Faultrocksandfaultmechanisms断层和断层机理rhsibson.pdfVIP

Fault rocks and fault mechanisms R. H. S I B S O N S U M M A R Y Physical factors likely to affect the genesis of the with the production of mylonite series rocks various fault rocks--frictional properties, tem- possessing strong tectonite fabrics. In some cases, perature, effective stress normal to the fault and fault rocks developed by transient seismic fault- differential stress--are examined in relation to ing can be distinguished from those generated the energy budget of fault zones, the main by slow aseismic shear. Random-fabric fault velocity modes of faulting and the type of fault- rocks may form as a result of seismic faulting ing, whether thrust, wrench, or normal. In a within the ductile shear zones from time to conceptual model of a major fault zone cutting time, but tend to be obliterated by continued crystalline quartzo-feldspathic crust, a zone of shearing. Resistance to shear within the fault elastico-frictional (EF) behaviour generating zone reaches a peak value (greatest for thrusts random-fabric fault rocks (gouge--breccia-- and least for normal faults) around the EF/OP cataclasite series--pseudotachylyte) overlies a transition level, which for normal geothermal region where quasi-plastic (QP) processes of gradients and an adequate supply of water, rock deformation operate in ductile shear zones occurs at depths of lO-15 km. SINCE LAPWORTH$ (I885) description of the type mylonite from the Moine Thrust in N W Scotland, there have been m a n y petrographic descriptions and classifications of the texturally distinctive rocks found associated with f