The first scientists to witness exploding rock and molten lava from a deep sea volcano, seen during a 2009 expedition, report that the eruption was near a tear in the Earth’s crust that is mimicking the birth of a subduction zone.
Scientists on the expedition collected boninite, a rare, chemically distinct lava that accompanies the formation of Earth’s subduction zones.
Nobody has ever collected fresh boninite and scientists never had the opportunity to monitor its eruption before, said Joseph Resing, University of Washington oceanographer and lead author of an online article on the findings in Nature Geoscience. Earth’s current subduction zones are continually evolving but most formed 5 million to 200 million years ago. Scientists have only been able to study boninite collected from long-dead, relic volcanos millions of years old.
Resing was chief scientist on the expedition, funded by the National Oceanic and Atmospheric Administration and the National Science Foundation, that pinpointed the location of the West Mata volcano, erupting 4,000 feet (1,200 meters) below the surface in the Southwest Pacific Ocean.
“Everything about the eruption itself – how fast, how intense, the ratio of lava to explosive fragments, the amount and composition of gas released – is new to us,” said co-author Kenneth Rubin, University of Hawaii geologist. “Plus, having a young, fresh occurrence of this very rare rock type to study gives us the opportunity to examine subtle chemical and mineralogical variations in a pristine specimen.”
At subduction zones the oceanic crust on one tectonic plate slides beneath another, producing abundant volcanism and contributing heat, gases and mineral-laden fluids to ocean waters. Scientists have long studied the impact of subduction zones on geological and geochemical cycles. To puzzle out how subduction zones form and evolve they study inactive contemporary marine volcanos that do not produce boninite and they collect and study boninite lavas collected on land and examine cores collected from the deep sea.
“West Mata lies above the subducting Pacific plate and is part of the rapidly expanding Lau Basin, which is bounded by Samoa, Tonga and Fiji,” Resing said. “The large bend at the northern end of the Tonga trench produces a tear in the Pacific plate and creates unusual lavas that usually only form at very young subduction zones.”
Conditions are right for boninite to form, there’s lots of seawater released from subducting rock that mixes into relatively shallow mantle that has previously melted, causing the mantle to remelt at high temperatures. Boninite lavas are believed to be among the hottest from volcanoes that erupt on Earth.
“What makes this exciting is how uncommon these eruptions of boninite are, both now and in the past,” Rubin said. “Locked within the boninite is critical information about the rates and magnitudes of subduction-zone magmatism and global geochemical cycles.”
The scientists writing in Nature Geoscience think the release of gaseous water, carbon dioxide and sulfur dioxide from the slab is the reason the eruption was so explosive. No one realized such energetic eruptions happened so deep, Resing says.
Streams of red and gold lava 35 feet long shot through the water and lava-skinned bubbles some three feet across emerged.
West Mata, which the scientists estimate has been erupting for at least three years, and eight other elongated volcanoes that overlap each other in the northeast Lau Basin sit within one of the most magmatically active areas on Earth, Resing says.
“The basin may prove an important place to study submarine volcanic eruptions in relation to early stages of subduction,” he said.
Rubin and Robert Embley, with NOAA’s Pacific Marine Environmental Laboratory, Newport, Ore., and co-author on the paper, will return to the area in November for further study and to try to determine if the volcano is still actively erupting.
“Observing the eruption in real time was a rare and special opportunity because we know so little about how submarine volcanic activity behaves,” Embley said. “This is one of only a handful of ‘glimpses’ of the process we’ve had to date and is the first time we’ve actually observed natural submarine light from the glowing magma.
Note: This story has been adapted from a news release issued by the University of Washington
Geophysicists Terry Tullis, left, and David Goldsby have shown that rock surfaces sliding past each other in an earthquake can create intense heat but only at the pinpoint places where their surfaces actually touch. – Mike Cohea, Brown University
Most earthquakes that are seen, heard, and felt around the world are caused by fast slip on faults. While the earthquake rupture itself can travel on a fault as fast as the speed of sound or better, the fault surfaces behind the rupture are sliding against each other at about a meter per second.
But the mechanics that underlie fast slip during earthquakes have eluded scientists, because it’s difficult to replicate those conditions in the laboratory. “We still largely don’t understand what is going at earthquake slip speeds,” said David Goldsby, a geophysicist at Brown, “because it’s difficult to do experiments at these speeds.”
Now, in experiments mimicking earthquake slip rates, Goldsby and Brown geophysicist Terry Tullis show that fault surfaces in earthquake zones come into contact only at microscopic points between scattered bumps, called asperities, on the fault. These tiny contacts support all the force across the fault. The experiments show that when two fault surfaces slide against other at fast slip rates, the asperities may reach temperatures in excess of 2,700 degrees Fahrenheit, lowering their friction, the scientists write in a paper published in Science. The localized, intense heating can occur even while the temperature of the rest of the fault remains largely unaffected, a phenomenon known as flash heating.
“This study could explain a lot of the questions about the mechanics of the San Andreas Fault and other earthquakes,” said Tullis, professor emeritus of geological sciences, who has studied earthquakes for more than three decades.
The experiments simulated earthquake speeds of close to half a meter per second. The rock surfaces touched only at the asperities, each with a surface area of less than 10 microns – a tiny fraction of the total surface area. When the surfaces move against each other at high slip rates, the experiments revealed, heat is generated so quickly at the contacts that temperatures can spike enough to melt most rock types associated with earthquakes. Yet the intense heat is confined to the contact flashpoints; the temperature of the surrounding rock remained largely unaffected by these microscopic hot spots, maintaining a “room temperature” of around 77 degrees Fahrenheit, the researchers write.
“You’re dumping in heat extremely quickly into the contacts at high slip rates, and there’s simply no time for the heat to get away, which causes the dramatic spike in temperature and decrease in friction,” Goldsby said.
“The friction stays low so long as the slip rate remains fast,” said Goldsby, associate professor of geological sciences (research). “As slip slows, the friction immediately increases. It doesn’t take a long time for the fault to restrengthen after you weaken it.
The reason is the population of asperities is short-lived and continually being renewed, and therefore at any given slip rate, the asperities have a temperature and therefore friction appropriate for that slip rate. As the slip rate decreases, there is more time for heat to diffuse away from the asperities, and they therefore have lower temperature and higher friction.”
Flash heating and other weakening processes that lead to low friction during earthquakes may explain the lack of significant measured heat flows along some active faults like the San Andreas Fault, which might be expected if friction was high on faults during earthquakes. Flash heating in particular may also explain how faults rupture as “slip pulses,” wrinkle-like zones of slip on faults, which would also decrease the amount of heat generated.
If that is the case, then many earthquakes have been misunderstood as high-friction events. “It’s a new view with low dynamic friction. How can it be compatible with what we know?” asked Tullis, who chairs the National Earthquake Prediction Evaluation Council, an advisory body for the U.S. Geological Survey.
“Flash heating may explain it,” Goldsby replied.
Note: This story has been adapted from a news release issued by the Brown University
The “super-eruption” of a major volcanic system occurs about every 100,000 years and is considered one of the most catastrophic natural events on Earth, yet scientists have long been unsure about what triggers these violent explosions.
However, a new model presented this week by researchers at Oregon State University points to a combination of temperature influence and the geometrical configuration of the magma chamber as a potential cause for these super-eruptions.
Results of the research, which was funded by the National Science Foundation, were presented at the annual meeting of the Geological Society of America in Minneapolis, Minn.
Patricia “Trish” Gregg, a post-doctoral researcher at OSU and lead author on the modeling study, says the creation of a ductile halo of rock around the magma chamber allows the pressure to build over tens of thousands of years, resulting in extensive uplifting in the roof above the magma chamber. Eventually, faults from above trigger a collapse of the caldera and subsequent eruption.
“You can compare it to cracks forming on the top of baking bread as it expands,” said Gregg, a researcher in OSU’s College of Oceanic and Atmospheric Sciences. “As the magma chamber pressurizes at depth, cracks form at the surface to accommodate the doming and expansion. Eventually, the cracks grow in size and propagate downward toward the magma chamber.
“In the case of very large volcanoes, when the cracks penetrate deep enough, they can rupture the magma chamber wall and trigger roof collapse and eruption,” Gregg added.
The eruption of super-volcanoes dwarfs the eruptions of recent volcanoes and can trigger planetary climate change by inducing Ice Ages and other impacts. One such event was the Huckleberry Ridge eruption of present-day Yellowstone Park about two million years ago, which was more than 2,000 times larger than the 1980 eruption of Mount St. Helens in Washington.
“Short of a meteor impact, these super-eruptions are the worst environmental hazards our planet can face,” Gregg said. “Huge amounts of material are expelled, devastating the environment and creating a gas cloud that covers the globe for years.”
Previous modeling efforts have focused on an eruption trigger from within the magma chamber, which scientists thought would leave a visible trace in the form of a precursor eruption deposits, according to Shanaka “Shan” de Silva, an OSU geologist and co-author on the study. Yet there has been a distinct lack of physical evidence for a pre-cursor eruption at the site of these super-volcanoes.
The model suggests the reason there may be no precursor eruption is that the trigger comes from above, not from within, de Silva pointed out.
“Instead of taking the evidence in these eruptions at face value, most models have simply taken small historic eruptions and tried to scale the process up to super-volcanic proportions,” de Silva said. “Those of us who actually study these phenomena have known for a long time that these eruptions are not simply scaled-up Mt. Mazamas or Krakataus — the scaling is non-linear. The evidence is clear.”
