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  • richardmitnick 7:15 am on February 21, 2017 Permalink | Reply
    Tags: , Chemosynthesis, Geology, , , Strange Life Has Been Found Trapped Inside These Giant Cave Crystals   

    From Science Alert: “Strange Life Has Been Found Trapped Inside These Giant Cave Crystals” 

    ScienceAlert

    Science Alert

    20 FEB 2017
    BEC CREW

    1
    Alexander Van Driessche/Wikipedia

    A NASA scientist just woke them up.

    Strange microbes have been found inside the massive, subterranean crystals of Mexico’s Naica Mine, and researchers suspect they’ve been living there for up to 50,000 years.

    The ancient creatures appear to have been dormant for thousands of years, surviving in tiny pockets of liquid within the crystal structures. Now, scientists have managed to extract them – and wake them up.

    “These organisms are so extraordinary,” astrobiologist Penelope Boston, director of the NASA Astrobiology Institute, said on Friday at the annual meeting of the American Association for the Advancement of Science (AAAS) in Boston.

    The Cave of Crystals in Mexico’s Naica Mine might look incredibly beautiful, but it’s one of the most inhospitable places on Earth, with temperatures ranging from 45 to 65°C (113 to 149°F), and humidity levels hitting more than 99 percent.

    Not only are temperatures hellishly high, but the environment is also oppressively acidic, and confined to pitch-black darkness some 300 metres (1,000 feet) below the surface.

    2
    Peter Williams/Flickr

    In lieu of any sunlight, microbes inside the cave can’t photosynthesise – instead, they perform chemosynthesis using minerals like iron and sulphur in the giant gypsum crystals, some of which stretch 11 metres (36 feet) long, and have been dated to half a million years old.

    Researchers have previously found life living inside the walls of the cavern and nearby the crystals – a 2013 expedition to Naica reported the discovery of creatures thriving in the hot, saline springs of the complex cave system.

    But when Boston and her team extracted liquid from the tiny gaps inside the crystals and sent them off to be analysed, they realised that not only was there life inside, but it was unlike anything they’d seen in the scientific record.

    They suspect the creatures had been living inside their crystal castles for somewhere between 10,000 and 50,000 years, and while their bodies had mostly shut down, they were still very much alive.

    “Other people have made longer-term claims for the antiquity of organisms that were still alive, but in this case these organisms are all very extraordinary – they are not very closely related to anything in the known genetic databases,” Boston told Jonathan Amos at BBC News.

    What’s perhaps most extraordinary about the find is that the researchers were able to ‘revive’ some of the microbes, and grow cultures from them in the lab.

    “Much to my surprise we got things to grow,” Boston told Sarah Knapton at The Telegraph. “It was laborious. We lost some of them – that’s just the game. They’ve got needs we can’t fulfil.”

    At this point, we should be clear that the discovery has yet to be published in a peer-reviewed journal, so until other scientists have had a chance to examine the methodology and findings, we can’t consider the discovery be definitive just yet.

    The team will also need to convince the scientific community that the findings aren’t the result of contamination – these microbes are invisible to the naked eye, which means it’s possible that they attached themselves to the drilling equipment and made it look like they came from inside the crystals.

    “I think that the presence of microbes trapped within fluid inclusions in Naica crystals is in principle possible,” Purificación López-García from the French National Centre for Scientific Research, who was part of the 2013 study that found life in the cave springs, told National Geographic.

    “[But] contamination during drilling with microorganisms attached to the surface of these crystals or living in tiny fractures constitutes a very serious risk,” she says. I am very skeptical about the veracity of this finding until I see the evidence.”

    That said, microbiologist Brent Christner from the University of Florida in Gainesville, who was also not involved in the research, thinks the claim isn’t as far-fetched as López-García is making it out to be, based on what previous studies have managed with similarly ancient microbes.

    “[R]eviving microbes from samples of 10,000 to 50,000 years is not that outlandish based on previous reports of microbial resuscitations in geological materials hundreds of thousands to millions of years old,” he told National Geographic.

    For their part, Boston and her team say they took every precaution to make sure their gear was sterilised, and cite the fact that the creatures they found inside the crystals were similar, but not identical to those living elsewhere in the cave as evidence to support their claims.

    “We have also done genetic work and cultured the cave organisms that are alive now and exposed, and we see that some of those microbes are similar but not identical to those in the fluid inclusions,” she said.

    Only time will tell if the results will bear out once they’re published for all to see, but if they are confirmed, it’s just further proof of the incredible hardiness of life on Earth, and points to what’s possible out there in the extreme conditions of space.

    See the full article here .

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  • richardmitnick 2:11 pm on February 3, 2017 Permalink | Reply
    Tags: , , Geology, Gondwana, Mauritius a continent?, ,   

    From Smithsonian: “Researchers Think They’ve Found a Mini Continent in the Indian Ocean” 

    smithsonian
    Smithsonian.com

    February 2, 2017
    Jason Daley

    1
    The beautiful Mauritius island may be hiding a chunk of continent. (Sapsiwai via iStock)

    About 200 million years ago, the supercontinent of Gondwana—essentially an an agglomeration of Africa, South America, India, Australia and Antarctica—began slowly ripping apart into the continents recognizable today. But a new study suggests that Gondwana spun out another continent that is now lost beneath the Indian Ocean.

    1
    Assemblage of continents, which constitute Gondwana. Image Credit: Griem (2007)

    As Alice Klein reports for New Scientist, researchers studying the earth’s crust found that parts of the Indian Ocean’s seafloor had slightly stronger gravitaitonal fields, suggesting that the crust might be thicker there.

    The island of Mauritius exhibited this extra oomph, which led Lewis Ashwal, a geologist at the University of the Witwatersrand, South Africa, and his colleagues to propose that the island was sitting atop a sunken chunk of continent.

    The researchers studied the geology of the island and rocks spewed out during periods of ancient volcanism. One particular mineral they were looking for are zircons, tough minerals that contains bits of uranium and thorium. The mineral can last billions of years and geologists can use these to acurately date rocks.

    The search paid off. The researchers recovered zircons as old as 3 billion years, Ashwal says in a press release. But the island rocks are no older than 9 million years old. The researchers argue that the old rock is evidence that the island is sitting on a much older crust that was once part of a continent. The zircons are remnants of this much older rock and were likely pushed up by volcanic activity. They published their results in the journal Nature Communications.

    According to Paul Hetzel at Seeker, researchers had previously discovered zircons on Mauritius’ beaches, but were unable to rule out the possibility that they were brought there by the ocean. The new finding confirms that the zircon comes from the island itself.

    Mauritia was likely a small continent, about a quarter the size of Madagascar, reports Klein. As the Indian plate and the Madagascar plate pulled apart, it stretched and broke up the small continent, spreading chunks of it across the Indian Ocean.

    3
    One of the 3-billion-year-old zircon crystals discovered on Mauritius (Wits University )

    “According to the new results, this break-up did not involve a simple splitting of the ancient super-continent of Gondwana, but rather, a complex splintering took place with fragments of continental crust of variable sizes left adrift within the evolving Indian Ocean basin,” Ashwal says in the press release [phys.org].

