ABSTRACT

Long-term, progressive deformation along the Fish Springs fault in Owens Valley, California, is recorded by numerous offset landforms including a cinder cone, several debris-flow fans and levees, a stream channel, and lava flows of nearby Crater Mountain. The cinder cone is dated (39Ar/40Ar, 314±36 ka, 2s; Martel et al., 1987). 10Be and 26Al model exposure ages (n = 68) constrain the ages of five fan units, suggesting abandonment after 107, 14, 13, and 8 ka. One fan remains active, and has experienced deposition throughout the Holocene. Soil profile development on three fans where boulders were sampled for 10-Be and 26-Al indicates distinct ages. Soils and cosmogenic isotope data suggest fan deposits may correlate with the Tahoe and late Tioga glaciations. Lesser amounts of deposition appear to have occurred in the Holocene. Soil Profile Development Index (PDI) values from Fish Springs compared with those determined elsewhere (Merced, CA; Ventura, CA; Las Cruses, NM; and Susquehanna Valley, PA) suggest relatively slow rates of soil formation for fan surfaces at Fish Springs. Age estimates imply a vertical displacement rate for the Fish Springs fault of 0.24 ± 0.03 mm yr-1.