Volcanic stratigraphy and intrusions in the Renault–Dufresnoy and Duprat–Montbray formations: implications for metal endowment in the lower Blake River group, Rouyn-Noranda, Quebec

Metal Earth is a geoscience project funded by the Canada First Research Excellence Fund and operated by the Mineral Exploration Research Centre at the Harquail School of Earth Sciences. The preliminary work presented here is part of a two-year M.Sc. research project funded by Metal Earth that will focus on the metallogeny of volcanic strata in a square-shaped area of ~90 km² along Chemin de la Mine, 30 km northwest of Rouyn-Noranda, Quebec (Figure 1).

Volcanic and volcaniclastic rocks in the study area belong to two formations that are part of the lower Blake River group (BRG), the 2702–2696 ±0.8 Ma Renault–Dufresnoy formation (RDF) and the 2702 Ma Duprat–Montbray formation (DMF; Figure 2; McNicoll et al., 2014). Volcanic rocks in both formations are intermediate to mafic, whereas volcaniclastic rocks are intermediate to mafic in the RDF (Ross et al., 2011) but felsic in the DMF (Liaghat and MacLean, 1995). The field area also includes two ellipsoidal synvolcanic felsic intrusions covering ~6 km², the Monsabrais pluton (Ross et al., 2008) in the RDF and the Fabie pluton (McNicoll et al., 2014) in the DMF. Both formations also host small (<2 km²), younger intrusions of intermediate compositions. The contact between the RDF and DMF is the eaststriking Baie Fabie shear zone (BFSZ). The metamorphic grade in the area varies from subgreenschist to greenschist facies (Ross et al., 2008). Two rhyolite-hosted volcanogenic massive sulphide (VMS) deposits, Fabie and Magusi, occur within the DMF (Meyers and McLean, 1983; Liaghat and MacLean, 1995). These deposits were mined and produced 1.3 Mt, with an average grade of 1.99 % Cu, 4.12 % Zn, 42.8 g/t Ag and 1.27 g/t Au.

The main goals of the project are to: 1) define the contact relationships between the RDF and DMF; 2) establish a stratigraphy for the DMF; and 3) construct the volcanic setting/environment for the two VMS deposits.

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