Foundering lithosphere imaged beneath the southern Sierra Nevada, California, USA.

Boyd, Oliver S; Jones, Craig H; Sheehan, Anne F · Science · 2004

basic_science · Level V

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Abstract

Seismic tomography reveals garnet-rich crust and mantle lithosphere descending into the upper mantle beneath the southeastern Sierra Nevada. The descending lithosphere consists of two layers: an iron-rich eclogite above a magnesium-rich garnet peridotite. These results place descending eclogite above and east of high P wave speed material previously imaged beneath the southern Great Valley, suggesting a previously unsuspected coherence in the lithospheric removal process.