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Tonalite-dominated magmatism in the Abitibi Subprovince, Canada, and significance for Cu-Au magmatic-hydrothermal systems

Mathieu Lucie, Crépon Alexandre et Kontak Daniel J.. (2020). Tonalite-dominated magmatism in the Abitibi Subprovince, Canada, and significance for Cu-Au magmatic-hydrothermal systems. Minerals, 10, (3), p. 242.

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URL officielle: http://dx.doi.org/doi:10.3390/min10030242

Résumé

In Archean greenstone belts, magmatism is dominated by intrusive and volcanic rocks with tholeiitic affinities, as well as tonalite- and granodiorite-dominated large-volume batholiths, i.e., tonalite–trondhjemite–granodiorite (TTG) suites. These intrusions are associated with poorly documented mineralization (Cu-Au porphyries) that, in the Neoarchean Abitibi Subprovince (>2.79 to ~2.65 Ga), Superior Province, Canada, are associated with diorite bearing plutons, i.e., tonalite–trondhjemite–diorite (TTD) suites. The importance of TTG versus TTD suites in the evolution of greenstone belts and of their magmatic-hydrothermal systems and related mineralization is unconstrained. The aim of this study was to portray the chemistry and distribution of these suites in the Abitibi Subprovince. The study used data compiled by the geological surveys of Québec and Ontario to evaluate the chemistry of TTG and TTD suites and uncovered two coeval magmas that significantly differentiated (fractional crystallization mostly): 1) a heavy rare earth elements (HREE)-depleted tonalitic magma from high pressure melting of an hydrated basalt source; and 2) a hybrid HREE-undepleted magma that may be a mixture of mantle-derived (tholeiite) and tonalitic melts. The HREE-depleted rocks (mostly tonalite and granodiorite) display chemical characteristics of TTG suites (HREE, Ti, Nb, Ta, Y, and Sr depletion, lack of mafic unit, Na-rich), while the other rocks (tonalite and diorite) formed TTD suites. Tonalite-dominated magmatism, in the Abitibi Subprovince, comprises crustal melts as well as a significant proportion of mantle-derived magmas and this may be essential for Cu-Au magmatic-hydrothermal mineralizing systems.

Type de document:Article publié dans une revue avec comité d'évaluation
ISSN:2075-163X
Volume:10
Numéro:3
Pages:p. 242
Version évaluée par les pairs:Oui
Date:2020
Identifiant unique:10.3390/min10030242
Sujets: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:tonalite, granodiorite, diorite, TTG suite, TTD suite, magmatic-hydrothermal systems, Archean magmatism, greenstone belt, Abitibi Subprovince, Cu-Au mineralization
Déposé le:16 juin 2020 17:53
Dernière modification:16 juin 2020 17:53
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