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  • richardmitnick 1:53 pm on July 29, 2015 Permalink | Reply
    Tags: , , Geology   

    From ASU Via KJZZ: “Debate Continues Over Age Of The Grand Canyon” 

    ASU Bloc

    ASU

    KJZZ
    1

    July 27, 2015
    Melissa Sevigny

    1
    A view from the South Rim of the Grand Canyon. (Photo by Melissa Sevigny – KNAU)

    New research supports the long-held hypothesis that the Grand Canyon is as young as 6 million years. That’s what geologists originally believed before a different study claimed it was tens of millions of years older.

    The study, which was conducted by geologists at Arizona State University, compares the western Grand Canyon with the Grand Wash Cliffs. It found that the canyon is steeper than the cliffs, which suggests erosion started more recently.

    “So our conclusion is that it’s younger than the activity on the Grand Wash Fault,” said Andrew Darling, lead author of the study. “If the canyon’s younger than the fault, that would be consistent with the 6 million year old canyon age.”

    A previous study in 2012 revitalized research and debate when it claimed the Grand Canyon might be as old as 70 million years. That study looked at the decay of radioactive elements in rocks. The ASU study looked at geomorphology, particularly erosion rates.

    See the full article here.

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    ASU is the largest public university by enrollment in the United States.[11] Founded in 1885 as the Territorial Normal School at Tempe, the school underwent a series of changes in name and curriculum. In 1945 it was placed under control of the Arizona Board of Regents and was renamed Arizona State College.[12][13][14] A 1958 statewide ballot measure gave the university its present name.
    ASU is classified as a research university with very high research activity (RU/VH) by the Carnegie Classification of Institutions of Higher Education, one of 78 U.S. public universities with that designation. Since 2005 ASU has been ranked among the Top 50 research universities, public and private, in the U.S. based on research output, innovation, development, research expenditures, number of awarded patents and awarded research grant proposals. The Center for Measuring University Performance currently ranks ASU 31st among top U.S. public research universities.[15]

    ASU awards bachelor’s, master’s and doctoral degrees in 16 colleges and schools on five locations: the original Tempe campus, the West campus in northwest Phoenix, the Polytechnic campus in eastern Mesa, the Downtown Phoenix campus and the Colleges at Lake Havasu City. ASU’s “Online campus” offers 41 undergraduate degrees, 37 graduate degrees and 14 graduate or undergraduate certificates, earning ASU a Top 10 rating for Best Online Programs.[16] ASU also offers international academic program partnerships in Mexico, Europe and China. ASU is accredited as a single institution by The Higher Learning Commission.

    ASU Tempe Campus
    ASU Tempe Campus

     
  • richardmitnick 9:36 am on July 23, 2015 Permalink | Reply
    Tags: , Geology,   

    From OSU: “Satellites peer into rock 50 miles beneath Tibetan Plateau” 

    OSU

    Ohio State University

    July 21, 2015
    Pam Frost Gorder

    1
    Topography (left) and a shaded relief map (right) of the rock deep beneath the Tibetan Plateau. Color indicates kilometers below Earth’s surface. Image by Younghong Shin of the Korea Institute of Geosciences and Mineral Resource, courtesy of The Ohio State University.

    Gravity data captured by satellite has allowed researchers to take a closer look at the geology deep beneath the Tibetan Plateau.

    The analysis, published in the journal Nature Scientific Reports, offers some of the clearest views ever obtained of rock moving up to 50 miles below the plateau, in the lowest layer of Earth’s crust.

    There, the Indian tectonic plate presses continually northward into the Eurasian tectonic plate, giving rise to the highest mountains on Earth—and deadly earthquakes, such as the one that killed more than 9,000 people in Nepal earlier this year.

    The study supports what researchers have long suspected: Horizontal compression between the two continental plates is the dominant driver of geophysical processes in the region, said C.K. Shum, professor and Distinguished University Scholar in the Division of Geodetic Science, School of Earth Sciences at The Ohio State University and a co-author of the study.

    “The new gravity data onboard the joint NASA-German Aerospace Center GRACE gravimeter mission and the European Space Agency’s GOCE gravity gradiometer missionenabled scientists to build global gravity field models with unprecedented accuracy and resolution, which improved our understanding of the crustal structure,” Shum said. “Specifically, we’re now able to better quantify the thickening and buckling of the crust beneath the Tibetan Plateau.”

    NASA Grace
    NASA/Grace

    ESA GOCE Spacecraft
    ESA/GOCE

    Younghong Shin

    Shum is part of an international research team led by Younghong Shin of the Korea Institute of Geosciences and Mineral Resource. With other researchers in Korea, Italy and China, they are working together to conduct geophysical interpretations of the Tibetan Plateau geodynamics using the latest combined gravity measurements by the GOCE gravity gradiometer and the GRACE gravimeter missions.

    Satellites such as GRACE and GOCE measure small changes in the force of gravity around the planet. Gravity varies slightly from place to place in part because of an uneven distribution of rock in Earth’s interior.

    The resulting computer model offers a 3-D reconstruction of what’s happening deep within the earth.

    As the two continental plates press together horizontally, the crust piles up. Like traffic backing up on a congested freeway system, the rock follows whatever side roads may be available to relieve the pressure.

    But unlike cars on a freeway, the rock beneath Tibet has two additional options for escape. It can push upward to form the Himalayan mountain chain, or downward to form the base of the Tibetan Plateau.

    The process takes millions of years, but caught in the 3-D image of the computer model, the up-and-down and side-to-side motions create a complex interplay of wavy patterns at the boundary between the crust and the mantle, known to researchers as the Mohorovičić discontinuity, or “Moho.”

    “What’s particularly useful about the new gravity model is that it reveals the Moho topography is not random, but rather has a semi-regular pattern of ranges and folds, and agrees with the ongoing tectonic collision and current crustal movement measured by GPS,” Shin said.

    As such, the researchers hope that the model will provide new insights into the analysis of collisional boundaries around the world.

    Co-author Carla Braitenberg of the University of Trieste said that the study has already helped explain one curious aspect of the region’s geology: the sideways motion of the Tibetan Plateau. While India is pushing the plateau northward, GPS measurements show that portions of the crust are flowing eastward and even turning to the southeast.

    “The GOCE data show that the movement recorded at the surface has a deep counterpart at the base of the crust,” Braitenberg said. Connecting the rock flow below to movement above will help researchers better understand the forces at work in the region.

