The strength profile for bimineralic shear zones: an insight from high-temperature shearing experiments on calcite-halite mixtures
The strength profile for bimineralic shear zones: an insight from high-temperature shearing experiments on calcite-halite mixtures
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DOI：
10.1016/s0040-1951(98)00112-7
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发表时间：
1998-09-30
期刊：
影响因子：
2.9
通讯作者：
Shimamoto, T
中科院分区：
文献类型：
--
作者：
Kawamoto, E;Shimamoto, T
剪切实验混合岩盐方解石层（0.7毫米厚）已进行了解双矿物断层带的行为，使用高温双轴试验机在0.3 μ m/s的滑动速率和剪切应变约30。温度升高到700摄氏度，与正常应力成线性比例，实验地热约为22摄氏度/MPa，模拟天然地热梯度。试验数据表明，矿物成分对极限摩擦强度和残余摩擦强度的影响是不同的。Tharp的框架模型（1983）定量地解释了极限摩擦强度，而在大剪切应变下的残余摩擦强度可以通过Jordan的两块体模型（1988）预测。因此，随着位移的增加，双矿物剪切带的摩擦行为从框架模型转变为两块体模型。夹杂物的岩盐，较弱的成员，在量小至5%的体积，减少摩擦几乎到纯岩盐的水平，并抑制粘滑在大的剪切应变，因为岩盐颗粒是非常剪切应变集中的区域。双矿物剪切带在大剪应变下的强度剖面和滑移模式，包括地震行为的下限，主要由较弱的成员控制。本文的结果推翻了Strehlau的断层模型（1986）。在Scholz的断层模型（1988年）中，单个组成矿物的作用并不明确，他的模型与现有的实验数据不一致。(C)1998 Elsevier Science B. V.保留所有权利。
Shearing experiments on mixed halite-calcite layers (0.7 mm thick) have been performed to understand the behavior of bimineralic fault zones, using a high-temperature biaxial testing machine at a slip rate of 0.3 mu m/s and shear strains to about 30. Temperature was increased to 700 degrees C in linear proportion to the normal stress, with the experimental geotherm of about 22 degrees C/MPa, simulating the natural geothermal gradient. The experimental data clearly demonstrate that the effect of mineral composition on the ultimate frictional strength is distinctly different from that on the residual frictional strength. Tharp's framework model (1983) quantitatively accounts for the ultimate frictional strength, whereas the residual frictional strength at large shear strains can be predicted by Jordan's two-block model (1988). Thus, the frictional behavior of a bimineralic shear zone changes from the framework model to the two-block model with increasing displacement. Inclusion of halite, the weaker member, in quantities as small as 5% by volume, reduces the friction almost to the level of pure halite and suppresses stick-slip at large shear strains, because halite grains are extremely sheared at the zone of strain concentration. The strength profile and the slip mode, including the lower limit of seismic behavior, of bimineralic shear zones at large shear strains are controlled primarily by the weaker member. The present results disprove Strehlau's fault model (1986). The role of individual constituent mineral is not clarified in Scholz's fault model (1988), and his model disagrees with existing experimental data. (C) 1998 Elsevier Science B.V. All rights reserved.