Fabric anisotropy controls faulting in the continental crust

Abstract

The influence of pre-existing structural anisotropy on faulting in the continents is best tested in recently exhumed crust (e.g. Nanga Parbat Massif, NW Himalayas), where earlier brittle structures have been annealed. The kinematics of young faults, formed in a single, continuing tectonic regime (NNW compression), are distinctly different, depending upon the orientation of the early ductile foliations around them. Faulting is subparallel and statistically simple where foliation is moderately dipping but highly complex where foliation is steeply dipping. Thus structural anisotropy does control faulting in the continental crust, a result with important implications for seismogenesis, fluid flow and basin evolution.