Cooling and ice growth across the Eocene-Oligocene transition
The Eocene-Oligocene (E-O) climate transition (ca. 34 Ma) marks a period of Antarctic ice growth and a major step from early Cenozoic greenhouse conditions toward today's glaciated climate state. The transition is represented by an increase in deep-sea benthic foraminiferal oxygen isotope (18O)...
Published in: | Geology |
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Main Authors: | , , , , |
Format: | Article in Journal/Newspaper |
Language: | unknown |
Published: |
Geological Society of America
2008
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Subjects: | |
Online Access: | https://orca.cardiff.ac.uk/id/eprint/10101/ https://doi.org/10.1130/G24584A.1 |
Summary: | The Eocene-Oligocene (E-O) climate transition (ca. 34 Ma) marks a period of Antarctic ice growth and a major step from early Cenozoic greenhouse conditions toward today's glaciated climate state. The transition is represented by an increase in deep-sea benthic foraminiferal oxygen isotope (18O) values occurring in two main steps that reflect the temperature and 18O of seawater. Existing benthic Mg/Ca paleotemperature records do not display a cooling across the transition, possibly reflecting a saturation state effect on benthic foraminiferal Mg/Ca ratios at deep-water sites. Here we present data from exceptionally well preserved foraminifera deposited well above the calcite compensation depth that provide the first proxy evidence for an 2.5 °C ocean cooling associated with the ice growth. This permits interpretation of E-O 18O records without invoking Northern Hemisphere continental-scale ice. |
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