Deformation pattern around the conjoining strike‐slip fault systems in the Basin and Range, southeast Nevada: The role of strike‐slip faulting in basin formation and inversion

Abstract

Within the extensional regime of the Basin and Range, strike‐slip faults create a regional pattern of opposing sense of fault systems. The relationship between these faults and other deformational features nearby is enigmatic. This paper addresses a diverse assemblage of contractional and extensional structures reflecting local uplift and subsidence, respectively, at the junction of two large Neogene strike‐slip faults in southeastern Nevada, the right‐lateral Las Vegas Valley shear zone and the left‐lateral Bitter Spring Valley fault of the Lake Mead fault system. First, a middle Miocene lacustrine carbonate basin, the Bitter Ridge‐Lovell Wash carbonate basin, formed north of the strike‐slip faults. Second, the lacustrine basin inverted locally, while sediments accumulated south of the strike‐slip faults. Third, the study area was deformed by north‐northeast trending, high‐angle oblique faults with normal and left‐slip components. The results, both from field observations and numerical modeling of the intersecting strike‐slip faults, show that the Las Vegas Valley shear zone and the Bitter Spring Valley fault may have produced the basin in the north and its intense contractional deformation as well as the southward shift of deposition during the inversion event. We conclude that conjoining strike‐slip fault systems can promote localized vertical tectonics and lead to basin formation and uplift right next to each other. Subsequent inversion of the earlier basinal deposits, however, requires a reversal in the sense of slip across the Las Vegas Valley shear zone and a change in the regional stress system.