    Klein reports that other islands in the Indian Ocean, including Cargados Carajos, Laccadive and the Chagos islands might also exist on top of fragments of the continent now dubbed Mauritia.

    Surprisingly, this may not be the only lost continent out there. In 2015, researchers at the University of Oslo found evidence that Iceland may sit on top of a sunken slice of crust. And in 2011, researchers found evidence that a micro-continent has existed off the coast of Scotland for about a million years.

    See the full article here .

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  • richardmitnick 9:18 am on January 23, 2017 Permalink | Reply
    Tags: , Complex cells that go back maybe 1 ¾ billion years, Conditions right for complex life may have come and gone in Earth’s distant past, Geology, Selenium, ,   

    From U Washington: “Conditions right for complex life may have come and gone in Earth’s distant past” 

    U Washington

    University of Washington

    January 17, 2017
    Peter Kelley

    1
    This is a 1.9-billion-year-old stromatolite — or mound made by microbes that lived in shallow water — called the Gunflint Formation in northern Minnesota. The environment of the oxygen “overshoot” described in research by Michael Kipp, Eva Stüeken and Roger Buick may have included this sort of oxygen-rich setting that is suitable for complex life.Eva Stüeken.

    Conditions suitable to support complex life may have developed in Earth’s oceans — and then faded — more than a billion years before life truly took hold, a new University of Washington-led study has found.

    The findings, based on using the element selenium as a tool to measure oxygen in the distant past, may also benefit the search for signs of life beyond Earth.

    In a paper published Jan. 18 in the Proceedings of the National Academy of Sciences, lead author Michael Kipp, a UW doctoral student in Earth and space sciences, analyzed isotopic ratios of the element selenium in sedimentary rocks to measure the presence of oxygen in Earth’s atmosphere between 2 and 2.4 billion years ago.

    Kipp’s UW coauthors are former Earth and space sciences postdoctoral researcher Eva Stüeken — now a faculty member at the University of St. Andrews in Scotland — and professor Roger Buick, who is also a faculty member with the UW Astrobiology Program. Their other coauthor is Andrey Bekker of the University of California, Riverside, whose original hypothesis this work helps confirm, the researchers said.

    “There is fossil evidence of complex cells that go back maybe 1 ¾ billion years,” said Buick. “But the oldest fossil is not necessarily the oldest one that ever lived – because the chances of getting preserved as a fossil are pretty low.

    “This research shows that there was enough oxygen in the environment to have allowed complex cells to have evolved, and to have become ecologically important, before there was fossil evidence.” He added, “That doesn’t mean that they did — but they could have.”

    Kipp and Stüeken learned this by analyzing selenium traces in pieces of sedimentary shale from the particular time periods using mass spectrometry in the UW Isotope Geochemistry Lab, to discover if selenium had been changed by the presence of oxygen, or oxidized. Oxidized selenium compounds can then get reduced, causing a shift in the isotopic ratios which gets recorded in the rocks. The abundance of selenium also increases in the rocks when lots of oxygen is present.

    Buick said it was previously thought that oxygen on Earth had a history of “none, then some, then a lot. But what it looks like now is, there was a period of a quarter of a billion years or so where oxygen came quite high, and then sunk back down again.”

    The oxygen’s persistence over a long stretch of time is an important factor, Kipp stressed: “Whereas before and after maybe there were transient environments that could have occasionally supported these organisms, to get them to evolve and be a substantial part of the ecosystem, you need oxygen to persist for a long time.”

    Stüeken said such an oxygen increase has been guessed at previously, but it was unclear how widespread it was. This research creates a clearer picture of what this oxygen “overshoot” looked like: “That it was moderately significant in the atmosphere and surface ocean – but not at all in the deep ocean.”

    What caused oxygen levels to soar this way only to crash just as dramatically?

    “That’s the million-dollar question,” Stüeken said. “It’s unknown why it happened, and why it ended.”

    “It is an unprecedented time in Earth’s history,” Buick said. “If you look at the selenium isotope record through time, it’s a unique interval. If you look before and after, everything’s different.”

    The use of selenium — named after the Greek word for moon — as an effective tool to probe oxygen levels in deep time could also be helpful in the search for oxygen — and so perhaps life — beyond Earth, the researchers said.

    Future generations of space-based telescopes, they note, will give astronomers information about the atmospheric composition of distant planets. Some of these could be approximately Earth-sized and potentially have appreciable atmospheric oxygen.

    “The recognition of an interval in Earth’s distant past that may have had near-modern oxygen levels, but far different biological inhabitants, could mean that the remote detection of an oxygen-rich world is not necessarily proof of a complex biosphere,” Kipp said.

    Buick concluded, “This is a new way of measuring oxygen in a planet’s historical past, to see whether complex life could have evolved there and persisted long enough to evolve into intelligent beings.”

    The research was funded by grants from the National Science Foundation, NASA and the NASA Astrobiology Institute and Canada’s Natural Sciences and Engineering Research Council.

    See the full article here .

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  • richardmitnick 12:07 pm on December 22, 2016 Permalink | Reply
    Tags: , Explorers Find Passage to Earth’s Dark Age, Geology,   

    From Quanta: “Explorers Find Passage to Earth’s Dark Age” 

    Quanta Magazine
    Quanta Magazine

    December 22, 2016
    Natalie Wolchover

    1
    Earth scientists hope that their growing knowledge of the planet’s early history will shed light on poorly understood features seen today, from continents to geysers. Eric King

    Geochemical signals from deep inside Earth are beginning to shed light on the planet’s first 50 million years, a formative period long viewed as inaccessible to science.

    In August, the geologist Matt Jackson left California with his wife and 4-year-old daughter for the fjords of northwest Iceland, where they camped as he roamed the outcrops and scree slopes by day in search of little olive-green stones called olivine.

    A sunny young professor at the University of California, Santa Barbara, with a uniform of pearl-snap shirts and well-utilized cargo shorts, Jackson knew all the best hunting grounds, having first explored the Icelandic fjords two years ago. Following sketchy field notes handed down by earlier geologists, he covered 10 or 15 miles a day, past countless sheep and the occasional farmer. “Their whole lives they’ve lived in these beautiful fjords,” he said. “They look up to these black, layered rocks, and I tell them that each one of those is a different volcanic eruption with a lava flow. It blows their minds!” He laughed. “It blows my mind even more that they never realized it!”

    The olivine erupted to Earth’s surface in those very lava flows between 10 and 17 million years ago. Jackson, like many geologists, believes that the source of the eruptions was the Iceland plume, a hypothetical upwelling of solid rock that may rise, like the globules in a lava lamp, from deep inside Earth. The plume, if it exists, would now underlie the active volcanoes of central Iceland. In the past, it would have surfaced here at the fjords, back in the days when here was there — before the puzzle-piece of Earth’s crust upon which Iceland lies scraped to the northwest.

    Other modern findings [Nature]about olivine from the region suggest that it might derive from an ancient reservoir of minerals at the base of the Iceland plume that, over billions of years, never mixed with the rest of Earth’s interior. Jackson hoped the samples he collected would carry a chemical message from the reservoir and prove that it formed during the planet’s infancy — a period that until recently was inaccessible to science.

