer worms, so less oxygen-reducing digging, the researchers explain. “We think these animals may have completely transformed geochemical cycles,” says Dahl, whose team reported its work online this week in Nature Geoscience.
“Although we are still far from knowing to what extent worms and their ilk influenced the geochemical history of our planet, this is a novel and testable hypothesis, which will inspire novel thinking,” writes Filip Meysman, a biogeochemist at the Royal Netherlands Institute for Sea Research in Yerseke, in a commentary on the research in Nature Geoscience. But he cautions that the rapid increase in the extent of worms’ burrowing modeled in the new study may have been limited to some areas of the ancient ocean and has yet to be shown to be a global phenomenon.
“In hindsight, the result isn’t particularly surprising or counterintuitive,” adds biogeochemist Lee Kump of Pennsylvania State University, University Park, in an e-mail to Science. Still, he says, “I wish I’d thought of that.”
Note : The above story is based on materials provided by Eli Kintisch “American Association for the Advancement of Science”