Scientists Discover Amazon River Is 11 Million Years Old

Researchers at the University of Liverpool have discovered that the Amazon River, and its transcontinental drainage, is around 11 million years old and took its present shape about 2.4 million years ago.

University of Liverpool researchers, in collaboration with the University of Amsterdam and Petrobras, the national oil company of Brazil, analyzed sedimentary material taken from two boreholes near the mouth of the river to calculate the age of the Amazon river and the Amazon deep sea fan.

Prior to this study the exact age of the Amazon, one of the two largest rivers in the world, was not known. Until recently the Amazon Fan, a submarine sediment column around 10km thick, had proven difficult to penetrate, the researchers note. New exploration efforts by Petrobas, however, have lea to two new boreholes being drilled near the mouth of the Amazon -- one 2.5 miles below sea level -- which resulted in new sedimentological and paleontological analysis of samples from the river sediment.

"River sediment records provide a unique insight into the palaeoclimate and geography of the hinterland," says Jorge Figueiredo from the University's Department of Earth and Ocean Sciences.

"This new research has large implications for our understanding of South American paleogeography and the evolution of aquatic organisms in Amazonia and on the Atlantic coast. The origin of the Amazon river is a defining moment: a new ecosystem came into being at the same time as the uplifting Andes formed a geographic divide."

The study was published in the scientific journal, Geology.

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Sensitive Laser Instrument Could Aid Search for Life on Mars

Minuscule traces of cells can be detected in a mineral likely present on Mars, a new study shows. The results, obtained using a technique developed at the U.S. Department of Energy's Idaho National Laboratory (INL), could help mission scientists choose Martian surface samples with the most promise for yielding signs of life.

INL's instrument blasts off tiny bits of mineral and looks for chemical signatures of molecules commonly found in cells. While other methods require extensive sample handling, this analysis relies on a "point-and-shoot" laser technique that preserves more of the rock and reduces contamination risk. In the current online issue of the peer-reviewed Geomicrobiology Journal, the researchers report they could detect biomolecules at concentrations as low as 3 parts per trillion.

High sensitivity is crucial for NASA's search for life on Mars, says INL scientist Jill Scott, whose team collaborated with researchers at the University of Montana-Missoula on the study.

"The worst-case scenario is a false negative," Scott says. "If you're just missing stuff, that would be devastating."

While other techniques also have achieved parts-per-trillion sensitivity, they often require scientists to first extract the organic cell remnants from the mineral. This type of preparation can use up large amounts of sample and potentially introduce contamination.

INL's method is based on a technique called laser desorption mass spectroscopy. By focusing a laser beam on a spot less than one-hundredth the width of a pencil point, the researchers can knock microscopic fragments off the mineral. Those fragments react with organic molecules to form detectable charged particles called ions. The team can then study the ion patterns for signatures that might be specific to biomolecules.

Typically, this method would require the organic molecules to be embedded in a synthetic matrix that encourages ion formation. But the INL team simply relies on the rock to act as the matrix, eliminating the need for sample preparation.

"We thought, what can the rock do for you?" Scott says. "You don't want to damage the sample more than you have to. You'd like to just shoot it directly."

With funding from NASA's Astrobiology program, the researchers have done previous studies showing that minerals like halite and jarosite yield distinct ion patterns when organic molecules are present. This time, they tried thenardite, a compound thought to be part of the Martian surface. Because thenardite is left behind when lakes dry up, its presence could signify the past existence of water -- and hence life.

The team tested thenardite samples taken from the evaporated Searles Lake bed in California. They also created artificial thenardite samples that contained traces of stearic acid, which is left behind by dead cells, and glycine, the simplest amino acid used by organisms on Earth. In all cases, the researchers found a distinct ion pattern that did not appear for thenardite alone, suggesting they had detected a signature for the biomolecules.

The team also measured the sensitivity of its instrument for the first time. By testing more and more dilute artificial samples, they found they could detect the stearic acid signature at levels as low as 3 parts per trillion. In fact, the signatures became even more distinct as concentration dropped, presumably because more ion-producing matrix surrounded each biomolecule.

While the instrument is too big to send into space, it could potentially be used for analysis if NASA brings Martian samples back to Earth.

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100 Million Years AD

Jan Zalasiewicz, a lecturer in geology at the University of Leicester, has published a new study looking at the lasting impression made by mankind -- 100 million years hence.

He takes the perspective of alien explorers arriving on Earth -- their geologists study the layers of rock, using the many clues to piece together its history over several billion years

A story unfolds of moving and changing continents, rising and falling oceans, ice ages, and evidence of life going back many millions of years. They grow familiar with its phases of change, the rise of great new ecosystems, and occasional catastrophic collapses of life, according to an announcement of the project.