    After returning to California, he sent his samples to Richard Walker to ferret out that message. Walker, a geochemist at the University of Maryland, is processing the olivine to determine the concentration of the chemical isotope tungsten-182 in the rock relative to the more common isotope, tungsten-184. If Jackson is right, his samples will join a growing collection of rocks from around the world whose abnormal tungsten isotope ratios have completely surprised scientists. These tungsten anomalies reflect processes that could only have occurred within the first 50 million years of the solar system’s history, a formative period long assumed to have been wiped from the geochemical record by cataclysmic collisions that melted Earth and blended its contents.

    The anomalies “are giving us information about some of the earliest Earth processes,” Walker said. “It’s an alternative universe from what geochemists have been working with for the past 50 years.”

    2
    Matt Jackson and his family with a local farmer in northwest Iceland. Courtesy of Matt Jackson.

    The discoveries are sending geologists like Jackson into the field in search of more clues to Earth’s formation — and how the planet works today. Modern Earth, like early Earth, remains poorly understood, with unanswered questions ranging from how volcanoes work and whether plumes really exist to where oceans and continents came from, and what the nature and origin might be of the enormous structures, colloquially known as “blobs,” that seismologists detect deep down near Earth’s core. All aspects of the planet’s form and function are interconnected. They’re also entangled with the rest of the solar system. Any attempt, for instance, to explain why tectonic plates cover Earth’s surface like a jigsaw puzzle must account for the fact that no other planet in the solar system has plates. To understand Earth, scientists must figure out how, in the context of the solar system, it became uniquely earthlike. And that means probing the mystery of the first tens of millions of years.

    “You can think about this as an initial-conditions problem,” said Michael Manga, a geophysicist at the University of California, Berkeley, who studies geysers and volcanoes. “The Earth we see today evolved from something. And there’s lots of uncertainty about what that initial something was.”

    Pieces of the Puzzle

    On one of an unbroken string of 75-degree days in Santa Barbara the week before Jackson left for Iceland, he led a group of earth scientists on a two-mile beach hike to see some tar dikes — places where the sticky black material has oozed out of the cliff face at the back of the beach, forming flabby, voluptuous folds of faux rock that you can dent with a finger. The scientists pressed on the tar’s wrinkles and slammed rocks against it, speculating about its subterranean origin and the ballpark range of its viscosity. When this reporter picked up a small tar boulder to feel how light it was, two or three people nodded approvingly.

    A mix of geophysicists, geologists, mineralogists, geochemists and seismologists, the group was in Santa Barbara for the annual Cooperative Institute for Dynamic Earth Research (CIDER) workshop at the Kavli Institute for Theoretical Physics. Each summer, a rotating cast of representatives from these fields meet for several weeks at CIDER to share their latest results and cross-pollinate ideas — a necessity when the goal is understanding a system as complex as Earth.

    Earth’s complexity, how special it is, and, above all, the black box of its initial conditions have meant that, even as cosmologists map the universe and astronomers scan the galaxy for Earth 2.0, progress in understanding our home planet has been surprisingly slow. As we trudged from one tar dike to another, Jackson pointed out the exposed sedimentary rock layers in the cliff face — some of them horizontal, others buckled and sloped. Amazingly, he said, it took until the 1960s for scientists to even agree that sloped sediment layers are buckled, rather than having piled up on an angle. Only then was consensus reached on a mechanism to explain the buckling and the ruggedness of Earth’s surface in general: the theory of plate tectonics.

    Projecting her voice over the wind and waves, Carolina Lithgow-Bertelloni, a geophysicist from University College London who studies tectonic plates, credited the German meteorologist Alfred Wegener for first floating the notion of continental drift in 1912 to explain why Earth’s landmasses resemble the dispersed pieces of a puzzle. “But he didn’t have a mechanism — well, he did, but it was crazy,” she said.

    3
    Earth scientists on a beach hike in Santa Barbara County, California. Natalie Wolchover/Quanta Magazine

    A few years later, she continued, the British geologist Sir Arthur Holmes convincingly argued that Earth’s solid-rock mantle flows fluidly on geological timescales, driven by heat radiating from Earth’s core; he speculated that this mantle flow in turn drives surface motion. More clues came during World War II. Seafloor magnetism, mapped for the purpose of hiding submarines, suggested that new crust forms at the mid-ocean ridge — the underwater mountain range that lines the world ocean like a seam — and spreads in both directions to the shores of the continents. There, at “subduction zones,” the oceanic plates slide stiffly beneath the continental plates, triggering earthquakes and carrying water downward, where it melts pockets of the mantle. This melting produces magma that rises to the surface in little-understood fits and starts, causing volcanic eruptions. (Volcanoes also exist far from any plate boundaries, such as in Hawaii and Iceland. Scientists currently explain this by invoking the existence of plumes, which researchers like Walker and Jackson are starting to verify and map using isotope studies.)

    The physical description of the plates finally came together in the late 1960s, Lithgow-Bertelloni said, when the British geophysicist Dan McKenzie and the American Jason Morgan separately proposed a quantitative framework for modeling plate tectonics on a sphere.

    The tectonic plates of the world were mapped in 1996, USGS.
    The tectonic plates of the world were mapped in 1996, USGS.

    Other than their existence, almost everything about the plates remains in contention. For instance, what drives their lateral motion? Where do subducted plates end up — perhaps these are the blobs? — and how do they affect Earth’s interior dynamics? Why did Earth’s crust shatter into plates in the first place when no other planetary surface in the solar system did? Also completely mysterious is the two-tier architecture of oceanic and continental plates, and how oceans and continents came to ride on them — all possible prerequisites for intelligent life. Knowing more about how Earth became earthlike could help us understand how common earthlike planets are in the universe and thus how likely life is to arise.

    The continents probably formed, Lithgow-Bertelloni said, as part of the early process by which gravity organized Earth’s contents into concentric layers: Iron and other metals sank to the center, forming the core, while rocky silicates stayed in the mantle. Meanwhile, low-density materials buoyed upward, forming a crust on the surface of the mantle like soup scum. Perhaps this scum accumulated in some places to form continents, while elsewhere oceans materialized.

    Figuring out precisely what happened and the sequence of all of these steps is “more difficult,” Lithgow-Bertelloni said, because they predate the rock record and are “part of the melting process that happens early on in Earth’s history — very early on.”

    Until recently, scientists knew of no geochemical traces from so long ago, and they thought they might never crack open the black box from which Earth’s most glorious features emerged. But the subtle anomalies in tungsten and other isotope concentrations are now providing the first glimpses of the planet’s formation and differentiation. These chemical tracers promise to yield a combination timeline-and-map of early Earth, revealing where its features came from, why, and when.

    A Sketchy Timeline

    Humankind’s understanding of early Earth took its first giant leap when Apollo astronauts brought back rocks from the moon: our tectonic-less companion whose origin was, at the time, a complete mystery.

    The rocks “looked gray, very much like terrestrial rocks,” said Fouad Tera, who analyzed lunar samples at the California Institute of Technology between 1969 and 1976. But because they were from the moon, he said, they created “a feeling of euphoria” in their handlers. Some interesting features did eventually show up: “We found glass spherules — colorful, beautiful — under the microscope, green and yellow and orange and everything,” recalled Tera, now 85. The spherules probably came from fountains that gushed from volcanic vents when the moon was young. But for the most part, he said, “the moon is not really made out of a pleasing thing — just regular things.”

