• journal_title：Geology
• Contributor：Enriqueta Barrera ; Samuel M. Savin ; Ellen Thomas ; Charles E. Jones
• Publisher：Geological Society of America
• Date：1997-
• Format：text/html
• Language：en
• Identifier：10.1130/0091-7613(1997)025<0715:EFTCRC>2.3.CO;2
• journal_abbrev：Geology
• issn：0091-7613
• volume：25
• issue：8
• firstpage：715

Fluctuations in oxygen (δ¹⁸O) and carbon (δ¹³C) isotope values of benthic foraminiferal calcite from the tropical Pacific and Southern Oceans indicate rapid reversals in the dominant mode and direction of the thermohaline circulation during a 1 m.y. interval (71–70 Ma) in the Maastrichtian. At the onset of this change, benthic foraminiferal δ¹⁸O values increased and were highest in low-latitude Pacific Ocean waters, whereas benthic and planktic foraminiferal δ¹³C values decreased and benthic values were lowest in the Southern Ocean. Subsequently, benthic foraminiferal δ¹⁸O values in the Indo-Pacific decreased, and benthic and planktic δ¹³C values increased globally. These isotopic patterns suggest that cool intermediate-depth waters, derived from high-latitude regions, penetrated temporarily to the tropics. The low benthic δ¹³C values at the Southern Ocean sites, however, suggest that these cool waters may have been derived from high northern rather than high southern latitudes. Correlation with eustatic sea-level curves suggests that sea-level change was the most likely mechanism to change the circulation and/or source(s) of intermediate-depth waters. We thus propose that oceanic circulation during the latest Cretaceous was vigorous and that competing sources of intermediate- and deep-water formation, linked to changes in climate and sea level, may have alternated in importance.