Mountainous Fib: Andes Lie About Their Age: Page 2


The discovery is especially appreciated by geologists studying the nearby Altiplano, which appears to have a very different history.

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“The Puna and other Altiplano look similar, but they have different mechanisms,” said Carmala Garzione, professor and chair of the Department of Earth and Environmental Sciences at the University of Rochester. “There are fundamentally different processes that are leading to the uplift.”

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Both are part of the uplift caused by the subduction of ocean crust under the South American continent. But there are other things going on to thicken the crust and cause the mountains to buoy especially high in the Andes compared to other subduction zones.

The Altiplano, for instance, has a large, high basin. Whereas the Puna has several smaller basins. This, to Garzione, suggests that the Puna has been shortened, or squeezed, which could play a role in its earlier high elevation.

“The next step will be to get more geophysical data to get more information at depth,” said Garzione. Seismic data could help show the structures inside and under the mountains to explain the history even better. There is historic seismic data from the 1990s that is being reprocessed by other researchers to learn more about the subsurface, she said.

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