Keyword: tectonics
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In the 1960-70s, every geology textbook was rewritten, as the previous verities were DESTROYED! Alfred Wegner (1880-1930) was, posthumously, proven correct, in the face of the academia that scoffed at him. What was needed, was the mechanism, that the technology of WW2 provided.
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Earth is far from a solid mass of rock. The outer layer of our planet – known as the lithosphere – is made up of more than 20 tectonic plates; as these gargantuan slates glide about the face of the planet, we get the movement of continents, and interaction at the boundaries, not least of which is the rise and fall of entire mountain ranges and oceanic trenches. Yet there's some debate over what causes these giant slabs of rock to move around in the first place. Amongst the many hypotheses put forward over the centuries, convection currents generated by...
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A group of University of Wyoming professors and students has identified an unusual belt of igneous rocks that stretches for over 2,000 miles from British Columbia, Canada, through Idaho, Montana, Nevada, southeast California and Arizona to Sonora, Mexico. “Geoscientists usually associate long belts of igneous rocks with chains of volcanoes at subduction zones, like Mount Shasta, Mount Hood, Mount St. Helens and Mount Rainer,” says Jay Chapman, an assistant professor in UW’s Department of Geology and Geophysics. “What makes this finding so interesting and mysterious is that this belt of igneous rocks is located much farther inland, away from the...
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The first emergence and persistence of continental crust on Earth during the Archaean (4 billion to 2.5 billion years ago) has important implications for plate tectonics, ocean chemistry and biological evolution. This happened about a half-billion years earlier than previously thought, according to new research being presented at the EGU General Assembly 2021.Once land becomes established through dynamic processes like plate tectonics, it begins to weather and add crucial minerals and nutrients to the ocean. A record of these nutrients is preserved in the ancient rock record. Previous research used strontium isotopes in marine carbonates, but these rocks are usually...
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The small Monterey County town of Parkfield boasts a lofty title: the earthquake capital of the world.
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[S]eismic researchers have discovered the underside of a rocky slab of Earth's surface layer, or lithosphere, that has been pulled more than 400 miles beneath northeastern China by the process of tectonic subduction. The study, published by a team of Chinese and U.S. researchers in Nature Geoscience, offers news evidence about what happens to water-rich oceanic tectonic plates as they are drawn through Earth's mantle beneath continents. Rice University seismologist Fenglin Niu, a co-corresponding author, said the study provides the first high-resolution seismic images of the top and bottom boundaries of a rocky, or lithospheric, tectonic plate within a key...
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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...
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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...
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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...
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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...
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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...
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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...
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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...
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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...
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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...
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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...
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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...
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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.
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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,...
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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...
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