    Those same forces led to the deadly Nepal earthquake in April 2015. But Shum said that the new model almost certainly won’t help with earthquake forecasting—at least not in the near future.

    “I would say that we would understand the mechanism more if we had more measurements,” he said, but such capabilities “would be very far away.”

    Even in California—where, Shum pointed out, different tectonic processes are at work than in Tibet—researchers are unable to forecast earthquakes, despite having abundant GPS, seismic and gravity data. Even less is known about Tibet, in part because the rough terrain makes installing GPS equipment difficult.

    Other co-authors on the study included Sang Mook Lee of Seoul National University; Sung-Ho Na of the University of Science and Technology in Daejeon, Korea;

    Kwang Sun Choi of Pusan National University; Houtse Hsu of the Institute of Geodesy & Geophysics, Chinese Academy of Sciences; and Young-Sue Park and Mutaek Lim of the Korea Institute of Geosciences and Mineral Resource.

    This research was supported by the Basic Research Project of the Korea Institute of Geoscience and Mineral Resources, funded by the Ministry of Science, ICT and Future Planning of Korea. Shum was partially supported by NASA’s GRACE Science Team Program and Concept in Advanced Geodesy Program. Braitenberg was partially supported by the European Space Agency’s Center for Earth Observation as part of the GOCE User ToolBox project.

    See the full article here.

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  • richardmitnick 8:20 am on June 5, 2015 Permalink | Reply
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    From Michigan Tech: “Clues to the Earth’s Ancient Core” 

    Michigan Tech bloc

    Michigan Technical University

    June 4, 2015
    Allison Mills

    1
    Aleksey Smirnov drills into an outcrop in Australia’s Widgiemooltha dike swarm.

    Old rocks hold on to their secrets. Now, a geophysicist at Michigan Technological University has unlocked clues trapped in the magnetic signatures of mineral grains in those rocks.. These clues will help clear up the murky history of the Earth’s early core.

    The journal Earth and Planetary Science Letters published a paper on the subject earlier this year. Aleksey Smirnov, an associate professor of geophysics and adjunct associate professor of physics at Michigan Tech, led the study. The work is a part of a large research program led by Smirnov and supported by the National Science Foundation (NSF), including his CAREER Award, a prestigious NSF grant. Through this work, he has traveled the world seeking rocks that provide insight into the ancient earth’s core.

    Earth’s Ancient Geodynamo

    The magnetic field comes from the earth’s core: The solid inner core, made of iron, spins and powers convective currents in the liquid outer core. Those currents create the magnetic field, and the system is called the geodynamo.

    “At any point, the field can be described by its direction and strength,” Smirnov says, adding that the modern magnetic field is weaker than that of a refrigerator magnet and that intensity has changed throughout geologic time. “What we call paleointensity in our paper refers to the field’s strength,” he explains.

    Smirnov and his co-author, David Evans of Yale University, examined the paleointensity measurements of rocks more than two billion years old. Rocks that old record a magnetic field from a rather mysterious geodynamo.

    That’s because the core didn’t always have a solid center — it used to be all liquid. And being liquid would make for a weak, chaotic magnetic field.

    “What happened at some point, because the earth is constantly cooling, the center formed a small, solid inner core,” Smirnov says. “But this event is uncertain in terms of timing.”

    A number of models analyze what this timing could have been, but they estimate any time between half a billion years ago and three billion years ago — which is like saying an adolescent will hit puberty sometime between ages 8 to 30. To better pinpoint the timing of the inner core’s formation, Smirnov scours the world for old Precambrian rocks.

    Magnetic Records in Rocks

    Smirnov focuses on rocks that are not just old, but magnetic, and he tests the samples in the Earth Magnetism Lab at Michigan Tech. Within the lab is a room, built above the concrete floor and boxed in with a special steel alloy — it’s a metal-free zone. Inside the room, Smirnov uses a magnetometer: a device that measures magnetic properties in rocks and, more specifically, their iron-rich minerals.

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    Magnetite is an iron oxide with magnetic properties, and when it crystallizes in a rock, it records the strength and orientation of the earth’s magnetic field. Some rocks record this better than others; an ideal rock cools fast and is well-preserved.

    “Because of the rarity of well-preserved extrusive Precambrian rocks,” Smirnov writes in his paper, “relatively quickly cooled shallow intrusions such as mafic dikes and sills represent an attractive alternative target for paleointensity studies.”

    The rocks Smirnov and his team sampled in Australia’s Widgiemooltha dike swarm are the best available, considering the cluster of intrusive rock formations has been eroded, buried and baked over the past two billion years. The dike swarm is important because the Widgiemooltha rocks, collected from 24 different field sites, contain key magnetite grains. After some time in the lab’s magnetometer, the minerals begin to reveal their long-held magnetic secrets.

    Basal Mantle Ocean and Beyond

    Given the rocks’ age and the chaotic nature of the early magnetic field, Smirnov predicted the paleointensity recorded in the magnetite grains would be weak. However, he and his team found the paleointensity readings were relatively strong.

    “This contradicts the models that show a young solid inner core — and right now, that’s a mystery,” Smirnov says. Although, he adds, there is a new theory that is consistent with this data.

    In the basal mantle ocean theory, the boundary between the solid mantle — the bulk of earth’s interior — and the early earth’s core could have been swaddled in a dense layer of partially melted rock. The difference in composition and density could have been enough to jumpstart a stronger magnetic field.

    Delving deeper into the core’s evolution has significance beyond the earth’s interior, too. The magnetic field helps protect life on earth from cosmic radiation. Understanding the ancient geodynamo could also expand our knowledge of earth’s earliest life. Smirnov plans to study that connection — and more exceptionally old rocks — in the next leg of his research.

    See the full article here.

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    Michigan Tech Campus
    Michigan Technological University (http://www.mtu.edu) is a leading public research university developing new technologies and preparing students to create the future for a prosperous and sustainable world. Michigan Tech offers more than 130 undergraduate and graduate degree programs in engineering; forest resources; computing; technology; business; economics; natural, physical and environmental sciences; arts; humanities; and social sciences.
    The College of Sciences and Arts (CSA) fills one of the most important roles on the Michigan Tech campus. We play a part in the education of every student who comes through our doors. We take pride in offering essential foundational courses in the natural sciences and mathematics, as well as the social sciences and humanities—courses that underpin every major on campus. With twelve departments, 28 majors, 30-or-so specializations, and more than 50 minors, CSA has carefully developed programs to suit many interests and skill sets. From sound design and audio technology to actuarial science, applied cognitive science and human factors to rhetoric and technical communication, the college offers many unique programs.

