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Keyword: tectonics

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  • The Earth’s interior is teeming with dead plates

    10/19/2017 10:14:29 AM PDT · by MtnClimber · 18 replies
    Ars Technica ^ | 18 Oct, 2017 | HOWARD LEE
    Last week, scientists released a monumental interactive catalog that tracks 94 ancient tectonic plates lurking deep within Earth’s mantle, a resource they’re calling an “Atlas of the Underworld.” Although scientists have known for decades that tectonic plates plunge into the Earth’s interior at subduction zones, until recently, those plates disappeared off the geological map once they stopped generating earthquakes, which happens after they’re around 670km below the surface. In the last few years, seismic tomography, which uses waves from earthquakes to make images of the planet’s interior, has restored their visibility. It has revealed subducted plates sinking in the mantle...
  • Large meteorite impacts drove plate-tectonic processes on the early Earth

    10/12/2017 1:03:40 PM PDT · by JimSEA · 15 replies
    Psys.org ^ | 9/26/17 | C. O’Neill
    An international study led by researchers at Macquarie University has uncovered the ways in which giant meteorite impacts may have helped to kick-start our planet's global tectonic processes and magnetic field. The study, being published in the premier journal Nature Geoscience, explores the effect of meteorite bombardment, in geodynamic simulations of the early Earth. Our results indicate that giant meteorite impacts in the past could have triggered events where the solid outer section of the Earth sinks into the deeper mantle at ocean trenches – a process known as subduction. This would have effectively recycled large portions of the Earth's...
  • Extreme geothermal activity discovered beneath New Zealand’s Southern Alps

    06/03/2017 6:45:31 AM PDT · by JimSEA · 37 replies
    Science Daily ^ | 6/1/2017 | Rupert Sutherland, et al
    An international team, including University of Southampton scientists, has found unusually high temperatures, greater than 100°C, close to Earth's surface in New Zealand -- a phenomenon typically only seen in volcanic areas such as Iceland or Yellowstone, USA. The researchers made the discovery while boring almost a kilometre into the Alpine Fault, the major tectonic boundary between the Australian and Pacific plates -running the length of the country's South Island. The team was working to better understand what happens at a tectonic plate boundary in the build-up to a large earthquake. The Deep Fault Drilling Project (DFDP) borehole, was drilled...
  • New theory on how Earth's crust was created

    05/08/2017 1:25:53 PM PDT · by JimSEA · 28 replies
    Science Daily ^ | 5/5/2017 | Don R. Baker, et al
    More than 90% of Earth's continental crust is made up of silica-rich minerals, such as feldspar and quartz. But where did this silica-enriched material come from? And could it provide a clue in the search for life on other planets? Conventional theory holds that all of the early Earth's crustal ingredients were formed by volcanic activity. Now, however, McGill University earth scientists Don Baker and Kassandra Sofonio have published a theory with a novel twist: some of the chemical components of this material settled onto Earth's early surface from the steamy atmosphere that prevailed at the time. First, a bit...
  • Diamond’s 2-billion-year growth charts tectonic shift in early Earth’s carbon cycle

    02/24/2017 6:09:37 PM PST · by JimSEA · 8 replies
    Science Daily ^ | 2/23/2017 | S. Timmerman
    A study of tiny mineral 'inclusions' within diamonds from Botswana has shown that diamond crystals can take billions of years to grow. One diamond was found to contain silicate material that formed 2.3 billion years ago in its interior and a 250 million-year-old garnet crystal towards its outer rim, the largest age range ever detected in a single specimen. Analysis of the inclusions also suggests that the way that carbon is exchanged and deposited between the atmosphere, biosphere, oceans and geosphere may have changed significantly over the past 2.5 billion years. 'Although a jeweller would consider diamonds with lots of...
  • Heat from Earth’s core could be underlying force in plate tectonics

    01/19/2017 7:30:36 AM PST · by MtnClimber · 38 replies
    University of Chicago ^ | 17 Jan, 2017 | Greg Borzo
    For decades, scientists have theorized that the movement of Earth’s tectonic plates is driven largely by negative buoyancy created as they cool. New research, however, shows plate dynamics are driven significantly by the additional force of heat drawn from the Earth’s core. The new findings also challenge the theory that underwater mountain ranges known as mid-ocean ridges are passive boundaries between moving plates. The findings show the East Pacific Rise, the Earth’s dominant mid-ocean ridge, is dynamic as heat is transferred. David B. Rowley, professor of geophysical sciences at the University of Chicago, and fellow researchers came to the conclusions...
  • Seismically active Katmandu region in store for larger earthquake

    12/06/2016 12:23:49 AM PST · by JimSEA · 7 replies
    Phys.org ^ | 12/05/2016 | Steve Wesnousky of the University of Nevada
    An earthquake much more powerful and damaging than last year's 7.8 magnitude quake could rock Katmandu and the Himalayan Frontal Fault, an international team of seismic experts has concluded. The unsettling news comes after field research and analysis in the year following the 2015 Gorkha earthquake, which killed 9,000 people and destroyed 600,000 structures throughout the region. Read more at: http://phys.org/news/2016-12-seismically-katmandu-region-larger-earthquake.html#jCp "We conducted a number of paleoearthquake studies in the vicinity of Katmandu in the past year, digging trenches and studying soils and faultlines looking back over the past 2,000 years," Wesnousky said. "Coupled with the historical record, it's apparent...
  • Rip in crust drives undersea volcanism

