Mineral Association and Iron Species in Wujialong Fault of Jiangshan, Zhejiang Province:Implications for Fault Activity

Wang Chao; Li Guangrong; Guo Fusheng; Guo Chao; Dai Jiaqi

Abstract：As a result of the excavation of building construction, 6 small size fresh faults exposed in Wujialong of Jiangshan City, Zhejiang Province, which was sub-branch of Jiangshao fault.Field geological survey, X-ray powder diffraction and M9 ssbauer spectroscopy were used to study the mineral composition and iron species of fault gouges and wall rocks of 3 small faults (F1, F2 and F3) in Wujialong fault.After comparative analysis and research we found that: (1) The wall rocks and fault gouges are mainly composed of quartz and clay minerals, and also contain a small amount of albite and calcite.The clay minerals are mainly composed of illite and IS layer, and also contain small amount of chlorite, kaolinite and KS layer and trace amount of montmorillonite and vermiculite. (2) Except the JS07 sample, the rock forming minerals content is higher than that of fault gouges whereas to the clay content in fault gouges is higher than that of wall rocks. (3) Clay mineral in F1 fault is dom-inated by illite, indicating a relative stable environment.The content of illite in F2 and F3 fault gouges are lower than that in wall rocks, montmorillonite and IS layer is higher than that in wall rocks, indicating that it was formed in wet, strong oxidizing environment. (4) The high content of reduced iron of wall rocks in F1 may suggest that the formation of wall rocks is involved in the process of reducing substances, the high levels of oxidized iron of F1, F3 fault zone and F3 hanger, indicating either F1, F3 faults are inactive and/or they are inner-block fault. (5) The types and association of clay minerals in the fault zone and the redox environment generally show that the Wujialong fault is in a relatively stable environment, however, the content of illite in the fault zone is high, which is conducive to the fault activity.The activity of Wujialong fault and the possibility of earthquake should be taken into consideration seriously.