Eemian marine mollusks and barnacles from Ristinge Klint, Denmark: hydrodynamics and oxygen deficiency

Abstract

Taphonomic analysis of Eemian marine mollusks and barnacles at Ristinge Klint on the island of Langeland (Denmark) provides a distinct record of a temporal succession in preservation states. Four different states of preservation are recognized and related to a decreasing hydrodynamic regime in the depositional setting of the Eemian Baltic Sea. The states show a deepening-upward transition from shallow bay environment towards deeper offshore environment. The depositional setting changed significantly in hydrodynamics about 620 and 1550 years into the Eemian (130,000 to 115,000 years BP), according to biostratigraphic correlation with the varves of the Bispingen succession. The taxonomic composition of the paleofauna supports such a deepening-upward interpretation with a contemporaneous change from brackish water to nearly full marine conditions. The sea bottom was affected by at least one period of oxygen deficiency. The analysis also shows that the preservation of shells varies according to differences in shell structures and life habits. Here we show how these differences should be considered in paleoenvironmental reconstructions based on taphonomic analyses. Taphonomy may play an important role in understanding the hydrodynamic conditions within the Eemian Baltic Sea.