But then they stumble on something quite different in a thin layer of rock: a striking signal of climate changes, extinctions and strange movements of wildlife across the planet. Following this trail, decoding clues in the rocks takes them to the petrified remains of cities, and finally to the fossilized bones of those, long dead, who built them.

Zalasiewicz says: "From the perspective of 100 million years in the future–a geologist's view–the reign of humans on Earth would seem very short: we would almost certainly have died out long before then. What footprint will we leave in the rocks? What would have become of our great cities, our roads and tunnels, our cars, our plastic cups in the far distant future? What fossils would we leave behind?

"My study shows how scientists put together clues from the rocks to understand the past, its landscapes and climate, and the nature of the creatures that inhabited it," he adds. "A thin layer of silt here, a trace formed by a crawling worm there–the clues are often subtle and difficult to read. But by such clues would future geologists–whether hyper-evolved rat or alien visitor–work out our story. My study explores which of our structures are likely to leave traces, and what future explorers might make of us and the impact we made on our environment.

"Looking to the distant future gives us a warning for the present: our activities have already left a significant footprint on the planet, and not a flattering one. It is not too late to limit it. We would not wish to be dubbed by future explorers the 'amazingly clever and utterly foolish two-legged ape'."

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Liquid Water Found Flowing on Mars? Not Yet

Liquid water has not been found on the Martian surface within the last decade after all, according to new research.

The finding casts doubt on the 2006 report that the bright spots in some Martian gullies indicate that liquid water flowed down those gullies sometime since 1999.

"It rules out pure liquid water," says lead author Jon Pelletier of The University of Arizona in Tucson.

Pelletier and his colleagues used topographic data derived from images of Mars from the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter. Since 2006, HiRISE has been providing the most detailed images of Mars ever taken from orbit.

The researchers applied the basic physics of how fluid flows under Martian conditions to determine how a flow of pure liquid water would look on the HiRISE images versus how an avalanche of dry granular debris such as sand and gravel would look.

"The dry granular case was the winner," says Pelletier, a UA associate professor of geosciences. "I was surprised. I started off thinking we were going to prove it's liquid water."

Finding liquid water on the surface of Mars would indicate the best places to look for current life on Mars, says co-author Alfred McEwen, a UA professor of planetary sciences.

"What we'd hoped to do was rule out the dry flow model -- but that didn't happen," says McEwen, the HiRISE principal investigator and director of UA's Planetary Image Research Laboratory.

An avalanche of dry debris is a much better match for their calculations and also what their computer model predicts, said Pelletier and McEwen.

Pelletier says, "Right now the balance of evidence suggests that the dry granular case is the most probable."

They added that their research does not rule out the possibility that the images show flows of very thick mud containing about 50 percent to 60 percent sediment. Such mud would have a consistency similar to molasses or hot lava. From orbit, the resulting deposit would look similar to that from a dry avalanche.

The team's research article, "Recent bright gully deposits on Mars: wet or dry flow?" is being published in the March issue of Geology.

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The Biggest Bug Known

The gigantic fossil claw of an 390 million-year-old sea scorpion, recently found in Germany, shows that ancient arthropods — spiders, insects, crabs and the like — were surprisingly larger than their modern-day counterparts.

“Imagine an eight-foot-long scorpion,” says O. Erik Tetlie, postdoctoral associate in the Department of Geology and Geophysics at Yale, and an author of the report online in Royal Society Biology Letters. “The claw itself is a foot-and-a-half long — indicating that these ancient arthropods were much larger than previous estimates — and certainly the largest seen to date.”

Colleague and co-author Markus Poschmann discovered the fossil claw from this ancient sea scorpion, Jaekelopterus rhenaniae, in a quarry near Prüm in Germany. This creature, which lived between 460 and 255 million years ago is of a group that have been known for some time to be among the largest extinct arthropods, based on both body fossils and trace fossils.

According to the authors, it is believed that these extinct aquatic creatures are the ancestors of modern scorpions and spiders.

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New Deep-Sea Hydrothermal Vents, Life Form Discovered

A new "black smoker"--an undersea mineral chimney emitting hot springs of iron-darkened water--has been discovered at 8,500-foot depths by an expedition funded by the US National Science Foundation (NSF) to explore the Pacific Ocean floor off Costa Rica.

Scientists from Duke University, the Universities of New Hampshire and South Carolina, and the Woods Hole Oceanographic Institution in Massachusetts have named their discovery the Medusa Hydrothermal Vent Field.

The researchers chose that name to highlight the presence there of a unique pink form of the jellyfish order stauromedusae. The jellyfish resemble "the serpent-haired Medusa of Greek myth," says expedition leader Emily Klein, a geologist at Duke University.

