Triassic and Jurassic Rift Basin Record of Continental Breakup along the Eastern North American Margin, U.S.A.

Abstract

Continental rift margins and their sedimentary systems provide a rich record of progressive rifting from lithospheric stretching to breakup. Over the past decade, new rift models based on numerical simulations, geophysical datasets, and observations from fossil margins transformed our understanding of continental rifting. But our understanding of sediment provenance and routing systems in relation to these new rift models is poorly understood. These new rift models make clear predictions of geometry, subsidence, surface evolution, and 2D sediment dispersal patterns. The U.S. Eastern North American Margin (ENAM) provides excellent exposures of the Triassic and Jurassic rift basins and provide a sedimentary record to test the new rift models. Similar rifted margins in the north-central Atlantic provide considerable hydrocarbon potential. Hence, improving the fundamental understanding of the depositional evolution provides insights on hydrocarbon potential of the little explored U.S. ENAM. We propose a study to reconstruct the tectonostratigraphic history and determine the spatial/ temporal trends in rift basin formation using: 1) stratigraphy to reconstruct basin morphology and depositional systems and 2) detrital zircon (DZ) double dating to determine sediment sources/dispersal paths. Together these data will provide tectonostratigraphic datasets to test the modern rift models and reconstruct the evolution of continental breakup. Preliminary DZ U-Pb results from the Culpeper Basin in VA show: 1) Carnian deposition sourced from the rift flank, 2) Norian strata sourced from the east (~100 km), and 3) Jurassic deposition proximally sourced from the hanging and footwall. These results indicate two paleodrainage reconfigurations. The first at the onset of lithospheric necking and the second at the onset of CAMP.

AAPG Datapages/Search and Discovery Article #90351 © 2019 AAPG Foundation 2019 Grants-in-Aid Projects