     
  • richardmitnick 1:21 pm on April 6, 2015 Permalink | Reply
    Tags: , Geology, , Sinkholes   

    From livescience: “Why Dangerous Sinkholes Keep Appearing Along the Dead Sea” 

    Livescience

    April 06, 2015
    Tanya Lewis

    1
    Credit: Eli Raz

    For millennia, the salty, mineral-rich waters of the Dead Sea have drawn visitors and health pilgrims to its shores. But in recent years, gaping chasms have been opening up without warning along its banks, posing a threat to such visitors and tourism in general.

    4
    Satellite photograph showing the location of the Dead Sea

    Nestled between Israel and the Palestinian territories to the west, and Jordan to the east, the Dead Sea is famous for is extreme salinity (34 percent salt, almost 10 times as salty as the ocean), and for having the lowest elevation on Earth, at 1,407 feet (429 meters) below sea level.

    But for the past few decades, the sea has been shrinking rapidly, due to the diversion of water from the Jordan River (which feeds the Dead Sea) and mineral mining from its waters in the south. The water’s surface is currently receding by about 3 feet (1 m) per year, according to Hanan Ginat, a geologist and academic chairman of the Dead Sea and Arava Research Center, in Israel.

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    For the past few decades, the sea has been receding by about 3 feet (1m) per year, due to the diversion of water from the Jordan River (which feeds the Dead Sea) and mineral mining from its waters in the south. As the briny water recedes, fresh groundwater wells up and dissolves layers of salt, creating large underground cavities, above which sinkholes form. (Image credit: Eli Raz)

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    Geologist Eli Raz of Israel’s Dead Sea and Arava Research Center has studied the sinkhole problem in depth. Raz found that many of the craters developed along seismic fault lines in the Jordan Rift Valley. Inside these faults, the dissolved salts are less stable and more susceptible to invading freshwater, which hollows out the gaping holes, Raz’s studies suggest. (Image credit: Eli Raz)

    As the briny water recedes, fresh groundwater wells up and dissolves layers of salt, creating large underground cavities, above which sinkholes form. The holes can open up without warning, Ginat told Live Science. “We’re looking for systems to forecast where they will happen, but it’s very complicated,” he added.

    The main reason for the Dead Sea’s decline is diversion of water from the Jordan River, which used to provide about 450 billion gallons (1.7 billion cubic meters), but now only provides about 20 percent of that, Ginat said. A factory called Dead Sea Works, which pumps out seawater to harvest its salts and minerals, plays a role in the problem, he said.

    Ginat’s colleague at Dead Sea and Arava Research Center, geologist Eli Raz, has studied the sinkhole problem in depth. Raz found that many of the craters developed along seismic fault lines in the Jordan Rift Valley. Inside these faults, the dissolved salts are less stable and more susceptible to invading freshwater, which hollows out the gaping holes, Raz’s studies suggest.

    The sinkholes were first noticed in the 1970s, but have been forming more rapidly in recent years. The holes are dangerous for people who visit or live in the area, and while no one has been killed, the problem should be taken seriously, researchers warn. The sinkholes can reach up to 82 feet (25 m) deep and 131 feet (40 m) in diameter, and nearby holes sometimes join to form giant ones, according to Raz and his colleagues. More than 4,000 sinkholes exist today, mostly on the sea’s western shores, Ginat said.

    However, there may be a way to stave off the Dead Sea’s decline. Authorities have proposed a canal that would run from the Red Sea to the Dead Sea, called the Red Sea-Dead Sea Conduit, which, in addition to providing water to Jordan, Israel and the Palestinian territories, would bring salt water to the Dead Sea and generate electricity to supply its own energy. Israel and Jordan approved the first stage of the project last month, Ginat said.

    “You can’t stop the sinkholes,” Ginat said. But when people plan roads, buildings and other infrastructure, they should take note of the research, “and choose where to put things [based on] the knowledge we have about the sinkholes,” he said.

    Other areas of the world are also home to puzzling sinkholes. For instance, in Siberia, at least seven giant craters have been found since 2014, which scientists believe to be the result of the explosive release of methane gas from melting permafrost. Researchers have called for urgent investigation of the craters out of safety concerns.

    See the full article here.

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  • richardmitnick 9:32 am on January 14, 2015 Permalink | Reply
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    From astrobio.net: “Rare Mineral found in a Wisconsin Crater” 

    Astrobiology Magazine

    Astrobiology Magazine

    Jan 14, 2015
    Aaron L. Gronstal

    1
    With support from the NASA Astrobiology Program, Cavosie brought students from the University of Puerto Rico to study outcrops at the Rock Elm meteorite impact structure. Reidite was found in the samples they collected. Credit: Aaron Cavosie

    Scientists have discovered one of the rarest minerals on Earth in a Wisconsin impact crater.

    Aaron Cavosie of the University of Puerto Rico, and member of the NASA Astrobiology Institute Team at the University of Wisconsin, brought students to an impact site in Rock Elm, Wisconsin to collect samples. In those samples, Cavosie and colleagues discovered the mineral reidite, making Rock Elm the fourth site on Earth where the mineral has been found in nature.

    Reidite is created at high pressures and was first identified in the laboratory in the 1960s. The conditions in which reidite forms have been well-constrained by experiments in the lab but, prior to Rock Elm, it was only found naturally in the Chesapeake Bay Impact Structure (Virginia), the Ries Crater (Germany), and the Xiuyan Crater (China).

    The Rock Elm structure is 6.5 kilometers in diameter and was formed during the Middle Ordovician. This means that the reidite found at Rock Elm is at least 450 million years old, making it the oldest preserved reidite yet discovered.

    Another important aspect of the research is that the reidite was found in sandstone – the first time the mineral was spotted in this type of rock. There are many other impact structures that have been formed in sandstone, and its possible that a re-examination of these sites could reveal more reidite.

