Structural Analysis of Deformation Texture Crustal and Upper Mamtle Materials and Rheology of the Earth

我们分析了橄榄岩样品的结构，研究了上地幔的变形过程。由于橄榄石的择优取向，橄榄岩样品表现出7-8%的P波速度各向异性。为了确定橄榄岩中橄榄石的粒度分布、S面积、周长P和纵横比，对2000多个颗粒进行了统计分析。长径比、圆度和平均直径的平均值(和标准差)分别为1.83(0.48)、0.66(0.58)和59.1(52.7)微米。粒子参数的直方图一般符合伽玛分布函数。观察到粒子参数之间的相关性，例如周长与面积成正比，如P^&lt；α&gt；S^&lt；0.54&gt；橄榄石颗粒形状自相似，分维约为1.1。此外，对橄榄石的组构分析表明，大的残留颗粒与其滑移系统取向相反，不会发生变形。然而，细小的颗粒被再结晶，因为它们的取向不与滑移系相反。因此，颗粒大小取决于橄榄石的晶格取向。我们还分析了一种石灰岩的变形织构。确定了平行(XY平面)和垂直(XZ平面)面理的薄片的颗粒参数。在XZ面上线理清晰，但在XY面上未观察到线理，方解石呈等粒状。事实上，我们得到了XZ平面的平均长宽比和圆度分别为1.91和0.55，而XY平面的平均长宽比和圆度分别为1.68和0.57。

We analyzed texture of a peridotite sample, and investigated deformation process in the upper mantle. The peridotite sample shows P-wave velocity anisotropy of 7-8 % due to preferred orientation of olivine. In order to determine distribution of grain size, area S, perimeter P and aspect ratio of olivine in peridotite, more than 2000 grains are statistically analyzed. Average values (and standard deviations) of aspect ratio, roundness and mean diameter are I..83 (0.48), 0.66 (0.58) and 59.1 (52.7) mum, respectively. Histograms of the particle parameters generally fit to the Gamma distribution function. Correlation between particle parameters is observed ; e.g., perimeter is proportional to area as P^<alpha> S^<0.54>. The shapes of olivine grains are self-similar, and the fractal dimension is about 1.1. Further, fabric analysis of olivine shows that large relict grains are oriented against their slip systems and are not subject to deformation. However, small grains are recrystallized because their orientation is not against the slip systems. As such, grain size depends on lattice orientation of olivine.We also analyzed deformation texture of a limestone. Particle parameters were determined for the thin sections parallel (XY-plane) and perpendicular (XZ-plane) to the foliation. Lineation is clear in the XZ-plane ; however, no lineation is observed and calcite is equi-granular in the XY-plane. In fact, we obtain average aspect ratio and roundness of 1.91 and 0.55, respectively, for the XZ-plane, and of 1.68 and 0.57 for the XY-plane.