Eroding Australia: slowly.
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Date
2008-07
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Publisher
Elsevier
Abstract
We use in situ produced 10Be and 26Al to quantify erosion rates across a wide variety of field settings in Australia. Here we present the full suite of data from our diverse studies to provide an overview of how Austalia is eroding, as well as showing how robust this methodology is. Field sites range from several soil-mantled landscapes spanning the passive margin escarpment of southeastern Australia, to rocky, bedrock dominated landscapes in the Flinders Ranges and the Central Australia Outback. Also, in the far north, we examine an undisturbed catchment in the rugged topography of Arnhem Land: Tin Camp Creek. We sample detrital sands draining the landscape in a nested fashion at each of our field sites: from small to large catchments. We also sample across the slopes to quantify point-specific rates of soil production and bedrock erosion. Soil production rates and mechanisms across the escarpment have been presented in previous publications and will be used here to compare with a new, ‘humped’ soil prodction function from the Arnhem Land field site. In the rocky landscapes of the Flinders Ranges and MacDonnell Ranges, we sample the blocky slopes as well as catchment sands to constrain a block failure model for slope retreat. Point specific rates are also compared with detrital rates for Kings Canyon and the Todd River drainage to examine the potential for long-term landscape equilibrium. To conclude we show the first, unequivocal example of a regolith mantled landscape eroding in dynamic equilibrium from the western MacDonnell Range. Rates span an order of magnitude, from about 4 to 40 m/Ma across the escarpment in southeastern Australia. The ‘humped’ soil production function peaks at just over 20 m/Ma under about 30 cm of soil and decreases to less than 5 m/Ma under 70 cm of soil. Rates in the Outback are extremely slow, from less than 1 in places to the distance evidence for equilbrium in the Western MacDonnells, at about 7 m/Ma. These results raise many provocative questions and suggest new directions for quantifying how landscapes evolve. Copyright © 2008 Published by Elsevier Ltd.
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Keywords
Australia, Erosion, Soils, Sand, Beryllium, Aluminium
Citation
Heimsath, A., Chappell, J., Hancock, G., Fink, D., & Fifield, K. (2008). Eroding Australia: slowly. Presentation to the 18th Annual V.M. Goldschmidt Conference (Goldschmidt 2008) - "from Sea to Sky", 13th - 18th July 2008. Vancouver, Canada: University of British Columbia. In Geochimica et Cosmochimica Acta, 72(12), A363. doi:10.1016/j.gca.2008.05.011