Amorphous material in high strain experimental fault gouges
Amorphous material in high strain experimental fault gouges
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DOI：
10.1029/jb095ib10p15589
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发表时间：
1990-09
影响因子：
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通讯作者：
R. Yund;M. Blanpied;T. Tullis;J. Weeks
中科院分区：
文献类型：
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作者：
R. Yund;M. Blanpied;T. Tullis;J. Weeks
用透射电子显微镜观察了室温旋转剪切滑动实验中产生的胶泥的微观结构。通过在花岗岩、石英岩或大理石的地面上滑动来产生刨削，但有一项实验使用了1毫米厚的模拟刨削层。除了一个样品外，所有样品的滑动表面都加了水。结晶塑性过程在花岗岩和石英岩的断层泥中不起作用，在大理石中起次要作用。此外，花岗岩泥中含有5-60%的非晶态物质，石英岩泥中含有−50%的非晶态物质。在花岗岩样品中，无定形物质的组成通常位于富K和富Na，Ca的长石之间，尽管部分可能是富硅的。微观结构关系表明，非晶态材料是由碎块粉碎而不是熔化形成的。随着平均剪切应变的增加，非晶态物质的数量增加，最大的结晶碎片的尺寸减小，尽管各花岗岩泥层的微观结构几乎一致。这些观察结果表明，滑移在“Y”形剪切面和/或R1Riedel剪切面上发生局部滑移后，整个钻层必须继续发生变形。建议在断层泥中发生循环变形，以适应活动滑动面上几何不规则性的通过。
The microstructures of gouges produced in room temperature, rotary shear sliding experiments were examined by transmission electron microscopy. Gouges were produced by sliding on ground surfaces of granite, quartzite, or marble except for one experiment in which a 1-mm-thick simulated gouge layer was used. Water was added to the sliding surfaces of all but one sample. Crystal plastic processes play no role in the granite and quartzite gouges and a minor role in the marbles. All of the gouges consist of mostly submicron crystalline fragments; in addition, the granite gouges contain 5–60% amorphous material, and the quartzite gouge contains −50% amorphous material. In the granite samples the composition of the amorphous material commonly lies between K-rich and Na,Ca-rich feldspars, although portions may be silica-rich. The microstructural relations suggest that the amorphous material forms by comminution of fragments rather than by melting. The amount of amorphous material increases, and the size of the largest crystalline fragments decreases, with an increase in average shear strain, although the microstructure is nearly uniform throughout each granite gouge layer. These observations suggest that after slip becomes localized on “Y” shear surfaces and/or R1 Riedel shears the entire gouge layer must continue to undergo deformation. It is suggested that cyclic deformation in the gouge must occur to accommodate the passage of geometric irregularities on the active slip surfaces.