Chronology of pluton emplacement and regional deformation in thesouthern Sierra Nevada Batholith, California

Abstract

Cretaceous plutonic rocks of the southern Sierra Nevada batholithbetween latitudes 35.5 degrees N and 36 degrees N lie in a strategicposition that physically links shallow, subvolcanic levels of thebatholith to lower-crustal (-35 km deep) batholitnic rocks. Thisregion preserves an oblique crustal section through the southernSierra Nevada batholith. Prior studies have produced large U/Pb zircondata sets for an aerially extensive region of the batholith to thenorth of this area and for the lower-crustal rocks of the Tehachapicomplex to the south. We present a large set of new U/Pb zircon agedata that ties together the temporal relations of pluton emplacementand intra-arc ductile deformation for the region. We define fiveinformal intrusive suites in the area based on petrography, structuralsetting, U/Pb zircon ages, and patterns in initial (super 87) Sr/(super 86) Sr (Sr (sub 1) ). Two regionally extensive intrusivesuites, the 105-98 Ma Bear Valley suite and 95-84 Ma Domelands suite,underlie the entire southwestern and eastern regions of the studyarea, respectively, and extend beyond the limits of the study area. Athird regionally extensive suite (101-95 Ma Needles suite) cuts outthe northern end of the Bear Valley suite and extends for an unknowndistance to the north of the study area. The Bear Valley and Needlessuites are tectonically separated from the Domelands suite by theproto-Kern Canyon fault, which is a regional Late Cretaceous ductileshear zone that runs along the axis of the southern Sierra Nevadabatholith. The 105-102 Ma Kern River suite also lies west of theproto-Kern Canyon fault and constitutes the subvolcanic plutoniccomplex for the 105-102 Ma Erskine Canyon sequence, an approximately2-km-thick silicic ignimbrite-hypabyssal complex. The 100-94 Ma SouthFork suite lies east of the proto-Kern Canyon fault. It recordstemporal and structural relations of high-magnitude ductile strain andmigmatization in its host metamorphic pendant rocks commensurate withmagmatic emplacement. Integration of t!

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