Geoscience Reference
In-Depth Information
Chapter 4
The Development of the Baltic Sea Basin During
the Last 130 ka
Thomas Andrén, Svante Björck, Elinor Andrén, Daniel Conley,
Lovisa Zillén, and Johanna Anjar
Abstract
During the Eemian interglacial 130-115 ka BP, the hydrology of the
Baltic Sea was significantly different from the Holocene. A pathway between the
Baltic basin and the Barents Sea through Karelia existed during the first ca. 2.5 ka of
the interglacial. Both sea surface temperature and salinity of the SW Eemian Baltic
Sea were much higher, ca. 6
◦
C and 15‰, respectively, than at present. A first early
Weichselian Scandinavian ice advance is recorded in NW Finland during marine
isotope stage (MIS) 4 and the first Baltic ice lobe advance into SE Denmark is dated
to 55-50 ka BP. From the last glacial maximum that was reached ca. 22 ka BP, the
ice sheet retreated northward with a few still-stands and readvances; however, by ca.
10 ka BP the entire basin was deglaciated. Weak inflows of saline water were regis-
tered in the southern and central Baltic Sea ca. 9.8 ka BP with full brackish marine
conditions reached at ca. 8 ka BP and the maximum Holocene salinity was recorded
between 6 and 4 ka BP. The present Baltic Sea is characterized by a marked halo-
cline preventing the vertical water exchange resulting in hypoxic bottom conditions
in the deeper part of the basin.
Keywords
Baltic Sea
·
Eemian
·
Scandinavian ice sheet
·
Weichselian
·
Baltic Ice
Lake
·
Yoldia Sea
·
Ancylus Lake
·
Littorina Sea
·
Hypoxia
4.1 Introduction
During the last decade, significant efforts have been focused on the recent develop-
ment of the Baltic Sea. This has resulted in different explanatory mechanisms for
its present state and different possible remedies to change its present eutrophication
influencing the Baltic has meant that it has gradually become more common to place
