Authors / CoAuthors
Mernagh, T.P. | Mikucki, E.J. | Heinrich, C.A.
Abstract
The Mount Charlotte gold deposit comprises a series of steeply plunging, vein stockwork orebodies that are surrounded by three concentric and mineralogically distinct alteration haloes. Fluid inclusions from quartz veins within each alteration zone have been analyzed and compared to determine possible temperature and chemical trends. Fluid inclusions associated with Type I alteration are mostly 3 phase, aqueous inclusions containing liquid + vapor CO2. These inclusions homogenize from 98 to 304?C with a mode at 235?C. Inclusions in Type II alteration are generally two-phase, liquid- or vapor-rich fluid inclusions and they homogenize at temperatures around 270?C. Type III alteration contains two distinct types of fluid inclusions. The most abundant population consists of coexisting liquid- and vapor-rich, two-phase aqueous inclusions which homogenize around 312?C. The second and rarer fluid inclusion population consists of methane-rich inclusions containing approximately 5 vol.% vapor and these homogenize around 264?C. This indicates that there is a general decrease in the temperature of the fluids from Type III alteration to Type I alteration with an average variation of 65?C across the orebody. The CH4 content of the fluids, as determined by laser Raman microprobe analyses of fluid inclusions, decreases from Type III alteration to Type I alteration. The fluids associated with Type I alteration contain little or no CH4, whereas, the fluids associated with Type II and Type III alteration contain considerable quantities of CH4 with some Type III inclusions containing only methane and water. These lateral and vertical zonation patterns indicate that mineralization at Mount Charlotte was accompanied by cooling and oxidation of the ore-bearing fluid as it reacted with the host rocks. Gold precipitation occurred by a combination of desulphidation and oxidation of an initially reduced, ore-bearing fluid. Phase separation during tectonic activity may have also led to the precipitation of minor amounts of free gold within the quartz veins and along vein margins.
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nonGeographicDataset
eCat Id
37368
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Cnr Jerrabomberra Ave and Hindmarsh Dr GPO Box 378
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Keywords
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- External PublicationScientific Journal Paper
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- AU-WA
- Australian and New Zealand Standard Research Classification (ANZSRC)
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- Earth Sciences
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- Published_Internal
Publication Date
2002-01-01T00:00:00
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geoscientificInformation
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Unknown
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[-31.0, -30.5, 121.0, 121.5]
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