Lithospheric controls on the formation of provinces hosting giant orogenic gold deposits |
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Authors: | Frank P Bierlein David I Groves Richard J Goldfarb Benoit Dubé |
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Institution: | (1) Centre for Exploration Targeting, School of Earth and Geophysical Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, WA, 6009, Australia;(2) Tectonics Special Research Centre, School of Earth and Geophysical Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, WA, 6009, Australia;(3) United States Geological Survey, Federal Center, P.O. Box 25046, MS 973, Denver, CO 80225-0046, USA;(4) Geological Survey of Canada, 490 rue de la Couronne, Quebec, G1K 9A9, Canada |
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Abstract: | Ages of giant gold systems (>500 t gold) cluster within well-defined periods of lithospheric growth at continental margins, and it is the orogen-scale processes during these mainly Late Archaean, Palaeoproterozoic and Phanerozoic times that ultimately determine gold endowment of a province in an orogen. A critical factor for giant orogenic gold provinces appears to be thickness of the subcontinental lithospheric mantle (SCLM) beneath a province at the time of gold mineralisation, as giant gold deposits are much more likely to develop in orogens with subducted oceanic or thin continental lithosphere. A proxy for the latter is a short pre-mineralisation crustal history such that thick SCLM was not developed before gold deposition. In constrast, orogens with protracted pre-mineralisation crustal histories are more likely to be characterised by a thick SCLM that is difficult to delaminate, and hence, such provinces will normally be poorly endowed. The nature of the lithosphere also influences the intrinsic gold concentrations of potential source rocks, with back-arc basalts, transitional basalts and basanites enriched in gold relative to other rock sequences. Thus, segments of orogens with thin lithosphere may enjoy the conjunction of giant-scale fluid flux through gold-enriched sequences. Although the nature of the lithosphere plays the crucial role in dictating which orogenic gold provinces will contain one or more giant deposits, the precise siting of those giants depends on the critical conjunction of a number of province-scale factors. Such features control plumbing systems, traps and seals in tectonically and lithospherically suitable terranes within orogens. |
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Keywords: | Orogenic gold Giant gold deposits Metallogeny Tectonics Lithosphere Endowment |
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