    “I get the sense that, because reidite had never been found in this kind of rock, if something’s never found there, your not going to go look for it purposefully,” said Cavosie in an interview with Wisconsin Public Radio. “Now that we’ve identified this recorder of even far more extreme impact conditions than what was known previously at Rock Elm, that tool can be applied to many, many other localities to try to recreate the impact conditions and better understand the effects on the surface environments of some of these impacts.”

    Wisconsin Public Radio produced an interview with Aaron Cavosie and Bill Cordua of UW-River Falls, who discovered the Rock Elm disturbance. To listen to the show, visit: http://www.wpr.org/listen/682916

    The initial findings were presented at the 2014 GSA Annual Meeting in Vancouver.

    See the full article here.

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  • richardmitnick 10:00 pm on January 2, 2015 Permalink | Reply
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    From U Chicago: “Modern genetics confirm ancient relationship between fins and hands” 

    U Chicago bloc

    University of Chicago

    December 29, 2014
    John Easton

    Paleontologists have documented the evolutionary adaptations necessary for ancient lobe-finned fish to transform pectoral fins used underwater into strong, bony structures, such as those of Tiktaalik roseae. This enabled these emerging tetrapods, animals with limbs, to crawl in shallow water or on land. But evolutionary biologists have wondered why the modern structure called the autopod—comprising wrists and fingers or ankles and toes—has no obvious morphological counterpart in the fins of living fishes.

    t
    Tiktaalik

    In the Dec. 22, 2014, issue of the Proceedings of the National Academy of Sciences, researchers argue previous efforts to connect fin and fingers fell short because they focused on the wrong fish. Instead, they found the rudimentary genetic machinery for mammalian autopod assembly in a non-model fish, the spotted gar, whose genome was recently sequenced.

    “Fossils show that the wrist and digits clearly have an aquatic origin,” said Neil Shubin, the Robert R. Bensley Distinguished Service Professor of Organismal Biology and Anatomy and a leader of the team that discovered Tiktaalik in 2004. “But fins and limbs have different purposes. They have evolved in different directions since they diverged. We wanted to explore, and better understand, their connections by adding genetic and molecular data to what we already know from the fossil record.”

    Initial attempts to confirm the link based on shape comparisons of fin and limb bones were unsuccessful. The autopod differs from most fins. The wrist is composed of a series of small nodular bones, followed by longer thin bones that make up the digits. The bones of living fish fins look much different, with a set of longer bones ending in small circular bones called radials.

    The primary genes that shape the bones, known as the HoxD and HoxA clusters, also differ. The researchers first tested the ability of genetic “switches” that control HoxD and HoxA genes from teleosts—bony, ray-finned fish—to shape the limbs of developing transgenic mice. The fish control switches, however, did not trigger any activity in the autopod.

    Teleost fish—a vast group that includes almost all of the world’s important sport and commercial fish—are widely studied. But researchers began to realize they were not the ideal comparison for studies of how ancient genes were regulated. When they searched for wrist and digit-building genetic switches, they found “a lack of sequence conservation” in teleost species.

    They traced the problem to a radical change in the genetics of teleost fish. More than 300 million years ago, after the fish-like creatures that would become tetrapods split off from other bony fish, a common ancestor of the teleost lineage went through a whole-genome duplication—a phenomenon that has occurred multiple times in evolution.

    By doubling the entire genetic repertoire of teleost fish, this WGD provided them with enormous diversification potential. This may have helped teleosts to adapt, over time, to a variety of environments worldwide. In the process, “the genetic switches that control autopod-building genes were able to drift and shuffle, allowing them to change some of their function, as well as making them harder to identify in comparisons to other animals, such as mice,” said Andrew Gehrke, a graduate student in the Shubin Lab and lead author of the study.

    Not all bony fishes went through the whole genome duplication, however. The spotted gar, a primitive freshwater fish native to North America, split off from teleost fishes before the WGD.

    When the research team compared Hox gene switches from the spotted gar with tetrapods, they found “an unprecedented and previously undescribed level of deep conservation of the vertebrate autopod regulatory apparatus.” This suggests, they note, a high degree of similarity between “distal radials of bony fish and the autopod of tetrapods.”

    They tested this by inserting gar gene switches related to fin development into developing mice. This evoked patterns of activity that were “nearly indistinguishable,” the authors note, from those driven by the mouse genome.

    “Overall,” the researchers conclude, “our results provide regulatory support for an ancient origin of the ‘late’ phase of Hox expression that is responsible for building the autopod.”

    This study was supported by the Brinson Foundation, the National Science Foundation, the Brazilian National Council for Scientific and Technological Development grants, the National Institutes of Health, the Volkswagen Foundation in Germany, the Alexander von Humboldt-Foundation, the Spanish and Andalusian governments, and Proyecto de Excelencia.

    Additional authors include Mayuri Chandran and Tetsuya Nakamura from the University of Chicago; Igor Schneider from the Instituto de Ciencias Biologicas, Universida de Federal do Para, Belem, Brazil; Elisa de la Calle-Mustienes, Juan J. Tena, Carlos Gomez-Marin and José Luis Gómez-Skarmeta from the Centro Andaluz de Biología del Desarrollo, Sevilla, Spain; and Ingo Braasch and John H. Postlethwait from the Institute of Neuroscience, University of Oregon.

    See the full article here.

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    An intellectual destination

    One of the world’s premier academic and research institutions, the University of Chicago has driven new ways of thinking since our 1890 founding. Today, UChicago is an intellectual destination that draws inspired scholars to our Hyde Park and international campuses, keeping UChicago at the nexus of ideas that challenge and change the world.

     
  • richardmitnick 8:45 am on December 20, 2014 Permalink | Reply
    Tags: , Geology, ,   

    From Leeds: “Scientists observe the Earth grow a new layer under an Icelandic volcano” 

    Leeds

    University of Leeds

    15 December 2014
    No Writer Credit

    New research into an Icelandic eruption has shed light on how the Earth’s crust forms, according to a paper published today in Nature.

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    When the Bárðarbunga volcano, which is buried beneath Iceland’s Vatnajökull ice cap, reawakened in August 2014, scientists had a rare opportunity to monitor how the magma flowed through cracks in the rock away from the volcano.

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    The molten rock forms vertical sheet-like features known as dykes, which force the surrounding rock apart.

    Study co-author Professor Andy Hooper from the Centre for Observation and Modelling of Earthquakes, volcanoes and Tectonics (COMET) at the University of Leeds explained: “New crust forms where two tectonic plates are moving away from each other. Mostly this happens beneath the oceans, where it is difficult to observe.

