The Jebel Ohier deposit—a newly discovered porphyry copper–gold system in the Neoproterozoic Arabian–Nubian Shield, Red Sea Hills, NE Sudan

Abstract

Ongoing exploration in the Red Sea Hills of NE Sudan has led to the identification of a large alteration–mineralization system within a relatively undeformed Neoproterozoic intrusive–extrusive succession centered on Jebel Ohier. The style of mineralization, presence of an extensive stockwork vein network within a zoned potassic-propylitic-argillic-advanced argillic-altered system, a mineralization assemblage comprising magnetite-pyrite-chalcopyrite-bornite (±gold, silver and tellurides), and the recurrence of fertile mafic to intermediate magmatism in a developing convergent plate setting all point to a porphyry copper–gold association, analogous to major porphyry Cu–Au–Mo deposits in Phanerozoic supra-subduction settings such as the SW Pacific. Preliminary U–Pb age dating yielded a maximum constraint of c. 730 Ma for the emplacement of the stockwork system into a significantly older (c. 800 Ma) volcanic edifice. The mineralization formed prior to regional deformation and accretion of the host terrane to a stable continental margin at by c. 700 Ma, thus ensuring preservation of the deposit. The Jebel Ohier deposit is interpreted as a relatively well-preserved, rare example of a Neoproterozoic porphyry Cu–Au system and the first porphyry Cu–Au deposit to be identified in the Arabian–Nubian Shield.