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Naturaliste Plateau, offshore Western Australia: A submarine window into Gondwana assembly and breakup

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Halpin, JA and Crawford, AJ and Direen, NG and Coffin, MF and Forbes, CJ and Borissova, I (2008) Naturaliste Plateau, offshore Western Australia: A submarine window into Gondwana assembly and breakup. Geology, 36 (10). pp. 807-810. ISSN 0091-7613

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Abstract

The origin of the submarine Naturaliste Plateau off the southwestern coast of Australia is controversial; previous work supports both oceanic and continental affinities for the basement to volcanic and sedimentary sequences. We report the first evidence of reworked Mesoproterozoic (ca. 1230–1190 Ma) continental crust, based on laser ablation–inductively coupled plasma–mass spectrometry analysis of zircons from granite and orthogneiss samples dredged from the southern margin of the plateau. Thermobarometry of peak metamorphic minerals and electron microprobe chemical dating of monazite reveal that these igneous rocks were metamorphosed to ~700 °C and ~6.5 kbar during the Cambrian Pinjarra Orogeny at ca. 515 Ma. These data confirm a continental origin for a significant swathe of the southern Naturaliste Plateau, and suggest that the protoliths may have affinities to Mesoproterozoic crust within the Albany-Fraser-Wilkes Orogen (Australia-Antarctica). The present Naturaliste Plateau basement beneath its volcanic carapace probably represents a middle- to lower-crustal extensional allochthon exhumed during Cretaceous hyperextensional breakup between Australia and Antarctica.

Item Type: Article
Keywords: extensional allochthon, Naturaliste Plateau, Pinjarra Orogen, U-Pb zircon ages, U-Th-Pb monazite ages
Journal or Publication Title: Geology
Page Range: pp. 807-810
ISSN: 0091-7613
Identification Number - DOI: 10.1130/G25059A.1
Additional Information: © 2008 Geological Society of America, P.O. Box 9140, Boulder, CO 80301-9140 USA (http://www.geosociety.org)
Date Deposited: 20 Nov 2008 04:53
Last Modified: 18 Nov 2014 03:52
URI: http://eprints.utas.edu.au/id/eprint/7895
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