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Geochronological, geochemical and Pb isotopic compositions of Tasmanian granites (southeast Australia): controls on petrogenesis, geodynamic evolution and tin mineralisation
journal contribution
posted on 2023-05-19, 12:50 authored by Wei HongWei Hong, David CookeDavid Cooke, Huston, DL, Maas, R, Sebastien MeffreSebastien Meffre, Thompson, J, Lejun ZhangLejun Zhang, Fox, NLarge 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 Sn–W 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 Sn–W 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.
Funding
Society of Economic Geologists Foundation Inc
History
Publication title
Gondwana ResearchVolume
46Pagination
124-140ISSN
1342-937XDepartment/School
School of Natural SciencesPublisher
Int Assoc Gondwana ResearchPlace of publication
Kochi Univ, Faculty Science Akebono-Cho 2-5-1, Kochi, Japan, 780-8520Rights statement
© 2017 International Association for Gondwana Research. Published by Elsevier.Repository Status
- Restricted