It takes a “perfect storm” of conditions to grow an eruptible magma chamber of this size, Gregg says, which is one reason super-volcano eruptions have occurred infrequently throughout history. The magma reservoirs feeding the eruptions could be as large as 10,000- to 15,000-square cubic kilometers, and the chamber requires repeated intrusions of magma from below to heat the surrounding rock and make it malleable. It is that increase in ductility that allows the chamber to grow without magma evacuation in a more conventional manner.
When magma chambers are smaller, they may expel magma before maximum pressure is reached through frequent small eruptions.
The Yellowstone eruption is one of the largest super-volcano events in history and it has happened several times. Other super-volcano sites include Lake Toba in Sumatra, the central Andes Mountains, New Zealand and Japan.
Gregg said that despite its explosive history, it doesn’t appear that Yellowstone is primed for another super-eruption anytime soon, though the slow process of volcanic uplift is taking place every day.
“The uplift of the surface at Yellowstone right now is on the order of millimeters,” she explained. “When the Huckleberry Ridge eruption took place, the uplift of the whole Yellowstone region would have been hundreds of meters high, and perhaps as much as a kilometer.”
Other authors on the investigation include Erik Grosfils, of Pomona College, and John Parmigiani, an OSU engineer.
Note : The above story is reprinted from materials provided by Oregon State University.
Scientists at Delft University of Technology (TU Delft, The Netherlands) have successfully matched a layer of sediment from the dunes near Heemskerk to a severe storm flood that occurred in either 1775 or 1776. This type of information helps us gain more insight into past storm floods and predict future surges more accurately.
The scientists’ findings have been be published in the online edition of the scientific magazine Geology, and will be cover story of the November paper edition.
Historic knowledge
Our historic knowledge about storm floods (and water levels) on the Dutch coast is relatively limited. Records were not kept consistently until the late nineteenth century. This is unfortunate, because the limited historical archive makes it difficult to formulate statistical conclusions and predictions about future storm floods. It is also harder for us to establish whether storm floods are becoming more severe over the years.
Heemskerk
With the support of Technology Foundation STW and in cooperation with scientists from the Geological Survey of the Netherlands (TNO) and Deltares, scientists at TU Delft have now shown that historic storm-flood data can be augmented using luminescence dating. The team, led by Dr Jakob Wallinga, published their findings in the scientific magazine Geology.
The method was applied to a layer of sediment in the dunes near Heemskerk, created during a storm flood centuries ago and exposed by a storm in 2007. The level to which the storms and waves pushed the water can be deduced from the height of this layer. During the storm-surge in question, the water was higher than the catastrophic flood of 1953.
In order to put these data on a historical timeline, however, it is essential to know when the storm occurred. The scientists have now been able to show that in all probability the layer of sediment was deposited in 1775 or 1776. Historical sources indicate that severe storm floods took place in both years.
Grains of sand
Optical stimulated luminescence was used for the dating procedure. It simply requires a sample of sand from the sediment layer. The technique is based on the phenomenon that grains of sand can emit a faint light signal when they are illuminated with a certain frequency of light. The strength of the luminescence signal grows stronger over time as a result of natural radioactivity (background radiation) from the surroundings. However, the signal is reset to zero when the grains of sand are exposed to sunlight.
The strength of the luminescence signal (and the local strength of the background radiation) indicates the length of time since the grains were last exposed to light; in other words, the moment when they were ‘buried’. Using luminescence dating, a precision of 5% is achievable.
C-14
Luminescence dating requires nothing more than grains of sand, which means it can be used instead of the popular C-14 method at different sites and in different situations. After all, C-14 dating requires organic material. Luminescence dating can be used to date sediment from anywhere between just a few years to over 150,000 years old. It is also used in other disciplines, such as archaeology and art history.
The geologic forces that shape the Earth’s surface do their work in the lithosphere, often out of sight and far below the surface. Researchers have now measured the lithosphere’s thickness in southern California. It varies widely, from less than 25 miles to nearly 60 miles. – Fischer Lab, Brown University
Rifting is one of the fundamental geological forces that have shaped our planet. Were it not for the stretching of continents and the oceans that filled those newly created basins, Earth would be a far different place. Yet because rifting involves areas deep below the Earth’s surface, scientists have been unable to understand fully how it occurs.
What is known is that with rifting, the center of the action lies in the lithosphere, which makes up the tectonic plates and includes the crust and part of the upper mantle. In a paper in Science, researchers at Brown University produce the highest-resolution picture of the bottom of the lithosphere in southern California, one of the most complex, captivating geologic regions in the world. The team found the lithosphere’s thickness differs markedly throughout the region, yielding new insights into how rifting shaped the southern California terrain.
“What we’re getting at is how (continental) plates break apart,” said Vedran Lekic, a postdoctoral researcher at Brown University and first author on the paper. “What happens below the surface is just not known.”
The team measured the boundary separating the lithosphere from the more ductile layer just below it known as the asthenosphere in a 400-by-300-mile grid, an area that includes Santa Barbara, Los Angeles, San Diego and the Salton Trough. The lithosphere’s thickness varies surprisingly from less than 25 miles to nearly 60 miles, the researchers write.
“We see these really dramatic changes in lithosphere thickness, and these occur over very small horizontal distances,” said Karen Fischer, professor of geological sciences at Brown and a paper author. “That means that the deep part of the lithosphere, the mantle part, has to be strong enough to maintain relatively steep sides.”
“This approach provides a new way to put observational constraints on how strong the rocks are at these depths,” she added.
Specifically, the researchers found two areas of particular interest. One is the Western Transverse Range Block. The plate lies below Santa Barbara, yet some 18 million years ago, it was located some 125 miles to the south and hugged the coastline. At some point, this plate swung clockwise, rotating more than 90 degrees and journeyed northward, like a mobile, swinging door. Interestingly, the lithosphere remained intact, while the area left behind the swinging plate, called the Inner Continental Borderland and which lies off the coast of Los Angeles, was stretched, the Brown geophysicists believe. Indeed, the lithosphere is nearly 30 percent thinner in the area left behind than the range block.
“The fact that the Western Tranverse Range Block retained its lithosphere along its journey tells us the mantle-lithosphere (of the block) must be very strong,” Lekic said.
Another interesting feature noted by the researchers is the Salton Trough, which encompasses the Salton Sea and the city of Palm Springs, and “is a classic example of rifting,” according to Fischer. Some 6 million years ago, the continental plate at this location was stretched, but the question remains whether it simply thinned or whether it actually broke apart, creating new lithosphere in between. In the paper, the researchers confirm that the lithosphere is thin, but “we can’t tell which of these scenarios happened,” Fischer said. However, the thickness of the mantle part of the lithosphere and the fact that deformation at the surface runs all the way to the base of the lithosphere in roughly the same geographical location are new constraints against which modelers can test their predictions, she added.
The team made use of permanent seismic recording stations set up by the Southern California Seismic Network and other networks, as well as seismometers from the EarthScope USarray Transportable Array, a grid of National Science Foundation-funded stations that is gathering earthquake information as it moves west to east across the nation. To measure the lithosphere’s depth, the authors looked at how waves generated by earthquakes – called S waves and P waves – convert from type S to type P across the boundary between the lithosphere and the asthenosphere.
The team will compare its results with those of another famous rift system in East Africa, from a study at the University of Bristol led by Kate Rychert, who earned her doctorate at Brown in 2007.
Scott French, who earned his baccalaureate at Brown and is now a doctoral student at Berkeley Seismological Laboratory in California, is an author on the paper. The National Science Foundation funded the study, through its Earthscope program and an Earth Sciences postdoctoral fellowship to Lekic.
Note: This story has been adapted from a news release issued by the Brown University
This is a perspective of the seafloor showing preliminary results of gas seeps detected by multibeam sonar in vicinity of Biloxi Dome in Northern Gulf of Mexico. Gas seep locations are shown as blue dots and are overlaid on the seafloor bathymetry that was collected – Image produced by the University of New Hampshire Center for Coastal and Ocean Mapping/Joint Hydrographic Center using IVS Fledermaus software.
A technology commonly used to map the bottom of the deep ocean can also detect gas seeps in the water column with remarkably high fidelity, according to scientists from the University of New Hampshire and the National Oceanic and Atmospheric Administration (NOAA). This finding, made onboard the NOAA ship Okeanos Explorer in the Gulf of Mexico, will lead to more effective mapping of these gas seeps and, ultimately, enhanced understanding of our ocean environments.
The mapping technology, multibeam sonar, is an echo-sounding technology that surveys a wide, fan-shaped swath of the seafloor, providing much greater coverage than the single-beam sonar systems previously used to map seeps. “We wanted to see whether we could map a large area of gaseous seeps effectively using this technology, and how well the multibeam sonar compared to our very sensitive single-beam sonars,” says Tom Weber of UNH’s Center for Coastal Mapping, who was lead scientist of this mission.
“It turns out it works wonderfully.” The multibeam sonar on the Okeanos Explorer produced data to make high-resolution maps of gas in the water column in depths ranging from 3,000 to 7,000 feet.
Working jointly with scientists and technicians from NOAA’s Office of Ocean Exploration and Research (OER) and the Bureau of Ocean Energy Management (BOEM), Weber and colleagues mapped more than 17,000 square kilometers of the Gulf of Mexico from Aug. 22 through Sept. 10, 2011.
Sonar finds features on the ocean floor much the way a bat tracks its dinner: “It’s an acoustic wave hitting the target and reflecting back,” says Weber. Multibeam sonar sends those sound waves in many directions at the same time, enabling it to “see” a swath of targets that is much wider than what would be observed with a single-beam sonar. While it’s known to be an effective tool for mapping large, stable items like the bottom of the ocean, it wasn’t designed to detect targets within the water column.
