Abrupt reversal in ocean overturning during the Palaeocene/Eocene warm period

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doi: 10.1038/nature04386
Author(s): Nunes, Flavia; Norris, Richard D.
Author Affiliation(s): Primary:
Scripps Institution of Oceanography, La Jolla, CA, United States
Volume Title: Nature (London)
Source: Nature (London), 439(7072), p.60-63. Publisher: Macmillan Journals, London, United Kingdom. ISSN: 0028-0836 CODEN: NATUAS
Note: In English. 24 refs.; illus., incl. sketch maps
Summary: Carbon isotope data from 14 deep-sea sites in four ocean basins (location maps presented with deep-ocean circulation flow paths based on C isotopes) are used as a tracer of nutrients to reconstruct changes in deep-ocean circulation across the Palaeocene/Eocene boundary, and different models for the role of cirulation in the global climate are assessed. The longer a water mass is isolated from the surface, the more nutrients and 12C it acquires thus imparting a negatve δ13C signature as deep waters age. C isotopes thus trace nutrient content in water masses, with the most positive C isotopic ratios indicating zones of deep-water formation, while increasingly negative δ13C ratios characterize old deep waters as they move from their original sites. The δ13C values from the four basins are compared before, during and after the C isotope excursion associated with the Palaeocene/Eocene Thermal Maximum (PETM) to monitor deep-ocean circulation, and the results indicate a significant change in this pattern across the P/E boundary, and details are discussed. Deep-water circulation patterns thus changed from Southern Hemisphere overturning to Northern Hemisphere overturning at the start of the PETM and lasted for > 40 000 yr eventually returning to the original circulation pattern. It is suggested that greenhouse conditions can initiate abrupt deep-ocean circulation changes in < a few thousand yr but which may last, as in the case of the Palaeocene/Eocene, 100 000 yr.
Year of Publication: 2006
Research Program: DSDP Deep Sea Drilling Project
ODP Ocean Drilling Program
Key Words: 02 Geochemistry; 12 Stratigraphy, Historical Geology and Paleoecology; Biostratigraphy; C-13/C-12; Carbon; Cenozoic; Climate change; Cores; Deep Sea Drilling Project; Eocene; Foraminifera; Geochemistry; Global; Greenhouse effect; Invertebrata; Isotope ratios; Isotopes; Marine sediments; Microfossils; Models; O-18/O-16; Ocean Drilling Program; Oxygen; Paleo-oceanography; Paleocene; Paleocirculation; Paleoclimatology; Paleoecology; Paleoenvironment; Paleogene; Paleotemperature; Protista; Sediments; Stable isotopes; Tertiary; World ocean
Record ID: 2006051003
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom

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