The Development of the Baltic Sea Basin During the Last 130 ka

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 SWEemian 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 fewstill-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 themaximum 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.