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WITHDRAWN Effects of Olivine Fabric Type on Seismic Anisotropy in the Mantle Wedge: A Wavefield Modeling Case Study

Description: 

WITHDRAWN Shear wave splitting (SWS) observations of core-refracted phases (XKS) can potentially constrain upper mantle dynamics, strain geometries, and deformation conditions, based on the relationships between strain and anisotropy for the different types of olivine fabric that could occur. Parameters that describe SWS (the fast splitting direction and the delay time between fast and slow quasi-S waves), only provide an integrated view of anisotropic fabrics traversed along the XKS path. Given the poor depth resolution of core phases, constraining the origin of anisotropy, or even the individual contribution of a specific depth region, is challenging for XKS phases. However, global wavefield simulations provide an effective tool to explore the individual and combined influence of different anisotropic regions on the splitting of XKS waveforms for synthetic models. This can be particularly helpful in complex regions such as subduction systems, in which observed XKS splits can potentially be affected by anisotropy in the overriding lithospheric plate, the mantle wedge, the lithospheric slab, and the sub-slab asthenosphere. The goal of this work is to carry out synthetic modeling of XKS splitting measurements in a generic subduction zone setting to explore the potential contributions from different olivine fabric types in different portions of the subduction system on the expected XKS SWS pattern. We implement a series of forward models in the AxiSEM3D wavefield modeling framework. Specifically, we investigate the effects on splitting parameters for different combinations of A-, B-, and E-type olivine above and below the slab, with a particular focus on the SWS patterns due to mantle wedge anisotropy and the related conditions that can be inferred from the occurrence of the different fabric types. This work will help to improve our understanding of how SWS measurements reveal deformation and dynamics in subduction systems.

Session: Earth’s Structure from the Crust to the Core [Poster]

Type: Poster

Date: 4/16/2025

Presentation Time: 08:00 AM (local time)

Presenting Author: Eric

Student Presenter: No

Invited Presentation: 

Poster Number: 99

Authors