Gas seeps – primarily but not exclusively methane – are numerous in the Gulf of Mexico, emanating from natural fissures in the seafloor. They can be associated with oil, but oil was not the focus for Weber and his collaborators. Finding and mapping gaseous seeps, says Weber, helps scientists better understand the ocean: its methane fluxes, carbon cycle, and deep-water marine environments.
Further, the Gulf of Mexico is home to many active oil-drilling sites, and mapping the gaseous seeps in the water column will inform scientific as well as regulatory decisions. “In the deep ocean, there are life forms like tubeworms and clams associated with gas seeps, and they’re treated as protected resources,” Weber says.
Further, mapping these seeps will give researchers baseline data on what exists in the water column, helping them determine whether future seeps are natural or unwanted byproducts of drilling.
“Mapping the seafloor and the water column are essential first steps in exploring our largely unknown ocean,” says Weber. “This expedition confirms earlier indications that multibeam technology provides a valuable new tool in the inventory to detect plumes of gas in the water column, and especially in deep water.”
Also on the mission from UNH were CCOM research scientist Jonathan Beaudoin and graduate students Kevin Jerram (pursuing an M.S. in ocean engineering) and Maddie Schroth-Miller (pursuing an M.S. in applied mathematics). NOAA’s expedition coordinator and lead NOAA scientist on the mission was Mashkoor Malik, who graduated from UNH in 2005 with a M.S. in ocean mapping.
Note: This story has been adapted from a news release issued by the University of New Hampshire
Pablo Dávila-Harris looks at part of the huge landslide deposit discovered on Tenerife, showing the chaotic and shattered rubble from the collapsed volcano. (The central dark debris-block is about 15 meters in diameter and must weigh many tons). (Credit: Pablo Dávila-Harris)
Volcanologists from the University of Leicester have uncovered one of the world’s best-preserved accessible examples of a monstrous landslide that followed a huge volcanic eruption on the Canarian island of Tenerife.
Seven hundred and thirty-three thousand years ago, the southeast slopes of Tenerife collapsed into the sea, during the volcanic eruption. The onshore remains of this landslide have just been discovered amid the canyons and ravines of Tenerife’s desert landscape by volcanologists Pablo Dávila-Harris and Mike Branney of the University of Leicester’s Department of Geology.
The findings have been published in this October’s edition of the international journal Geology. The research was funded by CONACYT, Mexico.
Dr Branney said: “It is one of the world’s best-preserved accessible examples of such an awesome phenomenon, because the debris from such landslides mostly spreads far across the deep ocean floor, inaccessible for close study.
“The beautifully-displayed Tenerife rubble includes blocks of rapidly chilled lava, added as the volcano erupted. Radioactive minerals within them enabled the researchers’ colleague, Michael Storey at Roskilde University, Denmark, to provide such a precise date for this natural catastrophe.
“Climate change is often invoked as a trigger for ocean-island landslides, but in this case it seems that a growing dome of hot lava triggered the landslide by pushing the side of the volcano outwards.
“In the shattered landscape that remained, lakes formed as rivers were dammed by debris, and the change to the shape of the island altered the course of explosive volcanic eruptions for hundreds of thousands of years afterwards.”
The researchers state that such phenomena are common but infrequent, and understanding them is vital, for their effects go far beyond a single ocean island. Tsunamis generated from such events may travel to devastate coastlines thousands of miles away.
“Understanding the Earth’s more violent events will help us be prepared, should repeat performances threaten,” they state.
Note : The above story is reprinted from materials provided by University of Leicester, via EurekAlert!, a service of AAAS.
The best forecasts for earthquakes are about 10 times more accurate than a random prediction, a new study by scientists in California finds. (Credit: iStockphoto/Michal Bryc)
Earthquake prediction remains an imperfect science, but the best forecasts are about 10 times more accurate than a random prediction, according to a study published Sept. 26 in the Proceedings of the National Academy of Sciences.
In the study, UC Davis researchers compare seven different earthquake forecasts (including their own) that were submitted to a competition organized by the Southern California Earthquake Center.
The findings should help researchers both develop better earthquake forecasts and improve their tools for assessing those forecasts, said Donald Turcotte, a distinguished professor of geology at UC Davis and co-author of the paper.
The center launched the competition in 2005 based on a previous forecast published by the UC Davis group in 2001. Teams were invited to forecast the probability of an earthquake of magnitude 4.95 or greater, from Jan. 1, 2006, to Dec. 31, 2010, in almost 8,000 grid squares covering California and bordering areas.
During this time, 31 earthquakes struck in 22 grid squares, with the largest being the magnitude 7.2 earthquake just south of the U.S.-Mexican border in April 2010. All seven forecasts showed some utility in forecasting the locations of likely earthquakes: The best forecasts were about 10 times better than a random forecast.
The forecast submitted by the UC Davis group was the most accurate in picking the locations of the earthquakes, correctly labeling 17 of 22 grids and giving the highest probability of an earthquake in eight of these 17. Using a different forecasting method, Agnes Helmstetter of UCLA and colleagues gave the highest average probability of an earthquake for all 22 affected grids, although it did less well at assigning a higher probability to grid squares where an earthquake occurred.
“Just as there are alternative ways to forecast earthquakes, there are also alternative ways to evaluate the success of the forecasts,” Turcotte said, noting that other publications evaluating the forecasts are expected.
The UC Davis group includes professors John Rundle and Turcotte, postdoctoral researcher James Holliday, and graduate students Ya Ting Lee and Michael Sachs. Also contributing were Chien-Chih Chen, National Central University, Taiwan; Kristy Tiampo, University of Western Ontario; and Andrea Donnellan of the Jet Propulsion Laboratory, Pasadena.
Note: This story has been adapted from a news release issued by the University of California – Davis
An international team of scientists has provided new insights into the processes behind the evolution of the planet by demonstrating how salty water and gases transfer from the atmosphere into Earth’s interior.
The paper was published in Nature Geoscience on September 26.
Scientists have long argued about how Earth evolved from a primitive state in which it was covered by an ocean of molten rock, into the planet we live on today with a solid crust made of moving tectonic plates, oceans and an atmosphere.
Lead author Dr Mark Kendrick from the University of Melbourne’s School of Earth Sciences said inert gases trapped inside Earth’s interior provide important clues into the processes responsible for the birth of our planet and the subsequent evolution of its oceans and atmosphere.
“Our findings throw into uncertainty a recent conclusion that gases throughout the Earth were solely delivered by meteorites crashing into the planet,” he said.
The study shows atmospheric gases are mixed into the mantle, inside Earth’s interior, during the process called ‘subduction’, when tectonic plates collide and submerge beneath volcanoes in subduction zones.
“This finding is important because it was previously believed that inert gases inside the Earth had primordial origins and were trapped during the formation of the solar system,” Dr Kendrick said.
Because the composition of neon in Earth’s mantle is very similar to that in meteorites, it was recently suggested by scientists that most of Earth’s gases were delivered by meteorites during a late meteorite bombardment that also generated visible craters on Earth’s moon.
“Our study suggests a more complex history in which gases were also dissolved into the Earth while it was still covered by a molten layer, during the birth of the solar system,” he said.
It was previously assumed that gases could not sink with plates in tectonic subduction zones but escaped during eruption of overlying volcanoes.
“The new study shows this is not entirely true and the gases released from Earth’s interior have not faithfully preserved the fingerprint of solar system formation.”
To undergo the study researchers collected serpentinite rocks from mountain belts in Italy and Spain. These rocks originally formed on the seafloor and were partially subducted into Earth’s interior before they were uplifted into their present positions by collision of the European and African plates.
“The serpentinite rocks are special because they trap large amounts of seawater in their crystal structure and can be transported to great depths in the Earth’s mantle by subduction,” he said.
By analysing the inert gases and halogens trapped in these rocks, the team was able to show gases are incompletely removed by the mineral transformations that affect serpentinites during the subduction process and hence provide new insights into the role of these trapped gases in the evolution of the planet.
The study was done in collaboration with researchers from the Australian National University, Canberra and The University of Genoa, Italy.
Note : The above story is reprinted from materials provided by University of Melbourne.
A snapshot taken from a first-principles molecular dynamics simulation of liquid m thane in contact with a hydrogen-terminated diamond surface at high temperature and pressure. The spontaneous formation of longer hydrocarbons are readily found during the simulations. Lawrence Livermore National Laboratory image. Hydrocarbon Forming Environmentse
Geologists and geochemists believe that nearly all (more than 99 percent) of the hydrocarbons in commercially produced crude oil and natural gas are formed by the decomposition of the remains of living organisms, which were buried under layers of sediments in the Earth’s crust, a region approximately 5-10 miles below the Earth’s surface.
But hydrocarbons of purely chemical deep crustal or mantle origin (abiogenic) could occur in some geologic settings, such as rifts or subduction zones said Galli, a senior author on the study.
Formation Under Extreme Conditions
A new computational study published in the Proceedings of the National Academy of Sciences reveals how hydrocarbons may be formed from methane in deep Earth at extreme pressures and temperatures.
The thermodynamic and kinetic properties of hydrocarbons at high pressures and temperatures are important for understanding carbon reservoirs and fluxes in Earth.
The work provides a basis for understanding experiments that demonstrated polymerization of methane to form high hydrocarbons and earlier methane forming reactions under pressure.
What Are Hydrocarbons?
Hydrocarbons (molecules composed of the elements hydrogen and carbon) are the main building block of crude oil and natural gas. Hydrocarbons contribute to the global carbon cycle (one of the most important cycles of the Earth that allows for carbon to be recycled and reused throughout the biosphere and all of its organisms).
The team includes colleagues at UC Davis, Lawrence Livermore National Laboratory and Shell Projects & Technology. One of the researchers, UC Davis Professor Giulia Galli, is the co-chair of the Deep Carbon Observatory’s Physics and Chemistry of Deep Carbon Directorate and former LLNL researcher.
