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Tectonomagmatic Evolution of the Southern Great Bear Magmatic Zone (Northwest Territories, Canada): Implications for the Genesis of Iron Oxide-Alkali–Altered Hydrothermal Systems.

Montreuil, Jean-François; Corriveau, Louise; Davis, William J. (2016). Tectonomagmatic Evolution of the Southern Great Bear Magmatic Zone (Northwest Territories, Canada): Implications for the Genesis of Iron Oxide-Alkali–Altered Hydrothermal Systems. Economic Geology , vol. 111 , nº 8. p. 2111-2138. DOI: 10.2113/econgeo.111.8.2111.

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Résumé

The Great Bear magmatic zone in northwestern Canada is a Paleoproterozoic volcano-plutonic belt of high K, calc-alkaline to shoshonitic affinity interpreted as a continental arc that formed between 1.87 and 1.85 Ga following the short-lived Calderian orogeny. Tectonomagmatic evolution of this magmatic zone favored the formation of multiple iron oxide and alkali alteration systems within a time frame of 10 m.y., as constrained geochronologically within error between 1875 and 1865 Ma. This illustrates a temporal and genetic relationship between shoshonitic to high K, calc-alkaline continental arc magmatism and the formation of iron oxide-rich deposits and alkali alteration associated with iron oxide-copper-gold (IOCG) mineralization. Early rhyolitic magmatism formed the basal sequence of the Lou assemblage under a compressive (or transpressive) tectonic regime. Between 1872 and 1867 Ma, an apparent higher magmatic production is linked to a marked change in composition of the volcanic and plutonic rocks, from rhyolite to intermediate/felsic and locally mafic. Compositional homogeneity of the intrusive and volcanic rocks of the Mazenod and Bea assemblages, termination of ductile to brittle-ductile deformation along the main deformation zones, and transition to widespread brittle fracturing and breccia formation are interpreted to reflect a change in the regional stress regime, from compressional/transpressional to extensional/transtensional. This change in stress regimes is associated with iron oxide-rich mineralization that initially formed the NICO Au-Bi-Co deposit, followed by IOCG mineralization in the NICO and Sue-Dianne deposits as well as albitite-hosted U mineralization in the Southern Breccia.

Type de document: Article
Mots-clés libres: cobalt deposits; copper deposits; deformation; deposits; gold deposits; iron; iron deposits; mineralogy; ore deposit geology; rocks; tectonics; volcanic rocks; volcanoes
Centre: Centre Eau Terre Environnement
Date de dépôt: 04 mai 2018 19:16
Dernière modification: 04 mai 2018 19:16
URI: http://espace.inrs.ca/id/eprint/5702

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