Modeling of Seismic Anisotropy Observations Reveals Plausible Lowermost Mantle Flow Directions Beneath Siberia

Observations of seismic anisotropy just above the core-mantle boundary are a powerful way to understand dynamics lowermost mantle. Here we present models in mantle beneath Siberia based on new and previously published body wave observations. We compile set measurements variety data types, including differential splitting SK(K)S-PKS S-ScS phases polarities PdP SdS reflections off D? discontinuity. carry out ray theoretical forward modeling these sets combination, using novel approach that allows for tighter constraints geometry than would be possible single type. each phase alone only provide limited information; by combining different types into one approach, can constrain more tightly. test range plausible mechanisms anisotropy, candidate minerals (bridgmanite, post-perovskite, ferropericlase), dominant slip systems, orientations, consider both single-crystal elasticity elastic tensors polycrystalline texture modeling. In general, find post-perovskite (with either [100](010) or [100](001) system) bridgmanite best fit The best-fitting suggest shear direction southwest northeast at base This is consistent with flow directed toward Perm anomaly, potentially driven slab remnants impinging boundary.