The use of natural 14C as a tracer to identify the incorporation of younger material into the organic component of sediments from the Carpentaria Basin, Australia

A 'chemically inert' organic fraction was isolated from samples taken from a sediment core that was collected from the Gulf of Carpentaria, lying between Australia and Papua New Guinea. Accelerator mass spectrometry (AMS) 14C ages obtained from this fraction become younger with depth, the maximum 14C concentration being 107% M, then become older again. The shape of the plot of apparent 14C age with depth can be compared to a typical concentration plot of a compound being passed through a chromatographic column. The shape of the so-called natural chromatogram has a relatively sharp leading edge, then gradually tails off. Stable carbon isotope values indicate that the material is most probably a non polar compound (or mixture) of yet unknown origin. (author)