Logo image
Back
Establishing high precision trace element maps of the main dust source areas of eastern and south-central Australia
Abstract   Peer reviewed

Establishing high precision trace element maps of the main dust source areas of eastern and south-central Australia

B S Kamber, H A McGowan, Samuel K Marx and L M Petherick
Geochimica et Cosmochimica Acta, Vol.71(15, Supplement 1), p.A460
Goldschmidt Conference, 2007 (Cologne, Germany, 19-Aug-2007–24-Aug-2007)
2007
DOI: https://doi.org/10.1016/j.gca.2007.06.019
url
https://doi.org/10.1016/j.gca.2007.06.019View
Published Version

Abstract

Geochemistry high precision trace element maps dust Australia
Continental-scale geochemical mapping relies on precise and accurate chemical analyses of surface samples. Eggins et al. (1997) demonstrated that appropriate analytical protocols can yield high precision (typically better than 1-2% rsd) and accurate trace element data for >40 elements by inductivelycoupled- plasma mass spectrometry (ICP-MS). Here we present such a high-precision geochemical dataset (40 trace elements) for the source areas of dust that is transported across the Eastern Australian seaboard. These source areas (river floodplains, palaeo-lakebeds, dunes, playas) have generally similar relative trace element abundances, typical of upper continental crust. However, the new ICP-MS data document geochemical provinces on the sub-catchment scale. The geochemical provinciality is largely inherited from the main erosion source lithologies and translates into provenance resolution of ca. 50 × 50 km. When modern far-travelled (up to 4,000 km) mineral dust of known provenance (from ground observation) is compared to the surface geochemical map, we find excellent agreement with the source area for many elements (McGowan et al., 2005). Mismatching elements are those affected by: (i) density sorting (Zr, Hf, HREE); (ii) reprecipitation (Be, Sr) and (iii) air pollution (first and second order transition metals, Tl and Pb). Comparison of 210Pb activity between known source areas from the geochemical map and far-travelled dust demonstrates clearly that the enrichment in metals like Pb, Zn and Cu happens during atmospheric transport through the coastal East Australian pollutant plumes (Marx et al., 2005). For the purpose of dust provenancing, for which Zr, Hf and HREE are unsuitable, it is sufficient to digest surface sediments in closed beakers at 130°C. However, we also demonstrate that only high-P digestion at 200°C yields complete sets of accurate data for all elements. This factor will severely increase the effort and cost of any rigorous surface geochemical mapping project.

Details

Metrics

4 File views/ downloads
580 Record Views
Logo image