    In hindsight, this is not surprising: Chemical analysis at Caltech and other labs indicated that the moon formed from Earth material, which appears to have gotten knocked into orbit when the 60 to 100 million-year-old proto-Earth collided with another protoplanet in the crowded inner solar system. This “giant impact” hypothesis of the moon’s formation [Science Direct], though still hotly debated [Nature]in its particulars, established a key step on the timeline of the Earth, moon and sun that has helped other steps fall into place.

    5
    A panorama of the Taurus-Littrow Valley created from photographs by Apollo 17 astronaut Eugene Cernan. Astronaut Harrison Schmitt is shown using a rake to collect samples. NASA

    Chemical analysis of meteorites is helping scientists outline even earlier stages of our solar system’s timeline, including the moment it all began.

    First, 4.57 billion years ago, a nearby star went supernova, spewing matter and a shock wave into space. The matter included radioactive elements that immediately began decaying, starting the clocks that isotope chemists now measure with great precision. As the shock wave swept through our cosmic neighborhood, it corralled the local cloud of gas and dust like a broom; the increase in density caused the cloud to gravitationally collapse, forming a brand-new star — our sun — surrounded by a placenta of hot debris.

    Over the next tens of millions of years, the rubble field surrounding the sun clumped into bigger and bigger space rocks, then accreted into planet parts called “planetesimals,” which merged into protoplanets, which became Mercury, Venus, Earth and Mars — the four rocky planets of the inner solar system today. Farther out, in colder climes, gas and ice accreted into the giant planets.

    6
    The planets of the solar system as depicted by a NASA computer illustration. Orbits and sizes are not shown to scale.
    Credit: NASA

    7
    Researchers use liquid chromatography to isolate elements for analysis. Rock samples dissolved in acid flow down ion-exchange columns, like the ones in Rick Carlson’s laboratory at the Carnegie Institution in Washington, to separate the elements. Mary Horan.

    The last of the Earth-melting “giant impacts” appears to have been the one that formed the moon; while subtracting the moon’s mass, the impactor was also the last major addition to Earth’s mass. Perhaps, then, this point on the timeline — at least 60 million years after the birth of the solar system and, counting backward from the present, at most 4.51 billion years ago — was when the geochemical record of the planet’s past was allowed to begin. “It’s at least a compelling idea to think that this giant impact that disrupted a lot of the Earth is the starting time for geochronology,” said Rick Carlson, a geochemist at the Carnegie Institution of Washington. In those first 60 million years, “the Earth may have been here, but we don’t have any record of it because it was just erased.”

    Another discovery from the moon rocks came in 1974. Tera, along with his colleague Dimitri Papanastassiou and their boss, Gerry Wasserburg, a towering figure in isotope cosmochemistry who died in June, combined many isotope analyses of rocks from different Apollo missions on a single plot, revealing a straight line called an “isochron” that corresponds to time. “When we plotted our data along with everybody else’s, there was a distinct trend that shows you that around 3.9 billion years ago, something massive imprinted on all the rocks on the moon,” Tera said.

    As the infant Earth navigated the crowded inner solar system, it would have experienced frequent, white-hot collisions, which were long assumed to have melted the entire planet into a global “magma ocean.” During these melts, gravity differentiated Earth’s liquefied contents into layers — core, mantle and crust. It’s thought that each of the global melts would have destroyed existing rocks, blending their contents and removing any signs of geochemical differences left over from Earth’s initial building blocks.

    The last of the Earth-melting “giant impacts” appears to have been the one that formed the moon; while subtracting the moon’s mass, the impactor was also the last major addition to Earth’s mass. Perhaps, then, this point on the timeline — at least 60 million years after the birth of the solar system and, counting backward from the present, at most 4.51 billion years ago — was when the geochemical record of the planet’s past was allowed to begin. “It’s at least a compelling idea to think that this giant impact that disrupted a lot of the Earth is the starting time for geochronology,” said Rick Carlson, a geochemist at the Carnegie Institution of Washington. In those first 60 million years, “the Earth may have been here, but we don’t have any record of it because it was just erased.”

    Another discovery from the moon rocks came in 1974. Tera, along with his colleague Dimitri Papanastassiou and their boss, Gerry Wasserburg, a towering figure in isotope cosmochemistry who died in June, combined many isotope analyses of rocks from different Apollo missions on a single plot, revealing a straight line called an “isochron” that corresponds to time. “When we plotted our data along with everybody else’s, there was a distinct trend that shows you that around 3.9 billion years ago, something massive imprinted on all the rocks on the moon,” Tera said.

    Wasserburg dubbed the event the “lunar cataclysm.” [Science Direct]. Now more often called the “late heavy bombardment,” it was a torrent of asteroids and comets that seems to have battered the moon 3.9 billion years ago, a full 600 million years after its formation, melting and chemically resetting the rocks on its surface. The late heavy bombardment surely would have rained down even more heavily on Earth, considering the planet’s greater size and gravitational pull. Having discovered such a momentous event in solar system history, Wasserburg left his younger, more reserved colleagues behind and “celebrated in Pasadena in some bar,” Tera said.

    As of 1974, no rocks had been found on Earth from the time of the late heavy bombardment. In fact, Earth’s oldest rocks appeared to top out at 3.8 billion years. “That number jumps out at you,” said Bill Bottke, a planetary scientist at the Southwest Research Institute in Boulder, Colorado. It suggests, Bottke said, that the late heavy bombardment might have melted whatever planetary crust existed 3.9 billion years ago, once again destroying the existing geologic record, after which the new crust took 100 million years to harden.

    In 2005, a group of researchers working in Nice, France, conceived of a mechanism to explain the late heavy bombardment — and several other mysteries about the solar system, including the curious configurations of Jupiter, Saturn, Uranus and Neptune, and the sparseness of the asteroid and Kuiper belts. Their “Nice model” [Nature] posits that the gas and ice giants suddenly destabilized in their orbits sometime after formation, causing them to migrate. Simulations by Bottke and others indicate that the planets’ migrations would have sent asteroids and comets scattering, initiating something very much like the late heavy bombardment. Comets that were slung inward from the Kuiper belt during this shake-up might even have delivered water to Earth’s surface, explaining the presence of its oceans.

    With this convergence of ideas, the late heavy bombardment became widely accepted as a major step on the timeline of the early solar system. But it was bad news for earth scientists, suggesting that Earth’s geochemical record began not at the beginning, 4.57 billion years ago, or even at the moon’s beginning, 4.51 billion years ago, but 3.8 billion years ago, and that most or all clues about earlier times were forever lost.

    Extending the Rock Record

    More recently, the late heavy bombardment theory and many other long-standing assumptions about the early history of Earth and the solar system have come into question, and Earth’s dark age has started to come into the light. According to Carlson, “the evidence for this 3.9 [billion-years-ago] event is getting less clear with time.” For instance, when meteorites are analyzed for signs of shock, “they show a lot of impact events at 4.2, 4.4 billion,” he said. “This 3.9 billion event doesn’t show up really strong in the meteorite record.” He and other skeptics of the late heavy bombardment argue that the Apollo samples might have been biased. All the missions landed on the near side of the moon, many in close proximity to the Imbrium basin (the moon’s biggest shadow, as seen from Earth), which formed from a collision 3.9 billion years ago. Perhaps all the Apollo rocks were affected by that one event, which might have dispersed the melt from the impact over a broad swath of the lunar surface. This would suggest a cataclysm that never occurred.

