Title: Strontium isotopic response during OAE2
Speaker: ACES Candidate Mr. Lucien Nana Yobo
PhD Candidate, University of Houston
Abstract: Ocean anoxic events are characterized by increased organic richness of marine sediment on a global scale with accompanying positive excursions in sedimentary organic and inorganic carbon isotope values. Increased supplies of nutrients to the oceans are required to sustain elevated levels of marine productivity necessary to account for high
carbon export fluxes during ocean anoxic events. Submarine eruptions of one or more large igneous provinces are the proposed trigger for OAE 2, and the CO2 induced global warming and increased rainfall acidification are both factors that can increased continental weathering rates and therefore nutrient inputs to the oceans. On the other hand, seawater interactions with hot basalts at LIP eruptions sites can deliver ferrous iron and other metals and reduced
gases to seawater that can stimulate increased productivity in surface waters and increased oxygen demand in deep waters. The relative importance of continental and submarine weathering drivers of expanding ocean anoxia during OAE 2 are difficult to disentangle. In this talk, we present a new high-resolution record of seawater 87Sr/86Sr in a pelagic carbonate succession from the Eagle Ford Formation in Texas. With the help of a box model of the ocean Sr cycle, and knowledge of the contrasting 87Sr/86Sr signatures of continental weathering and submarine weathering inputs of Sr to the oceans, the relative magnitudes of the continental weathering and submarine weathering fluxes of Sr to the oceans during OAE 2 is determined. Finally, the new 87Sr/86Sr data offers a significant refinement to the
temporal pattern of changing 87Sr/86Sr in the global ocean over OAE2.
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