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The role of magma sources, oxidation states and fractionation in determining the granite metallogeny of eastern Australia

Phillip L. Blevin and Bruce W. Chappell
The role of magma sources, oxidation states and fractionation in determining the granite metallogeny of eastern Australia (in The second Hutton symposium on the origin of granites and related rocks; proceedings, P. E. Brown (editor) and B. W. Chappell (editor))
Special Paper - Geological Society of America (1992) 272: 305-316

Abstract

The ore-element associations of granite-related ore deposits in E Australian Palaeozoic fold belts can be related to the inferred relative oxidation state, halogen content and degree of fractional crystallization within the associated granite suites. The basic association of Mo, Cu and Au with oxidized I-type granites is confirmed and Sn is shown to be associated with both reduced S- and I-types. W is associated with a variety of granite types and shows little dependence on inferred magma redox state. The observed behaviour of ore elements during fractionation is consistent with models of ore element sequestering by sulphides and Fe-Ti phases whose stability is normally function signO (sub 2) - dependent. Fractional crystallization acts to amplify this process through the progressive removal of compatible elements and the concentration of incompatible elements into decreasing melt volumes. The halogen content is also important; S-type granites are poorer in Cl than I-types; Cl decreases and F increases in both S- and I-types with fractional crystallization. Low Cl contents combined with low magma function signO (sub 2) seem to provide an adequate explanation for the rarity of Mo, Cu, Pb and Zn type mineralization with S-type granites.


ISSN: 0072-1077
EISSN: 2331-219X
Coden: GSAPAZ
Serial Title: Special Paper - Geological Society of America
Serial Volume: 272
Title: The role of magma sources, oxidation states and fractionation in determining the granite metallogeny of eastern Australia
Title: The second Hutton symposium on the origin of granites and related rocks; proceedings
Author(s): Blevin, Phillip L.Chappell, Bruce W.
Author(s): Brown, P. E.editor
Author(s): Chappell, B. W.editor
Affiliation: Australian National University, Department of Geology, Canberra, Australia
Affiliation: University of St. Andrews, Department of Geology, St. Andrews, United Kingdom
Pages: 305-316
Published: 1992
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
ISBN: 0-8137-2272-1
Meeting name: The second Hutton symposium on the Origin of granites and related rocks
Meeting location: Canberra, AUS, Australia
Meeting date: 19910923Sept. 23-28, 1991
References: 55
Accession Number: 1993-010082
Categories: Economic geology, geology of ore depositsIgneous and metamorphic petrology
Document Type: Serial Conference document
Bibliographic Level: Analytic
Annotation: Originally publ. in Transact. R. Soc. Edinburgh, Earth Sci., Vol. 83, parts 1 and 2
Illustration Description: illus. incl. sketch maps
S42°00'00" - S30°00'00", E143°00'00" - E150°15'00"
Secondary Affiliation: Australian National University, AUS, Australia
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United KingdomTwickenhamUKUnited Kingdom
Update Code: 1993
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