Fusing Methane into Larger Hydrocarbons
“Our simulation study shows that methane molecules fuse to form larger hydrocarbon molecules when exposed to the very high temperatures and pressures of the Earth’s upper mantle,” Galli said. “We don’t say that higher hydrocarbons actually occur under the realistic ‘dirty’ Earth mantle conditions, but we say that the pressures and temperatures alone are right for it to happen.
Galli and colleagues used the Mako computer cluster in Berkeley and computers at Lawrence Livermore to simulate the behavior of carbon and hydrogen atoms at the enormous pressures and temperatures found 40 to 95 miles deep inside the Earth. They used sophisticated techniques based on first principles and the computer software system Qbox, developed at UC Davis.
Extreme Temperature & Pressure of Formation
They found that hydrocarbons with multiple carbon atoms can form from methane, (a molecule with only one carbon and four hydrogen atoms) at temperatures greater than 1,500 K (2,240 degrees Fahrenheit) and pressures 50,000 times those at the Earth’s surface (conditions found about 70 miles below the surface).
“In the simulation, interactions with metal or carbon surfaces allowed the process to occur faster — they act as ‘catalysts,’ ” said UC Davis’ Leonardo Spanu, the first author of the paper. The research does not address whether hydrocarbons formed deep in the Earth could migrate closer to the surface and contribute to oil or gas deposits. However, the study points to possible microscopic mechanisms of hydrocarbon formation under very high temperatures and pressures. Galli’s co-authors on the paper are Spanu; Davide Donadio at the Max Planck Institute in Meinz, Germany; Detlef Hohl at Shell Global Solutions, Houston; and Eric Schwegler of Lawrence Livermore National Laboratory.
Note : release by the Lawrence Livermore National Laboratory.
The use of horizontal drilling in conjunction with hydraulic fracturing has greatly expanded the ability of producers to profitably produce natural gas from low permeability geologic formations, particularly shale formations. Application of fracturing techniques to stimulate oil and gas production began to grow rapidly in the 1950s, although experimentation dates back to the 19th century.
Starting in the mid- 1970s, a partnership of private operators, the U.S. Department of Energy and the Gas Research Institute endeavored to develop technologies for the commercial production of natural gas from the relatively shallow Devonian (Huron) shale in the Eastern United States. This partnership helped foster technologies that eventually became crucial to producing natural gas from shale rock, including horizontal wells, multi-stage fracturing, and slick-water fracturing. [1]
The use of horizontal drilling
Horizontal Drilling Technology
Practical application of horizontal drilling to oil production began in the early 1980s, by which time the advent of improved downhole drilling motors and the invention of other necessary supporting equipment, materials, and technologies, particularly downhole telemetry equipment, had brought some applications within the realm of commercial viability. [2]
The Work of Mitchell Energy and Development
The advent of large-scale shale gas production did not occur until Mitchell Energy and Development Corporation experimented during the 1980s and 1990s to make deep shale gas production a commercial reality in the Barnett Shale in North-Central Texas. As the success of Mitchell Energy and Development became apparent, other companies aggressively entered this play so that by 2005, the Barnett Shale alone was producing almost half a trillion cubic feet per year of natural gas. As natural gas producers gained confidence in the ability to profitably produce natural gas in the Barnett Shale and confirmation of this ability was provided by the results from the Fayetteville Shale in North Arkansas, they began pursuing other shale formations, including the Haynesville, Marcellus, Woodford, Eagle Ford and other shales.
The Natural Gas “Game Changer”
The development of shale gas plays has become a “game changer” for the U.S. natural gas market. The proliferation of activity into new shale plays has increased shale gas production in the United States from 0.39 trillion cubic feet in 2000 to 4.87 trillion cubic feet in 2010, or 23 percent of U.S. dry gas production. Shale gas reserves have increased to about 60.6 trillion cubic feet by year-end 2009, when they comprised about 21 percent of overall U.S. natural gas reserves, now at the highest level since 1971. [3]
The growing importance of U.S. shale gas resources is also reflected in EIA’s Annual Energy Outlook 2011 (AEO2011) energy projections, with technically recoverable U.S. shale gas resources now estimated at 862 trillion cubic feet. Given a total natural gas resource base of 2,543 trillion cubic feet in the AEO2011 Reference case, shale gas resources constitute 34 percent of the domestic natural gas resource base represented in the AEO2011 projections and 50 percent of lower 48 onshore resources. As a result, shale gas is the largest contributor to the projected growth in production, and by 2035 shale gas production accounts for 46 percent of U.S. natural gas production.
Diffusion of Shale Gas Technologies
The successful investment of capital and diffusion of shale gas technologies has continued into Canadian shales as well. In response, several other countries have expressed interest in developing their own nascent shale gas resource base, which has lead to questions regarding the broader implications of shale gas for international natural gas markets. The U.S. Energy Information Administration (EIA) has received and responded to numerous requests over the past three years for information and analysis regarding domestic and international shale gas. EIA’s previous work on the topic has begun to identify the importance of shale gas on the outlook for natural gas. [4] It appears evident from the significant investments in preliminary leasing activity in many parts of the world that there is significant international potential for shale gas that could play an increasingly important role in global natural gas markets.
To gain a better understanding of the potential of international shale gas resources, EIA commissioned an external consultant, Advanced Resources International, Inc. (ARI), to develop an initial set of shale gas resource assessments. This paper briefly describes key results, the report scope and methodology and discusses the key assumptions that underlie the results. The full consultant report prepared for EIA is in Attachment A. EIA anticipates using this work to inform other analysis and projections, and to provide a starting point for additional work on this and related topics.
Shale Gas in Worldwide Basins
In total, the report assessed 48 shale gas basins in 32 countries, containing almost 70 shale gas formations. These assessments cover the most prospective shale gas resources in a select group of countries that demonstrate some level of relatively near-term promise and for basins that have a sufficient amount of geologic data for resource analysis. The map at the top of this page shows the location of these basins and the regions analyzed. The map legend indicates four different colors on the world map that correspond to the geographic scope of this initial assessment:
Red colored areas represent the location of assessed shale gas basins for which estimates of the ‘risked’ gas-in-place and technically recoverable resources were provided.
Yellow colored area represents the location of shale gas basins that were reviewed, but for which estimates were not provided, mainly due to the lack of data necessary to conduct the assessment.
White colored countries are those for which at least one shale gas basin was considered for this report.
Gray colored countries are those for which no shale gas basins were considered for this report.
The International Shale Gas Resource Base
Although the shale gas resource estimates will likely change over time as additional information becomes available, the report shows that the international shale gas resource base is vast. The initial estimate of technically recoverable shale gas resources in the 32 countries examined is 5,760 trillion cubic feet, as shown in Table 1. Adding the U.S. estimate of the shale gas technically recoverable resources of 862 trillion cubic feet results in a total shale resource base estimate of 6,622 trillion cubic feet for the United States and the other 32 countries assessed.
To put this shale gas resource estimate in some perspective, world proven reserves [5] of natural gas as of January 1, 2010 are about 6,609 trillion cubic feet, [6] and world technically recoverable gas resources are roughly 16,000 trillion cubic feet, [7] largely excluding shale gas. Thus, adding the identified shale gas resources to other gas resources increases total world technically recoverable gas resources by over 40 percent to 22,600 trillion cubic feet.
Conservative Basin Estimates
The estimates of technically recoverable shale gas resources for the 32 countries outside of the United States represents a moderately conservative ‘risked’ resource for the basins reviewed. These estimates are uncertain given the relatively sparse data that currently exist and the approach the consultant has employed would likely result in a higher estimate once better information is available. The methodology is outlined below and described in more detail within the attached report, and is not directly comparable to more detailed resource assessments that result in a probabilistic range of the technically recoverable resource. At the current time, there are efforts underway to develop more detailed shale gas resource assessments by the countries themselves, with many of these assessments being assisted by a number of U.S. federal agencies under the auspices of the Global Shale Gas Initiative (GSGI) which was launched in April 2010. [8]
Highly Dependent Countries
Delving deeper into the results at a country level, there are two country groupings that emerge where shale gas development may appear most attractive. The first group consists of countries that are currently highly dependent upon natural gas imports, have at least some gas production infrastructure, and their estimated shale gas resources are substantial relative to their current gas consumption. For these countries, shale gas development could significantly alter their future gas balance, which may motivate development. Examples of countries in this group include France, Poland, Turkey, Ukraine, South Africa, Morocco, and Chile. In addition, South Africa’s shale gas resource endowment is interesting as it may be attractive for use of that natural gas as a feedstock to their existing gas-to-liquids (GTL) and coal-to-liquids (CTL) plants.
Countries with a Natural Gas Infrastructure
The second group consists of those countries where the shale gas resource estimate is large (e.g., above 200 trillion cubic feet) and there already exists a significant natural gas production infrastructure for internal use or for export. In addition to the United States, notable examples of this group include Canada, Mexico, China, Australia, Libya, Algeria, Argentina, and Brazil. Existing infrastructure would aide in the timely conversion of the resource into production, but could also lead to competition with other natural gas supply sources. For an individual country the situation could be more complex.
References for World Shale Ga
[1] G.E. King, Apache Corporation, “Thirty Years of Gas Shale Fracturing: What Have We Learned?”, prepared for the SPE Annual Technical Conference and Exhibition (SPE 133456), Florence, Italy, (September 2010); and U.S. Department of Energy, DOE’s Early Investment in Shale Gas Technology Producing Results Today, (February 2011), web site.
