In-situ measurement of texture development rate in CaIrO3 post-perovskite
In-situ measurement of texture development rate in CaIrO3 post-perovskite
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DOI：
10.1016/j.pepi.2016.05.007
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发表时间：
2016-08-01
影响因子：
2.3
通讯作者：
Mariani, Elisabetta
中科院分区：
文献类型：
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作者：
Hunt, Simon A.;Walker, Andrew M.;Mariani, Elisabetta
后钙钛矿变形过程中晶体择优取向(CPO)的发展速度对解释地幔下部的地震各向异性是至关重要的，但后钙钛矿的稳定场阻碍了对其进行高应变变形实验。因此，为了限制后钙钛矿中CPO的发展速度，我们将CaIrO3，一种后钙钛矿后镁硅的低压类似物，在3.2 Gpa和400℃的简单剪切下变形为0.81的剪切应变(伽马)。从变形过程中获得的X射线衍射图，我们反转了CPO作为应变的函数。通过比较粘塑性自洽(VPSC)模型的CPO，我们将CaIrO_3中非主滑移系的临界分辨剪应力(CRSS)约束为比主滑移系[100](010)强6倍的数量级。这个值比以前的研究假设的要小得多，如果适用于MgSiO_3，则意味着D‘’层中的地震各向异性的发展比之前假设的要慢。(C)2016年提交人。爱思唯尔出版公司(Elsevier B.V.)
The rate of crystallographic preferred orientation (CPO) development during deformation of post-perovskite is crucial in interpreting seismic anisotropy in the lowermost mantle but the stability field of MgSiO3 post-perovskite prevents high-strain deformation experiments being performed on it. Therefore, to constrain the rate of CPO development in post-perovskite, we deformed CaIrO3, a low-pressure analogue of MgSiO3 post-perovskite, in simple shear at 3.2 GPa and 400 degrees C to a shear strain (gamma) of 0.81. From X-ray diffraction patterns acquired during deformation, we invert for CPO as a function of strain. By comparing the CPO that develops with visco-plastic self-consistent (VPSC) models we constrain the critical resolved shear stresses (CRSS) of the non-primary slip-systems in CaIrO3 to be of order 6 times stronger than the primary [100](010) slip system. This value is significantly less than has been assumed by previous studies and if applicable to MgSiO3 implies that seismic anisotropy in the D '' layer develops slower than has previously been assumed. (C) 2016 The Authors. Published by Elsevier B.V.