Long-Lived Interactions

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Science  03 Jan 2003:
Vol. 299, Issue 5603, pp. 13
DOI: 10.1126/science.299.5603.13d

Subduction is an efficient method to transport larger ions that prefer to reside in Earth's crust, such as potassium and barium (Ba), into the mantle, where higher pressures and temperatures lead to chemical reactions and structural transformations of mineral phases. Catlos and Sorensen (p. 92) have measured the 40Ar-39Ar ages of distinct Ba-enriched regions of mica grains from two former subduction zones to estimate the temporal extent of fluid-rock reactions. The results suggest that fluid-rock reactions occurred in these subduction zones over time scales of 25 to 60 million years. Thus, the microscopic changes in the minerals can be used to trace the megascopic changes in the crust and mantle over long time periods.

CREDIT: CATLOS AND SORENSON CREDIT: (TOP TO BOTTOM) COWEN ET AL.;.

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