Reinterpretation of Relationships Among Keystone Thrust, Red Springs Thrust, Contact Thrust, and Cottonwood Fault, Clark County, Nevada: ABSTRACT

Abstract

The basin-range and Sevier tectonic events are well-documented in Clark County, Nevada. Other tectonic events have been interpreted from structural relationships in the Spring Mountains. These include an early thrust-faulting event and a high-angle faulting event that occurred between emplacement of the early thrust and emplacement of the Keystone thrust. The results of this study indicate that there was not an early thrust event nor was there high-angle faulting prior to the Sevier deformational event. The Cottonwood fault and the Contact thrust in the Spring Mountains are interpreted here as a lateral ramp and floor thrust beneath a duplex fault zone. The Keystone thrust forms the roof thrust for the duplex fault End_Page 855------------------------------ zone that bows up the upper plate of the Keystone thrust. The Red Springs thrust is interpreted as the Keystone thrust, which was broken and differentially rotated during Neogene oroclinal bending associated with the Las Vegas shear zone. The structural relationships in the Spring Mountains do not require any Mesozoic or Cenozoic deformational episodes other than the well-known Sevier and basin-range events. End_of_Article - Last_Page 856------------