    8
    Lucy Reading-Ikkanda for Quanta Magazine

    Furthermore, the oldest known crust on Earth is no longer 3.8 billion years old. Rocks have been found in two parts of Canada dating to 4 billion and an alleged 4.28 billion years ago, refuting the idea that the late heavy bombardment fully melted Earth’s mantle and crust 3.9 billion years ago. At least some earlier crust survived.

    In 2008, Carlson and collaborators reported the evidence of 4.28 billion-year-old rocks in the Nuvvuagittuq greenstone belt in Canada. When Tim Elliott, a geochemist at the University of Bristol, read about the Nuvvuagittuq findings, he was intrigued to see that Carlson had used a dating method also used in earlier work by French researchers that relied on a short-lived radioactive isotope system called samarium-neodymium. Elliott decided to look for traces of an even shorter-lived system — hafnium-tungsten — in ancient rocks, which would point back to even earlier times in Earth’s history.

    The dating method works as follows: Hafnium-182, the “parent” isotope, has a 50 percent chance of decaying into tungsten-182, its “daughter,” every 9 million years (this is the parent’s “half-life”). The halving quickly reduces the parent to almost nothing; by 50 million years after the supernova that sparked the sun, virtually all the hafnium-182 would have become tungsten-182.

    That’s why the tungsten isotope ratio in rocks like Matt Jackson’s olivine samples can be so revealing: Any variation in the concentration of the daughter isotope, tungsten-182, measured relative to tungsten-184 must reflect processes that affected the parent, hafnium-182, when it was around — processes that occurred during the first 50 million years of solar system history. Elliott knew that this kind of geochemical information was previously believed to have been destroyed by early Earth melts and billions of years of subsequent mantle convection. But what if it wasn’t?

    Elliott contacted Stephen Moorbath, then an emeritus professor of geology at the University of Oxford and “one of the grandfather figures in finding the oldest rocks,” Elliott said. Moorbath “was keen, so I took the train up.” Moorbath led Elliott down to the basement of Oxford’s earth science building, where, as in many such buildings, a large collection of rocks shares the space with the boiler and stacks of chairs. Moorbath dug out specimens from the Isua complex in Greenland, an ancient bit of crust that he had pegged, in the 1970s, at 3.8 billion years old.

    Elliott and his student Matthias Willbold powdered and processed the Isua samples and used painstaking chemical methods to extract the tungsten. They then measured the tungsten isotope ratio using state-of-the-art mass spectrometers. In a 2011 Nature paper, Elliott, Willbold and Moorbath, who died in October, reported that the 3.8 billion-year-old Isua rocks contained 15 parts per million more tungsten-182 than the world average — the first ever detection of a “positive” tungsten anomaly on the face of the Earth.

    The paper scooped Richard Walker of Maryland and his colleagues, who months later reported [Science] a positive tungsten anomaly in 2.8 billion-year-old komatiites from Kostomuksha, Russia.

    Although the Isua and Kostomuksha rocks formed on Earth’s surface long after the extinction of hafnium-182, they apparently derive from materials with much older chemical signatures. Walker and colleagues argue that the Kostomuksha rocks must have drawn from hafnium-rich “primordial reservoirs” in the interior that failed to homogenize during Earth’s early mantle melts. The preservation of these reservoirs, which must trace to the first 50 million years and must somehow have survived even the moon-forming impact, “indicates that the mantle may have never been well mixed,” Walker and his co-authors wrote. That raises the possibility of finding many more remnants of Earth’s early history.

    9
    The 60 million-year-old flood basalts of Baffin Bay, Greenland, sampled by the geochemist Hanika Rizo (center) and colleagues, contain isotope traces that originated more than 4.5 billion years ago. Don Francis (left); courtesy of Hanika Rizo (center and right).

    The researchers say they will be able to use tungsten anomalies and other isotope signatures in surface material as tracers of the ancient interior, extrapolating downward and backward into the past to map proto-Earth and reveal how its features took shape. “You’ve got the precision to look and actually see the sequence of events occurring during planetary formation and differentiation,” Carlson said. “You’ve got the ability to interrogate the first tens of millions of years of Earth’s history, unambiguously.”

    Anomalies have continued to show up in rocks of various ages and provenances. In May, Hanika Rizo of the University of Quebec in Montreal, along with Walker, Jackson and collaborators, reported in Science the first positive tungsten anomaly in modern rocks — 62 million-year-old samples from Baffin Bay, Greenland. Rizo hypothesizes that these rocks were brought up by a plume that draws from one of the “blobs” deep down near Earth’s core. If the blobs are indeed rich in tungsten-182, then they are not tectonic-plate graveyards as many geophysicists suspect, but instead date to the planet’s infancy. Rizo speculates that they are chunks of the planetesimals that collided to form Earth, and that the chunks somehow stayed intact in the process. “If you have many collisions,” she said, “then you have the potential to create this patchy mantle.” Early Earth’s interior, in that case, looked nothing like the primordial magma ocean pictured in textbooks.

    More evidence for the patchiness of the interior has surfaced. At the American Geophysical Union meeting earlier this month, Walker’s group reported [2016 AGU Fall Meeting] a negative tungsten anomaly — that is, a deficit of tungsten-182 relative to tungsten-184 — in basalts from Hawaii and Samoa. This and other isotope concentrations in the rocks suggest the hypothetical plumes that produced them might draw from a primordial pocket of metals, including tungsten-184. Perhaps these metals failed to get sucked into the core during planet differentiation.

    10
    Tim Elliott collecting samples of ancient crust rock in Yilgarn Craton in Western Australia. Tony Kemp

    Meanwhile, Elliott explains the positive tungsten anomalies in ancient crust rocks like his 3.8 billion-year-old Isua samples by hypothesizing that these rocks might have hardened on the surface before the final half-percent of Earth’s mass — delivered to the planet in a long tail of minor impacts — mixed into them. These late impacts, known as the “late veneer,” would have added metals like gold, platinum and tungsten (mostly tungsten-184) to Earth’s mantle, reducing the relative concentration of tungsten-182. Rocks that got to the surface early might therefore have ended up with positive tungsten anomalies.

    Other evidence complicates this hypothesis, however — namely, the concentrations of gold and platinum in the Isua rocks match world averages, suggesting at least some late veneer material did mix into them. So far, there’s no coherent framework that accounts for all the data. But this is the “discovery phase,” Carlson said, rather than a time for grand conclusions. As geochemists gradually map the plumes and primordial reservoirs throughout Earth from core to crust, hypotheses will be tested and a narrative about Earth’s formation will gradually crystallize.

    Elliott is working to test his late-veneer hypothesis. Temporarily trading his mass spectrometer for a sledgehammer, he collected a series of crust rocks in Australia that range from 3 billion to 3.75 billion years old. By tracking the tungsten isotope ratio through the ages, he hopes to pinpoint the time when the mantle that produced the crust became fully mixed with late-veneer material.

