Grain-size composition of Quaternary South Atlantic sediments and its paleoceanographic significance.

The grain-size composition is an fundamental property of sediments. The grain-size signature contains information about the history of a deposit such as sediment source, input mechanism, accumulation, redistribution, modification or alteration of sediment compounds. In previous studies mainly downcore results of grain-size distributions were used to infer climate variability from the changes of sediment input or current intensity. The spatial aspect of sediment input and distribution is often neglected. The use of grain-size composition in carbonate-dissolution studies in most previous studies is restricted to the sand content as a dissolution indicator. The detailed grain-size distribution of the calcareous sediment compounds is rarely used for paleoceanographic reconstructions. Hitherto, the direct link between the size distributions and the particles behind is very rough.