A detailed geological, geochemical and mineralogical study of the koorae prospect and the host rocks of the Topsails intrusive suite, Hinds lake area, Newfoundland

Abstract

The Topsails Intrusive Suite (TIS) and Springdale Group comprise widespread, Silurian, post-orogenic A-type intrusive and volcanic rocks m west-central Newfoundland. Magmatic-hydrothermal Cu-Mo-Ag-Au and intrusion related U-rare earth element (REE) mineralization occur locally in these rocks near Hinds Lake. A peralkaline, amphibole-clinopyroxene granite and hydrothermal-volcanic breccia host chalcopyrite, bornite, covellite, pyrite, molybdenite and chalcocite. Magmatic-hydrothermal quartz, copper sulfides, magnetite, Fe-Ti oxides and calcic clinopyroxene replace primary amphibole and pyroxene. Common accessory minerals are hematite, zircon, fluorite and monazite. Uranium-Pb zircon ages of host amphibole-clinopyroxene granite and rhyolite yield ages of 430 ± 1.4 Ma and 428 ± 1.6 Ma, respectively, suggesting that Cu-Mo-Ag-Au mineralization is associated with early TIS peralkaline granite magmatism and equivalent volcanic rocks of the Springdale Group. Uranium and REE are hosted in late stage felsic dykes, present in accessory monazite- (Ce, La), zircon, allanite- (Ce), pyrochlore, and thorite. Felsic dykes are among the youngest and most fractionated rocks of the TIS (likely younger than - 427 Ma).