Interhemispheric appraisal of the value of alkenone indices as temperatureand salinity proxies in high-latitude locations

Alkenone sediment data from the Nordic seas and North Atlantic are compared to those from Sikes et al. [1997] for the Southern Ocean to evaluate furth er U-37(K) and U-37(K)' as proxies to estimate cold temperatures (<10 degre es C) and the effect of salinity and temperature in the relative abundance of 37:4 to the total abundance of C-37 alkenones (37:4%). U-37(K) and U-37( K)' are found to be equally viable as proxies, but there are significant re gional differences in their cold temperature dependence. The measurement of 37:4% in cores from the North Atlantic region can be used to identify situ ations when U-37(K)' is not a reliable paleothermometer. Variations in sali nity are probably responsible for changes in the sedimentary record of 37:4 %, and a preliminary calibration has been obtained for 37:4%=f(salinity). T his new relationship should be further confirmed through field or laborator y experiments, but it paves the way to derive a molecular proxy to reconstr uct paleosalinity in surface waters.