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40Ar-39Ar dating of detrital muscovite in provenance investigations: a case study from the Adelaide Rift Complex, South Australia

Haines, P.W; Turner, S.P; Kelley, S.P; Wartho, J.A and Sherlock, S.C (2004). 40Ar-39Ar dating of detrital muscovite in provenance investigations: a case study from the Adelaide Rift Complex, South Australia. Earth and Planetary Science Letters, 227(3-4) pp. 297–311.

DOI (Digital Object Identifier) Link: http://dx.doi.org/10.1016/j.epsl.2004.08.020
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Abstract

Detrital zircon ages are commonly used to investigate sediment provenance and supply routes. Here, we explore the advantages of employing multiple, complimentary techniques via a case study of the Neoproterozoic and Cambrian of the Adelaide Rift Complex, South Australia. Detrital muscovite Ar-Ar ages are presented from stratigraphic units, or equivalents, that have previously been the subject of U-Pb detrital zircon dating, and, in some cases, whole-rock Sm-Nd isotope studies. The zircon age ranges and whole-rock Sm-Nd isotope data suggest that early Neoproterozoic sediments from near the base of the Adelaide Rift Complex comprise a mixture of detritus derived from the adjacent Gawler Craton (Palaeoproterozoic to earliest Mesoproterozoic) and overlying Gairdner flood basalts. In contrast, detrital muscovites from this level have a broad scatter of Mesoproterozoic infrared (IR) laser total fusion Ar-Ar ages, while UV laser traverses indicate that the age spread reflects partial resetting by multiple heating events, rather than a mixture of sources. Younger Neoproterozoic sediments document replacement of the Gawler Craton by the more distant Musgrave and/or Albany-Fraser Orogens as the main provenance. The Cambrian Kanmantoo Group marks an abrupt change in depositional style and a new sediment source. The Kanmantoo Group have older Nd model ages than underlying strata, yet are dominated by near to deposition-aged (~500-650 Ma) detrital zircons and muscovites, suggesting rapid cooling and exhumation of a tectonically active provenance region. Although this source remains uncertain, evidence points towards the distant Pan-African orogenic belts. Deposition in the Adelaide Rift Complex was terminated in the late Early Cambrian by the Delamerian Orogeny, and the results of previous detrital mineral dating studies from the Lachlan Fold Belt to the east are consistent with at least partial derivation of these sediments from reworked upper Adelaide Rift Complex (Kanmantoo Group), rather than a continuation of sediment supply from the Kanmantoo Group sediment source. More broadly, the data suggest a close link between basin formation and orogen exhumation, and we also speculate that mantle plumes have played a significant role in crustal evolution at this Palaeo-Pacific margin of Gondwanaland, challenging the notion that subduction zones are the principle sites of crustal growth and sediment provenance. (C) 2004 Elsevier B.V. All rights reserved.

Item Type: Journal Article
Copyright Holders: 2004 Elsevier B.V.
ISSN: 0012-821X
Keywords: Ar–Ar dating; sediment provenance; Neoproterozoic; Cambrian; South Australia
Academic Unit/Department: Science > Environment, Earth and Ecosystems
Interdisciplinary Research Centre: Centre for Earth, Planetary, Space and Astronomical Research (CEPSAR)
Item ID: 2101
Depositing User: Simon Kelley
Date Deposited: 05 Jun 2006
Last Modified: 04 Jul 2011 15:17
URI: http://oro.open.ac.uk/id/eprint/2101
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