PROVENANCE AND PALEODRAINAGE EVOLUTION DURING CONTINENTAL BREAKUP ALONG THE EASTERN NORTH AMERICAN MARGIN, USA

New geophysical data, including long-offset reflection and refraction seismic datasets, geological studies of exhumed fossil analogs, lithospheric scale numerical modeling, and advances in analytical techniques, revolutionized the fundamental concepts of continental break-up. However, our understanding of the surface topographic evolution in response to progressive rifting and the sedimentary source-to-sink dynamics of magma-poor or magma-rich continental rifted margins remains rudimentary. Topographic surface evolution and sediment routing offer an opportunity to reconstruct lithospheric processes driving dynamic topography and large-wavelength geometries.

The Triassic to Jurassic syn-rift basins along the Eastern North American Margin (ENAM) provide a ~30 Mya record of progressive rifting spanning diffuse stretching, crustal thinning, and the transition to magmatic break-up. The alluvial, fluvial, and lacustrine lithofacies of the Newark Supergroup comprise the Carnian to Sinemurian syn-rift strata and were deposited in a series of half grabens bound by faults formed along the preexisting Appalachian structural grain. We use detrital zircon (DZ) and detrital apatite (DA) U/Pb geo-thermochronology to determine the provenance of the Newark Supergroup and to reconstruct the paleodrainages of the U.S. ENAM during progressive rifting and magmatic breakup.

Here we present new DZ and DA U/Pb provenance analyses from the Triassic to Jurassic syn-rift sedimentary rocks of the Hartford, Newark, Gettysburg, and Culpeper basins. These basins contain zircons with Laurentian, Axial, and Peri-Gondwanan realm affinities and show marked shifts in DZ U/Pb provenance indicative of two major paleodrainage reconfigurations. The first, during the Norian middle syn-rift, is a result of a combination of rift flank uplift and crustal necking. The second, at the onset of Central Atlantic Magmatic Province (CAMP) magmatism, is a result of local and regional uplift due to CAMP-related heating. Extensive DA U/Pb analyses from each syn-rift basin provide additional provenance detail due to the ability to recognize mid-temperature tectono-magmatic events of ENAM. Given the magnitude of zircon recycling during Appalachian orogenies, DA U/Pb analyses provide critical insight into provenance evolution.