    11/16/2016 8:01:44 AM PST · by JimSEA · 26 replies
    Science Daily ^ | 11/14/2016 | Lamont-Doherty Earth Observatory
    Scientists analyzing a volcanic eruption at a mid-ocean ridge under the Pacific have come up with a somewhat contrarian explanation for what initiated it. Many scientists say undersea volcanism is triggered mainly by upwelling magma that reaches a critical pressure and forces its way up. The new study says the dominant force, at least in this case, was the seafloor itself -- basically that it ripped itself open, allowing the lava to spill out. The eruption took place on the East Pacific Rise, some 700 miles off Mexico. "Mid-ocean ridges are commonly viewed as seafloor volcanoes, operating like volcanoes on...
  • Life in ancient oceans enabled by erosion from land

    09/27/2016 2:27:11 PM PDT · by JimSEA · 12 replies
    Science Daily ^ | 9/28/2016 | University of Wisconsin-Madison
    As scientists continue finding evidence for life in the ocean more than 3 billion years ago, those ancient fossils pose a paradox. Organisms, including the single-celled bacteria living in the ocean at that early date, need a steady supply of phosphorus, but "it's very hard to account for this phosphorus unless it is eroding from the continents," says Aaron Satkoski, a scientist in the geoscience department at the University of Wisconsin-Madison. "So that makes it really hard to explain the fossils we see at this early era." Satkoski, who is first author of a new report on ocean chemistry from...
  • Deep 'scars' from ancient geological events play role in current earthquakes

    06/10/2016 4:36:30 PM PDT · by JimSEA · 21 replies
    Science Daily ^ | 6/10/2016 | Philip J. Heron, et al
    Super-computer modelling of Earth's crust and upper-mantle suggests that ancient geologic events may have left deep 'scars' that can come to life to play a role in earthquakes, mountain formation, and other ongoing processes on our planet. This changes the widespread view that only interactions at the boundaries between continent-sized tectonic plates could be responsible for such events. A team of researchers from the University of Toronto and the University of Aberdeen have created models indicating that former plate boundaries may stay hidden deep beneath the Earth's surface. These multi-million-year-old structures, situated at sites away from existing plate boundaries, may...
  • How the spectacular Hawaiian-Emperor seamount chain became so bendy

    05/12/2016 5:23:38 PM PDT · by JimSEA · 4 replies
    Science Daily ^ | 5/11/2016 | University of Sydney
    The physical mechanism causing the unique, sharp bend in the Hawaiian-Emperor seamount chain has been uncovered in a collaboration between the University of Sydney and the California Institute of Technology (Caltech). Led by a PhD candidate at the University of Sydney's School of Geosciences, researchers used the Southern Hemisphere's most highly integrated supercomputer to reveal flow patterns deep in the Earth's mantle -- just above the core -- over the past 100 million years. The flow patterns explain how the enigmatic bend in the Hawaiian-Emperor seamount chain arose. True to the old adage -- as above, so below -- the...
  • Embracing Catastrophic Plate Tectonics

    04/29/2016 8:22:42 AM PDT · by fishtank · 19 replies
    Institute for Creation Research ^ | May 2016 | Tim Clarey, Ph.D.
    Embracing Catastrophic Plate Tectonics by Tim Clarey, Ph.D. * Evidence for Creation Some Christians hesitate to embrace the notion that the earth’s outer surface is moving—and moved even more dramatically during the Flood year. However, tremendous amounts of empirical data suggest significant plate movement occurred just thousands of years ago.1 Much of these data are independent of secular deep time and the geologic timescale. In addition, the catastrophic plate tectonics (CPT) model offers a mechanism for the flooding of the continents, the subsequent lowering and draining of the floodwaters, and a cause for the post-Flood Ice Age.
  • How earthquakes might trigger faraway volcanoes

    04/28/2016 9:03:59 AM PDT · by JimSEA · 21 replies
    Science ^ | 4/26/2016 | Ian Randell
    On 14 April, a magnitude-6.2 earthquake struck the Japanese island of Kyushu. Two days later, Japanese officials reported towering plumes of smoke at Mount Aso, a volcano 42 kilometers away from the quake’s epicenter. A small eruption was occurring. Could the distant earthquake have triggered it? Mount Aso has had far bigger eruptions over the past few years, well before the earthquake occurred, so it was probably just a coincidence. But a new study concludes that the idea of so-called far-field triggering is not so far-fetched. Big earthquakes can slosh around the bubbly magma underneath volcanoes hundreds of kilometers away,...
  • Ancient tectonic activity was trigger for ice ages

