Determining vorticity axes from grain-scale dispersion of crystallographic orientations
Determining vorticity axes from grain-scale dispersion of crystallographic orientations
复制标题
根据晶体取向的晶粒尺度色散确定涡度轴
DOI：
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发表时间：
2015
期刊：
影响因子：
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通讯作者：
B. Tikoff
中科院分区：
文献类型：
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作者：
Z. Michels;S. Kruckenberg;Joshua R. Davis;B. Tikoff
运动剪切感指标是剪切带构造解释的重要工具。解释剪切感指标的适当平面是涡度法向面，这通常是通过织物（叶理、线理）方向推断出来的。然而，应变模型表明，这种织物在确定运动框架时可能不可靠。我们展示了一种新的定量方法的应用，晶体涡度轴（CVA）分析，利用旋转统计从晶体取向在晶粒尺度上计算色散轴。我们应用CVA分析样品从三个剪切区，表现出不同的运动学和变形几何。在所有情况下，计算出的晶粒尺度弥散轴的总和在试样尺度上产生晶体涡度的首选轴，该轴与独立确定的体涡度轴一致。这种新方法可以独立于片理和线理信息来评估涡度轴的位置，并且不需要对变形的运动学进行假设。
Kinematic shear sense indicators are critical tools for tectonic interpretation of shear zones. The appropriate plane in which to interpret shear sense indicators is the vorticity normal surface, which is often inferred using fabric (foliation, lineation) orientation. Strain modeling, however, suggests that such fabrics can be unreliable for determining a kinematic framework. We demonstrate the application of a new quantitative method, crystallographic vorticity axis (CVA) analysis, that utilizes rotation statistics to calculate dispersion axes from crystallographic orientations at the grain scale. We apply CVA analysis to samples from three shear zones that exhibit distinct kinematics and deformation geometries. In all cases, the aggregate of calculated grain-scale dispersion axes yields a preferred axis of crystallographic vorticity at the specimen scale that is coincident with the independently determined bulk vorticity axis. This new method allows the position of vorticity axes to be evaluated independently of foliation and lineation information, and without assumptions about the kinematics of deformation.