Camp Rock fault slip rate and folding of the Lenwood anticline: Contributions to eastern California shear zone strain accumulation.

摘要

Geologic mapping, 10Be geochronology, and fold modeling provide insight into reconciling discrepant geologic and geodetic slip rates across a portion of the eastern California shear zone. The Camp Rock fault is one of six faults that make up the shear zone. Two alluvial fans of different generations, offset by the fault, yield ages of 100+/-30 ka and 56.4+/-7.7 ka. Offsets on these fans are 41+/-25 m and 22+/-2 m respectively, yielding a long-term slip rate of 0.4 +0.3/-0.1 mm/yr for the fault. This is only 2-7% of the geodetic strain rate across the shear zone. The Camp Rock fault terminates northward into the Lenwood anticline. Modeling of this fold indicates ∼3.8 km of north-south shortening, of which ∼1.0-2.4 km is not transferred to Camp Rock fault slip but is maintained east of the fault. Such regionally distributed shortening may help to reconcile geologic and geodetic strain rates.