Abstract
We present the results of a study of the Buffalo Valley, Buena Vista, and southern Shoshone faults in central Nevada. The three active normal faults accommodate extension within the slowly deforming Basin and Range Province in central Nevada. For the Buffalo Valley fault, field and lidar observations indicate that deformation is distributed across several parallel strands that progressively displace alluvial fans. Fault trace mapping, vertical displacement estimates, soil pit descriptions from displaced surfaces, and 36Cl exposure age dates from two soil profiles and a single boulder are used to characterise the geomorphology and slip rate of the fault. Cumulative displacement across the oldest surface is 21 m and late Pleistocene surfaces are displaced 8-8.6 m. Soils developed into late Pleistocene surfaces have stage II+ to III carbonate development suggesting an age for surface abandonment 60-200 ka. 36Cl soil depth profile analyses refine the age of these surfaces at a minimum of 54 +4/-2 ka and possibly up to 118 ±18 ka where the vertical displacement is 8 m, and a minimum of 77 +5/-1 ka and possibly up to 213 +7/-11 ka where the displacement is 8.6 m, which collectively suggest a vertical slip rate of 0.04 - 0.15 mm/yr. The Buena Vista and southern Shoshone faults were mapped at single sites where faulted fan surfaces were observed, and boulders were sampled for 10Be exposure age dating. Slip rates of 0.02 - 0.09 mm/yr and 0.02 - 0.08 mm/yr for the Buena Vista and southern Shoshone faults, respectively, are estimated from scarp heights and correlation of fan surfaces to Buffalo Valley, and consideration of boulder 10Be exposure ages. The results contribute towards the refinement of seismic hazard models and the assessment of geothermal systems in the region.