Title

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

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.

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Link to publisher version (DOI)

http://dx.doi.org/10.1016/j.apgeochem.2010.05.007