530 Ma zircon age for ophiolite from the New England orogen: Oldest rocks known from eastern Australia

Geology
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Abstract

New ion microprobe data provide constraints on the timing of formation of ophiolitic rocks in the New England tectonic collage in eastern Australia. Results for analyses of magmatic zircons from plagiogranite of the Weraerai terrane ophiolite at Upper Bingara give a 206pb/238|j ag e Qf 53Q ± 6 Ma (2a). This plagiogranite is the oldest rock from eastern Australia yet identified. Existing tectonic models suggest that progressively younger crust was accreted to the eastern margin of Gondwanan Australia throughout the Paleozoic. This cannot be reconciled easily with the Cambrian age for these ophiolitic rocks, which are juxtaposed between Devonian terranes and are at least 1000 km east of the nearest lithologically similar rocks of comparable age. We speculate that younger, thin-skinned terranes may have been thrust westward over the continental freeboard of eastern Australia during the late Paleozoic.

Publication type Article
Publication Subtype Journal Article
Title 530 Ma zircon age for ophiolite from the New England orogen: Oldest rocks known from eastern Australia
Series title Geology
DOI 10.1130/0091-7613(1992)020<0125:MZAFOF>2.3.CO;2
Volume 20
Issue 2
Year Published 1992
Language English
Publisher Geological Society of America
Contributing office(s) Geology, Minerals, Energy, and Geophysics Science Center
Description 4 p.
First page 125
Last page 128
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