The crucial role of temperature in high-velocity weakening of faults: Experiments on gouge using host blocks with different thermal conductivities
The crucial role of temperature in high-velocity weakening of faults: Experiments on gouge using host blocks with different thermal conductivities
复制标题
温度在断层高速弱化中的关键作用：使用不同导热系数的主块进行过凿实验
DOI：
10.1130/g37310.1
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发表时间：
2016
期刊：
影响因子：
5.8
通讯作者：
Toshihiko Shimamoto
中科院分区：
文献类型：
--
作者：
Lu Yao;Shengli Ma;John D. Platt;André R. Niemeijer;Toshihiko Shimamoto
本文研究了在地震滑动速率下，断层泥动态弱化过程中温升的重要作用，所用基质材料分别为黄铜、不锈钢、钛合金和辉长岩，其热导率（λh）分别为123、15、5.8和3.25 W/m/K。我们的实验主要是在中国四川龙门山断层采集的断层泥上进行的，主要由伊利石和石英组成。当λ h减小时，由于断层泥中的温度升高，断层泥的高速弱化变得更加明显。显微结构观察显示焊接滑动区材料和更紧凑的滑动面的断层泥变形与低λhhost块，这可能是由烧结过程指示较高的温度。这些结论得到了使用有限元法进行的温度计算的支持。所观察到的摩擦行为，变形微观结构和计算的温度的差异表明，摩擦加热驱动的温度上升是必不可少的，在地震速度的断层泥的动态弱化。我们表明，我们的数据与闪速加热模型非常一致，尽管热化学加压可能也很重要。我们的一些实验中，纳米粒子存在，但表现出可忽略不计的削弱，表明纳米粒子单独存在是不足以导致动态削弱故障。
We study the important role of temperature rise in the dynamic weakening of fault gouge at seismic slip rates by using host blocks composed of brass, stainless steel, titanium alloy, and gabbro with thermal conductivities (λh) of 123, 15, 5.8, and 3.25 W/m/K, respectively. Our experiments are performed mostly on fault gouge collected from the Longmenshan fault, Sichuan, China, consisting primarily of illite and quartz. High-velocity weakening of gouge becomes more pronounced as λhdecreases because the temperature in the gouge increases. Microstructure observations reveal welded slip-zone material and more compact slip surfaces for the gouge deformed with low-λhhost blocks, which is probably caused by a sintering process indicative of higher temperatures. These conclusions are supported by temperature calculation performed using the finite-element method. The observed differences in frictional behaviors, deformation microstructures, and calculated temperature demonstrate that temperature rise driven by frictional heating is essential in causing dynamic weakening of gouge at seismic velocities. We show that our data are in good agreement with the flash-heating model, though thermochemical pressurization may also be important. Some of our experiments, where nanoparticles are present but show negligible weakening, demonstrate that the presence of nanoparticles alone is not sufficient to cause dynamic weakening of faults.