A Library of Elastic Tensors for Lowermost Mantle Seismic Anisotropy Studies and Comparison with Seismic Observations

Elastic Tensor Library Information All metadata is included in the pdf file for descriptions of each elastic tensor. The exact mechanism for lowermost mantle seismic anisotropy remains unknown; however, work on the elasticity and deformation of lower mantle materials has constrained a few possible options. The most probable minerals producing anisotropy are bridgmanite, post-perovskite, and ferropericlase. While there is an extensive literature on the elasticity and deformation of lower mantle minerals, we create a comprehensive uniform database of D” anisotropy scenarios. In order to characterize a range of the possible fabrics for D” anisotropy, we carry out VPSC (visco-plastic self-consistent modeling) to predict textures for each proposed mineral and dominant slip system. We numerically deform each mineral under different geometrical scenarios: simple shear, pure shear, and extension. By using published single crystal elasticity values, we produce a library of 336 candidate elastic tensors.

弹性张量库信息：所有元数据均收录于各弹性张量说明对应的PDF文件中。下地幔底部地震各向异性的确切成因至今仍未明确，但针对下地幔物质的弹性与形变开展的研究已缩小了若干可能的候选方向。最可能产生各向异性的矿物为布里奇曼石（bridgmanite）、后钙钛矿（post-perovskite）以及铁方镁石（ferropericlase）。尽管现有大量关于下地幔矿物弹性与形变的研究文献，但我们仍构建了一套覆盖D″层各向异性情景的统一综合数据库。为表征D″层各向异性的各类潜在晶格组构，我们采用黏塑性自洽模型（visco-plastic self-consistent modeling，VPSC），对每种候选矿物及其主导滑移系统的晶格组构进行预测。我们通过数值模拟，对各矿物在简单剪切、纯剪切及拉伸三种不同几何形变情景下的形变过程进行模拟。结合已发表的单晶弹性参数，我们最终构建了包含336个候选弹性张量的数据库。