Effects of clay content on the frictional strength and fluid transport property of faults
Effects of clay content on the frictional strength and fluid transport property of faults
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DOI：
10.1029/2006jb004678
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发表时间：
2007-08
影响因子：
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通讯作者：
M. Takahashi;K. Mizoguchi;K. Kitamura;K. Masuda
中科院分区：
文献类型：
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作者：
M. Takahashi;K. Mizoguchi;K. Kitamura;K. Masuda
[1]我们研究了脆性变形中粘土的存在的两个影响：摩擦强度的降低和跨断层流体流动的阻碍。在80 MPa法向应力、5 MPa孔隙水压力和室温条件下，对钠蒙脱石粉末和颗粒石英沿着30°预切表面的各种混合物的泥的滑动变形过程中的渗透性进行了监测。泥的摩擦系数随粘土含量的增加而降低并不简单，但在50体积%时急剧下降粘粒含量由于变形引起的渗透率降低随着粘土含量从0增加到24体积%而增加，在18和24 vol. %时，粘粒含量然而，在具有大于29 vol. %粘土含量、变形仅使渗透率降低0.5个数量级。因此，过渡性粘土含量占断层强度和流体输运性质的主导地位，分别为50和29体积%，分别这些值几乎同意以及使用具有相等大小的碎屑（石英）框架的模型获得的值。当粘土含量达到29体积%时，粘土基质可以完全填充由最紧密堆积的石英骨架维持的孔隙，而填充几乎不能维持石英-石英接触的框架的孔所需的含量为50体积%。
[1] We examined two effects of the presence of clay in brittle deformations: the reduction in frictional strength and the impediment of across-fault fluid flow. Permeability was monitored during the sliding deformation of a gouge of various mixes of Na-montmorillonite powder and granular quartz along a 30° precut surface of Berea sandstone under 80 MPa of normal stress, 5 MPa of pore water pressure, and room temperature. The decrease in the friction coefficient of a gouge with increasing clay content was not simple, but showed a sharp drop at 50 vol.% clay content. The reduction in permeability due to deformation increased with increasing clay content from 0 to 24 vol.%, and a dramatic reduction of ∼2.5 orders of magnitude occurred at 18 and 24 vol.% clay content. However, in a gouge with more than 29 vol.% clay content, deformation reduced the permeability by only 0.5 orders of magnitude. Thus the transitional clay contents at which the clay dominated the properties of fault strength and fluid transport were 50 and 29 vol.%, respectively. These values almost agree well with values obtained using a model with an equal-sized clast (quartz) framework. The clay matrix can completely fill the pores sustained by a closest-packed quartz framework when the clay content reaches 29 vol.%, whereas the content required to fill the pores of a framework that can barely sustain quartz-quartz contact is 50 vol.%.