Correlation of Swedish glacial varves with the Greenland (GRIP) oxygen isotope recordJournal of Quaternary Science, Vol. 14, No. 4, p. 361-371, 1999
T. Andrén and J. Björck
Department of Quaternary Research, Stockholm University, S-10691, Stockholm, Sweden.
Ice and Climate, The Niels Bohr Institute, Juliane Maries Vej 30, DK-2100 Copenhagen, Denmark
A mean varve thickness curve has been constructed for a part of the Swedish varve chronology from the northwestern Baltic proper. The mean varve thickness curve has been correlated with the δ18O record from the GRIP ice-core using the Younger Dryas-Preboreal climate shift. This climate shift was defined by pollen analyses. The Scandinavian ice-sheet responded to a warming at the end of the Younger Dryas, ca. 10 995 to 10 700 clay-varve yr BP. Warming is recorded as a sequence of increasing mean varve thickness and ice-rafted debris suggesting intense calving of the ice front. The Younger Dryas-Preboreal climatic shift is dated to ca. 10 650 clay-varve yr BP, about 40 yr after the final drainage of the Baltic Ice Lake. Both the pollen spectra and a drastic increase in varve thickness reflect this climatic shift. A climate deterioration, correlated with the Preboreal oscillation, is dated to ca. 10 440 to 10 320 clayvarve yr BP and coincides with the brackish water phase of the Yoldia Sea stage. The ages of the climatic oscillations at the Younger Dryas-Preboreal transition show an 875 yr discrepancy compared with the GRIP record, suggesting a large error in the Swedish varve chronology in the part younger than ca. 10 300 clay-varve yr BP.