Isotopic composition and physical oceanography of water profiles from Greenland

Isotopic composition of strontium and oxygen and strontium concentrations from 4 hydrographic sites in Scoresby Sund Fjord and 6 rivers draining the adjacent Jameson Land have been investigated. Schuchert Flod, the major river on Jameson Land, erodes a large celestite (SrSO4) deposit. Dissolved Sr in Schuchert Flod has 87Sr/86Sr = 0.7137 and is responsible for most of the continental Sr flux to the fjord. The Sr isotope data have been used to construct a mixing model for the surface water in Scoresby Sund Fjord. Salinity (S) and Sr concentrations (CSr) of brackish water from the fjord show conservative mixing between river water and seawater. Results of the 87Sr/86Sr–salinity mixing model of seawater and fresh water were used to interpret the isotopic composition of Sr (87Sr/86Sr) and oxygen (d18Oc) of recent and interglacial (Eemian ~120 ka) shallow-water bivalve shells from the coast of Jameson Land. Because of the high CSr in some of the rivers draining Jameson Land, a correlation exists between 87Sr/86Sr and d18Oc of recent and interglacial shallow water bivalve shells from the coast of Jameson Land. Higher-than-seawater 87Sr/86Sr values in shells from the Langelandselv interglaciation can be explained only if the shells were formed close to a Sr-rich fresh water source which is not present in the Langelandselv area today. These results suggest that there was a different river and drainage system on the Jameson Land peninsula during the Last Interglacial. The 87Sr/86Sr values indicate that shell formation took place in waters with salinities between 20 and 31‰ in a fjord with less glacial melt-water than seen today.