Mineralogy,paragenesis and origin of the Ag-Ni,Co arsenide mineralisation,Camsell River,N. W. T. Canada

Polymetallic hydrothermal vein mineralisation of the Ag-Ni, Co Arsenide type, and containing Bi and U, occurs in three mines and five uneconomic veins in the Camsell River area. Each occurrence is described in detail. The veins lie in sulphide-impregnated volcanic rocks of the Aphebian Great Bear Batholith. Large, NE-trending strike-slip faults were initiated during the terminal phases of orogeny (1750 m.y.), and were active intermittently for at least 300 m.y. The veins are located in splays and tension-fractures form the primary faults, and mineralised lenses are found in dilatant zones in these structures. The mineralisation shows a generalised paragenesis of U → Ag+arsenides → Bi, Sulphides, Sulphosalts, but there are variations. A model is presented to explain the temporal and spatial controls of mineralisation and to explain the perturbations in the paragenesis. It is concluded that the mineralisation is of magmatic origin and lateral secretion models are rejected. Discussions of the ultimate origin of the ore elements are not presented here.