Late Quaternary Climate Variations Reflected in Baltic Sea Sediments - The Baltic Sea Basin - page 127

the oxygen isotope record of the GISP2 ice core was used by Stuiver et al. ( 1997 )
to point at the relation between atmospheric and salt circulation pattern in the North
Atlantic. Mayewski et al. ( 1997 , 2004 ) called attention on the variability of global
storm intensity following the 1500-years cycle. In particular the latter one seems
to be reflected by facies change in the Baltic Sea. The elevated K-concentration in
zones A6, B2, B4, and B6 of core 303610-12 (Fig. 5.11 ) can tentatively be corre-
lated to periods of aeolian erosion of the central Asian deserts during cold periods
(Mayewski et al. 1997 , 2004 , O'Brien et al. 1995 ) . Accordingly, we assume we may
have a mixed regional to global climate signal in the periodicity of Baltic Sea basin
sediments.
5.7 Summary
The Baltic Sea and its sediments serve as a textbook in climate and environmental
history of the Baltic area and the North Atlantic realm. High sedimentation rates in
the central parts of the Baltic basin qualify the sediments and their facies to reflect
the dynamics of the atmospheric circulation of the North Atlantic, and also its mod-
ification due to the variation of Eurasian anticyclones on the inter-annual time scale.
Methods of basin analysis have been applied to draw a picture of the development
of the Eastern Gotland Basin in space and time from the Late Pleistocene to the
modern warm period. Sediment echosounders have been used for the identification
of coring stations, where gravity corers have been used for sampling up to 12 m
sediments representing the 12,000 years of basin history. Sediment physical param-
eters measured with a multi-sensor core logger (MSCL) serve as reference variables
for the physico-stratigraphic zonation and basinwide correlation sediment cores. In
particular
(a) The physico-stratigraphic zones determined for a “master station” coincide with
the main stages of the geological development of the Baltic Basin. The older
sequences (A zones) consist mainly of freshwater sediments from the Baltic Ice
Lake and the Ancylus Lake. Rapid sea level rise through the entrance of the
Baltic Sea caused a sudden increase of ocean water inflow into the Baltic Basin
(Littorina Sea with its transgression(s)) changing the environment of the Baltic
Basin permanently to a brackish-marine one. This shift is marked in the sed-
iment column by a change from homogeneous to laminated sediments of the
B zones due to the establishment of a halocline and anoxic bottom water. The
facies shift from zones A to B can be lithostratigraphically correlated basinwide
as well as within the sediment cores as within the sediment echosounder pro-
files. By interpolation of these stratigraphic boundaries thickness maps of A and
B zone sediments have been constructed. The different locations of the deposi-
tional centres for A and B zones show that the Littorina transgression caused a
general shift of the hydrographic system of the central Baltic Basin. Whereas
during the deposition of the lacustrine A zone sediments, a coast-to-basin