Late Quaternary Climate Variations Reflected in Baltic Sea Sediments - The Baltic Sea Basin - page 117

Table 5.2 Factor (principle
components, PC) loadings,
XRF data for master station,
core 303610-12

PC 1 PC 2 PC 3

Al − 0.949103 0.202158 0.054130

Si − 0.958174 0.145036 0.041052

P − 0.452261 − 0.149140 0.413834

S 0.346463 − 0.100103 − 0.851123

− 0.593041

Cl 0.677206 0.223976

−

K 0.969052 0.182937 0.048005

−

Ca 0.018410 0.791265 0.298696

Ti − 0.926965 0.129994 0.029933

Cr − 0.489651 − 0.336852 0.132195

Mn 0.659964 0.608977 0.093181

Fe − 0.665403 − 0.242609 − 0.598784

Co − 0.411766 − 0.618346 − 0.256555

Expl. var 5.688367 2.047864 1.493389

Prp. totl 0.474031 0.170655 0.124449

from A6 to the B6 zone in core 211660-5 (in Harff et al. 2001a ) this assumption can
be confirmed as the homogeneous, bioturbated sediments of zones A6, B2, B4, and
B6 show in general lower values than those at laminated zones B1, B3, and B5 (see
Sect. 5.4.3 ) . In order to specify the depositional environment for the different zones,
from Ancylus Lake sediments to the recent Baltic Sea, geochemical parameters as
well as diatom data have to be included in the analysis.
For the facies interpretation we have furthermore conducted a PCA (princi-
ple component analysis) for the data on concentration of geochemical elements.
Table 5.2 shows the factor loadings. High negative loadings for Al, Si, K, Ti, (Fe)
identify factor 1 as a proxy for detritical minerals derived from terrestrial sources. K
has the highest loading of this factor and points to an illitic clay component (Gingele
and Leipe 1997 ) . Factor 2 is determined by high loadings for Mn and Ca which rep-
resents the early diagenetic formation of a Ca-Mn-carbonate (rhodochrosite) phase
(see Neumann et al. 1997 , Alvi and Winterhalter 2001 ; Sohlenius et al. 1996 , 2001 ,
Burke and Kemp 2002 , Sternbeck et al. 2000 ) . Factor 3 expresses the dominant posi-
tion of sulphur (negative loadings) which is at least partly connected to a reduced
iron sulphide phase, but additionally strongly bound to the organic-rich laminated
mud sequences (organic sulphur) and can therefore regarded as proxy for the oxy-
gen depletion in the paleo-bottom water. In contrast, in factor 3 P is known to be
released from the sediment during anoxic conditions (Emeis et al. 2003 ; Conley
et al. 2009 ) .
We concentrate here on the principle components 1 and 3, which express
syngenetically controlled processes.
In Fig. 5.11 , the downcore concentration of K, Ti, and S is presented for core
303610-12 together with the physico-stratigraphic zonation of this core. Compared
to zones A6, B2, B4, and B6 being characterized by relatively high values of K and
Ti, zones B1, B3, and B5 show clearly lower concentrations of these elements. The
reason is attributed to higher terrestrial discharge to the basin during the deposition
of B2, B4, and B6 zone sediments compared to those of zones B1, B3, and B5.