A 200 KA GEOMAGNETIC CHRONOSTRATIGRAPHY FOR THE LABRADOR SEA - INDIRECT CORRELATION OF THE SEDIMENT RECORD TO SPECMAP

A chronostratigraphic framework for the last 200 ka, based on relative variations of geomagnetic paleointensity, has been derived for the La brador Sea where delta(18)O stratigraphies are compromised by lack of benthic foraminifera and environmental perturbations of the planktic r ecord. Relative paleointensity records derived from three Labrador Sea piston cores are correlated to a recently developed 200 ka paleointen sity composite (Sint-200) [Y. Guyodo, J.-P. Valet, Earth Planet. Sci. Lett. 143 (1996) 23-36]. The chronology fbr Sint-200 was derived by co rrelating oxygen isotope stratigraphies from individual paleointensity records to the SPECMAP chronostratigraphy. The correlation of Sint-20 0 to Labrador Sea paleointensity records allows the SPECMAP chronology to be imported into the Labrador Sea. Although comparisons of the chr onostratigraphy based on paleointensity correlations with those derive d from AMS C-14 dates and delta(18)O data indicate significant discrep ancies, support for the new chronostratigraphic framework is provided by: (1) consistent correlation of Labrador Sea detrital layers to Nort h Atlantic Heinrich layers; (2) general consistency between planktic d elta(18)O values and the SPECMAP reference curve; and (3) feasible pre diction for the age of ash layer 2. As the new chronostratigraphy is t ied to SPECMAP, Labrador Sea sediment cores can now be directly compar ed with any SPECMAP dated record. (C) 1998 Elsevier Science B.V. All r ights reserved.