Abrupt episode of mid-Cretaceous ocean acidification triggered by massive volcanism

• Published in: Nature Geoscience
• Main Authors: Jones, Matthew M., Sageman, Bradley B., Selby, David, Jacobson, Andrew D., Batenburg, Sietske J., Riquier, Laurent, Macleod, Kenneth G., Huber, Brian T., Bogus, Kara A., Tejada, Maria Luisa G., Kuroda, Junichiro, Hobbs, Richard W.
• Other Authors: Department of Earth and Planetary Sciences Evanston, Northwestern University Evanston, Department of Environmental, Earth and Geospatial Sciences Durham (DEEGS), North Carolina Central University Durham, University of North Carolina System (UNC)-University of North Carolina System (UNC), Departament de Dinàmica de la Terra i de l’Oceà Barcelona, Universitat de Barcelona (UB), Institut des Sciences de la Terre de Paris (iSTeP), Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Department of Geological Sciences, University of Missouri, University of Missouri Columbia (Mizzou), University of Missouri System-University of Missouri System, School of Geography, Earth and Environmental Sciences Birmingham, University of Birmingham Birmingham, Smithsonian Institution, National Museum of Natural History, Camborne School of Mines, College of Engineering, Mathematics and Physical Sciences, University of Exeter, Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Department of Ocean Floor Geoscience, Ocean Research Institute, The University of Tokyo (UTokyo), Department of Earth Sciences Durham, Durham University
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2023
• Subjects: Earth Science; [SDU]Sciences of the Universe [physics]; Ocean acidification
• Online Access: https://insu.hal.science/insu-04139380; https://doi.org/10.1038/s41561-022-01115-w

International audience Large-igneous-province volcanic activity during the mid-Cretaceous triggered a global-scale episode of reduced marine oxygen levels known as Oceanic Anoxic Event 2 approximately 94.5 million years ago. It has been hypothesized that this geologically rapid degassing of volcanic carbon dioxide altered seawater carbonate chemistry, affecting marine ecosystems, geochemical cycles and sedimentation. Here we report on two sites drilled by the International Ocean Discovery Program offshore of southwest Australia that exhibit clear evidence for suppressed pelagic carbonate sedimentation in the form of a stratigraphic interval barren of carbonate minerals, recording ocean acidification during the event. We then use the osmium isotopic composition of bulk sediments to directly link this protracted ~600 kyr shoaling of the marine calcite compensation depth to the onset of volcanic activity. This decrease in marine pH was prolonged by biogeochemical feedbacks in highly productive regions where elevated heterotrophic respiration added carbon dioxide to the water column. A compilation of mid-Cretaceous marine stratigraphic records reveals a contemporaneous decrease of sedimentary carbonate content at continental slope sites globally. Thus, we contend that changes in marine carbonate chemistry are a primary ecological stress and important consequence of rapid emission of carbon dioxide during many large-igneous-province eruptions in the geologic past.