Kinematic evolution of the Olinghouse fault and the role of a major sinistral fault in the Walker Lane dextral shear zone, Nevada, USA

摘要

The Olinghouse fault is a highly oblique sinistral fault in the northern Walker Lane dextral shear zone. In this study, we use geologic mapping and structural analysis of 56 fault surfaces and several folds to constrain the evolution and kinematic role of the Olinghouse fault within the Walker Lane. We document a two-stage development of the Olinghouse fault, with an early phase of extension between 12 and 10 Ma followed by left-lateral shear with a component of extension beginning at 8 to 5 Ma. The sinistral Olinghouse fault has played a relatively complex kinematic role in the evolution of the Walker Lane, including acting as a boundary for clockwise vertical-axis block rotation, a strain transfer zone between loci of extension, and a structural domain boundary redistributing strain between the Carson and Pyramid Lake domains. The fault has accumulated similar to 2.5-3 km of left-lateral offset at an average rate of 0.3-0.6 mm/yr. The complexity of this sinistral-normal fault zone within a broad zone of dextral shear was likely influenced by the propagation of Walker Lane dextral shear into a zone of pre-existing crustal structure.