Late Quaternary slip history of the Mill Creek strand of the San Andreas fault in San Gorgonio Pass, southern California: The role of a subsidiary left-lateral fault in strand switching

摘要: The fault history of the Mill Creek strand San Andreas (SAF) in Gorgonio Pass region, along with reconstructed geomorphology surrounding this strand, reveals important role left-lateral Pinto Mountain regional switching. has 7.1–8.7 km total slip. Following displacement, offset 1–1.25 km, as SAF slip transferred to Bernardino, Banning, and Garnet Hill strands. An alluvial complex within Mission watershed can be linked palinspastic reconstruction drainage segments constrain strand. We investigated surface remnants through detailed geologic mapping, morphometric stratigraphic analysis, geochronology, pedogenic analysis. degree soil development constrains duration stability when correlated other regional, independently dated pedons. This correlation indicates that oldest surfaces are significantly older than 500 ka. Luminescence dates 106 ka 95 from (respectively) 5 4 m beneath a younger fan consistent age estimates based on soil-profile development. Offset by suggests short-term rate ~10–12.5 mm/yr for fault, lower long-term rate. Uplift Yucaipa Ridge block during period activity is thermochronologic modeled uplift estimates.