Late Quaternary Vertical Displacement Rate Across the Fish Springs Fault, Owens Valley Fault Zone, California

Abstract

AbstractA cinder cone located 11 km south of Big Pine, California, is vertically displaced 78 ± 6 m by the Fish Springs fault of the Owens Valley fault zone. The surfaces of Tahoe-age and Tioga-age alluvial fans that overlie the cone are vertically displaced 31 ± 3 and 3.3 ± 0.3 m, respectively. Neither the cinder cone nor the Tioga-age fan appears to have been laterally offset. The cone is dated by the39Ar/40Ar method at 314,000 ± 36,000 yr B.P. (2σ), indicating an average late Quaternary vertical displacement rate of 0.25 ± 0.03 mm/yr (2σ). The age of the Tahoe glaciation is uncertain, but probably corresponds to the age of marine oxygen isotope stage 4 and/or 6 (65,000–75,000 and 128,000–195,000 yr, respectively). If the older fan were deposited during stage 4, then the average post-Tahoe vertical displacement rate probably was at least twice the pre-Tahoe late Quaternary rate. If the displacement rate has been constant during the last 314,000 yr, then the surface of the Tahoe-age fan is dated at 124,000 ± 19,000 yr B.P., and the bulk of the fan most likely would have been deposited during stage 6. Based on the displacement of the surface of the Tioga-age (10,600 – 26,000 yr) fan, the average Holocene displacement rate appears to have been slightly less than the average late Quaternary rate.