Late Quaternary Climate Variations Reflected in Baltic Sea Sediments - The Baltic Sea Basin - page 118

Fig. 5.11 Concentration of K (blue) and Ti (purple) ( left panel )andS( right panel ), expressed
by XRF counts, and physico-stratigraphic zonation of sediments in core 313610-12 at the “master
station” of the Eastern Gostland Basin
This higher terrestrial discharge can be explained either by higher precipitation and
river runoff or stronger erosion of the southern coasts due to storm-driven wave and
coastal current activity.
The lower concentrations of K and Ti in B1, B3, and B5 sediments stand for a rel-
ative decrease in terrestrial discharge together with pelagic deposition. Additionally,
the K-concentrations can be interpreted as a function of aeolian dust deposition.
In Fig. 5.11 , also the concentration of S as a function of core depth together with
the physico-stratigraphic zonation is presented for core 313610-12. For our interpre-
tation we have to take into account that the high S-concentrations in zone A6 are due
to Fe-sulphides formed diagenetically within Ancylus Lake sediments. In contrast,
the sulphur content in the B zones is regarded to be bound to organic sulphur com-
plexes as well as to diagenetic iron sulphide phases (pyrite) being formed in anoxic
environment (Sternbeck and Sohlenius 1997 ) . Therefore, high sulphur concentration
is interpreted as an indicator for anoxic environment. The sulphur concentrations
range between an average of 500 XRF counts for homogeneous (oxic) sediments
and 2000 XRF counts for laminated (anoxic) sediments. According to these values
we interpret the top of the (Ancylus) zone A6, and zones B2, B4, and B6 deposited
under oxic conditions, whereas zones B1, B3, and B5 originate from anoxic bottom
water. It is, however, also visible from the S-concentration curve that the lower parts