基岩区断层黏滑与蠕滑的地质标志和岩石力学实验证据  

THE GEOLOGICAL AND ROCK MECHANICAL DISTINCTION EVIDENCE BETWEEN STICK-SLIP AND CREEP IN HOST ROCK SEGMENTS OF FAULT

作　　者：周永胜[1] ZHOU Yong-sheng(State Key Laboratory of Earthquake Dynamics,Institute of Geology,China Earthquake Administration,Beijing 100029,China)

机构地区：[1]中国地震局地质研究所地震动力学国家重点实验室

出　　处：《地震地质》2019年第5期1266-1272,共7页Seismology and Geology

基　　金：国家重点研发计划项目(2018YFC1503404);中国地震局地质研究所基本科研业务专项(IGCEA1813)共同资助

摘　　要：文中总结了基岩断层带黏滑与蠕滑的地质标志与岩石力学实验证据,分析了控制黏滑与蠕滑的物理机制。断层带内的矿物组成、矿物变形机制、流体作用和断层带变形方式等是控制黏滑与蠕滑的主要因素。富含黏土矿物的断层泥具有速度强化型摩擦滑动,控制着断层蠕滑,而以方解石、石英、长石及辉石等造岩矿物为主的断层泥在大陆浅源地震的震源深度条件下具备黏滑条件。脆性破裂伴随的扩容过程是断层黏滑的必要条件,而压实、碎裂和塑性剪切变形形成的叶理和小褶皱对应于蠕滑。在流体作用下,压溶使孔隙和微裂隙愈合,有利于断层强度的恢复和断层闭锁,既是断层发生不稳定滑动的根源,也是断层带局部存在高压流体的条件,而在流体作用下的退变质反应与水解反应生成黏土矿物和层状及环状硅酸盐矿物,不仅降低了断层带的强度,还导致断层向蠕滑转变。断层带内均匀分布多个剪切面和较宽的变形带对应于蠕滑,局部化的R剪切及Y剪切、窄变形带和摩擦镜面对应于黏滑。Paleo-seismic and fault activity are hard to distinguish in host rock areas compared with soft sedimentary segments of fault.However,fault frictional experiments could obtain the conditions of stable and unstable slide,as well as the microstructures of fault gouge,which offer some identification marks between stick-slip and creep of fault.We summarized geological and rock mechanical distinction evidence between stick-slip and creep in host rock segments of fault,and analyzed the physical mechanisms which controlled the behavior of stick-slip and creep.The chemical composition of fault gouge is most important to control stick-slip and creep.Gouge composed by weak minerals,such as clay mineral,has velocity weakening behavior,which causes stable slide of fault.Gouge with rock-forming minerals,such as calcite,quartz,feldspar,pyroxene,has stick-slip behavior under condition of focal depth.To the gouge with same chemical composition,the deformation mechanism controls the frictional slip.It is essential condition to stick slip for brittle fracture companied by dilatation,but creep is controlled by compaction and cataclasis as well as ductile shear with foliation and small fold.However,under fluid conditions,pressure solution which healed the fractures and caused strength recovery of fault,is the original reason of unstable slide,and also resulted in locking of fault with high pore pressure in core of fault zone.Contrast with that,rock-forming minerals altered to phyllosilicates in the gouges by fluid flow through degenerative reaction and hydrolysis reaction,which produced low friction fault and transformations to creep.The creep process progressively developed several wide shear zones including of R,Y,T,P shear plane that comprise gouge zones embedded into wide damage zones,which caused small earthquake distributed along wide fault zones with focal mechanism covered by normal fault,strike-slip fault and reverse fault.However,the stick-slip produced mirror-like slide surfaces with very narrow gouges along R shear plane

关 键 词：黏滑 蠕滑 基岩断层 

分 类 号：P315.2[天文地球—地震学]