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Geochronological, geochemical and Pb isotopic compositions of Tasmanian granites (southeast Australia): controls on petrogenesis, geodynamic evolution and tin mineralisation

Citation

Hong, W and Cooke, DR and Huston, DL and Maas, R and Meffre, S and Thompson, J and Zhang, L and Fox, N, Geochronological, geochemical and Pb isotopic compositions of Tasmanian granites (southeast Australia): controls on petrogenesis, geodynamic evolution and tin mineralisation, Gondwana Research, 46 pp. 124-140. ISSN 1342-937X (2017) [Refereed Article]


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DOI: doi:10.1016/j.gr.2017.03.009

Abstract

Large volumes of Devonian-Carboniferous granites were emplaced across Tasmania in southeast Australia, which was along the easternmost boundary of mid-Palaeozoic Gondwana. Some of these granites are associated with world class SnW deposits. Previous studies have focused mainly on relationships between granite petrogenesis and source rocks, and rarely on geochemical controls on Sn mineralisation. New zircon U-Pb ages of 405 to 396 Ma reveal that the George River Granodiorite, Grant Point Granite and Mt. Pearson Granite from eastern Tasmania intruded prior to the Tabberabberan Orogeny. The Coles Bay Granite has a U-Pb age of 388  7 Ma, implying that it was emplaced simultaneously with the Tabberabberan Orogeny in Tasmania. The western Tasmanian granites mostly intruded from 374 to 360 Ma, after the Tabberabberan Orogeny. Granites associated with SnW deposits are moderately to strongly fractionated, including the Housetop, Meredith, Pine Hill and Heemskirk granites. Lead isotopic compositions of K-feldspars from the analysed granites, combined with isotopic evidence from other studies, suggest that differentiated granites in Tasmania had been highly contaminated by a crustal (sedimentary) component, and that western Tasmanian granites had a crustal source with substantially different isotopic characteristics to that of eastern Tasmania, which has a character similar to the Lachlan Orogen in southeast Australia. Tin-mineralised granites in Tasmania formed in a post-collisional extensional margin, a favourable environment for the production of Sn-rich melts from the lower crust. Prolonged fractional crystallisation, low oxygen fugacity and enrichments of volatiles are crucial factors to promote Sn enrichment in magmatic-hydrothermal fluids exsolved from crystallised felsic magmas.

Item Details

Item Type:Refereed Article
Keywords:fractionated granite, Zircon U-Pb dating, K-feldspar, Pb isotopes, tin mineralisation, Tasmania
Research Division:Earth Sciences
Research Group:Geology
Research Field:Geochronology
Objective Division:Expanding Knowledge
Objective Group:Expanding Knowledge
Objective Field:Expanding Knowledge in the Earth Sciences
Author:Hong, W (Mr Wei Hong)
Author:Cooke, DR (Professor David Cooke)
Author:Meffre, S (Dr Sebastien Meffre)
Author:Thompson, J (Mr Jay Thompson)
Author:Zhang, L (Mr Lejun Zhang)
Author:Fox, N (Dr Nathan Fox)
ID Code:121911
Year Published:2017
Deposited By:CODES ARC
Deposited On:2017-10-19
Last Modified:2017-10-23
Downloads:0

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