DEGLACIAL AND HOLOCENE OSTRACODA FROM THE BALTIC SEA, SITES M0059, M0060 AND M0063 (IODP EXPEDITION 347)

The study presents the first description and analysis of continuous ostracod records cored from different parts of the Baltic Sea during the IODP Expedition 347. We take advantage of the high-resolution ostracod records from the postglacial sediments collected across the Baltic Sea basin to provide ostracod-based paleoreconstructions of the postglacial history of the region. The studied records reveal different ostracod assemblage successions that reflect sea-level and salinity changes in the studied area.

We used published and unpublished radiocarbon-based age models to provide a stratigraphic framework for the sites: van Helmond et al. (2017) for Site M0059; Obrochta et al. (2017) for Site M0063; and an unpublished age model for Site M0060 (Hytinnen et al., in prep).

Site M0060 in the Kattegat area between Denmark and Sweden documents a marine environment with high sedimentation rates during the most recent deglaciation, and after ~7,600 cal. yr BP, a modern-like near-shore environment. Site M0059 in the southwestern Baltic Sea, Little Belt area documents the transition from a freshwater lake to the brackish Littorina Sea at ~7,500 cal. yr BP. Site M0063 in the deepest location in the central Baltic, Landsort Deep, yielded little ostracod data, but allowed us to distinguish Yoldia Sea, Ancylus Lake and Littorina Sea intervals.

References:

1) Hyttinen, O., Kotilainen, A.T., Quintana-Krupinski, N, Wacker, L., Bennike, O., Obrochta, S., Jensen, J.B., Lougheed, B., Ryabchuk, D., Passchier, S., Snowball, I. Herrero-Bervera, E. and Andrén, T. Deglaciation dynamics of the Fennoscandian Ice Sheet (FIS) in the Kattegat, the gateway between the North Sea and the Baltic Sea Basin. In preparation.

2) Obrochta, S., Andrén, T., Fazekas, S., Lougheed, B., Snowball, I., Yokoyama, Y., Miyairi, Y., Kondo, R., Kotilainen, A., Hyttinen, O., Fehr, A. The undatables: Quantifying uncertainty in a highly expanded late glacial-holocene sediment sequence recovered from the deepest Baltic Sea basin - IODP site M0063. Geochemistry, Geophysics, Geosystems 18, 3 (2017), 858–871.

3) van Helmond, N. A., Krupinski, N. B. Q., Lougheed, B. C., Obrochta, S. P., Andrén, T., and Slomp, C. P. Seasonal hypoxia was a natural feature of the coastal zone in the Little Belt, Denmark, during the past 8ka. Marine Geology 387 (2017), 45–57.