[2] See: U.S. Energy Information Administration, “Drilling Sideways: A Review of Horizontal Well Technology and Its Domestic Application”, DOE/EIA-TR-0565 (April 1993).
[3] U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Proved Reserves, 2009, web site.
[4] Examples of EIA work that has spurred or resulted from interest in this topic includes: U.S. Energy Information Administration, AEO2011 Early Release Overview (Dec 2010); R. Newell, U.S. Energy Information Administration, “Shale Gas, A Game Changer for U.S. and Global Gas Markets?”, presented at the Flame – European Gas Conference, Amsterdam, Netherlands (March 2, 2010); H. Gruenspecht, U.S. Energy Information Administration, “International Energy Outlook 2010 With Projections to 2035”, presented at Center for Strategic and International Studies, Washington, D.C. (May 25, 2010); and R. Newell, U.S. Energy Information Administration, “The Long-term Outlook for Natural Gas”, presented to the Saudi Arabia – United States Energy Consultations, Washington, D.C. (February 2, 2011).
[5] Reserves refer to gas that is known to exist and is readily producible, which is a subset of the technically recoverable resource base estimate for that source of supply. Those estimates encompass both reserves and that natural gas which is inferred to exist, as well as undiscovered, and can technically be produced using existing technology. For example, EIA’s estimate of all forms of technically recoverable natural gas resources in the U.S. for the Annual Energy Outlook 2011 is 2,552 trillion cubic feet, of which 827 trillion cubic feet consists of unproved shale gas resources and 245 trillion cubic feet are proved reserves which consist of all forms of readily producible natural gas including 34 trillion cubic feet of shale gas.
[6] “Total reserves, production climb on mixed results,” Oil and Gas Journal (December 6, 2010), pp. 46-49.
[7] Includes 6,609 trillion cubic feet of world proven gas reserves (Oil and Gas Journal 2010); 3,305 trillion cubic feet of world mean estimates of inferred gas reserves, excluding the Unites States (USGS, World Petroleum Assessment 2000); 4,669 trillion cubic feet of world mean estimates of undiscovered natural gas, excluding the United States (USGS, World Petroleum Assessment 2000); and U.S. inferred reserves and undiscovered gas resources of 2,307 trillion cubic feet in the United States, including 827 trillion cubic feet of unproved shale gas (EIA, AEO2011).
[8] The Department of State is the lead agency for the GSGI, and the other U.S. government agencies that also participate include: the U.S. Agency for International Development (USAID); the Department of Interior’s U.S. Geological Survey (USGS); Department of Interior’s Bureau of Ocean Energy Management, Regulation, and Enforcement (BOEMRE); the Department of Commerce’s Commercial Law Development Program (CLDP); the Environmental Protection Agency (EPA), and the Department of Energy’s Office of Fossil
Energy (DOE/FE). Web site. Note : This note copied form geology site
Fossil of the baby nodosaur. (Credit: Ray Stanford)
Researchers at the Johns Hopkins University School of Medicine with help from an amateur fossil hunter in College Park, Md., have described the fossil of an armored dinosaur hatchling. It is the youngest nodosaur ever discovered, and a founder of a new genus and species that lived approximately 110 million years ago during the Early Cretaceous Era. Nodosaurs have been found in diverse locations worldwide, but they’ve rarely been found in the United States. The findings are published in the September 9 issue of the Journal of Paleontology.
“Now we can learn about the development of limbs and the development of skulls early on in a dinosaur’s life,” says David Weishampel, Ph.D., a professor of anatomy at the Johns Hopkins University School of Medicine. “The very small size also reveals that there was a nearby nesting area or rookery, since it couldn’t have wandered far from where it hatched. We have the opportunity to find out about dinosaur parenting and reproductive biology, as well as more about the lives of Maryland dinosaurs in general.”
The fossil was discovered in 1997 by Ray Stanford, a dinosaur tracker who often spent time looking for fossils close to his home; this time he was searching a creek bed after an extensive flood.
Stanford identified it as a nodosaur and called Weishampel, a paleontologist and expert in dinosaur systematics. Weishampel and his colleagues established the fossil’s identity as a nodosaur by identifying a distinctive pattern of bumps and grooves on the skull.
They then did a computer analysis of the skull shape, comparing its proportions to those of ten skulls from different species of ankylosaurs, the group that contains nodosaurs. They found that this dinosaur was closely related to some of the nodosaur species, although it had a shorter snout overall than the others. Comparative measurements enabled them to designate a new species, Propanoplosaurus marylandicus. In addition to being the youngest nodosaur ever found, it is the first hatchling of any dinosaur species ever recovered in the eastern United States, says Weishampel.
The area had originally been a flood plain, where Weishampel says that the dinosaur originally drowned. Cleaning the fossil revealed a hatchling nodosaur on its back, much of its body imprinted along with the top of its skull. Weishampel determined the dinosaur’s age at time of death by analyzing the degree of development and articulation capability of the ends of the bones, as well as deducing whether the bones themselves were porous, as young bones would not be fully solid.
Size was also a clue: the body in the tiny fossil was only 13 cm long, just shorter than the length of a dollar bill. Adult nodosaurs are estimated to have been 20 to 30 feet long. Weishampel also used the position and quality of the fossil to deduce the dinosaur’s method of death and preservation: drowning, and getting buried by sediment in the stream. Egg shells have never been found preserved in the vicinity, and by the layout of the bones and the size of some very small nodosaur footprints found nearby, led Weishampel to believe that the dinosaur was a hatchling, rather than an embryo, because it was able to walk independently.
“We didn’t know much about hatchling nodosaurs at all prior to this discovery,” says Weishampel. “And this is certainly enough to motivate more searches for dinosaurs in Maryland, along with more analysis of Maryland dinosaurs.”
Stanford has donated the hatchling nodosaur to the Smithsonian’s National Museum of Natural History, where it is now on display to the public and also available for research.
This study was funded by the Johns Hopkins Center of Functional Anatomy and Evolution.
Valerie DeLeon, also of the Center of Functional Anatomy and Evolution, was an additional author.
Note : The above story is reprinted from materials provided by Johns Hopkins Medical Institutions.
The NASA-led team used the 40-megahertz airborne sounding radar prototype to probe the desert subsurface above the Umm-El-Aish aquifer in northern Kuwait, creating this high-resolution cross section of the aquifer. The radargram shows variations in the depth of the water table from 161 to 171 feet (49 to 52 meters). Image credit: NASA/JPL-Caltech Mars Technology Used to Find Water on Earth
A NASA-led team has used radar sounding technology developed to explore the subsurface of Mars to create high-resolution maps of freshwater aquifers buried deep beneath an Earth desert, in the first use of airborne sounding radar for aquifer mapping.
The research may help scientists better locate and map Earth’s desert aquifers, understand current and past hydrological conditions in Earth’s deserts and assess how climate change is impacting them. Deserts cover roughly 20 percent of Earth’s land surface, including highly populated regions in the Arabian Peninsula, North Africa, west and central Asia and the southwestern United States.
An international team led by research scientist Essam Heggy of NASA’s Jet Propulsion Laboratory, Pasadena, California, recently traveled to northern Kuwait to map the depth and extent of aquifers in arid environments using an airborne sounding radar prototype. The 40-megahertz, low-frequency sounding radar was provided by the California Institute of Technology in Pasadena; and the Institut de Physique du Globe de Paris, France. Heggy’s team was joined by personnel from the Kuwait Institute for Scientific Research (KISR), Kuwait City.
Mapping Subsurface Aquifers by Helicopter
For two weeks, the team flew a helicopter equipped with the radar on 12 low-altitude passes (1,000 feet, or 305 meters) over two well-known freshwater aquifers, probing the desert subsurface down to the water table at depths ranging from 66 to 213 feet (20 to 65 meters). The researchers successfully demonstrated that the radar could locate subsurface aquifers, probe variations in the depth of the water table, and identify locations where water flowed into and out of the aquifers.
“This demonstration is a critical first step that will hopefully lead to large-scale mapping of aquifers, not only improving our ability to quantify groundwater processes, but also helping water managers drill more accurately,” said Muhammad Al-Rashed, director of KISR’s Division of Water Resources.
How Radar Sounding Works
The radar is sensitive to changes in electrical characteristics of subsurface rock, sediments and water- saturated soils. Water-saturated zones are highly reflective and mirror the low-frequency radar signal. The returned radar echoes explored the thick mixture of gravel, sand and silt that covers most of Kuwait’s northern desert and lies above its water table.
The team created high-resolution cross sections of the subsurface, showing variations in the fresh groundwater table in the two aquifers studied. The radar results were validated with ground measurements performed by KISR.
“This research will help scientists better understand Earth’s fossil aquifer systems, the approximate number, occurrence and distribution of which remain largely unknown,” said Heggy. “Much of the evidence for climate change in Earth’s deserts lies beneath the surface and is reflected in its groundwater. By mapping desert aquifers with this technology, we can detect layers deposited by ancient geological processes and trace back paleoclimatic conditions that existed thousands of years ago, when many of today’s deserts were wet.”
Climate Change Data from Desert Regions
Heggy said most recent observations, scientific interest and data analyses of global warming have concentrated on Earth’s polar regions and forests, which provide direct measurable evidence of large-scale environmental changes. Arid and semi-arid environments, which represent a substantial portion of Earth’s surface, have remained poorly studied. Yet water scarcity and salt content, changes in rainfall, flash floods, high rates of aquifer exploitation and growth of desert regions are all signs that suggest climate change and human activities are also affecting these arid and semi-arid zones.
