Ice-proximal Marine Sedimentation in the Ross Sea during LGM: Ice-sheet and Ocean Interactions

We present preliminary results from a multi-proxy study of different cores from the Ross Sea, Antarctica. Thirty cores have been sampled at the Antarctic Marine Geology Research Facility (AMRF), Florida State University in order to discriminate different source areas and to reconstruct the depositional setting and related climate implications in a peculiar ice-proximal marine setting. Sediment characterizations, trace elements (TE) and rare earth elements (REEs) compositional analysis and evaluation about their source areas have been performed on sediment cores collected widespread in the Ross Sea area. Analysis of 72 samples from thirty cores was performed to determine total concentration of Li, Be, Mg, Al, K, Ca, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Rb, Sr, Ag, Cd, Cs, Ba, Tl, Pb, Bi, Th, U, Y and REEs. This extensive geochemical characterization of cores from several sites in the Ross Sea, will allow to better define the sedimentary processes, to understand the evolution of the ice-proximal marine setting, to evaluate areas with different geochemical features related to different provenances. In particular REEs allow us to discriminate different source areas and to better define the ocean input in the sediment composition. Moreover, 17 sediment cores from Coulman High area collected along two transects were characterized in order to constrain sediment bulk composition, biogenic vs non-biogenic components and the related depositional setting. Sediments from the two transects show a completely different bulk composition, those from the Northern transect mainly consist of fine-grained sediments containing well-preserved biogenic carbonate remains. Sediments from the Southern cores mainly consist of dark greenish diatomaceous sandy mud containing abundant diatoms in fragments. Sedimentation along the two transects seems to reflect the extent of the ice sheets in an ice-proximal marine setting. REEs compositional analyses have confirmed different source regions, a local provenance for the Southern cores and an ocean input for the Northern sediments.