Late Quaternary Climate Variations Reflected in Baltic Sea Sediments - The Baltic Sea Basin - page 123

Fig. 5.14 Spectral density of p-wave velocity of core 211660-5, and PC1 score of XRF data of
core 303610-12
900-year peak is dominant for both the PC1 score of geochemical data of core
303610-12 and the p-wave velocity of core 211660-5. Periodicities of higher fre-
quencies are comparable, but do not completely coincide. The reason may be that
the age model of core 211660-1 was transferred to the cores at the master using a
lithostratigraphic correlation method which may have caused deviations in the high-
frequency fluctuations. In addition to the 900-year period we would like to note the
1500-years cycle, which can be read from the spectral densities in Fig. 5.14 . Even
if this frequency shows a lower significance than the 900-years period we regard it
notable as it is the first evidence of the “Bond Cycle” (Bond et al. 1997 , 2001 ) in
Holocene sediments of the Baltic Sea.
5.6 Discussion
We can conclude that the A zones have been deposited under well-ventilated con-
ditions relatively poor in organic matter production and preservation. At 8.16 cal.
years BP the lacustrine environment changed within the central Baltic basin rapidly
to brackish conditions by inflowing saline water of the Littorina transgression lead-
ing to the deposition of laminated sediments. As a result, benthic fauna emigrated,
making the accumulation of laminated sediments possible. This change in the envi-
ronment is caused by a sea level rise to be correlated with the atmospheric warming
phase after the significant cooling phase 8.8-8.2 k years ago (Sarnthein et al. 2003 ) .
Within the Littorina sedimentary facies physico-stratigraphic zonation indicates
shifts in the depositional environment on centennial time scales. According to
the diatom analysis within the B zones brackish-marine phases (B1, B3, B5) are
replaced periodically by phases of fresher water conditions (B2, B4, B6). Also the
influx of terrigenous matter is intensified. This can be concluded not only from the
geochemical data but also from the diatom record that shows an increase of aci-
dophilus species indicating erosion of coastal peat. Due to this fact we interpret the