Authors / CoAuthors
Fu, B. | Mernagh, T.P. | Fairmaid, A. | Phillips, D. | Kendrick, G.A.
Abstract
The Maldon gold deposit in central Victoria has geological, geochronological and fluid chemistry characteristics that distinguish it from typical vein-hosted, orogenic' gold deposits in this region. The deposit lies within the contact aureole of the Harcourt Granite and associated granitic dykes. The ore-bearing fluids are characterised by the presence of non-aqueous (i.e. carbonic) fluids, which exhibit complex freezing and heating behaviour, as well as mixed CO2-low-salinity aqueous fluids (mostly - 10 wt.% NaCl eq.). Raman analysis indicates that carbonic inclusions can vary from CO2-rich to CH4-rich, with N2 contents up to 38 mol.%. Higher-salinity brine inclusions, 20-22 wt.% NaCl eq., only occur locally. The Harcourt Granite is a moderately reduced, I-type granite and the reduced fluids (e.g. CH4-N2-rich) are believed to have formed within (or in close proximity to) thermal aureoles of the dykes or granites during contact metamorphism. This further supports the premise that the Maldon deposit is an 'orogenic' gold deposit that was metamorphosed and/or remobilised during the emplacement of post-orogenic intrusions/dykes. We conclude that some 'orogenic' gold deposits worldwide may have been completely overprinted by later magmatic/metamorphic events and are now only evident as reduced intrusion-related gold systems.
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nonGeographicDataset
eCat Id
74664
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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
- ( Theme )
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- economic geology
- ( Theme )
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- fluid inclusions
- Australian and New Zealand Standard Research Classification (ANZSRC)
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- Earth Sciences
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- Published_Internal
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2012-01-01T00:00:00
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geoscientificInformation
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[-38.0, -37.0, 142.5, 144.0]
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