Le magmatisme de la région de Kwyjibo, Province du Grenville (Canada) : intérêt pour les minéralisations de type fer-oxydes associées

Résumé 0

The granitic plutons located north of the Kwyjibo property in Quebec’s Grenville Province are of Mesoproterozoic age and belong to the granitic Canatiche Complex . The rocks in these plutons are calc-alkalic, K-rich, and meta- to peraluminous. They belong to the magnetite series and their trace element characteristics link them to intraplate granites. They were emplaced in an anorogenic, subvolcanic environment, but they subsequently underwent significant ductile deformation. The magnetite, copper, and fluorite showings on the Kwyjibo property are polyphased and premetamorphic; their formation began with the emplacement of hydraulic, magnetite-bearing breccias, followed by impregnations and veins of chalcopyrite, pyrite, and fluorite, and ended with a late phase of mineralization, during which uraninite, rare earths, and hematite were emplaced along brittle structures. The plutons belong to two families: biotite-amphibole granites and leucogranites. The biotite-amphibole granites are rich in iron and represent a potential heat and metal source for the first, iron oxide phase of mineralization. The leucogranites show a primary enrichment in REE (rare-earth elements), F, and U, carried mainly in Y-, U-, and REE-bearing niobotitanates. They are metamict and underwent a postmagmatic alteration that remobilized the uranium and the rare earths. The leucogranites could also be a source of rare earths and uranium for the latest mineralizing events.