    “However, in Iceland this happens beneath dry land. The events leading to the eruption in August 2014 are the first time that such a rifting episode has occurred there and been observed with modern tools, like GPS and satellite radar.”

    Although it has a long history of eruptions, Bárðarbunga has been increasingly restless since 2005. There was a particularly dynamic period in August and September this year, when more than 22,000 earthquakes were recorded in or around the volcano in just four weeks, due to stress being released as magma forced its way through the rock.

    Using GPS and satellite measurements, the team were able to track the path of the magma for over 45km before it reached a point where it began to erupt, and continues to do so to this day. The rate of dyke propagation was variable and slowed as the magma reached natural barriers, which were overcome by the build-up of pressure, creating a new segment.

    The dyke grows in segments, breaking through from one to the next by the build up of pressure. This explains how focused upwelling of magma under central volcanoes is effectively redistributed over large distances to create new upper crust at divergent plate boundaries, the authors conclude.

    As well as the dyke, the team found ‘ice cauldrons’ – shallow depressions in the ice with circular crevasses, where the base of the glacier had been melted by magma. In addition, radar measurements showed that the ice inside Bárðarbunga’s crater had sunk by 16m, as the volcano floor collapsed.

    COMET PhD student Karsten Spaans from the University of Leeds, a co-author of the study, added: “Using radar measurements from space, we can form an image of caldera movement occurring in one day. Usually we expect to see just noise in the image, but we were amazed to see up to 55cm of subsidence.”

    Like other liquids, magma flows along the path of least resistance, which explains why the dyke at Bárðarbunga changed direction as it progressed. Magma flow was influenced mostly by the lie of the land to start with, but as it moved away from the steeper slopes, the influence of plate movements became more important.

    Summarising the findings, Professor Hooper said: “Our observations of this event showed that the magma injected into the crust took an incredibly roundabout path and proceeded in fits and starts.

    “Initially we were surprised at this complexity, but it turns out we can explain all the twists and turns with a relatively simple model, which considers just the pressure of rock and ice above, and the pull exerted by the plates moving apart.

    The paper Segmented lateral dyke growth in a rifting event at Bárðarbunga volcanic system, Iceland is published in Nature on 15 December 2014.

    The research leading to these results has received funding from the European Community’s Seventh Framework Programme under Grant Agreement No. 308377 (Project FUTUREVOLC).

    Read the paper here: http://www.nature.com/nature/journal/vaop/ncurrent/full/nature14111.html

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    The University of Leeds was founded in 1904, but its origins go back to t­he nineteenth century with the founding of the Leeds School of Medicine in 1831 and then the Yorkshire College of Science in 1874.

    1

     
  • richardmitnick 7:44 pm on December 18, 2014 Permalink | Reply
    Tags: , Geology, ,   

    From Princeton: “New, tighter timeline confirms ancient volcanism aligned with dinosaurs’ extinction” 

    Princeton University
    Princeton University

    December 18, 2014
    Morgan Kelly, Office of Communications

    A definitive geological timeline shows that a series of massive volcanic explosions 66 million years ago spewed enormous amounts of climate-altering gases into the atmosphere immediately before and during the extinction event that claimed Earth’s non-avian dinosaurs, according to new research from Princeton University.

    A primeval volcanic range in western India known as the Deccan Traps, which were once three times larger than France, began its main phase of eruptions roughly 250,000 years before the Cretaceous-Paleogene, or K-Pg, extinction event, the researchers report in the journal Science. For the next 750,000 years, the volcanoes unleashed more than 1.1 million cubic kilometers (264,000 cubic miles) of lava. The main phase of eruptions comprised about 80-90 percent of the total volume of the Deccan Traps’ lava flow and followed a substantially weaker first phase that began about 1 million years earlier.

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    A definitive geological timeline from Princeton University researchers shows that a series of massive eruptions 66 million years ago in a primeval volcanic range in western India known as the Deccan Traps played a role in the extinction event that claimed Earth’s non-avian dinosaurs, and challenges the dominant theory that a meteorite impact was the sole cause of the extinction. Pictured above are the Deccan Traps near Mahabaleshwar, India. (Image courtesy of Gerta Keller, Department of Geosciences)

    The results support the idea that the Deccan Traps played a role in the K-Pg extinction, and challenge the dominant theory that a meteorite impact near present-day Chicxulub, Mexico, was the sole cause of the extinction. The researchers suggest that the Deccan Traps eruptions and the Chicxulub impact need to be considered together when studying and modeling the K-Pg extinction event.

    The Deccan Traps’ part in the K-Pg extinction is consistent with the rest of Earth history, explained lead author Blair Schoene, a Princeton assistant professor of geosciences who specializes in geochronology. Four of the five largest extinction events in the last 500 million years coincided with large volcanic eruptions similar to the Deccan Traps. The K-Pg extinction is the only one that coincides with an asteroid impact, he said.

    “The precedent is there in Earth history that significant climate change and biotic turnover can result from massive volcanic eruptions, and therefore the effect of the Deccan Traps on late-Cretaceous ecosystems should be considered,” Schoene said.

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    DeccanTrap_map
    The researchers suggest that the Deccan Traps eruptions and the meteorite impact near present-day Chicxulub, Mexico, need to be considered together when studying and modeling the Cretaceous-Paleogene extinction event. The main eruption phases for the Deccan Traps (in brown), which were once three times larger than France, began roughly 250,000 years before the extinction event, the researchers found. For the next 750,000 years, the volcanoes unleashed more than 1.1 million cubic kilometers (264,000 cubic miles) of lava, which comprised about 80-90 percent of the total volume of the Deccan Traps’ lava flow. The amount of carbon dioxide and sulfur dioxide the volcanoes poured out would have caused severe ecological fallout. (Illustration by Matilda Luk, Office of Communications)

    The researchers used a precise rock-dating technique to narrow significantly the timeline for the start of the main eruption, which until now was only known to have occurred within 1 million years of the K-Pg extinction, Schoene said. The Princeton group will return to India in January to collect more samples with the purpose of further constraining eruption rates during the 750,000-year volcanic episode.

