Geology & Mineralization
The Detour Lake gold mine is located within the northwestern portion of the Abitibi Greenstone Belt in the Superior Province of the Canadian Shield. The supracrustal rocks in the project area consist of mafic and ultamafic volcanic rocks of the Deloro Group in thrust contact to the south with the younger Caopatina sedimentary sequence. This regional east-west thrust zone is referred to as the Sunday Lake Deformation Zone ("SLDZ") and can be traced over a distance of more than 30 kilometres on the property. It is defined by a deeply mylonitized and mineralized siliceous alteration zone, referred to as the Chert Marker Horizon ("CMH"), which marks the contact between the basaltic and ultramafic terranes.
The bulk of the gold mineralization at the Detour Lake mine is found in the hanging wall of the SLDZ, in the Upper Detour Lake Formation, which is composed of a thick assemblage of tholeiitic mafic flows that are predominantly massive to pillowed, with minor rhyolitic flows and tuffs.
The mineralized east-west corridor forms a 200 metre wide (locally up to 350 metres) zone that is characterized by swarms of steeply dipping mineralized quartz veining splaying off the CMH in the Upper Detour Lake Formation. The richest gold mineralized zones are commonly associated with increased biotite alteration, shearing, narrow quartz veining and pyrite or pyrrhotite. Local zones of strong brecciation with sulphide infilling have also been recognized along with chalcopyrite, telluride minerals and visible gold. Visible gold is usually found as specks, clusters or fracture coatings, and its abundance may be associated with the chlorite and chalcopyrite content of the vein. Pillowed flows or hyaloclastites are the preferred hosts to mineralized zones. In the area of the Calcite Zone, the gold mineralization is closely associated with weak potassic and strong carbonate alteration and often contains carbonate in veinlets and quartz veins.