Trace-element systematics of sediments in the Murray-Darling Basin, Australia: sediment provenance and palaeoclimate implications of fine scale chemical heterogeneity

Authors

Samuel K. Marx, University of WollongongFollow
Balz S. Kamber, Trinity College Dublin

RIS ID

48570

Publication Details

Marx, S. K. & Kamber, B. S. (2010). Trace-element systematics of sediments in the Murray-Darling Basin, Australia: sediment provenance and palaeoclimate implications of fine scale chemical heterogeneity. Applied Geochemistry, 25 (8), 1221-1237.

Abstract

A high-resolution dataset of trace element concentrations is presented for the Murray-Darling Basin, Australia, Australia's most important river system. The data were obtained by solution quadrupole ICP-MS resulting in concentrations for 44 elements. Of these, 21 were determined with a long-term external precision of better than 1% and a further 13 at a precision better than 2%. Trace element maps for the surface sediments constructed from such high precision data reveal small but coherent variations in the four major sub-catchments of the basin, even in ratios of elements with very similar geochemical behaviour, such as Y/Ho, Nb/Ta and Zr/Hf. The origin of these chemical fingerprints of drainage systems are discussed in terms of the geochemical character of the upper continental crust. The potential of trace element maps for palaeo-environmental and climatic reconstruction is then illustrated. First, a sample of dust collected in a trap located in the far southeastern corner of the study area is used to pinpoint the location of the dust source. Next the fine-scale change in down-stream alluvial sediment chemistry is analysed to estimate the importance of sediment contribution from tributaries with a view to reconstructing river flow dynamics. Finally, the chemistry of dune sediments is compared with surrounding floodplain alluvium to estimate relative age of deposition. These examples demonstrate that in low-elevation river systems, such as the Murray-Darling Basin, extended trace element maps of sediment offer substantially more applications than radiogenic isotope data alone.