Dan Hammarlund

Late Weichselian and early Holocene partly carbonate-rich sediments from a small lacustrine deposit in Skane, southern Sweden, were analysed for stable carbon and oxygen isotopes and mollusc assemblages. The data from these analyses reveal a pronounced climatic warming at c. 12,400 BP, accompanied by a general change from continental to maritime conditions. Two significant climatic oscillations were identified, dated ate. 12,200-12,000 BP ande. 11,000-10,200 BP. The climatic cooling of the latter, corresponding to the Younger Dryas stadial, may have been initiated well before 11,000 BP. A climatic oscillation of minor amplitude may have occurred around 11,500 BP. Distinct variations in delta(13)C of bulk organic material and shell carbonate are discussed in terms of climatically-induced changes in lake-water chemistry. The general assumption of a positive correlation between delta(18)O of limnic carbonates and mean annual air temperature is questioned. A climatic warming may be associated with a depletion of (18)O in limnic carbonates. Comparisons of palaeoclimatic information from the stable isotope data with that provided by molluscs allow the identification of aspects of climatic and environmental change such as water temperature, water depth, and aquatic vegetation density. Changes in the mollusc assemblage reflect changes in the limnic environment and facilitates the interpretation of stable isotope data.