The Cause of Carbon Isotope Minimum Events on Glacial Terminations

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Science  19 Apr 2002:
Vol. 296, Issue 5567, pp. 522-525
DOI: 10.1126/science.1069401

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The occurrence of carbon isotope minima at the beginning of glacial terminations is a common feature of planktic foraminifera carbon isotopic records from the Indo-Pacific, sub-Antarctic, and South Atlantic. We use the δ13C record of a thermocline-dwelling foraminifera, Neogloboquadrina dutertrei, and surface temperature estimates from the eastern equatorial Pacific to demonstrate that the onset of δ13C minimum events and the initiation of Southern Ocean warming occurred simultaneously. Timing agreement between the marine record and the δ13C minimum in an Antarctic atmospheric record suggests that the deglacial events were a response to the breakdown of surface water stratification, renewed Circumpolar Deep Water upwelling, and advection of low δ13C waters to the convergence zone at the sub-Antarctic front. On the basis of age agreement between the absolute δ13C minimum in surface records and the shift from low to high δ13C in the deep South Atlantic, we suggest that the δ13C rise that marks the end of the carbon isotope minima was due to the resumption of North Atlantic Deep Water influence in the Southern Ocean.

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