Correlation of Swedish glacial varves with the Greenland (GRIP) oxygen isotope record
Journal of Quaternary Science, Vol. 14, No. 4, p. 361-371, 1999T. Andrén and J. Björck
Department of Quaternary Research, Stockholm University, S-10691, Stockholm, Sweden.
S. Johnsen
Ice and Climate, The Niels Bohr Institute, Juliane Maries Vej 30, DK-2100 Copenhagen, Denmark
ABSTRACT.
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.