With its snow-capped mountain peaks, rugged rock formations and largely untouched natural beauty, the Rocky Mountains have attracted scientists and recreationists for many years.
Despite the mountains’ overwhelming presence, scientists have speculated over the past several decades as to how the Rockies were actually formed nearly 80 to 55 million years ago — a time when the range would have been considered oceanfront property.
However, an 8-member @@8-member?@@team of scientists and geologists from four different universities across the nation believe they may be one step closer to providing an answer to this question.
Eugene Humphreys, a University geophysics professor who co-authored the study, described the formation of the Rockies as a delamination event in which the bottom portion of the North American Plate’s lithosphere, the Earth’s upper layer, came into contact with the Pacific Plate.@@you’re going to want to look up and see whether “plate” is capitalized@@ Over time, Humphreys said the North American Plate deteriorated, peeled and collapsed as the force between the two plates increased over time, causing it to sink into a magnetic, liquid-rich combination of magma and ocean water. This then forced the asthenosphere — a thick, underlying layer of fragile rock — to ascend and push up the remaining surface material.@@http://directory.uoregon.edu/telecom/directory.jsp?p=findpeople%2Ffind_results&m=staff&d=person&b=name&s=Eugene+Humphreys@@
Although the process of delamination is not particularly unusual and can be attributed to creating the southern portion of the Sierra Nevada mountain range and Oregon’s Wallowa Mountains, Humphreys said it is particularly interesting that the team was able to catch the process of delamination in progress.
“I doubt that it is unique; it just happens that we caught it in the process of delaminating, which to my knowledge has never been imaged before,” said Alan Levander, a Rice University geology and geophysics professor and lead author of the study. “The idea has been around since the 1980s, but evidence has been inconclusive or equivocal because of insufficient data.”@@http://www.glacier.rice.edu/faculty/levander/@@
To create a new type of data to support this theory, the research team applied tomography techniques similar to those used in CT scans and combined it with data from USArray, a network of observatories that monitor tectonic plate motion throughout the continental United States. Humphreys said these methods allowed the team to look more than 200 miles beneath the surface of the earth to create a visual picture that documents the detachment of the North American Plate.
“To a geologist, (it) may all be happening very quickly, but for most of us, in our human lives, this process would be very slow,” Humphreys said. “It may take a million years or something like that.”
Although the future repercussions of this process are not exactly clear, Levander said the delamination process would likely stop once all of the upper mantle attached to the delaminating crust begins to sink. As a result, Levander said a new gradient would be created at the top of the asthenosphere, which might cause the entire delamination process to occur in another area.
University geologist may have found formation origins of Rocky Mountains
Daily Emerald
May 8, 2011
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