Reconstructing Deep Circulation Strength in Fram Strait Using Grain Size Analysis

Abstract:

Marine sediment cores obtained from Fram Strait, the Arctic’s only deep passage for exchange with the world oceans, may capture records of past circulation between the Arctic and North Atlantic. Changes in grain size can be correlated to changes in bottom water current velocity, enabling the reconstruction of past deep circulation strength. We will present new sortable silt grain size data from sediment cores in Fram Strait, enhancing our understanding of deep circulation in this region throughout the Holocene and deglaciation. Cores from depths between 1 and 2.5 km on the Svalbard slope, Greenland slope, and in the central strait will provide a transect to compare data from areas dominated by northward Atlantic-derived waters, southward Arctic-derived waters, and east/west recirculation. Analyzing the coarse-fraction and sortable silt-sized fraction will assist us in untangling the effects of ice-rafting and current speed. These records, coupled with age models derived from radiocarbon and stable isotopic analyses from planktonic foraminifera, will provide new insight into the past dynamics of Arctic/Atlantic deep water exchange.