Report

Changes in Seismic Anisotropy Shed Light on the Nature of the Gutenberg Discontinuity

See allHide authors and affiliations

Science  27 Feb 2014:
1246724
DOI: 10.1126/science.1246724

You are currently viewing the abstract.

View Full Text

Log in to view the full text

Log in through your institution

Log in through your institution

Abstract

The boundary between the lithosphere and asthenosphere is associated with a plate-wide high seismic velocity “lid” overlying lowered velocities, consistent with thermal models. Seismic body waves also intermittently detect a sharp velocity reduction at similar depths, the Gutenberg (G) discontinuity, which cannot be explained by temperature alone. We compared an anisotropic tomography model with detections of the G to evaluate their context and relation to the lithosphere-asthenosphere boundary (LAB). We find that the G is primarily associated with vertical changes in azimuthal anisotropy and lies above a thermally controlled LAB, implying the two are not equivalent interfaces. The origin of the G is a result of frozen-in lithospheric structures, regional compositional variations of the mantle, or dynamically perturbed LAB.

View Full Text