Palaeoenvironments of a complete Eemian sequence at Mommark, South Denmark: foraminifera, ostracods and stable isotopes

A new investigation of the coastal cliff section at Mommark in southern Denmark has revealed a complete Eemian interglacial sequence for the first time in the southwestern Baltic area. Environmental changes through the lacustrine and marine interglacial deposits are discussed on the basis of foraminiferal assemblages and stable isotope composition as well as ostracods. In general, the assemblages indicate relatively high temperatures throughout the Eemian, and the Lusitanian foraminiferal species Pseudoeponides falsobeccarii Rouvillois has been reported for the first time from the Eemian of northwest Europe. A floating chronology of the deposits is based on a previously published correlation of the local pollen stratigraphy with annually laminated sequences in northern Germany. An initial early Eemian lacustrine phase, with ostracodal indication of deposition in a large freshwater lake, lasted until c. 300 years after the beginning of the interglacial, i.e. to the transition between the regional pollen zones E2 and E3. After that, marine conditions persisted almost throughout the interglacial, and the Cyprina Clay was deposited. The foraminiferal and ostracodal assemblages indicate that relatively deep water prevailed in the area until c. 6000 years after the beginning of the interglacial. However, both the foraminiferal assemblages and the oxygen isotope results show that a trend from relatively high salinity to lower salinity conditions had begun already at about 4000 years. After c. 6000 years the fauna indicates a gradual change to shallower water and further reduction in salinity, the latter also being reflected by a general decrease in the oxygen isotope values. The marine deposition ended at c. 10 600 years after the beginning of the Eemian, i.e. within the topmost part of pollen zone E7. This was succeeded by a late Eemian and early Weichselian freshwater phase.