OXYGEN AND CARBON-ISOTOPE COMPOSITION OF QUATERNARY BIVALVE SHELLS ASA WATER MASS INDICATOR - LAST INTERGLACIAL AND HOLOCENE, EAST GREENLAND

Oxygen and carbon isotope composition of arctic bivalve shells are use d in an attempt to reconstruct Surface water temperature and salinitie s in Scoresby Sund, East Greenland. The oxygen isotope compositions of Mya truncata, Hiatella arctica and Tridonta borealis have been compar ed with present day hydrological parameters. Modern shells yield oxyge n isotope values that, on the whole, reproduce the environmental tempe rature and sea water isotopic composition. Furthermore, it is possible to estimate the living depth of the analysed specimens. Analyses of g rowth increments from single shells show that there are large variatio ns from year to year in temperature and oxygen isotope composition of the surface waters of Scoresby Sund and that these variations decrease with depth. Analyses of Holocene shells indicate that the Polar Curre nt water, which flows from north to south along the East Greenland coa st was also present during the Holocene climatic optimum 8000-7000 yr B.P. Analyses of bivalve shells from the last interglacial show that S coresby Sund during that time was well circulated and that meltwater f rom the Greenland ice sheet and sea ice meltwater was important for th e temperature, salinity and isotopic compositon of the surface waters.