Sedimentology on surface samples from the Amundsen and Bellingshausen Seas

Surface sediments from the Antarctic continental margin in the Bellingshausen and Amundsen seas (Pacific sector of the Southern Ocean) were investigated in order to decipher their capability to record modern environmental conditions. Spatial distribution of terrigenous sand and mud reflect regional differences in current-induced redeposition of glaciogenic debris. Clay mineral assemblages in the shelf sediments are controlled by the supply of terrigenous detritus from source rocks in the adjacent hinterland suggesting the occurrence of yet unknown sedimentary rocks in the hinterland of the Amundsen Sea. Clay mineral distribution on the continental rise in the Bellingshausen Sea points to the continuation of a bottom current from the Antarctic Peninsula rise to at least 94°W. Foraminifer-bearing and opal-poor deposits prevail on the continental margin in the western Bellingshausen Sea and the Amundsen Sea, whereas diatom-bearing and carbonate-free sediments characterize the eastern Bellingshausen Sea. Different modes of biological production, which were deduced from accumulation rates of biogenic barium during Marine Isotope Stage 1 and recent productivity measurements, obviously control the spatial pattern of opal- and carbonate-bearing sediments in the study area.