PRELIMINARY INVESTIGATIONS INTO THE FISH LAKE VALLEY FAULT ZONE (FLVFZ) AND ITS INTERACTIONS WITH NORMAL FAULTING WITHIN EUREKA AND DEEP SPRINGS VALLEY

Fish Lake Valley Fault Zone (FLVFZ) is the northern continuation of the Furnace Creek Fault Zone (FCFZ), and is an important transfer structure within the Walker Lane Shear Zone, which has been interpreted to accommodate up to 15-25 percent of the Pacific-North American plate motion (Faulds et al., 2005). Though the FLVFZ has a long term rate (since 10 Ma) of 5 mm/yr (Reheis and Sawyer, 1997), it has a highly variable slip rate. In the middle Pleistocene, the rate has a maximum of up to 11 mm/yr which would accommodate nearly the entirety of slip within the Walker Lane, and yet this rate decreases significantly by the late Pleistocene due to unknown causes. Frankel et al. (2007b) utilized offset alluvial fans and ¹⁰Be cosmogenic dating along the northern section of the FLVFZ, and found it has accommodated late Pleistocene slip rates of ~2.5 to 3 mm/yr. In another paper that same year, Frankel et al. (2007a) found greater rates within the northern section of the Death Valley Fault Zone, which is interpreted to be contiguous with the FLVFZ. Utilizing ¹⁰Be and ³⁶Cl geochronology, offset alluvial fan channels resulted in a minimum rate of 4.2 +1.9/-1.1 mm/yr (Frankel et al, 2007a). This variation in slip rate has been proposed by previous workers to be due to strain transience, an increase in the overall strain rate, or due to other unknown structures (Lee et al., 2009). Currently, we are investigating the cause of this variation, and the possibility of the transfer of slip to faults south of the FLVFZ. Preliminary data will be shown from work done within Eureka Valley, and Deep Springs Valley, California utilizing scarp transects, geomorphic scarp modeling, and Optically Stimulated Luminescence (OSL) dating techniques. Fish Lake, Eureka, and Deep Springs Valleys offer a unique window into the evolution of bookcase faulting, and the transfer of strain between strike slip and normal faulting.