When did the South Atlantic Ocean ventilate? Testing for paleogeographic controls on Cretaceous carbon burial

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The oceans play a critical role in modulating Earth’s carbon cycle, climate, and habitability. Geoscientists rely on the sedimentary record of ocean basins to understand how the Earth and its oceans respond to geological and environmental change over long timescales. Ultimately, a better understanding of these feedbacks allows for predictions about how life on our planet has responded, or will respond, to external drivers such as climate or tectonics. This project will investigate links between physical surface processes, ocean oxygenation, and organic carbon burial during the establishment of the South Atlantic Ocean from 150-100 million years ago, a time period characterized by greenhouse to hothouse climate conditions. More broadly, this project will (1) generate new high school educational and professional development content; (2) enhance infrastructure for international research, collaboration, and community engagement in southern Patagonia; and (3) promote teaching, mentoring, and research with undergraduates in STEM.Continental break-up facilitates suitable conditions (e.g., restricted incipient ocean basins) for organic carbon burial. It is less clear, however, when/how these conditions are reversed by continued continental breakup and ocean basin ventilation and circulation. This project aims to determine the depositional response to local basin setting, regional tectonics, and global climate changes associated with the opening of a major oceanic gateway in the South Atlantic during the Early Cretaceous breakup of Gondwana. Preliminary results from southern Patagonia show there are discernable lithologic and chemostratigraphic boundaries in the stratigraphy of southern ocean basins recording changing environmental conditions. Constraining the timing of deposition with high precision geochronology and the chemical environments of deposition allows for comparisons between this study in Patagonia with age-correlative basins elsewhere. Moreover, through collaborations with Chilean paleontologists, the project will inform ongoing paleobiology studies of the environmental influences on the distribution and behavioral patterns of Cretaceous marine vertebrates.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.