    “These things never work out that simply,” Elliott said. “But you always start out with the simplest idea and see how it goes.”

    See the full article here .

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    Formerly known as Simons Science News, Quanta Magazine is an editorially independent online publication launched by the Simons Foundation to enhance public understanding of science. Why Quanta? Albert Einstein called photons “quanta of light.” Our goal is to “illuminate science.” At Quanta Magazine, scientific accuracy is every bit as important as telling a good story. All of our articles are meticulously researched, reported, edited, copy-edited and fact-checked.

     
  • richardmitnick 6:04 am on December 6, 2016 Permalink | Reply
    Tags: Geology, Inorganic geochemistry, Molecular environmental science, , ,   

    From Stanford: “Eureka moment leads to new method of studying environmental toxins” 

    Stanford University Name
    Stanford University

    March 31, 2016 [Stanford just saw fit to put this in social media.]
    Ker Than

    1
    View of the TVA Kingston Fossil Plant fly ash spill. Work using X-ray beams is clarifying how pollutants bind or release from solid surfaces and move into groundwater. Photo: Brian Stansberry via Wikimedia Commons

    A technique for probing the surface of particles revealed how toxins move from the soil to groundwater.

    In 1986, Gordon Brown used SLAC’s Stanford Synchrotron Radiation Lightsource (SSRL) to visualize something no one had ever seen before: the exact way that atoms bond to a solid surface.

    SLAC/SSRL
    SLAC/SSRL

    The work stemmed from a eureka moment that Brown had during the doctoral defense of graduate student Kim Hayes but has since grown into one of the seminal works in inorganic geochemistry, and even spawned a new field of study — molecular environmental science.

    Knowing how charged ions interact with solid surfaces is crucial for understanding how toxic metal ions such as lead, arsenic and mercury or radioactive elements such as uranium may be released from particles in soils and sediments and into groundwater or vice versa. Using the techniques Brown’s team helped pioneer, scientists today can paint exquisitely detailed pictures of how metal ions bind to different solid surfaces, including those on nanoparticles.

    “You can determine what other atoms are around the pollutant ions of interest, the inter-atomic distances separating them and the number and types of chemical bonds that keep them bound to the surface,” says Brown, a professor of geological sciences and of photon science. “This is crucial for understanding how easily they move from one place to another.”


    Access mp4 video here .

    Synchrotron-generated X-rays like those produced at SSRL are ideal for this type of investigation for a number of reasons, says John Bargar, a senior scientist at SLAC and Brown’s former PhD student. For one thing, synchrotron X-rays are highly focused, much like laser beams. “All of the photons produced are condensed into either a pencil beam or a narrow fan,” Bargar says. “That means you can use nearly all of the photons that you’re making with very little waste.”

    Another advantage of synchrotron X-rays, Brown says, is that their extremely high intensity makes it possible to detect and study pollutant ions at the very low concentration levels typically found in many polluted environmental samples.

    Moreover, synchrotron X-rays are polarized, meaning their waves vibrate primarily in a single plane. By modifying the direction of polarization, scientists can create very powerful probes for studying chemical bonds in molecules.

    “A metal ion sitting inside a larger molecule is surrounded by many bonds. Oftentimes, we don’t want to interrogate all of those bonds at once,” Bargar says. “With polarized X-rays, we can selectively interrogate the bonds in a specific orientation.”

    Recently, Brown and Bargar have collaborated to study how organic matter and live microbial organisms affect the binding affinities of different environmental pollutants to solid surfaces. Bargar and Brown are also investigating ways to harness bacterial aggregations called biofilms to neutralize the effects of environmental pollutants. In addition, they are also using synchrotron X-rays at SSRL to look for more efficient ways of safely extracting oil and gas from tight shales via hydraulic fracturing, a process that is transforming the energy landscape of the United States.

    “The X-ray beams synchrotrons are able to generate today are about 15 orders of magnitude brighter than what was available when I was a graduate student. This has led to a revolution in all areas of science and engineering,” Brown says. “I could collect the data for my entire PhD thesis in one morning at SSRL now.”

    See the full article here .

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    Leland and Jane Stanford founded the University to “promote the public welfare by exercising an influence on behalf of humanity and civilization.” Stanford opened its doors in 1891, and more than a century later, it remains dedicated to finding solutions to the great challenges of the day and to preparing our students for leadership in today’s complex world. Stanford, is an American private research university located in Stanford, California on an 8,180-acre (3,310 ha) campus near Palo Alto. Since 1952, more than 54 Stanford faculty, staff, and alumni have won the Nobel Prize, including 19 current faculty members

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  • richardmitnick 8:55 am on November 30, 2016 Permalink | Reply
    Tags: , , Geology, Ring of Fire, Scientists have found the largest exposed fault on Earth   

    From Science Alert: “Scientists have found the largest exposed fault on Earth” 

    ScienceAlert

    Science Alert

    29 NOV 2016
    BEC CREW

    1
    Pulau Banta island in the Banta Sea. Credit: Jialiang Gao/Wikimedia

    For the first time, researchers have confirmed the existence of the largest exposed fault on Earth, and it could explain how a 7.2-km-deep (4.5-mile) abyss formed in the Pacific Ocean.

    Discovered beneath the Banda Sea in eastern Indonesia, the massive fault plane runs right through the notorious Ring of Fire – an explosive region where roughly 90 percent of the world’s earthquakes and 75 percent of all active volcanoes occur.

    4
    SVG version of File:Pacific_Ring_of_Fire.png, recreated using WDB vector data using code mentioned in File:Worldmap_wdb_combined.svg. 11 February 2009. Gringer

    For almost a century, scientists have known about the Weber Deep – a massive chasm lurking near the Maluku Islands of Indonesia that forms the deepest point of Earth’s oceans not within a trench.

    But until now, no one could figure out how it formed.

    To investigate, geologists from the Australian National University (ANU) in Canberra and Royal Holloway University of London analysed maps of the sea floor taken from the Banda Sea region in the Pacific Ocean.

    They discovered that rocks sitting the bottom of the sea were cut by hundreds of straight parallel scars.

    Simulations of the sea floor suggested that a massive piece of crust bigger than Belgium was at some point ripped apart by a massive crack – or fault – in the oceanic plates to form a deep depression in the ocean floor.

    The activity appeared to have left behind the biggest exposed fault plane ever detected on Earth, which the researchers have tentatively called the Banda Detachment.

    When a fault forms in Earth’s crust, it forms two main features: a fault plane, which is the flat surface of a fault; and the fault line, which is the intersection of a fault plane with the ground surface.

    The team’s simulations showed that the Banda Detachment fault plane was exposed over an area of 60,000 square kilometres (23,166 square miles) when the sea floor cracked.

    “We had made a good argument for the existence of this fault we named the Banda Detachment, based on the bathymetry [underwater topography] data and on knowledge of the regional geology,” said one of the researchers, Gordon Lister from ANU.

    3
    Diagram showing the Banda Detachment fault beneath the Weber Deep basin. Credit: ANU

    But as far as the researchers were concerned, this massive fault didn’t exist until they saw evidence of it with their own eyes.

