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Intrusion-associated gold systems and multistage metallogenic processes in the Neoarchean Abitibi greenstone belt

Mathieu Lucie. (2021). Intrusion-associated gold systems and multistage metallogenic processes in the Neoarchean Abitibi greenstone belt. Minerals, 11, (3), p. 261.

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URL officielle: http://dx.doi.org/doi:10.3390/min11030261

Résumé

In gold-endowed greenstone belts, ore bodies generally correspond to orogenic gold systems (OGS) formed during the main deformation stage that led to craton stabilization (syntectonic period). Most OGS deposits postdate and locally overprint magmatic-hydrothermal systems, such as Au-Cu porphyry that mostly formed during the main magmatic stage (synvolcanic period) and polymetallic intrusion-related gold systems (IRGS) of the syntectonic period. Porphyries are associated with tonalite-dominated and sanukitoid plutons, whereas most IRGS are related to alkaline magmatism. As reviewed here, most intrusion-associated mineralization in the Abitibi greenstone belt is the result of complex and local multistage metallogenic processes. A new classification is proposed that includes (1) OGS and OGS-like deposits dominated by metamorphic and magmatic fluids, respectively; (2) porphyry and IRGS that may contain gold remobilized during subsequent deformation episodes; (3) porphyry and IRGS that are overprinted by OGS. Both OGS and OGS-like deposits are associated with crustal-scale faults and display similar gold-deposition mechanisms. The main difference is that magmatic fluid input may increase the oxidation state and CO2 content of the mineralizing fluid for OGS-like deposits, while OGS are characterized by the circulation of reduced metamorphic fluids. For porphyry and IRGS, mineralizing fluids and metals have a magmatic origin. Porphyries are defined as base metal and gold-bearing deposits associated with large-volume intrusions, while IRGS are gold deposits that may display a polymetallic signature and that can be associated with small-volume syntectonic intrusions. Some porphyry, such as the Côté Gold deposit, demonstrate that magmatic systems can generate economically significant gold mineralization. In addition, many deposits display evidence of multistage processes and correspond to gold-bearing or gold-barren magmatic-hydrothermal systems overprinted by OGS or by gold-barren metamorphic fluids. In most cases, the source of gold remains debated. Whether magmatic activity was essential or marginal for fertilizing the upper crust during the Neoarchean remains a major topic for future research, and petrogenetic investigations may be paramount for distinguishing gold-endowed from barren greenstone belts.

Type de document:Article publié dans une revue avec comité d'évaluation
Volume:11
Numéro:3
Pages:p. 261
Version évaluée par les pairs:Oui
Date:Mars 2021
Sujets:Sciences naturelles et génie > Génie
Sciences naturelles et génie > Sciences appliquées
Sciences naturelles et génie > Sciences naturelles > Sciences de la terre (géologie, géographie)
Département, module, service et unité de recherche:Départements et modules > Département des sciences appliquées > Unité d'enseignement en sciences de la Terre
Mots-clés:intrusion-related gold systems (IRGS), porphyry, magmatic-hydrothermal systems, multistage process, metallogenic model, systèmes aurifères liés aux intrusions (IRGS), porphyre, systèmes magmatiques-hydrothermaux, processus multi-étapes, modèle métallogénique
Déposé le:21 juin 2021 14:34
Dernière modification:21 juin 2021 14:34
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