Marine transgressions during Eemian in northern Poland: A high resolution record from the type section at Cierpięta

A core of the new borehole at Cierpięta in northern Poland was examined with sedimentological, palynological, plant macrofossil, diatom, malacological, and foraminiferal analyses and completed with radiocarbon, OSL and amino acid dating. Based on a floating scale chronology, a rapid marine transgression was found to have started in the southern Baltic region before 300 years from the beginning of the Eemian (RPAZ E1 or E2). Two pulses of increased salinity were distinguished (reaching 28 and 18 psu), with their maxima at about 800-3500 and 6200-6600 years since the beginning of the Eemian, suggesting a possible two-step transgression of the Eemian sea. Diatom species, typical for a tidal plain, were more abundant during transgressive phases, presumably not only due to seashore flooding but possibly also in response to more intensive tides. A final regression occurred some 7500 years after the beginning of the Eemian (end of RPAZ E5 or early E6) and the bay has been transformed into a lake-marshy reservoir. Studies of the section at Cierpięta are crucial for paleogeography of the Eemian sea in the southern Baltic region.