A molybdenum isotope record of Eocene Thermal Maximum 2: implications for global ocean redox during the early Eocene

Dickson, Alexander J. and Cohen, Anthony S. (2012). A molybdenum isotope record of Eocene Thermal Maximum 2: implications for global ocean redox during the early Eocene. Paleoceanography, 27(3), article no. PA3230.

DOI: https://doi.org/10.1029/2012PA002346

URL: http://www.agu.org/pubs/crossref/2012/2012PA002346...

Abstract

During the early Eocene, a series of short-term global warming events (‘hyperthermals’) occurred in response to the rapid release of carbon into the oceans and atmosphere. In order to investigate the response of ocean redox to global warming, we have determined the molybdenum isotope compositions (δ^98/95Mo) of samples spanning one such hyperthermal (Eocene Thermal Maximum 2 (ETM-2, 54.1Ma)), from Integrated Ocean Drilling Program Expedition 302 Site M0004A in the Arctic Ocean. The highest δ^98/95Mo in our sample set (2.00±0.11‰) corresponds to the development of local euxinia at Site M0004A during the peak of ETM-2, which we interpret as recording the global seawater δ^98/95Mo at that time. The ETM-2 seawater δ^98/95Mo is indistinguishable from a recent estimate of seawater δ^98/95Mo from an earlier hyperthermal (Paleocene Eocene Thermal Maximum (PETM, 55.9Ma), δ^98/95Mo = 2.08±0.11‰). It is argued that the similarity in seawater δ^98/95Mo during ETM-2 and the PETM was caused by the development of transient euxinia in the Arctic Ocean during each hyperthermal that allowed sediments accumulating in this basin to capture the long term δ^98/95Mo of early Eocene seawater. Our new data therefore place a minimum constraint on the magnitude of transient global seafloor deoxygenation during early Eocene hyperthermals.

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About

• Item ORO ID
• 35515
• Item Type
• Journal Item
• ISSN
• 0883-8305
• Project Funding Details

• Funded Project Name	Project ID	Funding Body
  Not Set	Not Set	NERC (Natural Environment Research Council)
  Not Set	Not Set	Open University

• Extra Information
• 9 pp.
• Keywords
• hyperthermals; early Eocene; Eocene Thermal Maximum 2; molybdenum isotopes; deoxygenation; Arctic Ocean
• Academic Unit or School
• Faculty of Science, Technology, Engineering and Mathematics (STEM) > Environment, Earth and Ecosystem Sciences
  Faculty of Science, Technology, Engineering and Mathematics (STEM)
• Copyright Holders
• © 2012 American Geophysical Union
• Depositing User
• Anthony Cohen