Preliminary results of new benthic foraminifera Mg/Ca temperature calibrations and reconstruction of bottom water temperatures and salinity from a transect along the northern branch of the North Atlantic Current

The purpose of the present study is to investigate the modern relationship between Mg/Ca in marine benthic foraminifera and bottom water temperatures in order to improve reconstructions of past ocean temperatures. Further we use the results of the modern relationship to investigate past temperatures in marine records from the Barents Sea and Svalbard margin covering the last 2 ka. In particular we aim to elucidate the natural variation in the inflow of warm Atlantic Water into the Arctic Ocean. In the years 2005-2010, several cruises during different seasons were conducted in the Svalbard area, retrieving both surface and down core samples. Five Arctic species of benthic foraminifera were collected in order to evaluate the relationship between Mg/Ca and temperature that can subsequently be used in down core temperature reconstructions. These species are: Nonionella labradorica, Cassidulina reniforme, Buccella frigida, Islandiella helenae and Elphidium excavatum forma clavata. Preliminary results indicate a correlation between temperature and Mg/Ca, and they also show interesting seasonal signals, implying the annual growth season for some of the species. More data points will be collected to draw more robust conclusions. In addition, three sediment cores containing sediments from the last 2K were collected creating a transect N-S (69-79 degrees N) along the flowpath of the North Atlantic Current: one from Malangen, northern Norway, one from the Barents Sea and one from Kongsfjorden, western Spitsbergen. The temperatures reconstructed from the Mg/Ca ratios were used to calculate the salinity contribution in the oxygen isotopes. Mg/Ca-ratios and stable isotopes show oscillations in temperature and salinity, hence elucidating which water masses prevailed at these sites during the last 2 ka.