DETRITAL ZIRCON GEOCHRONOLOGY OF ROOF PENDANTS IN THE FAIRVIEW QUADRANGLE AREA, SOUTHERN SIERRA NEVADA BATHOLITH, TULARE COUNTY, CALIFORNIA: INSIGHTS INTO PRE- AND SYN-MAGMATIC UPPER CRUSTAL ARCHITECTURE

The fragmented Paleozoic passive margin of North America is preserved in roof pendants within the Mesozoic Sierra Nevada batholith, along with the remnants of the syn-magmatic volcaniclastic and sedimentary record. Using detrital zircon geochronology we have investigated the age and provenance of marine metasedimentary and metavolcaniclastic rocks in five roof pendants in the Fairview area of the southern Sierra Nevada batholith in California. The roof pendants straddle the north-south trending intra-arc Kern Canyon fault and the proto-Kern Canyon shear zones. The pendants are comprised of metaquartzites, phyllites, metagreywackes, and marbles, intruded and engulfed by granodioritic, granitic, and dioritic plutons of the batholith. East of the Kern Canyon Fault the informally named Alder Creek (ACP) and Durwood (DP) pendants are both mid-Cretaceous (depo. ages c. 105 – 95 Ma). The DP includes two metavolcaniclastic quartzites that preserve volcanic textures indicative of deposition of silicic ignimbrites and intermediate composition peperite intrusions, interstratified with siliciclastic sediment and marble. We infer that both the DP and ACP are shallow marine successions, and that the DP experienced deposition of considerable silicic pyroclastic material, as well proximal eruption of and intrusion by intermediate magmas. The presence of thick beds of silicic ignimbrite suggests proximity to a major caldera. West of the Kern Canyon Fault three adjacent roof pendants yield very different ages. A psammitic bed within a turbiditic sequence in the informally named Fairview pendant (FP) is Cretaceous (depo. age c. 112 Ma). A psammitic bed within the adjacent and informally named Corral Creek pendant (CCP) is Neoproterozoic (depo. age c. 921 Ma). The CCP exhibits a detrital zircon population similar to that identified in Kernville / Shoo-Fly Terrane rocks elsewhere in the southern Sierra Nevada including a Kernville Terrane sample collected very close-by. Common 1.0 – 1.7 Ga zircon populations suggest that the Kernville Terrane (Corral Creek pendant) was the primary source of Proterozoic zircon to both the adjacent FP and the DP. Finally, phyllitic rocks in the informally named Kernville pendant have an ambiguous depositional age of either Cretaceous (c. 100 Ma) or Late Paleoproterozoic (c. 1716 Ma).