Geophysical characteristics of the Telfer gold deposits, Western Australia

Abstract

The Telfer gold deposits are hosted by Middle Proterozoic marine sedimentary rocks of the northeastern Paterson Orogen. They occur within two en echelon, asymmetric, doubly plunging anticlines, with ore being extracted from reefs and stockworks. Regional magnetic and gravity surveys have been undertaken to assist in mapping stratigraphy, intrusions and structures in the Telfer district. These surveys indicate the presence of intrusions close to the Telfer gold deposits, which is regarded as supporting a genetic relationship between granitoids and mineralisation. The Telfer mineralisation itself has no gravity or magnetic signature. The narrowness of the reefs, deep oxidation and the presence of shallow, thin, electrically resistive beds make the Telfer gold deposits a difficult geophysical target. Direct current resistivity techniques were used to assist mapping of the quartz reefs. Surface and downhole electromagnetic pulse surveys undertaken at Main Dome after overburden stripping detected subtle responses coincident with the Middle Vale Reef.