Summary:
The Éléonore operation is comprised of 368 mining claims and one mining lease, issued under the Quebec Mining Act, encompassing 48,210 acres (19,511 hectares). Éléonore is a clastic sediment-hosted stockwork-disseminated gold deposit
The Éléonore Operations host the Roberto gold deposit, which consists of the Roberto, East Roberto, and Zone du Lac lenses.
The Roberto deposit is a clastic sediment-hosted stockwork-disseminated gold deposit.
The Roberto deposit has historically been divided into the Roberto, Roberto East, Zone du Lac, North and Hanging Wall Zones. This nomenclature is based on their geographical location and the main alteration types observed. All of the zones are made up of many individual mineralized lenses.
The host rock of the mineralized zones is typically a thinly-bedded greywacke (bed thickness approximately 10 cm) near the contact with a massive greywacke unit, and locally, with a thin conglomerate unit. The steeply east-dipping Roberto East fault, marked by a thin black tourmaline marker band, forms the eastern limit of the mineralized vein cluster.
The structural hanging wall of the mineralized zones is characterized by a greywacke containing centimetre-scale aluminosilicate porphyroblasts overlain by a thin conglomerate unit. The aluminosilicate-bearing greywacke and the conglomerate appear tightly folded, with axes generally oriented in the east–west direction and refolded by the F2 event. This folding is in sharp contrast with the generally north– south-trending bedding in the mineralized zones. The structural footwall of the mineralized zones is characterized by greywacke, locally exhibiting a higher metamorphic grade, which contains a higher amount of pegmatite dikes and quartz veins.
The bulk of the gold mineralization at the Roberto deposit includes a wide range of mineralization styles (Fontaine et al., 2015a):
- Stockwork of quartz, dravite veinlets with microcline, phlogopite, and sulphides;
- Replacement zones (microcline, phlogopite, dravite) with traces of pyrrhotite, arsenopyrite, and rare löllingite (FeAs2; Roberto zone);
- Quartz, diopside, schorl, arsenopyrite veins (East Roberto zone);
- Atypical mineralized zones in quartz–feldspathic veinlets, high-grade quartz veins, high-grade paragneiss (North Zone and Hanging Wall Zone).
Mineralization shows variable proportions of disseminated arsenopyrite, löllingite, and pyrrhotite. Traces of pyrite, sphalerite, bornite, and chalcopyrite are also locally present.
The sulphide concentration within the mineralized zones varies between 1% and 5%, and primarily consists of arsenopyrite, löllingite, pyrrhotite and pyrite. The “waste” rock may contain sulphides, usually pyrrhotite, but this is in lesser amounts, from trace to 2%, and occurs mostly in the structural hanging wall.
The mineralized zones are generally 5 m to 6 m in true thickness, varying between 2 m and more than 20 m locally. Mineralization is considered to pre-date the final deformation phase (Ravenelle et al, 2010).
The mineralized zones are folded with increased thicknesses in the hinge of the folds while limbs are fairly straight and continuous. Transposition of the sedimentary beds post-mineralization may also explain some of the thickening of the mineralized zones.
The Roberto gold zones dip steeply to the east and rake (plunge) steeply to the northeast. All zones remain open at depth and along strike.