Authors / CoAuthors
Black, L.P. | Everard, J.L. | McClenaghan, M.P. | Korsch, R.J. | Calver, C.R.
Abstract
In eastern Tasmania, Devonian granites intrude the Ordovician-Early Devonian quartz-rich turbidites of the Mathinna Supergroup. The earliest (~400 Ma) I-type granodiorites may be arc-related and pre-date the Tabberabberan Orogeny (~388 Ma), which appears to represent the juxtaposition of Eastern and Western Tasmanian. Subsequently, more felsic and finally strongly fractionated I- and S-type granites were emplaced until ~373 Ma. In western Tasmania, mostly felsic and fractionated I- and S-types were emplaced from ~374-351 Ma, possibly in response to post-collisional crustal extension, into a more diverse terrane with depositional ages extending back to the Late Mesoproterozoic. Granites from the two terranes are readily distinguishable by the age spectra of their inherited zircon, which resemble those of the detrital zircon from sedimentary successions in their respective terranes. Furthermore, within each terrane both I and S-types yield similar inheritance patterns. This is interpreted to indicate a pivotal role for the sedimentary successions in the petrogenesis of both types. Western Tasmanian granites are also enriched in ~1600 Ma zircon, which is essentially unrepresented in the exposed supracrustal succession. This might date an important deep crustal igneous source rock, or represents a detrital component in sedimentary rocks derived from the Gawler Range Volcanics or equivalent rocks. There is no convincing evidence for an additional deep crustal component (of any age) in eastern Tasmania. If present, however, it would be expected to be of mafic composition and to have contributed little if any zircon to the felsic magmas.
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nonGeographicDataset
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69741
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- External Publication
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- geochronology
- ( Theme )
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- geochemistry
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- AU-TAS
- Australian and New Zealand Standard Research Classification (ANZSRC)
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- Earth Sciences
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- Published_Internal
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2009-11-09T00:00:00
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