The bell-shaped jellyfish sighted near the vents may be of a new species "because no one has seen this color before," says Karen Von Damm, a geologist at the University of New Hampshire.

According to Von Damm, stauromedusae are usually found away from high-temperature hydrothermal vents, where the fluids are a little bit cooler, not close to the vents as these are.
Aboard the Research Vessel (R/V) Atlantis, the researchers are studying ocean floor geology of the East Pacific Rise, one of the mid-ocean ridge systems where new crust is made as the earth spreads apart to release molten lava.

"Each new vent site has the potential to reveal new discoveries in interactions between hot rocks beneath the seafloor, the fluids that interact with those rocks and the oceans above, as well as a rich biosphere that depends on vent processes," says Adam Schultz, program director in NSF's Division of Ocean Sciences, which funded the expedition through its Ridge 2000 program. "This discovery has implications for understanding the origin of Earth's crust, its evolution over time and how living organisms adapt to extreme environmental conditions."

Jason II, a remotely-controlled robotic vehicle the scientists are using to probe the vent field, logged water temperatures of 330 degrees Celsius (626 degrees Fahrenheit) at the mouth of one of the vents. Jason II subsequently found a second vent about 100 yards away.

Von Damm said that heat-tolerant tubeworms found living on Medusa's chimneys, a type known as alvinellids, are commonplace in the equatorial Pacific and thrive on high-iron fluids. Jason also has retrieved two other types of tubeworms--tevnia and riftia--from the vent area.

In addition, the camera-studded robot, which can collect biological specimens with the aid of the mechanical arms it uses to remove rock samples, has gathered samples of mussels from the vent area.


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Scientists Use Seismic Waves To Locate Missing Rock Under Tibet

Geologists at the University of Illinois at Urbana-Champaign have located a huge chunk of Earth's lithosphere that went missing 15 million years ago. By finding the massive block of errant rock beneath Tibet, the researchers are helping solve a long-standing mystery, and clarifying how continents behave when they collide.

The Tibetan Plateau and adjacent Himalayan Mountains were created by the movements of vast tectonic plates that make up Earth's outermost layer of rocks, the lithosphere. About 55 million years ago, the Indian plate crashed into the Eurasian plate, forcing the land to slowly buckle and rise. Containing nearly one-tenth the area of the continental U.S., and averaging 16,000 feet in elevation, the Tibetan Plateau is the world's largest and highest plateau.

Tectonic models of Tibet vary greatly, including ideas such as subduction of the Eurasian plate, subduction of the Indian plate, and thickening of the Eurasian lithosphere. According to this last model, the thickened lithosphere became unstable, and a piece broke off and sank into the deep mantle.

"While attached, this immense piece of mantle lithosphere under Tibet acted as an anchor, holding the land above in place," says Wang-Ping Chen, a professor of geophysics at the University of Illinois. "Then, about 15 million years ago, the chain broke and the land rose, further raising the high plateau."

Until recently, this tantalizing theory lacked any clear observation to support it. Then doctoral student Tai-Lin (Ellen) Tseng and Chen found the missing anchor.

"This remnant of detached lithosphere provides key evidence for a direct connection between continental collision near the surface and deep-seated dynamics in the mantle," Tseng says.
"Moreover, mantle dynamics ultimately drives tectonism, so the fate of mantle lithosphere under Tibet is fundamental to understanding the full dynamics of collision."

Through a project called Hi-CLIMB -- an integrated study of the Himalayan-Tibetan Continental Lithosphere during Mountain Building, Tseng analyzed seismic signals collected at a number of permanent stations and at many temporary stations to search for the missing mass.
Hi-CLIMB created a line of seismic monitoring stations that extended from the plains of India, through Nepal, across the Himalayas and into central Tibet. "With more than 200 station deployments, Hi-CLIMB is the largest broadband (high-resolution) seismic experiment conducted to date," says Chen, who is one of the project's two principal investigators.

Using high-resolution seismic profiles recorded at many stations, Tseng precisely measured the velocities of seismic waves traveling beneath the region at depths of 300 to 700 kilometers. Because seismic waves travel faster through colder rock, Tseng was able to discern the positions of detached, cold lithosphere from her data. "We not only found the missing piece of cold lithosphere, but also were able to reconstruct the positions of tectonic plates back to 15 million years ago," Tseng says. "It therefore seems much more likely that instability in the thickening lithosphere was partially responsible for forming the Tibetan Plateau, rather than the wholesale subduction of one of the tectonic plates."

Other evidence, including the age and the distribution of volcanic rocks and extrapolation of current ground motion in Tibet, the researchers say, also indicates the remnant lithosphere detached about 15 million years ago.


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