Seismic anisotropy reveals crustal flow driven by mantle vertical loading in the Pacific NW.

ABSTRACT: Buoyancy anomalies within Earth's mantle create large convective currents that are thought to control the evolution of the lithosphere. While tectonic plate motions provide evidence for this relation, the mechanism by which mantle processes influence near-surface tectonics remains elusive. Here, we present an azimuthal anisotropy model for the Pacific Northwest crust that strongly correlates with high-velocity structures in the underlying mantle but shows no association with the regional mantle flow field. We suggest that the crustal anisotropy is decoupled from horizontal basal tractions and, instead, created by upper mantle vertical loading, which generates pressure gradients that drive channelized flow in the mid-lower crust. We then demonstrate the interplay between mantle heterogeneit

SUBMITTER: Castellanos JC 

PROVIDER: S-EPMC7439309 | biostudies-literature | 2020 Jul

REPOSITORIES: biostudies-literature