Seismic depth imaging of normal faulting in the southern Death Valley Basin

Abstract

Motivated by the need to image faults to test Cenozoic extension models for the Death Valley region of the western basin and range province, an area of strong lateral velocity variations, we examine the geometry of normal faulting in southern Death Valley by seismic depth imaging. We analyze COCORP Death Valley Line 9 to attain an enhanced image of shallow fault structure to 2.5 km depth. Previous work used standard seismic processing to infer normal faults from bed truncations, displacement of horizontal reflectors, and diffractions. We obtain a detailed velocity model by nonlinear optimization of first‐ arrival times picked from shot gathers, examine the unprocessed data for fault reflections, and use a Kirchhoff prestack depth imaging procedure to handle lateral velocity variations and arbitrary dips properly. Fault‐plane reflections reveal the listric true‐depth geometry of the normal fault at the Black Mountains range front in southern Death Valley. This is consistent with the concept of low‐angle extension in this region and strengthens its association with crustal‐scale magmatic plumbing.