Seawater oxygenation during the Paleocene-Eocene Thermal Maximum

Uncertainty over the trajectory of seawater oxygenation in the coming decades is of particular concern in the light of geological episodes of abrupt global warming that were frequently accompanied by lowered seawater oxygen concentrations. Here we present an assessment of global seawater oxygenation...

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Bibliographic Details
Published in:Geology (Boulder) 2012-07, Vol.40 (7), p.639-642
Main Authors: Dickson, Alexander J, Cohen, Anthony S, Coe, Angela L
Format: Article
Language:English
Subjects:
actinides
Arctic Coring EXpedition
Arctic Ocean
Cenozoic
climate change
cores
Expedition 302
geochemistry
Geological time
global change
Global warming
Integrated Ocean Drilling Program
IODP Site M0004
Isotopes
Lomonosov Ridge
marine environment
marine sediments
metals
Mo-95
Mo-98
Mo-98/Mo-95
modern analogs
molybdenum
Oxygen
paleo-oceanography
Paleocene-Eocene Thermal Maximum
paleoclimatology
Paleogene
rhenium
Seawater
sediments
Stratigraphy
Tertiary
uranium
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Summary:Uncertainty over the trajectory of seawater oxygenation in the coming decades is of particular concern in the light of geological episodes of abrupt global warming that were frequently accompanied by lowered seawater oxygen concentrations. Here we present an assessment of global seawater oxygenation from an interval of one of these warming episodes, the Paleocene-Eocene Thermal Maximum (PETM, 55.9 m.y. ago). Our results, obtained from Integrated Ocean Drilling Program Expedition 302 Site M0004 in the Arctic Ocean, are based on molybdenum isotope determinations and molybdenum, rhenium, and uranium abundances. These data indicate a small global expansion of low-oxygen marine environments in the upper part of the PETM interval compared with the present day. More extensive seawater deoxygenation may have occurred for as long as ∼100 k.y., associated with a high rate of global warming and carbon oxidation at the start of the PETM. Our data also reveal molybdenum isotope compositions in Arctic Ocean deposits that are outside the range currently documented in marine environments. These exceptional compositions could reflect either the influence of hydrothermal inputs or equilibrium isotope fractionations associated with molybdenum sulfide speciation.
ISSN:0091-7613
1943-2682
DOI:10.1130/G32977.1