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| Titel |
U-series constraints on sediment residence timescales in semi-arid Australia |
| VerfasserIn |
Heather Handley, Anthony Dosseto, P. O. Suresh, Tim Cohen, Simon Turner |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250034857
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| Zusammenfassung |
| Fractionation of uranium isotopes (234U and 238U) in fine-grained sediment (< 50 μm) can
be used to quantify timescales of sediment residence i.e. storage in soils and associated
transport in fluvial or aeolian systems. This information is invaluable for understanding the
relationships between climate, tectonics and landscape evolution. In particular, how sediment
transport and the landscape have responded to climate change over the past 100,000 yrs.
(234U/238U) activity ratios have been measured in the fine fraction (2-50 μm) of
palaeochannel sediments from the Katipiri Formation of the Cooper Creek in the Strzelecki
Desert (south Australia). Cooper Creek is one of three major rivers feeding the Lake Eyre
Basin, one of the largest internally-drained catchments in the world. Sediments were
collected from six palaeochannels with depositional ages ranging from 119±11 to 22±
ka (optically-stimulated luminescence (OSL) dating). U-series and OSL data are
combined in order to constrain the time elapsed between production by physical
weathering of the source bedrock (comminution age) and the deposition age, to give an
average residence time of the sediment in the catchment. Preliminary work yields
sediment residence timescales between 66±10 to 107±17 ka. The inferred residence
timescales for Cooper Creek sediments, in what today is a semi-arid environment, are
comparable to sediment residence timescales (of similar depositional age) in temperate
Australia. This suggests that the strong links observed between climate change and
sediment transport during the last glacial cycle in temperate Australia maybe be
witnessed Australia-wide. Future research is required to assess the contribution
of wind-blown dust and its effect on calculated sediment residence timescales. |
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