A GEOCHRONOLOGIC AND PROVENANCE STUDY OF THE GOLDSTEIN PEAK ROOF PENDANT, WEST-CENTRAL SIERRA NEVADA BATHOLITH, CALIFORNIA

The Goldstein Peak unit of the Lake Kaweah roof pendant is a newly recognized non-marine deposit composed of clastic metasediments surrounding a lens of metavolcanic rocks (van der Kolk et al., 2003). This unit contains well-rounded quartz pebble metaconglomerates of fluvial origin and polymictic pebble metaconglomerates of possible alluvial fan origin and appears to be one of only two non-marine, pre-mid Cretaceous units in California (Barth et al., 2004). A granite dike discordant with compositional layering within the Goldstein Peak unit and displaying wet-sediment intrusion structures provides a minimum depositional age estimate of 139 ± 1 Ma (Clemens-Knott and Saleeby, 2005). What is not known is where the rivers that deposited the Goldstein Peak sandstones and conglomerates originated and to where these rivers flowed. Paleogeographic considerations support a roughly westward flow direction, with a drainage basin in the highstanding Sierra Nevada arc and/or North American craton and a mouth in the Great Valley forearc basin. This study will test the hypothesis that the subangular polymictic pebble conglomerates were derived locally from the Sierra Nevada arc and that the well-rounded quartz pebble conglomerates sampled more distant sources. LA-MC-ICPMS analysis of eight detrital zircon populations from a suite of conglomerate samples collected through a 1-km thick section will better constrain the depositional age of what might be one of the oldest non-marine sedimentary units in California and provide a basis for assessing a possible sedimentologic connection between the Goldstein Peak unit and the Great Valley Sequence.