Damage zone and slip-surface evolution over μm to km scales in high-porosity Navajo sandstone, Utah
Damage zone and slip-surface evolution over μm to km scales in high-porosity Navajo sandstone, Utah
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DOI：
10.1016/s0191-8141(01)00035-9
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发表时间：
2001-12
影响因子：
3.1
通讯作者：
Z. Shipton;P. Cowie
中科院分区：
文献类型：
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作者：
Z. Shipton;P. Cowie
在犹他州的高孔隙度纳瓦霍砂岩中，沿沿着两公里尺度正断层的落差变化和变形的详细绘图已被用于研究该岩性中的断层生长。断层由一个或多个贯通的、条纹状的滑动面组成，可容纳大部分由变形带簇和短的、不相连的滑动面组成的损伤区所包围的偏移。与以前的模型在这种岩性的变形，我们发现，成核的滑动面开始可测量的抛出是可以忽略不计的变形带形成和数量增加。变形带和滑动面的微观结构和孔隙度是不同的，并且与它们所容纳的偏移量无关，即它们代表不同但同时发生的变形机制。可测量落差开始累积的点（断层尖端）由第一个贯通的连接滑动面标记。断层中心落差的增加会产生三维应变场，在损伤区内产生斜方结构几何形状。我们发现损伤区的总宽度随着偏移量的增加而增加。对于这些断层，损伤区宽度约为总断层落差的2.5倍。
Detailed mapping of throw variations and deformation along twokm-scale normal faults in the high-porosity Navajo sandstone, Utah, has been used to investigate fault growth in this lithology. The faults consist of one or more through-going, striated, slip-surfaces, accommodating the greater part of the offset surrounded by a damage zone consisting of deformation band clusters and short, unconnected slip-surfaces. In contrast to previous models for deformation in this lithology, we find that the nucleation of slip-surfaces begins where measurable throw is negligible and deformation bands are forming and increasing in number. The microstructure and porosity of deformation bands and slip surfaces are distinct and independent of the amount of offset that they accommodate, i.e. they represent different and yet contemporaneous deformation mechanisms. The point where measurable throw begins to accumulate (the fault tip) is marked by the first through-going connected slip-surface. Increase in throw towards the centre of the fault results in a three-dimensional strain field, producing orthorhombic structural geometries within the damage zone. We find that the total width of the damage zone increases as offset is accumulated. For these faults, the damage zone width is approximately 2.5 times the total fault throw.