Mars Water-Mapping Technology
The radar sounding prototype shares similar characteristics with two instruments flying on Mars-orbiting spacecraft: Mars Advanced Radar for Subsurface and Ionospheric Sounding (MARSIS), on the European Space Agency’s Mars Express, and Shallow Radar (SHARAD), on NASA’s Mars Reconnaissance Orbiter. MARSIS, jointly developed by JPL and the Italian Space Agency, probes the Martian subsurface sediments and polar ice caps to a maximum depth of about 1.9 miles (3 kilometers). SHARAD, also built by the Italian Space Agency, looks for liquid or frozen water in the first few hundred feet of Mars’ crust and probes Mars’ polar caps. Both instruments have found evidence of ice in the Martian subsurface, but have not yet detected liquid water. The Kuwait results may lead to revised interpretations of data from these two instruments.
The research follows earlier work by JPL scientists to probe the subsurface of the Sahara desert using higher-frequency Synthetic Aperture Radar instruments flown onboard three space shuttle missions in 1981, 1984 and 1994. That work located shallow drainage networks and large dry basins, suggesting the Sahara has had extensive surface water activity in its recent geological past.
Conditions in Kuwait Support Mapping
Kuwait’s well-mapped shallow aquifers and flat surface provided the team with an ideal test location. Extreme dryness, such as that present in this region of Kuwait, is necessary to allow the radar’s waves to penetrate deep into the surface and reflect on water-saturated layers beneath. Kuwait’s flat topography and low radio noise also reduced clutter and improved the radar signal’s return.
Mapping Aquifers in Hyper-Arid Regions
“Results of this study pave the way for potential airborne mapping of aquifers in hyper-arid regions such as the Sahara and Arabian Peninsula, and can be applied to design concepts for a possible future satellite mission to map Earth’s desert aquifers,” said Craig Dobson, program officer for Geodetic Imaging and Airborne Instrument Technology Transition programs at NASA Headquarters, Washington. The work is a pathfinder for the Orbiting Arid Subsurface and Ice Sheet Sounder (OASIS), a NASA spacecraft mission concept designed to map shallow aquifers in Earth’s most arid desert regions and measure ice sheet volume, thickness, basal topography and discharge rates.
Research Support
The study was co-funded by the California Institute of Technology’s Keck Institute for Space Studies and KISR. The Kuwaiti Police Air Force provided technical support for the flight tests.
JPL is managed for NASA by the California Institute of Technology in Pasadena.
Republished from a September, 2011 press release Alan Buis of NASA/JPL.
This is a split image showing highly diverse tropical forest in Borneo (Lambir) on the bottom and a lower diversity temperate beech forest in Jasmund National Park (Germany) on the top. (Credit: Christian Ziegler)
History and geology, not current ecology, are likely what has made tropical forests so variable from site to site, according to a new study published in the journal Science, co-authored by Liza Comita, research associate at the Smithsonian Tropical Research Institute in Panama.
“The same ecological processes seem to be working worldwide. The difference is that tropical organisms have been accumulating for vast periods of time,” said Nathan J.B. Kraft, post-doctoral fellow at the University of British Colombia, who led the research team.
“This study shows how collecting data using the same methods at sites around the world, similar to what we do at the Center for Tropical Forest Science-Smithsonian Institution Global Earth Observatories Network, offers new insights into the processes that shape ecological communities,” said Comita, formerly a post-doctoral fellow at the National Center for Ecological Analysis and Synthesis, now an assistant professor at The Ohio State University. “We found that measurements of variation in biodiversity from place to place, called beta diversity, are actually very similar as you move from the tropics to the poles when you account for the number of species present in the first place.”
Forests in Canada and Europe may have much more in common with tropical rainforests than previously believed. “We see that biodiversity patterns can be explained not by current ecological processes, unfolding over one or two generations, but by much longer-term historical and geological events,” said Kraft, who will join the faculty at the University of Maryland next year.
“Fossils tell a similar story,” said STRI scientist, Aaron O’Dea, co-author, with Willem Renema and others, of a 2008 article in Science showing that marine biodiversity hotspots could be traced back to ancient areas of tectonic activity. “Geological history reveals that glaciations and mass extinctions have lasting effects on the structure of biological communities. It bears witness to the devastation that occurs when accumulated biodiversity is lost: a threat we are facing today.”
The team, which also included researchers from institutions in the U.S., Canada and New Zealand, was supported by the U.S. National Center for Ecological Analysis and Synthesis and the U.S. National Science Foundation.
Note : The above story is reprinted from materials provided by Smithsonian Tropical Research Institute, via EurekAlert!, a service of AAAS.
The bones are from the 17 species of Cretaceous birds which went extinct around the time of the dinosaurs. The two on the far left are foot bones and the rest are shoulder bones. (Credit: Courtesy Yale University)
A new study puts an end to the longstanding debate about how archaic birds went extinct, suggesting they were virtually wiped out by the same meteorite impact that put an end to dinosaurs 65 million years ago
For decades, scientists have debated whether birds from the Cretaceous period — which are very different from today’s modern bird species — died out slowly or were killed suddenly by the Chicxulub meteorite. The uncertainty was due in part to the fact that very few fossil birds from the end of this era have been discovered.
Now a team of paleontologists led by Yale researcher Nicholas Longrich has provided clear evidence that many primitive bird species survived right up until the time of the meteorite impact. They identified and dated a large collection of bird fossils representing a range of different species, many of which were alive within 300,000 years of the impact.
“This proves that these species went extinct very abruptly, in terms of geological time scales,” said Longrich. The study appears the week of Sept. 19 in the journal Proceedings of the National Academy of Sciences.
The team examined a large collection of about two dozen bird fossils discovered in North America — representing a wide range of the species that existed during the Cretaceous — from the collections of Yale’s Peabody Museum of Natural History, the American Museum of Natural History, the University of California Museum of Paleontology, and the Royal Saskatchewan Museum. Fossil birds from the Cretaceous are extremely rare, Longrich said, because bird bones are so light and fragile that they are easily damaged or swept away in streams.
“The birds that had been discovered hadn’t really been studied in a rigorous way,” Longrich said. “We took a much more detailed look at the relationships between these bones and these birds than anyone had done before.”
Longrich believes a small fraction of the Cretaceous bird species survived the impact, giving rise to today’s birds. The birds he examined showed much more diversity than had yet been seen in birds from the late Cretaceous, ranging in size from that of a starling up to a small goose. Some had long beaks full of teeth.
Yet modern birds are very different from those that existed during the late Cretaceous, Longrich said. For instance, today’s birds have developed a much wider range of specialized features and behaviors, from penguins to hummingbirds to flamingoes, while the primitive birds would have occupied a narrower range of ecological niches.
“The basic bird design was in place, but all of the specialized features developed after the mass extinction, when birds sort of re-evolved with all the diversity they display today,” Longrich said. “It’s similar to what happened with mammals after the age of the dinosaurs.”
Longrich adds that this study is not the first to suggest that archaic birds went extinct abruptly. “There’s been growing evidence that these birds were wiped out at the same time as the dinosaurs,” Longrich said. “But this new evidence effectively closes the book on the debate.”
Other authors of the paper include Tim Tokaryk (Royal Saskatchewan Museum) and Daniel Field (Yale University).
Skeletal elements of Talos and Troodon illustrating select diagnostic characters of Talos sampsoni (UMNH VP 19479). (Credit: Zanno LE, Varricchio DJ, O’Connor PM, Titus AL, Knell MJ (2011) A New Troodontid Theropod, Talos sampsoni gen. et sp. nov., from the Upper Cretaceous Western Interior Basin of North America. PLoS ONE 6(9): e24487. doi:10.1371/journal.pone.0024487)
Raptor dinosaurs like the iconic Velociraptor from the movie franchise Jurassic Park are renowned for their “fear-factor.” Their terrifying image has been popularized in part because members of this group possess a greatly enlarged talon on their foot — analogous to a butcher’s hook. Yet the function of the highly recurved claw on the foot of raptor dinosaurs has largely remained a mystery to paleontologists. This week a collaboration of scientists unveil a new species of raptor dinosaur discovered in southern Utah that sheds new light on this and several other long-standing questions in paleontology, including how dinosaurs evolved on the “lost continent” of Laramidia (western North America) during the Late Cretaceous — a period known as the zenith of dinosaur diversity.
Their findings will be published in the journal PLoS ONE.
The new dinosaur — dubbed Talos sampsoni — is a member of a rare group of feathered, bird-like theropod dinosaurs whose evolution in North America has been a longstanding source of scientific debate, largely for lack of decent fossil material. Indeed, Talos represents the first definitive troodontid theropod to be named from the Late Cretaceous of North America in over 75 years. “Finding a decent specimen of this type of dinosaur in North America is like a lighting strike… it’s a random event of thrilling proportions,” said Lindsay Zanno, lead author of the study naming the new dinosaur. Zanno is an assistant professor of anatomy at the University of Wisconsin-Parkside and a research associate at the Field Museum of Natural History in Chicago, Illinois. Other members of the research team include Mike Knell (a graduate student at Montana State University) who discovered the new specimen in 2008 in the Kaiparowits Formation of Grand Staircase-Escalante National Monument (GSENM), southern Utah; Bureau of Land Management (BLM) paleontologist Alan Titus, leader of a decade-long paleontology reconnaissance effort in the monument; David Varricchio, Associate Professor of Paleontology, Montana State University; and Patrick O’Connor, Associate Professor of Anatomy, Ohio University Heritage College of Osteopathic Medicine.
Funding for the research was provided in part by the National Science Foundation, the Field Museum of Natural History, the Ohio University Heritage College of Osteopathic Medicine, and the Bureau of Land Management. Zanno’s research was supported by a John Caldwell-Meeker Fellowship and by a Bucksbaum Fellowship for young scientists. The bones of Talos sampsoni will be on exhibit for the first time in the Past Worlds Observatory at the new Utah Museum of Natural History, Salt Lake City, Utah.
