Exploration for cyprus style copper deposits, Sultanate of Oman: A case history

Abstract

Copper mining has occurred in the Sultanate of Oman since the 3rd millennium BC in sporadic episodes. Current mining has resulted from recent (post 1970) recognition of ancient mining centres and the economy of modern concentrator and smelting processes. Cyprus style copper/gold deposits are inherently low grade and small tonnage in nature, however, they occur in clusters along predictable structural zones. Observations, from submersible vehicles, on such deposits in mid-oceanic ridge environments have given insight to their origin and form that can be used in exploration. Airborne magnetic (and radiometric) surveys were contracted to map the geology and structure of prospective terrains in Oman and to recommend anomalous zones for follow-up. Magnetic anomalies, close to a known deposit, were chosen for exploration using transient electromagnetic and induced polarisation techniques and orientation surveys were also undertaken in areas of deep cover. Several TEM anomalies, of relatively moderate conductivity, were delineated by the surveys and tested by drilling. The programme produced two new copper/gold zones of higher than usual grade (greater than 2% copper and 1 g/t gold) but each less than 500 000 tonnes. The results confirmed that use of theoretical models in conjunction with modern airborne and ground geophysics could locate new zones of mineralisation.