Loess and floods: High-resolution multi-proxy data of Last Glacial Maximum (LGM) slackwater deposition in the Flinders Ranges, semi-arid South Australia

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Title Loess and floods: High-resolution multi-proxy data of Last Glacial Maximum (LGM) slackwater deposition in the Flinders Ranges, semi-arid South Australia
Author Haberlah, David; Williams, Martin A.J.; Halverson, Galen; McTainsh, Grant Harvey; Hill, Steven M.; Hrstka, Tomas; Jaime, Patricio; Butcher, Alan R.; Glasby, Peter
Journal Name Quaternary Science Reviews
Year Published 2010
Place of publication United Kingdom
Publisher Elsevier
Abstract Terrace remnants of late Pleistocene fine-grained valley-fill deposits (Silts) deeply entrenched by ephemeral traction load streams in arid areas remain a puzzle. They have been attributed to a variety of origins ranging from lacustrine to alluvial floodplains. We here report a centimetre-scale multi-proxy study of a 7 m section of Silts in the semi-arid Flinders Ranges of South Australia, which span the lead-up to and peak of the Last Glacial Maximum (LGM). The results of detailed lithostratigraphic mapping, high-resolution parametric particle-size analysis, Automated Mineralogy, induced magnetic susceptibility, carbon stable isotope geochemistry, and a chronostratigraphy based on 27 AMS radiocarbon and 6 luminescence ages are discussed in terms of sediment provenance, depositional environment and weathering history with the aim of reconstructing the regional palaeo-environment. The data are consistent with a fluctuating aeolian-fluvial interplay dominating the extended LGM environment with a greater impact on the landscape than all combined geomorphic processes since then. Accordingly, weathered slope mantles and loess accessions were eroded and entrained by numerous small and at least a dozen large-scale flood events, and trapped in an intra-montane floodplain extending into Brachina Gorge. Upstream of this narrow constriction, recurrent backflooding is discussed resulting in a thick sequence of layered to laminated slackwater couplets. Aggradation and degradation of valley-fills appear to be largely controlled by fine-sediment supply from the valley slopes, replenished by wind-blown dust from upwind playa lakes and source-bordering dunefields. In conclusion, this study demonstrates how dust storms and flooding rains can account for 'pluvial' features previously explained by the opposing effects of reduced precipitation and evaporation in the colder more arid glacial landscape of southern Australia.
Peer Reviewed Yes
Published Yes
Alternative URI http://dx.doi.org/10.1016/j.quascirev.2010.04.014
Volume 29
Issue Number 19-20
Page from 2673
Page to 2693
ISSN 0277-3791
Date Accessioned 2011-01-18
Language en_AU
Faculty Faculty of Science, Environment, Engineering and Technology
Subject Geology
URI http://hdl.handle.net/10072/37810
Publication Type Journal Articles (Refereed Article)
Publication Type Code c1

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