TY - JOUR
T1 - Uranium isotope evidence for two episodes of deoxygenation during Oceanic Anoxic Event 2
AU - Clarkson, Matthew
AU - Stirling, Claudine
AU - Jenkyns, Hugh C.
AU - Dickson, Alexander
AU - Porcelli, Donald
AU - Moy, Christopher
AU - Pogge van Strandmann, Philip
AU - Cooke, Ilsa
AU - Lenton, Tim
PY - 2018/3/20
Y1 - 2018/3/20
N2 - 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 new record of global ocean redox changes during OAE 2 using a combined geochemical and carbon cycle modelling 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 new dataset is then compared to 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 under constrained, 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 multi-phase Large Igneous Province (LIP) activity.
AB - 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 new record of global ocean redox changes during OAE 2 using a combined geochemical and carbon cycle modelling 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 new dataset is then compared to 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 under constrained, 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 multi-phase Large Igneous Province (LIP) activity.
U2 - 10.1073/pnas.1715278115
DO - 10.1073/pnas.1715278115
M3 - Article
SN - 0027-8424
VL - 115
SP - 2918
EP - 2923
JO - Proceedings of the National Academy of Sciences of the United States of America
JF - Proceedings of the National Academy of Sciences of the United States of America
IS - 12
ER -