汶川地震在北川县擂鼓镇和赵家沟村一带产生了一系列的同震地表破裂带, 采集破裂带内的同震断层泥, 同时采集了平武县南坝镇断裂带中的老断层泥。 采用X射线衍射和红外吸收光谱对新老断层泥样品进行测试, 综合分析其矿物成分、 粘土矿物含量及组合等特征。 分析结果显示新老断层泥的矿物成分存在较为明显的差异, 老断层泥主要由围岩的碎屑或碎粉组成, 而新鲜断层泥的主要成分则为粘土矿物。 其中新鲜断层泥中的粘土矿物成分主要为伊利石、 蒙脱石和伊蒙混层, 这一粘土矿物组合表明断层活动的演化环境主要为温暖湿润的环境, 粘土矿物所受构造应力变质作用主要表现为低温低压的浅变质作用, 这也一定程度上指示了该区域断层最新的活动方式可能是蠕移。 前人对汶川地震带断层泥的研究主要集中在其力学性质和结构以及构造方面, 而本文的研究则主要通过断层泥中矿物成分和粘土矿物含量的特征来判定断层活动的物理化学环境, 这对于断层环境演化和地震的活动机制研究具有重要的科学意义。

Wenchuan earthquake produced a series of co-seismic surface ruptures in Leigu and Zhaojiagou, and we collected samples of co-seismic fault gouge in the surface ruptures as well as the old gouge in the fault of Nanba. Testing The new and old fault gouge was tested with X-ray diffraction and infrared absorption spectra, and its characteristics such as mineral compositions, clay mineral contents and combinations were comprehensively analyzed. The results display obvious differences between the new and old fault gouge, showing that the old fault gouge is mainly composed of wall rock debris or milled powders, while the main components of new fault gouge are clay minerals. The assemblage of clay minerals composition shows that the environment of the fault activity was mainly warm and humid, and the clay minerals were mainly transformed by low temperature and low pressure dynamic metamorphism. And this also partly indicates that the latest way of the fault activity in this area may be a creeping. However the previous researches on the fault gouge of Wenchuan earthquake fault zone are mainly focused on its mechanical properties as well as its texture and structure, the research in this paper is to determine the physical and chemical environment of fault activity through the mineral compositions and clay mineral contents in the fault gouge characteristics, and this research has important scientific significance to the researches on the evolution of the fault environment and the activity mechanism of the earthquake.