RELATIONSHIPS BETWEEN LATE CRETACEOUS BASEMENT STRUCTURES AND LATE CENOZOIC FAULTING AND OVERLAP BASINS OF THE SOUTHERN SIERRA NEVADA REGION, CALIFORNIA

Topography of the Sierra Nevada changes abruptly at ~35.7°N, south of which there is more local relief and a southward decrease in average elevation. This is a result of multiple phases of extension that are focused in the southern Sierra. The first (large magnitude) Late Cretaceous phase of extension developed above a lateral ramp in the Rand-Coast Range subduction megathrust as the shallowly subducted Rand schist was extruded out of the subduction channel to the southwest. Upper plate Sierran basement was cut by crust penetrating shear zones, rotated clockwise, and stripped of its underlying mantle lithosphere. Differential extension was partitioned into three panels separated by the Kern Canyon-White Wolf and the Owens Valley transfer zones. Much of the extended terrane in the western panel lies in the San Joaquin Basin (SJB) subsurface. Basement shear zones reactivated as late Cenozoic structures include the eastern Sierra escarpment, normal scarps of the Kern Canyon-Breckenridge-White Wolf system, and the Garlock fault that developed over the hinge in the Rand fault lateral ramp. High-angle normal faulting and volcanism are well recorded across the southern Sierra and adjacent SJB at 21-16 Ma, forced by the opening of the Pacific-Farallon slab window. During this regime growth grabens and normal fault footwall tilt blocks produced sediment accommodation spaces across the southern Sierra and within the SJB. The Breckenridge scarp, and footwall tilt block of the (normal) proto-Garlock fault, along with other normal faults formed a Miocene basin across the southern Sierra that we call the Walker graben, which accumulated ~2 km of strata. Intra-SJB growth grabens were formed by the White Wolf and Edison fault zones, working in conjunction with sets of SW-down normal growth faults. Direct sediment provenance and dispersal links are well established between the Walker graben and SJB, with early Neogene volcaniclastic and fluvial linkages, and with fluvial re-distribution of the Walker graben fill into the SJB forced by Mio-Pliocene eastern Sierra escarpment faulting. Quaternary exhumation of the southern and eastern margins of the SJB is driven by fold-thrust deformation along the Tehachapi-San Emigdio ranges, and by epeirogenic uplift of the Kern arch forced by removal of its underlying residual mantle lithosphere.