    When they sailed out in the Pacific Ocean in eastern Indonesia, they identified prominent landforms in the water that were formed by the Banda Detachment fault plane.

    “I was stunned to see the hypothesised fault plane, this time not on a computer screen, but poking above the waves,” says one of the team, Jonathan Pownall from ANU. “The discovery will help explain how one of Earth’s deepest sea areas became so deep.”

    The team says the fact that the Weber Deep abyss formed right where the Banda Detachment was exposed could help researchers figure out how it formed.

    “Our research found that a 7 km-deep abyss beneath the Banda Sea off eastern Indonesia was formed by extension along what might be Earth’s largest-identified exposed fault plane,” says Pownall.

    The discovery could also help geologists predict the movements of one of the most tectonically active regions in the world – the Pacific Ring of Fire, a 40,000-km (25,000-mile) stretch of ocean dotted with no less than 452 volcanoes, which is around 75 percent of the world’s total.

    “In a region of extreme tsunami risk, knowledge of major faults such as the Banda Detachment, which could make big earthquakes when they slip, is fundamental to being able to properly assess tectonic hazards,” says Pownall.

    The research has been published in Geology.

    See the full article here .

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  • richardmitnick 5:59 am on November 23, 2016 Permalink | Reply
    Tags: , , , Curtin University, Geology, Meteorite recovered in WA with the help of stargazers and science app   

    From CSIRO via ABC: “Meteorite recovered in WA with the help of stargazers and science app” 

    CSIRO bloc

    Commonwealth Scientific and Industrial Research Organisation

    1
    ABC

    11.21.16
    Colin Cosier

    2
    The pristine meteorite sample recovered from Morawa, protected by a non-reactive Teflon bag. Supplied: Curtin University

    A meteorite estimated to be older than Earth has been recovered from a West Australian farm with the help of some enthusiastic stargazers and a phone app.

    The 1.15-kilogram meteor landed near Morawa on Halloween, discovered days later by members of Curtin University’s Desert Fireball Network (DFN).

    DFN founder Phil Bland said the fireball was located with the help of four skyward-pointing outback cameras and reports made to the Fireballs in the Sky citizen science app.

    He said retrieving the meteorite so quickly meant it is in good condition and scientifically valuable.

    “Our team was able to track the fall line and calculate its landing spot to within 200 metres of where it was subsequently found,” Professor Bland said.

    “It [the meteorite] is a type called a chondrite, which is a type of meteorite which has not been cooked up enough to melt.

    “So it can give us some information about that period of early solar system history.”

    “We’re hopeful, because we managed to get it in a very pristine way, that we can find some quite soluble elements or minerals in there, or volatile minerals that can tell us about water and organics in the solar system.

    “Meteorites tell us pretty much everything we want to know about the solar system … but unless we know where they came from, there’s a really big piece of that puzzle left.”

    3
    Curtin University’s Desert Fireball Network camera used a 30-second exposure to pick up the fireball. Supplied: Curtin University

    Prof Bland said of the 50,000 meteorites that have been discovered, the origins of only 20 to 30 are known.

    Meteorites decelerate to a free-fall velocity by the time they hit the earth, travelling at the same speed as a rock thrown from a tall building.

    Before falling through the atmosphere, the meteorite is predicted to have been 50-100 times bigger than its current size.

    Martin Towner from the Department of Applied Geology described the rock as a pristine, unweathered and a fresh sample.

    He said there was no visible impact on the ground where it was found, about 300 kilometres north-east of Perth.

    DFN’s Ben Hartig said they were at the correct field when they first looked, but called it a day before they found the meteor.

    The next morning they looked in another paddock, before it was finally discovered in the original field.

    “It was right at the end of the field, so we pretty much all thought we’d finished off that field and we then we see this black rock,” Mr Hartig said.

    Founder of WA’s Stargazers Club, Carol Redford, was one of those who uploaded her location to the app when she saw the meteorite streak through the sky.

    “I immediately grabbed my smart phone and headed outside,” said Ms Redford, who is also known as Galaxy Girl.

    4
    Desert Fireball Network search team with recovered meteorite. Supplied: Curtin University

    See the full article here .

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    CSIRO, the Commonwealth Scientific and Industrial Research Organisation, is Australia’s national science agency and one of the largest and most diverse research agencies in the world.

     
  • richardmitnick 8:41 am on October 14, 2016 Permalink | Reply
    Tags: , , , Geology, Microtektites, Signs of comet collision found in 5.5-million-year-old rocks, Spherules   

    From COSMOS: “Signs of comet collision found in 5.5-million-year-old rocks” 

    Cosmos Magazine bloc

    COSMOS

    14 October 2016
    Amy Middleton

    1
    Glass blobs in rocks found along the US east coast point to a comet collision a few million years ago. Marc Ward / Stocktrek Images / Getty Images

    Glassy spheres discovered in sedimentary rock have tipped off geologists about a previously unknown prehistoric comet crash – one that may have triggered a period of intense global warming.

    Morgan Schaller at the Rensselaer Polytechnic Institute in New York and colleagues found marble-like glassy spherules, known as microtektites, which they believe to be fragments of debris scattered into the air after an object collided with the Earth some 5.5 million years ago.

    They published their work in Science.

    2
    Examples of a few of the spherules examined in the study. M F Schaller et al, Science 2016

    The distinct structures and unique appearances of spherules, as well as the way they’re positioned in sediment, can offer clues about historic impact events.

    Schaller’s spherules were found in marine shelf sites on the Atlantic Coastal Plain, along the east coast of the US, dating back to the boundary between the Paleocene and Eocene epochs.

    This is known as the Paleocene-Eocene Thermal Maximum (PETM), one of the most dramatic climate events known to science.

    During this period, the global average temperature was 8 °C higher than it is today and the world largely devoid of ice. Massive amounts of carbon were injected into the atmosphere and oceans and many of the world’s organisms experienced drastic shifts in their evolution.

    This intense warming is particularly relevant to us, because it marks the closest comparative event to the global warming evident today.

    What may have kick-started the PETM is hotly debated, and theories stretch from volcanic degassing to the cycle of Earth’s orbit. Now, the possibility of a meteorite impact may be thrown into the mix.

    To draw clues from the spherules, the researchers analysed the size, structure, layout and abundance of the particles they had uncovered, and compared the data to evidence of other impact sites.

    Shape and colour of the fragments also offered clues about their origins.

    “The spherules often have surface pits and in some cases microcraters,” the researchers write, “indicating relative velocities high enough to fracture the spherules on impact with one another, or other objects, after solidification.”

    Not everyone’s convinced, though.

    Christian Koeberl, an impact specialist at the University of Vienna in Austria, said the spherules could have come from another time and been reworked into the PETM sediments.

    The researchers did not directly use radiometric dating on the spherules themselves – just the surrounding sediment.

    But the next step, according to the research team, is to uncover spherules in more locations and start to figure out how far the debris spread. This will help them eventually narrow down a potential crater location to mark the comet’s impact.

    See the full article here .

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  • richardmitnick 8:09 am on October 12, 2016 Permalink | Reply
    Tags: , , Geology, , , , ,   

    From Symmetry: “Recruiting team geoneutrino” 

    Symmetry Mag
    Symmetry

    10/11/16
    Leah Crane

    1
    Illustration by Sandbox Studio, Chicago with Corinne Mucha

    Physicists and geologists are forming a new partnership to study particles from inside the planet.