    Schoene and his co-authors gauged the age of petrified lava flows known as basalt by comparing the existing ratio of uranium to lead given the known rate at which uranium decays over time. The uranium and lead were found in tiny grains — less than a half-millimeter in size — of the mineral zircon. Zircon is widely considered Earth’s best “time capsule” because it contains a lot of uranium and no lead when it crystallizes, but it is scarce in basalts that cooled quickly. The researchers took the unusual approach of looking for zircon in volcanic ash that had been trapped between lava flows, as well as within thick basalt flows where lava would have cooled more slowly.

    The zircon dated from these layers showed that 80-90 percent of the Deccan Traps eruptions occurred in less than a million years, and began very shortly — in geological terms — before the K-Pg extinction. To produce useful models for events such as the K-Pg extinction, scientists want to know the sequence of events to within tens of thousands of years or better, not millions, Schoene said. Margins of millions of years are akin to “a history book with events that have no dates and are not written in chronological order,” he said.

    “We need to know which events happened first and how long before other events, such as when did the Deccan eruptions happen in relation to the K-Pg extinction,” Schoene said. “We’re now able to place a higher resolution timeframe on these eruptions and are one step closer to finding out what the individual effects of the Deccan Traps eruptions were relative to the Chicxulub meteorite.”

    Vincent Courtillot, a geophysicist and professor at Paris University Diderot, said that the paper is important and “provides a significant improvement on the absolute dating of the Deccan Traps.” Courtillot, who is familiar with the Princeton work but had no role in it, led a team that reported in the Journal of Geophysical Research in 2009 that Deccan volcanism occurred in three phases, the second and largest of which coincides with the K-Pg mass extinction. Numerous other papers from his research groups are considered essential to the development of the Deccan Traps hypothesis. (The Princeton researchers also plan to test the three-phases hypothesis, Schoene said. Their data already suggests that the second and third phase might be a single period of eruptions bridged by smaller, “pulse” eruptions, he said.)

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    DeccanTrap_rocks
    The researchers took an unusual approach to find the mineral needed to construct the timeline for the start of the main Deccan Traps eruption. They compared the existing ratio of uranium to lead in petrified lava flows known as basalts given the known rate at which uranium decays over time. To have enough uranium, however, the researchers needed the mineral zircon, which is scarce in basalts that cooled quickly. Turning to new sources, the researchers found zircon in soil deposits known as red boles (right) that formed in between eruptions and contain volcanic ash (left) that had been trapped between lava flows. They also located zircon within thick basalt flows where lava would have cooled more slowly. (Images courtesy of Blair Schoene, Department of Geosciences)

    The latest work builds on the long-time work by co-author Gerta Keller, a Princeton professor of geosciences, to establish the Deccan Traps as a main cause of the K-Pg extinction. Virginia Tech geologist Dewey McLean first championed the theory 30 years ago and Keller has since become a prominent voice among a large group of scientists who advocate the idea. In 2011, Keller published two papers that together proposed a one-two punch of Deccan volcanism and meteorite strikes that ended life for more than half of Earth’s plants and animals.

    Existing models of the environmental effects of the Deccan eruptions used timelines two to three times longer than what the researchers found, which underestimated the eruptions’ ecological fallout, Keller explained. The amount of carbon dioxide and sulfur dioxide the volcanoes poured out would have produced, respectively, a long-term warming and short-term cooling of the oceans and land, and resulted in highly acidic bodies of water, she said.

    Because these gases dissipate somewhat quickly, however, a timeline of millions of years understates the volcanoes’ environmental repercussions, while a timeframe of hundreds of thousands of years — particularly if the eruptions never truly stopped — provides a stronger correlation. The new work confirms past work by placing the largest Deccan eruptions nearer the K-Pg extinction, but shows a much shorter time frame of just 250,000 years, Keller said.

    “These results have significantly strengthened the case for volcanism as the primary cause for the mass extinction, as well as for the observed rapid climate changes and ocean acidification,” Keller said.

    “The Deccan Traps mass extinction hypothesis has already enjoyed wide acceptance based on our earlier work and a number of studies have independently confirmed the global effects of Deccan volcanism just prior to the mass extinction,” she said. “The current results will go a long way to strengthen the earlier results as well as further challenge the dominance of the Chicxulub hypothesis.”

    Schoene and Keller worked with Kyle Samperton, a doctoral student in Schoene’s research group; Thierry Adatte, a geologist with the University of Lausanne in Switzerland and Keller’s longtime collaborator; Brian Gertsch, who earned his Ph.D. from Princeton in 2010 and is now a research assistant at the University of Lausanne; Syed Khadri, a geology professor at Amravati University in India; and graduate student Michael Eddy and geology professor Samuel Bowring at the Massachusetts Institute of Technology.

    The paper, U-Pb geochronology of the Deccan Traps and relation to the end-Cretaceous mass extinction, was published Dec. 11 in Science. This work was supported by the Princeton Department of Geosciences’ Scott Fund; the National Science Foundation’s Continental Dynamics and Sedimentary Geology and Paleobiology programs; and the NSF Office of International Science and Engineering’s India Program (grant nos. EAR-0447171 and EAR-1026271).

    See the full article here.

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  • richardmitnick 11:40 am on December 16, 2014 Permalink | Reply
    Tags: , Geology, ,   

    From AAAS: “Greenhouse emissions similar to today’s may have triggered massive temperature rise in Earth’s past” 

    AAAS

    AAAS

    15 December 2014
    Tim Wogan

    About 55.5 million years ago, a burst of carbon dioxide raised Earth’s temperature 5°C to 8°C, which had major impacts on numerous species of plants and wildlife. Scientists analyzing ancient soil samples now say a previous burst of the greenhouse gas preceded this event, known as the Paleocene-Eocene thermal maximum (PETM), and probably triggered it. Moreover, they believe humans are pumping similar levels of carbon dioxide into the atmosphere right now, raising concerns that our own emissions may also destabilize Earth’s climate, triggering the planet to emit devastating bursts of carbon in the future.