The Nature of the Beast Troodontid theropods are a group of feathered dinosaurs closely related to birds. Members of this group are among the smallest non-avian dinosaurs known (as small as 100 grams) and are considered among the most intelligent. The group is known almost exclusively from Asia and prior to the discovery of Talos sampsoni, only two species were recognized in the Late Cretaceous of North America — one of which, the infamous Troodon, was one of the first dinosaurs ever named from North America.
As a result of their distinctive teeth and the possible presence of seeds preserved as gut contents in one species, several scientists have proposed an omnivorous or herbivorous diet for at least some troodontids. Other species possess relatively blade-like teeth indicative of a carnivorous diet. Zanno’s own work on theropod diet suggests that extensive plant eating was confined to more primitive members of the group, with more advanced members of the clade like Troodon and Talos likely consuming at least some prey.
Several troodontid specimens have recently been discovered that not only support a close relationship with birds but also preserve remarkable evidence of bird-like behavior. These include extraordinary specimens such as eggs and embryos within nests that document transitional phases in the evolution of bird-like reproductive physiology and egg-laying behavior, as well as specimens preserved in distinctive avian-like sleeping postures with their heads rotated back and tucked under their “wings.” Other troodontids provide evidence of “four-winged” locomotor capabilities, and perhaps most extraordinary, plumage coloration.
With an estimated body mass of 38 kilograms, the newly discovered Talos sampsoni is neither the smallest nor largest troodontid known. Its skeleton indicates that the new species was much smaller and more slender than its famous cousin Troodon, which is known from sediments of the same age in the northern part of Laramidia (Alberta, Canada and Montana, USA). “Talos was fleet-footed and lightly built,” Zanno says. “This little guy was a scrapper.”
Interestingly, the holotype specimen of Talos also tells us something about theropod behavior, particularly raptor behavior. This is because the second toe — that is, the one with the enlarged talon — of the left foot of the new specimen is deformed, indicating that the animal suffered a fracture or bite during its life.
This Little Talos Takes a Beating
When the team first began studying the Talos specimen, they noticed some unusual features on the second digit of the left foot, but initially assumed they were related to the fact that it belonged to a new species. “When we realized we had evidence of an injury, the excitement was palpable,” Zanno commented. “An injured specimen has a story to tell.” That’s because evidence of injury relates to function. The manner in which an animal is hurt can tell you something about what it was doing during life. An injury to the foot of a raptor dinosaur, for example, provides new evidence about the potential function of that toe and claw. In order to learn about the injury to the animal’s foot, the team scanned the individual bones using a high-resolution Computed Tomography (CT) scanner, similar to those used by physicians to examine bones and other organs inside the human body.
“Although we could see damage on the exterior of the bone, our microCT approach was essential for characterizing the extent of the injury, and importantly, for allowing us to better constrain how long it had been between the time of injury and the time that this particular animal died,” noted Patrick O’Connor, associate professor of anatomy at Ohio University. After additional CT scanning of other parts of the foot, Zanno and her team realized that the injury was restricted to the toe with the enlarged claw, and the rest of the foot was not impacted. More detailed study suggested that the injured toe was either bitten or fractured and then suffered from a localized infection.
“People have speculated that the talon on the foot of raptor dinosaurs was used to capture prey, fight with other members of the same species, or defend the animal against attack. Our interpretation supports the idea that these animals regularly put this toe in harm’s way,” says Zanno.
Perhaps even more interesting is the fact that the injured toe exhibits evidence of bone remodeling thought to have taken place over a period of many weeks to months, suggesting that Talos lived with a serious injury to the foot for quite a long time. “It is clear from the bone remodeling that this animal lived for quite some time after the initial injury and subsequent infection, and that whatever it typically did with the enlarged talon on the left foot, whether that be acquire prey or interact with other members of the species, it must have been capable of doing so fairly well with the one on the right foot,” added O’Connor.
Trackways made by animals closely related to Talos suggest that they held the enlarged talon off the ground when walking. “Our data support the idea that the talon of raptor dinosaurs was not used for purposes as mundane as walking,” Zanno commented. “It was an instrument meant for inflicting damage.”
What’s in a Name?
The name Talos pays homage to a mythological Greek figure of the same name, believed to have protected the island of Crete by throwing stones at invading ships. It is said that the Greek Talos, who was often depicted as a winged bronze figure, could run at lightening speed and circled the ancient island three times a day. The dinosaur Talos belongs to a group of theropods known to have feathery integument (and in some cases “wings”), lived on the small island continent of Laramidia or west North America during the Late Cretaceous, and was also a fast runner. The team chose the name Talos because of these similarities but also because the Greek Talos was said to have died from a wound to the ankle and it was clear that Talos had also suffered a serious wound to the foot. The species name “sampsoni” honors another famous figure — Dr. Scott Sampson of the PBS series Dinosaur Train.
Sampson, a research curator at the Utah Museum of Natural History and research faculty at the University of Utah, helped to spearhead a collaborative research effort known as the Kaiparowits Basin Project, a long-term research project that has been surveying and documenting the Late Cretaceous dinosaur fauna of the Kaiparowits Basin in southern Utah, with a focus on the Kaiparowits and Wahweap formations exposed in Grand Staircase-Escalante National Monument (GSENM). Thus far this effort has resulted in the discovery of up to a dozen new dinosaurs from GSENM that are challenging previous ideas regarding Late Cretaceous dinosaur evolution and diversity within Laramidia and spurring new ideas regarding dinosaur biogeography in the region.
A Tale of Two Continents
Dinosaurs of the Late Cretaceous were living in a greenhouse world. A warm and equitable global climate that was devoid of polar ice caps and above average spreading at mid-oceanic ridges caused massive flooding of low-lying continental areas and created expansive epicontinental seaways. In North America, a shallow seaway running from the Gulf of Mexico through to the Arctic Ocean divided the continent into two landmasses, East America (Appalachia) and West America (Laramidia) for several million years during the Late Cretaceous. It was during this time that the dinosaurs achieved their greatest diversity, and scientists have been working overtime to understand why. Take for example the dinosaurs of Laramidia. The natural assumption is that being large bodied, those dinosaurs that lived on the small island continent would have roamed the whole area.
However, recent fossil discoveries, particularly new dinosaurs from the Kaiparowits Formation, tell us that the true pattern is exactly the opposite. Thus far the dinosaurs from the Kaiparowits Formation in southern Utah are entirely unique, even from those dinosaurs living just a few hundred miles to the north in what is now Montana and Alberta.
Monument Paleontologist Alan Titus observed, “When we began looking in the remote Kaiparowits badlands we expected to see at least a few familiar faces. As it turns out, they are all new to science.
” And while recent discoveries from the Kaiparowits have substantiated this pattern for large-bodied herbivores like duck-bill and horned dinosaurs (for example Utahceratops), the pattern among small-bodied theropods was not clear.
“We already knew that some of dinosaurs inhabiting southern Utah during the Late Cretaceous were unique,” Zanno said, “but Talos tells us that the singularity of this ecosystem was not just restricted to one or two species. Rather, the whole area was like a lost world in and of itself.”
A Monumental Discovery
Talos sampsoni is the newest member of a growing list of new dinosaur species that have been discovered in Grand Staircase Escalante National Monument (GSENM) in southern Utah. Former President Clinton founded the monument in 1996, in part to protect the world class paleontological resources entombed within its 1.9 million acres of unexplored territory.
GSENM is one of the largest recently designated national monuments managed by the BLM, and one of the last pristine dinosaur graveyards in the US. The area has turned out to be a treasure trove of new dinosaur species, with at least 15 collected in just the past decade. Titus admits, “We had very few large fossils to substantiate the claim of ‘World Class’ paleontology when I started in 2000.
Now, I feel GSENM could easily qualify as a world heritage site on the basis of its dinosaurs alone, dozens of which have been found preserving soft tissue.” He also adds, “BLM support has been critical to the long term viability of the region’s paleontology research and is paying off in countless ways both to the public and scientists.”
Zanno, along with colleague Scott Sampson, named the first dinosaur from the monument — Hagryphus giganteus — in 2005. Hagryphus (widely touted in the press as the “turkey” dinosaur) is also a theropod dinosaur, but one that belongs to a different subgroup known as oviraptorosaurs (or egg thief reptiles). Other GSENM dinosaurs include five new horned dinosaurs including the recently described and bizarrely ornate Kosmoceratops and Utahceratops, three new duck-bill dinosaurs including the “toothy” Gryposaurus monumentensis, two new tyrannosaurs, as well as undescribed ankylosaurs (armored dinosaurs), marine reptiles, giant crocodyliforms, turtles, plants, and a host of other organisms.
The discovery of a new troodontid from the monument is the latest in a long string of incredible fossil discoveries from the area. “I was surprised when I learned that I had found a new dinosaur,” Knell said. “It is a rare discovery and I feel very lucky to be part of the exciting research happening here in the monument.” Knell stumbled across the remains of Talos sampsoni while scouring the badlands of the Kaiparowits Formation for fossil turtles as part of his dissertation research.
Work continues every year in GSENM and new, significant fossil finds are made every field season. Considering there are hundreds of thousands of acres of outcrop that have yet to be surveyed, it is no exaggeration to claim the region will remain an exciting research frontier for decades to come.
Note : The above story is reprinted from materials provided by Public Library of Science,
The carbon cycle, upon which most living things depend, reaches much deeper into the Earth than generally supposed-all the way to the lower mantle, researchers report.
