Correlation Between Temperature Records From Reykjanes Ridge Sediment and GISP2 Ice-core

S van Kreveld (Geologisch-Palaeontologisches Institut, Universitaet

Kiel, Olshausenstrasse 40, D-24118 Kiel, Germany; ph. +49-431-8801457; fax +49-431-880-4376; Internet: sk@gpi.uni-kiel.de); U Pflaumann (Geologisch-Palaeontologisches Institut, Universitaet Kiel, Olshausenstrasse 40, D-24118 Kiel, Germany; ph. +49-431-8802928; fax +49-431-880-4376; Internet: up@gpi.uni-kiel.de); M Sarnthein (Geologisch-Palaeontologisches Institut, Universitaet Kiel, Olshausenstrasse 40, D-24118 Kiel, Germany; ph. +49-431-8802882; fax +49-431-880-4376; Internet: ms@gpi.uni-kiel.de); P Grootes (Leibniz-Labor fuer Altersbestimmung und Isotopenforschung, Max Eythstrasse 11-13, D-24118 Kiel, Germany; ph. +49-431-8803894; fax +49-431-880-3356; Internet: pgrootes@leibniz.uni-kiel.de); M J Nadeau (Leibniz-Labor fuer Altersbestimmung und Isotopenforschung, Max Eythstrasse 11-13, D-24118 Kiel, Germany; ph. +49-431-8807390; fax +49-431-880-3356; Internet: mnadeau@leibniz.uni-kiel.de); H Erlenkeuser (Leibniz-Labor fuer Altersbestimmung und Isotopenforschung, Max Eythstrasse 11-13, D-24118 Kiel, Germany; ph. +49-431-8803896; fax +49-431-880-3356; Internet: pke47@rz.uni-kiel.de)

Ice core studies show fast short-term climatic changes during isotope stages 3 and 2. This rapid climate variability has been linked to meltwater events which reduce the heat and salt transport to the North Atlantic. In order to assess the ocean's influence on climate, we estimated sea surface temperature (SST) and salinity (SSS) at centennial-resolution covering the past 60-15 ka using a sediment core from the Reykjanes Ridge (SO82-5: 59N, 31W; 1416 m water depth). The chronology is based on 66 AMS 14C ages measured on monospecific samples of Neogloboquadrina pachyderma (sinistral), oxygen isotopes and ash layers.

The summer SST estimates vary from 2.5-10 degrees C in core SO82-5. The transition from stadial to interstadial conditions occurs rapidly and is characterized by a steep SST gradient. Our correlation with the GISP2 ice core shows that all but one Dansgaard-Oeschger interstadials correspond to a SST peak in core SO82-5.

Enhanced discharge of ice-rafted debris (IRD) in the Irminger Basin

occurred every 1-3 ka, more frequently than the 7-10 ka cycle generally associated with the Heinrich events. The majority of these IRD peaks occur near the end of the low SST and low SSS intervals. This timing indicates that the local iceberg events mostly developed during a later stage of periods characterized by extremely cold meltwater in the Irminger basin. This lag implies a yet unknown response function. The meltwater events end with a rapid increase in SST and SSS, that is coeval with the decrease in IRD, possibly indicating a retreat of the ice margin to the shelf.

Our correlations with the Greenland ice core indicate a close link between air and sea surface temperatures as well as the ice-rafting cycles at sub-millenium time scales.