Geologists attempt to solve enigma why Colorado Plateau is rising

April 29, 2011 – COLORADO – A team of scientists led by Rice University has figured out why the Colorado Plateau — a 130,000-square-mile region that straddles Colorado, Utah, Arizona and New Mexico — is rising even while parts of its lower crust appear to be falling. The massive, tectonically stable region of the western United States has long puzzled geologists. A paper published April 27 in the journal Nature shows how magmatic material from the depths slowly rises to invade the lithosphere — Earth’s crust and strong uppermost mantle. This movement forces layers to peel away and sink, said lead author Alan Levander, professor and the Carey Croneis Chair in Geology at Rice University. The invading asthenosphere is two-faced. Deep in the upper mantle, between about 60 and 185 miles down, it’s usually slightly less dense and much less viscous than the overlying mantle lithosphere of the tectonic plates; the plates there can move over its malleable surface. Levander said the combined Colorado Plateau images show the convective “drip” of the lithosphere just north of the Grand Canyon; the lithosphere is slowly sinking several hundred kilometers into the Earth. That process may have helped create the canyon itself, as lifting of the plateau over the last 6 million years defined the Colorado River’s route. Levander said USArray has found similar down-wellings in two other locations in the American West; this suggests the forces deforming the lower crust and uppermost mantle are widespread. In both other locations, the down-wellings happened within the past 10 million years. “But under the Colorado Plateau, we have caught it in the act,” he said. “We had to find a trigger to cause the lithosphere to become dense enough to fall off,” Levander said. The partially molten asthenosphere is “hot and somewhat buoyant, and if there’s a topographic gradient along the asthenosphere’s upper surface, as there is under the Colorado Plateau, the asthenosphere will flow with it and undergo a small amount of decompression melting as it rises.” -Science Daily

According to geologists, subduction along North American plate was one of the triggers that ignited the San Juan volcanic fields under Colorado eons ago. The eruption of the La Garita Caldera super-volcano in Colorado still ranks as one of the largest eruptions ever known to have occurred on planet Earth. The eruption was so powerful; it is believed to have rained down ash as far away as the Caribbean. The Volcanic Explosivity Index highest eruption scale is 8- but it is believed the La Garita eruption was a 9.1 on this index- making it perhaps 11 times more powerful than even Yellowstone’s most magnificent eruption. La Garita is an extinct super-volcano but as these findings prove, geological forces are still very much alive under the state of Colorado. -The Extinction Protocol

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