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Geophysics and Tectonics Seminar spring-2019

New Insights into the Seismic Structure and Evolution of the North American Upper Mantle

May 29, 2019, noon - 1 p.m.
Geology 1707

Presented By:
Walter Mooney
USGS

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I present new seismic images of the key structural elements of the upper mantle beneath North America. These images are significantly different from all previous studies. Unlike earlier work, we successfully image the cratonic lithosphere-asthenosphere boundary (LAB), and the 250-km-deep Lehmann discontinuity. We identify a pronounced, if enigmatic, low velocity layer (LVL) above the mantle transition zone (410-discontinuity). These results have important implications for the evolution of the upper mantle.