The findings, which are based on the chemistry of an unusual set of Brazilian diamonds, will be published online by the journal Science, at the Science Express Web site, on 15 September. Science is published by AAAS, the non-profit, international science society.
“This study shows the extent of Earth’s carbon cycle on the scale of the entire planet, connecting the chemical and biological processes that occur on the surface and in the oceans to the far depths of Earth’s interior,” said Nick Wigginton, associate editor at Science.
“Results of this kind offer a broader perspective of planet Earth as an integrated, dynamic system,” he said.
The carbon cycle generally refers to the movement of carbon through the atmosphere, oceans, and the crust. Previous observations suggested that the carbon cycle may even extend to the upper mantle, which extends roughly 400 kilometers into the Earth. In this region, plates of ocean crust-bearing a carbon-rich sediment layer-sink beneath other tectonic plates and mix with the molten rock of the mantle.
Seismological and geochemical studies have suggested that oceanic crust can sink all the way to the lower mantle, more than 660 kilometers down. But actual rock samples with this history have been hard to come by.
Michael Walter of the University of Bristol and colleagues in Brazil and the United States analyzed a set of “superdeep” diamonds from the Juina kimberlite field in Brazil. Most diamonds excavated at Earth’s surface originated at depths of less than 200 kilometers. Some parts of the world, however, have produced rare, superdeep diamonds, containing tiny inclusions of other material whose chemistry indicates that the diamonds formed at far greater depths.
The Juina-5 diamonds studied by Walter and colleagues contain inclusions whose bulk compositions span the range of minerals expected to form when basalt melts and crystallizes under the extreme high pressures and temperatures of the lower mantle.
Thus, these inclusions probably originated when diamond-forming fluids incorporated basaltic components from oceanic lithosphere that had descended into the lower mantle, the researchers have concluded.
If this hypothesis is correct, then the carbon from which the diamonds formed may have been deposited originally within ocean crust at the seafloor. A relative abundance of light carbon isotopes in the Juina-5 diamonds supports this idea, since this lighter form of carbon is found at the surface but not generally in the mantle, the authors say.
The diamond inclusions also include separate phases that appear to have “unmixed” from the homogenous pool of material. This unmixing likely happened as the diamonds traveled upward hundreds of kilometers into the upper mantle, the researchers say.
After the diamonds formed in the lower mantle, they may have been launched back near the surface by a rising mantle plume, Walter and colleagues propose.
Note: This story has been adapted from a news release issued by the American Association for the Advancement of Science
Scientists have speculated for some time that Earth’s carbon cycle extends deep into the planet’s interior, but until now there has been no direct evidence. The mantle-Earth’s thickest layer -is largely inaccessible. A team of researchers analyzed diamonds that originated from the lower mantle at depths of 435 miles (700 kilometers) or more, and erupted to the surface in volcanic rocks called kimberlites. The diamonds contain what are impurities to the gemologist, but are known as mineral inclusions to the geologist. Analysis shows compositions consistent with the mineralogy of oceanic crust. This finding is the first direct evidence that slabs of oceanic crust sank or subducted into the lower mantle and that material, including carbon, is cycled between Earth’s surface and depths of hundreds of miles.
The research is published online in Science Express.
The mantle extends from as little as 5 to 1,800 miles (10-2,900 kilometers) beneath Earth’s surface. Most diamonds are free from inclusions and come from depths less than 120 miles (200 km). But in a few localities researchers have found super-deep diamonds from the depths of the convecting upper and lower mantle, as well as the transition zone in between. Whereas inclusions in diamonds from the depths of the upper mantle and transition zone have been consistent with a surface-rock origin, none from the lower mantle have borne this signature until now.
The team, which included Carnegie scientists, was led by former Carnegie postdoctoral fellow Michael Walter, now a professor at the University of Bristol, UK. The scientists analyzed minute (one to two hundredths of a millimeter) mineral grains from six diamonds from the Juina region in Brazil. The analysis showed that diamond inclusions initially crystallized as a single mineral that could form only at depths greater than 435 miles (700 km). But the inclusions recrystallized into multiple minerals as they were carried up to the surface — first probably from a mantle upwelling known as a plume, then as they erupted to the surface in kimberlites
The diamonds were analyzed for carbon at Carnegie. Four of the diamonds contained low amounts of carbon-13, a signature not found in the lower mantle and consistent with an ocean-crust origin at Earth’s surface. “The carbon identified in other super-deep, lower mantle diamonds is chiefly mantle-like in composition,” remarked co-author Steven Shirey at Carnegie. “We looked at the variations in the isotopes of the carbon atoms in the diamonds. Carbon originating in a rock called basalt, which forms from lava at the surface, is often different from that which originates in the mantle, in containing relatively less carbon-13. These super-deep diamonds contained much less carbon-13, which is most consistent with an origin in the organic component found in altered oceanic crust.”
“I find it astonishing that we can use the tiniest of mineral grains to show some of the motions of the Earth’s mantle at the largest scales,” concluded Shirey.
The researchers on the paper are M.J. Walter, S. Kohn, G. Bulanova, and C. Smith of University of Bristol, UK; D. Araujo of Universidade de Brasilia-DF Brazil; A. Steele of Carnegie’s Geophysical Laboratory, and S. Shirey, E. Gaillou, and J. Wang of Carnegie’s Department of Terrestrial Magnetism. Funding was provided by the NSF in the US, the National Environmental Research Council (NERC) in the UK, and the Carnegie Institution for Science.
Note: This story has been adapted from a news release issued by the Carnegie Institution
The eruption of giant masses of magma in Siberia 250 million years ago led to the Permo-Triassic mass extinction when more than 90 % of all species became extinct. Scientists* report on a new idea with respect to the origin of the Siberian eruptions and their relation to the mass extinction in the recent issue of Nature.
Large Igneous Provinces (LIPs) are huge accumulations of volcanic rock at Earth’s surface. Within short geological time spans of often less than one million years their eruptions cover areas of several hundred thousand square kilometres with up to 4 kilometers thick lava flows. The Siberian Traps are considered the largest continental LIP.
A widely accepted idea is that LIPs originate through melting within thermal mantle plumes, a term applied to giant mushroom-shaped volumes of plastic mantle material that rise from the base of the mantle to the lithosphere, Earth’s rigid outer shell. The high buoyancy of purely thermal mantle plumes, however, should cause kilometer-scale uplift of the lithosphere above the plume head, but such uplift is not always present. Moreover, estimates of magmatic degassing from many LIPs are considered insufficient to trigger climatic crises. The team of scientists presents a numerical model and new geochemical data with which unresolved questions can now be answered.
They suggest that the Siberian mantle plume contained a large fraction of about 15 percent of recycled oceanic crust; i.e. the crust that had long before been subducted into the deep mantle and then, through the hot mantle plume, brought back to Earth’s lithosphere. This recycled oceanic crust was present in the plume as eclogite, a very dense rock which made the hot mantle plume less buoyant. For this reason the impingement of the plume caused negligible uplift of the lithosphere. The recycled crustal material melts at much lower temperatures than the normal mantle material peridotite, and therefore the plume generated exceptionally large amounts of magmas and was able to destroy the thick Siberian lithosphere thermally, chemically and mechanically during a very short period of only a few hundred thousand years. During this process, the recycled crust, being exceptionally rich in volatiles such as CO2
and halogens, degassed and liberated gases that passed through Earth crust into the atmosphere to trigger the mass extinction.
The model predicts that the mass extinction should have occurred before the main magmatic eruptions. Though based on sparse available data, this prediction seems to be valid for many LIPs.
*The international team of scientists included geodynamic modelers from the GFZ German Research Centre for Geosciences together with geochemists from the J. Fourier University of Grenoble, the Max Plank Institute in Mainz, and Vernadsky-, Schmidt- and Sobolev-Institutes of the Russian Academy of Sciences.
Note : The above story is reprinted from materials provided by Helmholtz Association of German Research Centres.
Numerous individual filaments in Late Cretaceous Canadian amber (specimen UALVP 52821). These filaments are morphologically similar to the protofeathers that have been found as compression fossils associated with some dinosaur skeletons. Pigment distributions within these filaments range from translucent (unpigmented) to near-black (heavily pigmented). (Credit: Image courtesy of University of Alberta)
Secrets from the age of the dinosaurs are usually revealed by fossilized bones, but a University of Alberta research team has turned up a treasure trove of Cretaceous feathers trapped in tree resin. The resin turned to resilient amber, preserving some 80 million-year-old protofeathers, possibly from non-avian dinosaurs, as well as plumage that is very similar to modern birds, including those that can swim under water.
U of A paleontology graduate student Ryan McKellar discovered a wide range of feathers among the vast amber collections at the Royal Tyrrell Museum in southern Alberta. This material stems from Canada’s most famous amber deposit, near Grassy Lake in southwestern Alberta.
The discovery of the 11 feather specimens is described as the richest amber feather find from the late Cretaceous period. The amber preserves microscopic detail of the feathers and even their pigment or colour. McKellar describes the colours as typically ranging from brown to black.
No dinosaur or avian fossils were found in direct association with the amber feather specimens, but McKellar says comparison between the amber and fossilized feathers found in rock strongly suggest that some of the Grassy Lake specimens are from dinosaurs. The non-avian dinosaur evidence points to small theropods as the source of the feathers
Some of the feather specimens with modern features are very similar to those of modern birds like the Grebe, which are able to swim underwater. The feathers can take on water giving the bird the ballast required to dive more effectively..
McKellar says the Grassy Lake find demonstrates that numerous evolutionary stages of feathers were present in the late Cretaceous period and that plumage served a range of functions in both dinosaurs and birds.
The U of A team’s research was published September 15, in the journal Science.
Note : The above story is reprinted from materials provided by University of Alberta,