    The Earth is like a hybrid car.

    Deep under its surface, it has two major fuel tanks. One is powered by dissipating primordial energy left over from the planet’s formation. The other is powered by the heat that comes from radioactive decay.

    We have only a shaky understanding of these heat sources, says William McDonough, a geologist at the University of Maryland. “We don’t have a fuel gauge on either one of them. So we’re trying to unravel that.”

    One way to do it is to study geoneutrinos, a byproduct of the process that burns Earth’s fuel. Neutrinos rarely interact with other matter, so these particles can travel straight from within the Earth to its surface and beyond.

    Geoneutrinos hold clues as to how much radioactive material the Earth contains. Knowing that could lead to insights about how our planet formed and its modern-day dynamics. In addition, the heat from radioactive decay plays a key role in driving plate tectonics.

    The tectonic plates of the world were mapped in 1996, USGS.
    The tectonic plates of the world were mapped in 1996, USGS

    Understanding the composition of the planet and the motion of the plates could help geologists model seismic activity.

    To effectively study geoneutrinos, scientists need knowledge both of elementary particles and of the Earth itself. The problem, McDonough says, is that very few geologists understand particle physics, and very few particle physicists understand geology. That’s why physicists and geologists have begun coming together to build an interdisciplinary community.

    “There’s really a need for a beyond-superficial understanding of the physics for the geologists and likewise a nonsuperficial understanding of the Earth by the physicists,” McDonough says, “and the more that we talk to each other, the better off we are.”

    There are hurdles to overcome in order to get to that conversation, says Livia Ludhova, a neutrino physicist and geologist affiliated with Forschungzentrum Jülich and RWTH Aachen University in Germany. “I think the biggest challenge is to make a common dictionary and common understanding—to get a common language. At the basic level, there are questions on each side which can appear very naïve.”

    In July, McDonough and Gianpaolo Bellini, emeritus scientist of the Italian National Institute of Nuclear Physics and retired physics professor at the University of Milan, led a summer institute for geology and physics graduate students to bridge the divide.

    “In general, geology is more descriptive,” Bellini says. “Physics is more structured.”

    This can be especially troublesome when it comes to numerical results, since most geologists are not used to working with the defined errors that are so important in particle physics.

    At the summer institute, students began with a sort of remedial “preschool,” in which geologists were taught how to interpret physical uncertainty and the basics of elementary particles and physicists were taught about Earth’s interior. Once they gained basic knowledge of one another’s fields, the scientists could begin to work together.

    This is far from the first interdisciplinary community within science or even particle physics. Ludhova likens it to the field of radiology: There is one expert to take an X-ray and another to determine a plan of action once all the information is clear. Similarly, particle physicists know how to take the necessary measurements, and geologists know what kinds of questions they could answer about our planet.

    Right now, only two major experiments are looking for geoneutrinos: KamLAND at the Kamioka Observatory in Japan and Borexino at the Gran Sasso National Laboratory in Italy. Between the two of them, these observatories detect fewer than 20 geoneutrinos a year.

    KamLAND
    KamLAND at the Kamioka Observatory in Japan

    INFN/Borexino Solar Neutrino detector, Gran Sasso, Italy
    INFN/Borexino Solar Neutrino detector, Gran Sasso, Italy

    Between the two of them, these observatories detect fewer than 20 geoneutrinos a year.

    Because of the limited results, geoneutrino physics is by necessity a small discipline: According to McDonough, there are only about 25 active neutrino researchers with a deep knowledge of both geology and physics.

    Over the next decade, though, several more neutrino detectors are anticipated, some of which will be much larger than KamLAND or Borexino. The Jiangmen Underground Neutrino Observatory (JUNO) in China, for example, should be ready in 2020.

    JUNO Neutrino detector China
    JUNO Neutrino detector China

    Whereas Borexino’s detector is made up of 300 tons of active material, and KamLAND’s contains 1000, JUNO’s will have 20,000 tons.

    The influx of data over the next decade will allow the community to emerge into the larger scientific scene, Bellini says. “There are some people who say ‘now this is a new era of science’—I think that is exaggerated. But I do think that we have opened a new chapter of science in which we use the methods of particle physics to study the Earth.”

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    Symmetry is a joint Fermilab/SLAC publication.


     
  • richardmitnick 1:15 pm on October 10, 2016 Permalink | Reply
    Tags: , , Geology, Intertropical Convergence Zone, Paleoceanography, Paleography   

    From Eos: “Simulating the Climate 145 Million Years Ago” 

    Eos news bloc

    Eos

    10.10.16
    Shannon Hall

    A new model shows that the Intertropical Convergence Zone wasn’t always a single band around the equator, which had drastic effects on climate.

    1
    Upper Jurassic (145- to 160-million-year-old) finely laminated organic carbon-rich shale interspersed with homogeneous, low-carbon mudrock of the Kimmeridge Clay Formation in Kimmeridge Bay, England. Variation in rock type reflects the ocean response to a monsoon-like climate 30°N during the Late Jurassic. Credit: Howard Armstrong

    The United Kingdom was once a lush oasis. That can be read from sediments within the Kimmeridge Clay Formation, which were deposited around 160 to 145 million years ago on Dorset’s “Jurassic Coast.” A favorite stomping ground for fossil hunters and the source rock for North Sea oil, the formation is rich in organic matter, which suggests that it likely formed when global greenhouse conditions were at least 4 times higher than present levels.

    Normally, organic matter disappears rapidly after an organism dies, as the nutrients are consumed by other life forms and the carbon decays. However, when the seas are starved of oxygen, which occurs when plankton numbers swell owing to increasing levels of carbon dioxide, then organic matter is preserved. An abundance of so-called black shales, or organic-rich muds, within the Kimmeridge Clay Formation points to this past.

    Here Armstrong et al. used those black shales to build new climate simulations that better approximate the climate toward the end of the Jurassic period. The model simulated 1422 years of time that suggested a radically different Intertropical Convergence Zone—the region where the Northern and Southern Hemisphere trade winds meet—than the one today. The convergence of these trade winds produces a global belt of clouds near the equator and is responsible for most of the precipitation on Earth.

    2
    This figure shows the path (in red) of the Intertropical Convergence Zone as it forks, where the Pacific Ocean met the western coast of the American continents. Credit: Armstrong et al. [2016]

    Today the Intertropical Convergence Zone in the Atlantic strays, at most, 12° away from the equator. However, 145 million years ago, when the continents were still much closer together, the model showed that the zone split, like a fork in the road, where the Pacific Ocean met the western coast of the American continents. The zone was driven apart by the proto-Appalachian mountain range to the north and the North African mountains to the south. The northern fork, which was much stronger than the southern one, extended as far as about 30° north, passing over the United Kingdom and the location of the Kimmeridge Clay Formation.

    Not only were the researchers able to verify that the United Kingdom was once a tropical oasis, but they were also able to simulate and map the climate 145 million years ago—research that will help scientists better understand how Earth will react to anthropogenic warming today and in the future. (Paleoceanography, doi:10.1002/2015PA002911, 2016)

    See the full article here .

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