The boundary between the lithosphere and asthenosphere is associated with a platewide 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 that 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.
CITATION STYLE
Beghein, C., Yuan, K., Schmerr, N., & Xing, Z. (2014). Changes in seismic anisotropy shed light on the nature of the Gutenberg discontinuity. Science, 343(6176), 1237–1240. https://doi.org/10.1126/science.1246724
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