DETRITAL ZIRCON PROVENANCE OF PRECAMBRIAN–CAMBRIAN MIOGEOCLINAL SEDIMENTARY ROCKS, NEVADA–UTAH BORDER

Provenance and sediment dispersal studies of miogeoclinal sedimentary rocks can help provide a more detailed picture of the evolution of the continental margin of North America. Previous studies from the northeastern Basin and Range indicate increasing local and decreasing distal sediment sources during the Precambrian to Cambrian, although few detrital zircon studies have been completed to supplement this work. To better understand the provenance of the northeastern Basin and Range during this time, we used LA-MC-ICP-MS at the University of Arizona to analyze detrital zircons from Precambrian–Cambrian quartzites in the Pilot, Deep Creek, and Snake Ranges along the Nevada–Utah border. Detrital spectra in the Precambrian McCoy Creek Group from all three ranges display peaks at 1.0–1.2 Ga and ~1.4 Ga, with fewer Archean grains and 1.6–1.8 Ga grains that increase in abundance through time. Zircons from the Cambrian Prospect Mountain Quartzite are dominated by 1.8 Ga ages in the Snake and Pilot Ranges, and 1.44 Ga and 1.72 point sources in the Deep Creek Range. These results are consistent with previous studies and indicate that Late Neoproterozoic sediments were derived from distal sources including Grenvillian and Granite-Rhyolite terranes from the eastern margin of North America, while subsequent Cambrian sediments came from more local sources including the Mojave, Mazatal, and Yavapai terranes. Possible explanations for the switch in sediment sources at the Precambrian–Cambrian boundary include the emergence of the proto-Tooele–Uinta Arch, which would have provided abundant 1.8 Ga detritus to the miogeocline, and shallow marine transgressions into mid-continental regions that would have precluded transport of grains across the continent.