DETRITAL ZIRCON INVESTIGATION OF SEDIMENTARY LINKAGES BETWEEN MESOZOIC SEDIMENTS OF THE CENTRAL CALIFORNIAN CORDILLERA AND SOUTHWESTERN LAURENTIA

U-Pb dating of detrital zircon grains separated from early Mesozoic metasedimentary rocks from the central Californian Cordilleran provide information regarding surface environments associated with the Sierra Nevada arc during the transition from a transform fault to a high-standing arc bounding the southwestern margin of Laurentia. Provenance and tectonic data form the basis for Late Triassic to Early Cretaceous paleogeographic reconstructions of sediment transport mechanisms and pathways across the axis of the compound Sierra Nevada arc (modern ~36°N lat.). During the Late Triassic epoch, hemi-pelagic protoliths of the southernmost Calaveras complex incorporated detrital zircon grains that were transported westward off of the Laurentian margin by turbidity currents. These zircon grains form the earliest record of Appalachian-aged zircons west of the arc axis. Deformation of the Calaveras complex was followed by deposition of Kings sequence marine turbidites that regionally blanketed the western flank of the low-standing, extensional Jurassic arc. Eolian transport of a grains from the Jurassic ergs provided ~75% of detrital zircons deposited in the marine graben complex developed on the western arc flank; additional grains were derived by reworking of Neoproterozoic-to-Paleozoic passive margin metasediments exposed in graben walls. Early Cretaceous accretion of the Franciscan Formation and elevation of the trench-slope break initiated sediment accumulation in the newly confined forearc basin, while transtensional basins developed on the eastern margin of the forearc basin trapped fluvial sediments carried westward from the eroding Jurassic arc. A preponderance of Jurassic zircon grains in the Early Cretaceous forearc and intra-arc basin sediments indicates deep incision and likely extension of the Jura-Triassic arc massif. An increased proportion of 1.6-1.8 Ga detrital zircon grains in the Early Cretaceous deposits relative to known local sources may indicate the existence of trans-arc fluvial systems sourced in the Sevier or Mogollon highlands. By the Early Cretaceous epoch, pre-Mesozoic-aged detrital zircon populations were homogenized across the forearc-intra-arc-foreland basins, with the proportion of Mesozoic arc zircons varying with proximity and connectivity with the arc.