Abstract

The Pinto Quadrangle, located along the southern extension of the Antelope Range, remains one of the key unmapped areas in the eastern Caliente-Enterprise zone (Hudson et al., 1998 and Axen, 1998, GASP 323), a regional east-northeast trending transfer zone. Current detailed (1:16,000) geologic mapping in conjunction with LANDSAT imagery reconnaissance has revealed different structural elements in the study area related to Tertiary plutonism and crustal extension. Early structural features related to plutonism include laccolithic doming (Pinto Dome) and gravity slide sheets originating from the west (Bull Valley Mountains). These features dominate the southern portion of the quadrangle, and reflect Miocene (22-20 Ma) Iron Axis plutonism.

Sedimentary and volcanic stratigraphy in the central and northern portions of the quadrangle (see Cornell et al., 2001, this volume) are cross-cut by sinistral NW faults and by throughgoing E-W oblique-slip faults associated with mid-Miocene Basin and Range faulting. Field relations show that the NW faults terminate into and are offset by the E-W fault set. These fault sets reside within a footwall block unroofed by the late Miocene to Quaternary west-dipping Antelope Range Fault. LANDSAT imagery analysis is proving to be useful in interpreting important structural and geomorphic details (i.e., range-front alluvial fan development) throughout the study area. Here we illustrate the mid-Miocene to Quaternary fault pattern based upon field mapping data augmented by remote sensing technology. (This work is supported in part by a USGS EDMAP grant.)