Palaeoenvironments in the southern Baltic Sea Basin during Marine Isotope Stage3: A multi-proxy reconstruction
Journal
Quaternary Science Reviews
Journal Volume
34
Pages
81-92
Date Issued
2012
Author(s)
Abstract
Sediment cores from Kriegers Flak in the southwestern Baltic Sea provide a unique possibility to study the Middle Weichselian history of the Baltic Basin. Three Weichselian interstadial units have been identified and are attributed to Marine Isotope Stage 3 (MIS 3, 60-25ka). The oldest unit A is characterized by a deglaciation sequence, gradually turning into brackish-water clay. The low-diversity benthic foraminiferal fauna, stable oxygen isotope values and Mg/Ca ratios indicate low temperature and salinity for unit A. A hiatus separates unit A from the overlying unit B, which was deposited in wetlands and shallow lakes between 42 and 36cal.ka BP. Macrofossil and pollen analyses indicate deposition of unit B in an area dominated by a tree-less open tundra environment, possibly with some birch and pine in sheltered positions. The uppermost unit C is characterized by clay deposition, including redeposition of material from older sediments (unit B). Optically stimulated luminescence (OSL) ages indicate deposition of unit C between 26 and 28.5ka. Radiocarbon ages of 39 and 40cal. ka BP for unit C are considered to be too old. The following depositional model is suggested: (I) Isostatic depression of the region after an advance of the Scandinavian Ice Sheet (SIS), most likely the Ristinge ice advance, previously dated to c. 55-50ka, enabled an inflow of marine waters into the Baltic Basin during the deposition of unit A. (II) Isostatic rebound caused a regression at Kriegers Flak, and a hiatus between units A and B. (III) Wetlands and smaller lakes formed in the uplifted area between 42 and 36cal.ka BP (unit B). (IV) Deposition of glaciolacustrine clays at Kriegers Flak demonstrates that a growing SIS dammed Kattegat and the Baltic Basin c. 28.5 to 26ka. The new evidence from Kriegers Flak provides a solid framework for future MIS 3 palaeoenvironmental reconstructions in the circum-Baltic area. © 2011 Elsevier Ltd.
Subjects
Baltic Sea Basin; Marine Isotope Stage 3; Palaeoenvironment; Scandinavian Ice Sheet
Other Subjects
Baltic sea; Brackish water; Deglaciations; Depositional models; Foraminiferal faunas; Ice sheet; Isostatic rebound; Kattegat; Low temperatures; Marine isotope; Marine isotope stages; Marine waters; Optically stimulated luminescence; Palaeoenvironment; Pollen analysis; Radiocarbon age; Redeposition; Scandinavian Ice Sheet; Sediment core; Shallow lakes; Stable oxygen isotopes; Uplifted areas; Anoxic sediments; Glacial geology; Glaciers; Lakes; Luminescence; Wetlands; Isotopes; brackish water; calcium; coniferous tree; deglaciation; foraminifera; ice sheet; isotopic ratio; low temperature; luminescence; magnesium; numerical model; oxygen isotope; paleoceanography; paleoenvironment; pollen; proxy climate record; radiocarbon dating; reconstruction; salinity; shallow water; shrub; stable isotope; wetland; Atlantic Ocean; Baltic Region; Baltic Sea; Scandinavia
Type
journal article