    2
    This figure is a simplified, schematic representation of the flows of energy between space, the atmosphere, and the Earth’s surface, and shows how these flows combine to trap heat near the surface and create the greenhouse effect. Energy exchanges are expressed in watts per square meter (W/m2) and derived from Kiehl & Trenberth (1997). The figure does not appear clear. I would change the 195 to atmospheric radiation into space, as it does not include the 40 radiated from the surface. Complete figure: (http://www.cgd.ucar.edu/cas/abstracts/files/kevin1997_1.html)

    The sun is responsible for virtually all energy that reaches the Earth’s surface. Direct overhead sunlight at the top of the atmosphere provides 1366 W/m2; however, geometric effects and reflective surfaces limit the light which is absorbed at the typical location to an annual average of ~235 W/m2. If this were the total heat received at the surface, then, neglecting changes in albedo, the Earth’s surface would be expected to have an average temperature of -18 °C (Lashof 1989). Of the surface heat captured by the atmosphere, more than 75% can be attributed to the action of greenhouse gases that absorb thermal radiation emitted by the Earth’s surface. The atmosphere in turn transfers the energy it receives both into space (38%) and back to the Earth’s surface (62%), where the amount transferred in each direction depends on the thermal and density structure of the atmosphere. This process by which energy is recycled in the atmosphere to warm the Earth’s surface is known as the greenhouse effect and is an essential piece of Earth’s climate. Under stable conditions, the total amount of energy entering the system from solar radiation will exactly balance the amount being radiated into space, thus allowing the Earth to maintain a constant average temperature over time.
    However, recent measurements indicate that the Earth is presently absorbing 0.85 ± 0.15 W/m2 more than it emits into space (Hansen et al. 2005). An overwhelming majority of climate scientists believe that this asymmetry in the flow of energy has been significantly increased by human emissions of greenhouse gases [1]. This figure was created by Robert A. Rohde from published data and is part of the Global Warming Art project

    1
    Rocks from the Bighorn Basin in Wyoming were used to reconstruct Earth’s climate at the time of the Paleocene-Eocene thermal maximum. (Scott Wing, Smithsonian Institution)

    The paper implies that even if we stopped emitting carbon dioxide right now, our descendants might still face huge temperature rises, says paleoclimatologist Gabriel Bowen of the University of Utah in Salt Lake City, the lead author of the new research. “It is a possibility,” he says, “and it’s a scary one.”

    Scientists accept that a massive injection of carbon into the atmosphere caused the PETM, but they don’t agree about where the gas came from. Some researchers say it originated from the release of carbon locked up under the ocean by an undersea landslide; others blame a comet crashing into Earth, causing carbon from both the comet and Earth to be oxidized to carbon dioxide and potentially causing wildfires or burning of carbon-rich peat bogs on Earth. They also don’t know how long the release lasted, with recent estimates ranging from 10 years to 20,000 years.

    One of the best ways to measure the prehistoric release of carbon into the atmosphere is to look at the ratio of two types of carbon atoms called isotopes. Carbon has two stable isotopes: About 99% of natural carbon is carbon-12, whereas the remaining 1% is mainly the heavier carbon-13, with trace amounts of radioactive carbon-14 that decay within a few thousand years to nitrogen. Living organisms have a slight preference for the lighter isotope, so carbon derived from organic sources (such as fossil fuels) is slightly depleted in carbon-13. If that carbon gets returned to the atmosphere at a faster rate than normal, atmospheric carbon dioxide has less carbon-13 than normal. Plants taking up this carbon dioxide become even more carbon-13 depleted, and when they decompose, this depletion is recorded in the soil.

    Sedimentary rock samples that have been compacted from soils formed at the time of the PETM contain less carbon-13 than normal. Sedimentary rocks of the Bighorn Basin in Wyoming contain one of the best records of soils from this period. Geologists have studied them for more than 100 years, but to obtain samples from soils of different periods, geologists had to analyze surface rocks from different parts of the basin and try to piece together a continuous geological history. Therefore, the Bighorn Basin Coring Project, run by the University of New Hampshire, Durham, drilled approximately 1 km of core from each of three different points in the basin to give geologists three clear, continuous records of how the soils had varied over time in a particular place.

    Bowen and colleagues analyzed one of these cores, tracking the variations in carbon isotope ratios in greater detail than had been previously possible by examining surface rocks. They report online today in Nature Geoscience that in soils beneath those laid down during the main rise in temperature about 55.5 million years ago, there was a distinct drop in the proportion of carbon-13. In soils immediately on top of these, the ratio seemed to recover to its normal value. Finally, soils on top of these showed a large drop in the proportion of carbon-13 corresponding to the PETM itself.

    So what was going on? The researchers concluded that there must have been two separate releases of carbon. The first, smaller release, about 2000 years before the main temperature rise, was followed by a recovery to normal climatic conditions. Later, a second, larger pulse caused the main event. “I’m fairly convinced that they’re related,” Bowen says. “We see nothing remotely similar during the many hundreds of thousands of years before this event. To have within a few thousand years these two major carbon isotope shifts and have that be circumstantial would be quite remarkable.”

    The researchers used climate models to investigate how the initial, smaller heating could have triggered the later surge in temperature. They estimate that the first thermal pulse is likely to have warmed Earth’s atmosphere by 2°C to 3°C, but that the atmospheric temperature would have gradually returned to normal as the heat was absorbed into the deep ocean. However, when that heat finally reached the ocean floor, it might have melted methane ices called clathrates, releasing the methane into the ocean and allowing it to make its way into the atmosphere. As a greenhouse gas, methane is 21 times more potent than carbon dioxide, so a sudden spike in methane emissions could lead to huge climate change.

    “The connection between these two pulses is something that it’s going to be really important to get a handle on,” Bowen says. The researchers believe the rate at which carbon dioxide escaped into the atmosphere during both bursts is unlikely to have been greater than the rate at which humans are emitting it now, and it may have been considerably lower. “Carbon release back then looked a lot like human fossil fuel emissions today,” Bowen says. “So we might learn a lot about the future from changes in climate, plants, and animal communities 55.5 million years ago.”

    “We think this is really good news for our contention that the release of carbon was very fast,” says marine geologist James Wright of Rutgers University, New Brunswick, an advocate of the comet impact hypothesis.

    Wright is not convinced, however, about the importance of the first pulse in triggering the second. He suggests that the most logical interpretation of the apparent cooling after the first pulse is that its significance was less than Bowen’s group believes, with limited effect on the overall ocean temperature, and that not just the atmosphere but rather the entire planet quickly returned to normal. “If that’s the case, then the first has nothing to do with the second,” Wright says. That, in turn, would require an alternative explanation for the PETM such as a comet impact.

    See the full article here.