    04/19/2016 2:48:05 PM PDT · by JimSEA · 19 replies
    Science Daily ^ | 4/19/2016 | Oliver Jagoutz, Francis A. Macdonald, Leigh Royden
    For hundreds of millions of years, Earth's climate has remained on a fairly even keel, with some dramatic exceptions: Around 80 million years ago, the planet's temperature plummeted, along with carbon dioxide levels in the atmosphere. The Earth eventually recovered, only to swing back into the present-day ice age 50 million years ago. Now geologists at MIT have identified the likely cause of both ice ages, as well as a natural mechanism for carbon sequestration. Just prior to both periods, massive tectonic collisions took place near the Earth's equator -- a tropical zone where rocks undergo heavy weathering due to...
  • Ancient rocks of Tetons formed by continental collisions

    02/01/2016 2:13:19 PM PST · by JimSEA · 36 replies
    Science Daily ^ | 1/29/2016 | Univ. of Wyoming
    University of Wyoming scientists have found evidence of continental collisions in Wyoming's Teton Range, similar to those in the Himalayas, dating to as early as 2.68 billion years ago. The research, published Jan. 22 in the journal Geochimica et Cosmochimica Acta, shows that plate tectonics were operating in what is now western Wyoming long before the collisions that created the Himalayas starting 40 million years ago. In fact, the remnants of tectonic activity in old rocks exposed in the Tetons point to the world's earliest known continent-continent collision, says Professor Carol Frost of UW's Department of Geology and Geophysics, lead...
  • [Earthquake] M7.2 - 91km N of Yelizovo, Russia

    01/30/2016 9:18:08 AM PST · by JimSEA · 12 replies
    USGS ^ | 1/30/2016 | USGS
    The January 30, 2016 M 7.2 earthquake beneath the Kamchatka Peninsula of Russia occurred as the result of oblique-normal faulting at a depth of 180 km. At the location of this earthquake, the Pacific plate is moving towards the west-northwest with respect to the North America and Eurasia plates at a rate of approximately 77 mm/yr. Note that some authors divide this region into several microplates that together define the relative motions between the larger Pacific, North America and Eurasia plates; these include the Okhotsk and Amur microplates that are respectively part of North America and Eurasia. The depth and...
  • Explosive underwater volcanoes were a major feature of 'Snowball Earth'

    01/21/2016 12:03:46 PM PST · by JimSEA · 16 replies
    Science Daily ^ | 1/18/2016 | University of Southampton
    Around 720-640 million years ago, much of the Earth's surface was covered in ice during a glaciation that lasted millions of years. Explosive underwater volcanoes were a major feature of this 'Snowball Earth', according to new research led by the University of Southampton. Many aspects of this extreme glaciation remain uncertain, but it is widely thought that the breakup of the supercontinent Rodinia resulted in increased river discharge into the ocean. This changed ocean chemistry and reduced atmospheric CO2 levels, which increased global ice coverage and propelled Earth into severe icehouse conditions. Because the land surface was then largely covered...
  • The Backwards Earthquakes

    12/19/2015 10:02:24 AM PST · by JimSEA · 29 replies
    Eos.org ^ | 12/15/2016 | Erin Ross
    Earthquakes in Idaho's panhandle are usually caused by the Earth's crust pulling apart. So why were earthquakes on 24 April pushing the crust together? Last April, a swarm of earthquakes shook the ground near Sandpoint, Idaho. Unused to shaking, Sandpoint’s residents took notice. So did local media, widely reporting on the events. But it wasn’t the size or location of the earthquakes that surprised scientists. Sandpoint lies along the Lewis and Clark Fault Zone, and previous earthquakes in the region were caused when the Earth’s crust pulled apart, which geologists call extension. But the earthquakes that struck on 24 April...
  • Indian Slab Lurches Downward Beneath Afghanistan

    11/02/2015 9:45:47 AM PST · by JimSEA · 10 replies
    AGU Blogosphere ^ | 10/25/2015 | Austin Elliot
    As I walked into the department this bright brisk morning, coffee cheerily in hand, the live global seismogram display in the atrium caught my eye with an alarming event that had just happened during my bike ride into work. *gasp* that looks bad *gasp* that looks bad BIG earthquake, somewhere in the vicinity of Central/Southern Asia. Indeed, an earthquake deep (>200 km) beneath the Hindu Kush mountains of Afghanistan had shaken a huge swath of Central and South Asia. The great depth of the earthquake meant less extreme shaking at the epicenter (nobody lives closer than 212 km from the...
  • Unexpected information about Earth's climate history from Yellow River sediment

    10/09/2015 10:35:39 AM PDT · by JimSEA · 14 replies
    Science Daily ^ | 10/9/2015 | Uppsala University
    By meticulously examining sediments in China's Yellow River, a Swedish-Chinese research group are showing that the history of tectonic and climate evolution on Earth may need to be rewritten. (Snip) Weathering of this eroded material also constitutes a further mechanism that may explain the reduced levels of atmospheric carbon dioxide at the beginning of the Ice Age. The researchers' next step will be to compare terrestrial and marine records of erosion to gauge how far sediment storage on land has impacted the marine record.