富层状硅酸盐糜棱岩在水热条件下的摩擦滑动特性及地震成核条件

最新的野外断层带研究发现很多断层糜棱岩中富含层状硅酸盐矿物。但有关此类断层糜棱岩的摩擦滑动特性对于断层动力学性质的影响的研究迄今为止还未系统地展开。本研究将在前人的工作基础上通过龙门山断裂带的野外工作了解发育糜棱岩断层带的构造活动史，并采集糜棱岩样品进行实验和分析。通过开展富层状硅酸盐糜棱岩在水热条件下的摩擦滑动实验，得到摩擦强度和摩擦滑动速度依赖性参数（a-b）随温度、压力和形变速率的变化。于此同时，设计不同的装样方式对糜棱岩中先存定向组构对于摩擦滑动特性的影响进行研究。对实验变形后样品使用电子扫描电镜、电子探针和透射电镜进行微观变形构造分析，确定糜棱岩断层泥的变形过程和机制。在与前人花岗岩和辉长岩的实验结果进行对比的基础上，依据糜棱岩实验结果和变形机制的研究提出新的断层动力学模型，以此约束龙门山断裂带深部的强度剖面；探讨断层上的地震成核条件和机制，为地震过程模拟提供实验数据。

Recent researches of natural fault zones reveal that phyllosilicates are rich in many fault mylonites. But the effects of frictional properties of such phyllosilicate-rich mylonites on mechanical faulting behaviour have not been studied systematically. Based on previous work, this research will first try to understand the tectonic evolution of the Longmenshan fault zone with mylonite developed through field work and in the same time collect mylonite samples for experiments and analyses. Friction experiments of mylonite will be conducted under hydrothermal conditions to obtain systematic data of frictional strength and rate dependence（a-b）as a function of temperature, pressure and strain rate. Meanwhile, a new sample assemblage will be designed to research the effects of pre-existing foliations of mylonite on its frictional properties. After shearing experiments, the microstructure of deformed samples will be analyzed with SEM, electronic probe and TEM to determine the deformation processes and mechanisms in mylonite gouge during shearing. A new fault model will be proposed based on the result of mylonite and its comparison with previous results of granite and gabbro. This model will be used to constrain the strength profile of Longmenshan fault zone, discuss the condition and mechanisms of earthquake nucleation and also provide data for numerical simulation of earthquake cycles.