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North Atlantic deepwater temperature change during late pliocene and late quaternary climatic cycles

Science

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, , , , , and
https://doi.org/10.1126/science.270.5240.1347

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Abstract

Variations in the ratio of magnesium to calcium (Mg/Ca) in fossil ostracodes from Deep Sea Drilling Project Site 607 in the deep North Atlantic show that the change in bottom water temperature during late Pliocene 41,000-year obliquity cycles averaged 1.5°C between 3.2 and 2.8 million years ago (Ma) and increased to 2.3°C between 2.8 and 2.3 Ma, coincidentally with the intensification of Northern Hemisphere glaciation. During the last two 100,000-year glacial-to-interglacial climatic cycles of the Quaternary, bottom water temperatures changed by 4.5°C. These results show that glacial deepwater cooling has intensified since 3.2 Ma, most likely as the result of progressively diminished deep-water production in the North Atlantic and of the greater influence of Antarctic bottom water in the North Atlantic during glacial periods. The ostracode Mg/Ca data also allow the direct determination of the temperature component of the benthic foraminiferal oxygen isotope record from Site 607, as well as derivation of a hypothetical sea-level curve for the late Pliocene and late Quaternary. The effects of dissolution on the Mg/Ca ratios of ostracode shells appear to have been minimal.

Additional publication details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
North Atlantic deepwater temperature change during late pliocene and late quaternary climatic cycles
Series title:
Science
DOI:
10.1126/science.270.5240.1347
Volume:
270
Issue:
5240
Year Published:
1995
Language:
English
Publisher:
American Association for the Advancement of Science
Description:
5 p.
First page:
1347
Last page:
1351