Abstract

U-Pb detrital zircon geochronology provides insight into the provenance of the upper Neoproterozoic–lower Cambrian Osgood Mountain Quartzite and the upper Cambrian–lower Ordovician Preble Formation in the Osgood Mountains of northern Nevada (USA). We analyzed 535 detrital zircon grains from six samples of quartz arenite by laser ablation–multicollector–inductively coupled plasma–mass spectrometry. The detrital zircon age data of these Neoproterozoic–lower Paleozoic passive margin units record a provenance change within the Osgood Mountain Quartzite. Comparison of these data with the work of others reveals that this change in provenance occurred in correlative strata throughout an east-west transect of the Great Basin. From latest Neoproterozoic through earliest Cambrian time, most grains were shed from the 1.0–1.2 Ga Grenville orogen. After that time, drainage patterns changed and most grains were derived from the 1.6–1.8 Ga Yavapai and Mazatzal provinces; very few grains from the Grenville orogen were found in the younger strata. We suggest that this shift records the uplift, in early Cambrian time, of the Transcontinental Arch. Our data also support our interpretation that the Osgood Mountain Quartzite and the Preble Formation are correlative to other contemporaneous passive margin strata in western Laurentia.

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