Stratabound copper deposits in east south-central Alaska: their characteristics and origin.

Abstract

XRD, petrographic and chemical studies have led to the identification of ten ore minerals in the deposits, the most abundant being digenite, chalcocite, djurleite, covellite, bornite and chalcopyrite. Greenstones exhibit Cu-Fe sulphides as well as the Cu-sulphides found in limestones. Mineralization was two-stage: 1) Cu was liberated from the metal oxides and mafic minerals and carried along existing fractures by circulating fluids from which it precipitated; 2) Cainozoic deformation induced fracturing which involved the meteoric water circulatory system, probably at T <200oC. -R.E.S.