March 23, 2009

Earth’s crust melts easier than thought

U.S. geologists say they've determined that as rocks become hotter in the Earth's crust, they become better insulators but poorer conductors.

The University of Missouri scientists said their findings from a study of how well rocks conduct heat at different temperatures provide insights into how magmas are formed and will possibly lead to better models of continental collision and the formation of mountain belts.

These results shed important light on a geologic question: how large bodies of granite magma can be formed in Earth's crust, said Sonia Esperanca, a program director at the National Science Foundation, which funded the research.

University of Missouri geologist Alan Whittington said that in the presence of external heat sources, rocks heat up more efficiently than previously thought.

We applied our findings to computer models that predict what happens to rocks when they get buried and heat up in mountain belts, such as the Himalayas today or the Black Hills in South Dakota in the geologic past, he said. We found that strain heating, caused by tectonic movements during mountain belt formation, easily triggers crustal melting.

The findings were detailed in the journal Nature.