关键词: 断层滑动, 摩擦特性, 断层泥, 蛇纹石, 速度依赖性

Abstract: The velocity-dependence of frictional strength of serpentine gouges has been measured at constant normal stress of 110 MPa,pore pressure of 10 MPa,temperature 25,100 and 200℃,and at sliding rate ranging from 0.001 to 10μm/s. At 25℃,the coefficient of friction of chrysotile gouge is very low (μ≈0.2～0.25),while lizardite and antigorite gouge are much stronger,with μ≈0.39 and 0.45,respectively. The frictional strengths of chrysotile and antigorite gouges change little with a temperature increase to 200℃,whereas the strength of lizardite gouge increases substantially with increasing temperature. At 25℃,all three gouges show a transition from weak velocity weakening at high slip rates to velocity strengthening at low slip rates. With increasing temperature,the velocity dependence of each gouge shifts towards more positive values,especially at high slip rates. Based on this study and previous results,we suggest that the presence of serpentine in the fault zone may contribute to the occurrence of stable creep rather than earthquakes,but this effect may be limited to shallow depths. Although chrysotile is one of the weakest rock-forming minerals,it is still too strong to explain the weakness of the San Andreas fault deduced from heat flow data.

Key words: Fault slip, Frictional property, Fault gouge, Serpentine, Velocity dependence