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

Within the extensional regime of the Basin and Range, strike-slip faul ts create a regional pattern of opposing sense of fault systems. The r elationship between these faults and other deformational features near by is enigmatic. This paper addresses a diverse assemblage of contract ional and extensional structures reflecting local uplift and subsidenc e, respectively, at the junction of two large Neogene strike-slip faul ts in southeastern Nevada, the right-lateral Las Vegas Valley shear zo ne and the left-lateral Bitter Spring Valley fault of the Lake Mead fa ult system. First, a middle Miocene lacustrine carbonate basin, the Bi tter Ridge-Lovell Wash carbonate basin, formed north of the strike-sli p faults. Second, the lacustrine basin inverted locally, while sedimen ts accumulated south of the strike-slip faults. Third, the study area was deformed by north-northeast trending, high-angle oblique faults wi th normal and left-slip components. The results, both from field obser vations and numerical modeling of the intersecting strike-slip faults, show that the Las Vegas Valley sheer zone and the Bitter Spring Valle y fault may have produced the basin in the north and its intense contr actional deformation as well as the southward shift of deposition duri ng the inversion event. We conclude that conjoining strike-slip fault systems can promote localized vertical tectonics and lead to basin for mation and uplift right next to each other. Subsequent inversion of th e earlier basinal deposits, however, requires a reversal in the sense of slip across the Las Vegas Valley shear zone and a change in the reg ional stress system. Copyright 1998 by the American Geophysical Union.