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Naturaliste Plateau, offshore Western Australia: A submarine window into Gondwana assembly and breakup
journal contribution
posted on 2023-05-16, 23:35 authored by Jacqueline HalpinJacqueline Halpin, Anthony CrawfordAnthony Crawford, Nicholas DireenNicholas Direen, Mike CoffinMike Coffin, Forbes, CJ, Borissova, IThe 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. © 2008 The Geological Society of America.
History
Publication title
GeologyVolume
36Issue
10Pagination
807-810ISSN
0091-7613Department/School
School of Natural SciencesPublisher
GEOLOGICAL SOC AMER, INCPlace of publication
BOULDER, CO 80301-9140 USARights statement
© 2008 Geological Society of America. Geological Society of America, P.O. Box 9140, Boulder, CO 80301-9140 USA (http://www.geosociety.org)Repository Status
- Restricted