PROVENANCE OF NEWARK SUPERGROUP DEPOSITS IN THE DEEP RIVER SUB-BASIN FROM DETRITAL ZIRCON ANALYSIS

During Late Triassic time, alluvial, fluvial and lacustrine deposition of the Newark Supergroup occurred along the developing U.S. Central Atlantic Margin as the margin transitioned from a post-collisional system to a rift system. Based mainly on stratigraphic analysis and conventional provenance techniques, such as conglomerate clasts counts and sandstone petrology, it has been hypothesized that Newark Supergroup strata were deposited in half-grabens and that basin fill was sourced mainly by erosion of eastern and western basin margins, with some basins becoming stratigraphically linked during the latest stage of preserved deposition. The Deep River sub-basin in North Carolina is the most southerly of the exposed Triassic Central Atlantic rift margin basins. We compare detrital zircon signatures of sandstones from the Carnian Pekin Formation with the Norian Sanford Formation preserved in the Deep River sub-basin in order to characterize the provenance of sediment in the Deep River basin and test for sediment influx from other sub-basins to the north during Late Triassic evolution of Newark Supergroup depositional systems. Approximately 40% of the 300 detrital zircon grains analyzed from each of the Pekin Formation and Sanford Formation samples form an early Cambrian population with a peak at ~546 Ma. Between 7-11% of the zircon in both samples form a late Neoproterozoic population with a peak at ~610 Ma. Each sample yielded just 9 ages that were >2000 Ma. Based on the detrital zircon age signatures, we interpret the source for Deep River sub-basin sediment is likely the Albemarle Group of the Carolina Terrane, which contains volcanogenic sandstone, felsic volcanic rocks, felsic (meta)intrusive rocks and associated metapelites; rocks of the Albemarle Group have recently been shown to yield abundant 540-560 Ma zircon. The petrology of the Albemarle Group is also consistent with the feldspathic litharenite composition of Deep River sandstone framework grains, which suggests a dissected arc provenance. The similarity and unimodal nature of the age distribution of the samples suggests sediment was derived from a local source to the west of the Deep River sub-basin and the drainage system was characterized by a regionally limited and largely static catchment.