Hans Wolfgang Hubberten

Oxygen and carbon isotope composition of Quaternary bivalve shells as a water mass indicator: Last interglacial and Holocene, East Greenland

Abstract Oxygen and carbon isotope composition of arctic bivalve shells are used in an attempt to reconstruct surface water temperature and salinities in Scoresby Sund, East Greenland. The oxygen isotope compositions of Mya truncata , Hiatella arctica and Tridonta borealis have been compared with present day hydrological parameters. Modern shells yield oxygen isotope values that, on the whole, reproduce the environmental temperature and sea water isotopic composition. Furthermore, it is possible to estimate the living depth of the analysed specimens. Analyses of growth increments from single shells show that there are large variations 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 Current water, which flows from north to south along the East Greenland coast was also present during the Holocene climatic optimum 8000-7000 yr B.P. Analyses of bivalve shells from the last interglacial show that Scoresby Sund during that time was well circulated and that meltwater from the Greenland ice sheet and sea ice meltwater was important for the temperature, salinity and isotopic composition of the surface waters.