On the relation between seismic anisotropy and finite strain

摘要: Because seismic anisotropy in the upper mantle is due primarily to lattice preferred orientation (LPO) of olivine crystals induced by deformation, observations can provide constraints on deformation and flow. In this paper, we use a previously published theory for deformation-induced LPO (Ribe Yu, 1991) quantify relation between two model compositions: pure (dunite) aggregate, harzburgite comprising 70% 30% enstatite. Analytical numerical solutions governing equations show that predicted (and hence also anisotropy) depends only finite strain, not path which strain produced. The magnitude ratios c1/c2 c2 /c3, where c1 > c3 are lengths principle axes ellipsoid, directions maximum minimum compressional wave velocity Vp coincide with c1. c3, respectively. We calculate percent anisotropies compresional shear waves propagating along three as functions axial our compositions. However, inferences obtained using these results likely be estimates because neglects effects dynamic recrystallization. Finally, present, byproduct study new direct method calculating produced an arbitiary history.