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Uranium isotope evidence for two episodes of deoxygenation during Oceanic Anoxic Event 2

Clarkson, MO; Stirling, CH; Jenkyns, HC; Dickson, AJ; Porcelli, D; Moy, CM; Pogge Von Strandmann, PAE; ... Lenton, TM; + view all (2018) Uranium isotope evidence for two episodes of deoxygenation during Oceanic Anoxic Event 2. Proceedings of the National Academy of Sciences , 115 (12) pp. 2918-2923. 10.1073/pnas.1715278115. Green open access

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Abstract

Oceanic Anoxic Event 2 (OAE 2), occurring ∼94 million years ago, was one of the most extreme carbon cycle and climatic perturbations of the Phanerozoic Eon. It was typified by a rapid rise in atmospheric CO2, global warming, and marine anoxia, leading to the widespread devastation of marine ecosystems. However, the precise timing and extent to which oceanic anoxic conditions expanded during OAE 2 remains unresolved. We present a record of global ocean redox changes during OAE 2 using a combined geochemical and carbon cycle modeling approach. We utilize a continuous, high-resolution record of uranium isotopes in pelagic and platform carbonate sediments to quantify the global extent of seafloor anoxia during OAE 2. This dataset is then compared with a dynamic model of the coupled global carbon, phosphorus, and uranium cycles to test hypotheses for OAE 2 initiation. This unique approach highlights an intra-OAE complexity that has previously been underconstrained, characterized by two expansions of anoxia separated by an episode of globally significant reoxygenation coincident with the “Plenus Cold Event.” Each anoxic expansion event was likely driven by rapid atmospheric CO2 injections from multiphase Large Igneous Province activity.

Type: Article
Title: Uranium isotope evidence for two episodes of deoxygenation during Oceanic Anoxic Event 2
Open access status: An open access version is available from UCL Discovery
DOI: 10.1073/pnas.1715278115
Publisher version: http://doi.org/10.1073/pnas.1715278115
Language: English
Additional information: This version is the author accepted manuscript. For information on re-use, please refer to the publisher’s terms and conditions.
Keywords: Oceanic anoxia, OAE, uranium isotopes, biogeochemical model, carbon cycle
UCL classification: UCL
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Earth Sciences
URI: https://discovery.ucl.ac.uk/id/eprint/10044997
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