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  • richardmitnick 2:47 pm on December 10, 2014 Permalink | Reply
    Tags: , , , Geology, ,   

    From astrobio.net: “Warmer Pacific Ocean could release millions of tons of seafloor methane” 

    U Washington

    University of Washington

    December 9, 2014
    Hannah Hickey

    Off the West Coast of the United States, methane gas is trapped in frozen layers below the seafloor. New research from the University of Washington shows that water at intermediate depths is warming enough to cause these carbon deposits to melt, releasing methane into the sediments and surrounding water.

    Researchers found that water off the coast of Washington is gradually warming at a depth of 500 meters, about a third of a mile down. That is the same depth where methane transforms from a solid to a gas. The research suggests that ocean warming could be triggering the release of a powerful greenhouse gas.

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    Sonar image of bubbles rising from the seafloor off the Washington coast. The base of the column is 1/3 of a mile (515 meters) deep and the top of the plume is at 1/10 of a mile (180 meters) deep.Brendan Philip / UW

    “We calculate that methane equivalent in volume to the Deepwater Horizon oil spill is released every year off the Washington coast,” said Evan Solomon, a UW assistant professor of oceanography. He is co-author of a paper to appear in Geophysical Research Letters.

    While scientists believe that global warming will release methane from gas hydrates worldwide, most of the current focus has been on deposits in the Arctic. This paper estimates that from 1970 to 2013, some 4 million metric tons of methane has been released from hydrate decomposition off Washington. That’s an amount each year equal to the methane from natural gas released in the 2010 Deepwater Horizon blowout off the coast of Louisiana, and 500 times the rate at which methane is naturally released from the seafloor.

    Dissociation of Cascadia margin gas hydrates in response to contemporary ocean warming
    Geophysical Research Letters | Dec. 5, 2014

    “Methane hydrates are a very large and fragile reservoir of carbon that can be released if temperatures change,” Solomon said. “I was skeptical at first, but when we looked at the amounts, it’s significant.”

    Methane is the main component of natural gas. At cold temperatures and high ocean pressure, it combines with water into a crystal called methane hydrate. The Pacific Northwest has unusually large deposits of methane hydrates because of its biologically productive waters and strong geologic activity. But coastlines around the world hold deposits that could be similarly vulnerable to warming.

    “This is one of the first studies to look at the lower-latitude margin,” Solomon said. “We’re showing that intermediate-depth warming could be enhancing methane release.”
    map of Washington coast

    The yellow dots show all the ocean temperature measurements off the Washington coast from 1970 to 2013. The green triangles are places where scientists and fishermen have seen columns of bubbles. The stars are where the UW researchers took more measurements to check whether the plumes are due to warming water.Una Miller / UW

    Co-author
    Una Miller, a UW oceanography undergraduate, first collected thousands of historic temperature measurements in a region off the Washington coast as part of a separate research project in the lab of co-author Paul Johnson, a UW professor of oceanography. The data revealed the unexpected sub-surface ocean warming signal.

    “Even though the data was raw and pretty messy, we could see a trend,” Miller said. “It just popped out.”

    The four decades of data show deeper water has, perhaps surprisingly, been warming the most due to climate change.

    “A lot of the earlier studies focused on the surface because most of the data is there,” said co-author Susan Hautala, a UW associate professor of oceanography. “This depth turns out to be a sweet spot for detecting this trend.” The reason, she added, is that it lies below water nearer the surface that is influenced by long-term atmospheric cycles.

    The warming water probably comes from the Sea of Okhotsk, between Russia and Japan, where surface water becomes very dense and then spreads east across the Pacific. The Sea of Okhotsk is known to have warmed over the past 50 years, and other studies have shown that the water takes a decade or two to cross the Pacific and reach the Washington coast.

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    Map of the Sea of Okhotsk

    “We began the collaboration when we realized this is also the most sensitive depth for methane hydrate deposits,” Hautala said. She believes the same ocean currents could be warming intermediate-depth waters from Northern California to Alaska, where frozen methane deposits are also known to exist.

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    The yellow dots show all the ocean temperature measurements off the Washington coast from 1970 to 2013. The green triangles are places where scientists and fishermen have seen columns of bubbles. The stars are where the UW researchers took more measurements to check whether the plumes are due to warming water.Una Miller / UW

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    Researchers used a coring machine to gather samples of sediment off Washington’s coast to see if observations match their calculations for warming-induced methane release. The photo was taken in October aboard the UW’s Thomas G. Thompson research vessel.Robert Cannata / UW

    Warming water causes the frozen edge of methane hydrate to move into deeper water. On land, as the air temperature warms on a frozen hillside, the snowline moves uphill. In a warming ocean, the boundary between frozen and gaseous methane would move deeper and farther offshore. Calculations in the paper show that since 1970 the Washington boundary has moved about 1 kilometer – a little more than a half-mile – farther offshore. By 2100, the boundary for solid methane would move another 1 to 3 kilometers out to sea.

    Estimates for the future amount of gas released from hydrate dissociation this century are as high as 0.4 million metric tons per year off the Washington coast, or about quadruple the amount of methane from the Deepwater Horizon blowout each year.

    Still unknown is where any released methane gas would end up. It could be consumed by bacteria in the seafloor sediment or in the water, where it could cause seawater in that area to become more acidic and oxygen-deprived. Some methane might also rise to the surface, where it would release into the atmosphere as a greenhouse gas, compounding the effects of climate change.
    researchers on ship

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    Evan Solomon (right) and Marta Torres (left, OSU) aboard the UW’s Thomas G. Thompson research vessel in October, with fluid samples from the seafloor that will help answer whether the columns of methane bubbles are due to ocean warming.Robert Cannata / UW

    Researchers now hope to verify the calculations with new measurements. For the past few years, curious fishermen have sent UW oceanographers sonar images showing mysterious columns of bubbles. Solomon and Johnson just returned from a cruise to check out some of those sites at depths where Solomon believes they could be caused by warming water.

    “Those images the fishermen sent were 100 percent accurate,” Johnson said. “Without them we would have been shooting in the dark.”

    Johnson and Solomon are analyzing data from that cruise to pinpoint what’s triggering this seepage, and the fate of any released methane. The recent sightings of methane bubbles rising to the sea surface, the authors note, suggests that at least some of the seafloor gas may reach the surface and vent to the atmosphere.

    The research was funded by the National Science Foundation and the U.S. Department of Energy. The other co-author is Robert Harris at Oregon State University.

    See the full article here.

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