TIMING AND KINEMATICS OF THE BITTER SPRING VALLEY FAULT AND RELATED SYN-EXTENSIONAL STRATA, LAKE MEAD EXTENSIONAL DOMAIN, NEVADA

The Lake Mead extensional domain in southern Nevada is the northern boundary of the Colorado River extensional corridor and trends roughly east-west from the Colorado Plateau to the Las Vegas Valley just south of the Paleozoic Cordilleran front (or Wasatch line) (Faulds et al., 2001). The Lake Mead domain has been called the transition zone between the distinctly different tectonic and lithologic domains of the northern and southern Basin and Range (Wernicke et al., 1988; Lamb et al., 2005). The northeast-striking, left-lateral Lake Mead fault system (LMF) and the northwest striking, right-lateral Las Vegas Valley Shear Zone (LVVSZ) define the northern end of the Lake Mead Extensional corridor and are two of the largest strike-slip features in the Basin and Range (Duebendorfer et al., 1998).

Many workers believe that the Lake Mead domain experienced between 60 and 90 km of east-west extension, based on the restoration of the Frenchman mountain block to a pre-extension position to the east (Wernicke et al., 1988; Duebendorfer et al., 1998; Duebendorfer and Fryxell, 2005). Restoration of Lake Mead extension is primarily dependant on the offset along the various strands of the Lake Mead fault system, including the Bitter Spring Valley Fault (BSVF) (Duebendorfer and Fryxell, 2005).

This study will focus on the poorly understood BSVF located near the convergence of the LVVSZ and the LMF system (Anderson 1973). Previous workers have related the BSVF to either the LVVSZ or the LMF (Anderson, 1973; Cakir, 1990; Lamb et al., 2005). The various interpretations of extension in the Lake Mead domain provide estimates of offset along the BSVF that range from 20 to 60 km (Bohannon, 1983; Cakir, 1990; Campanga and Aydin, 1991). The goal of this study is to better understand the roll of strike-slip faulting in large magnitude extensional settings and to help constrain the history of Miocene extension in the Lake Mead domain by studying the geometry, kinematics, and, relation to syn-extensional deposits of the BSVF.

This research project will include a detailed study of fault timing and kinematics as well as syn-tectonic basin analysis. I plan to (1) document the Bitter Spring Valley fault and local geology with mapping at scales of 1:5,000 and 1:10,000, (2) conduct a detailed structural analysis of fault kinematics for the BSVF and other local features.