Sunnyside Deposit: A Calibration Site for Airborne EM Systems

The Sunnyside deposit is a part of the Selebi-Phikwe nickel mine (Botswana), which has a resource of 68 Mt at 0.8% Ni and 0.88% Cu ( Figure 1 ). It is small, but has some high grade intersections of up to 2.3% Ni and 1.12% Cu over 1 m. The nickel belt has been flown by several airborne EM systems including GeoTEM, Spectrem, VTEM, SkyTEM and XCite. Albidon (Pty) Ltd started the airborne surveys in 2008 by flying VTEM system. African Nickel Limited followed, having flown a Spectrem survey in late 2012, which was succeded by a SkyTEM survey in early 2013. At the same time, moving loop ground EM survey was carried out, and then in early 2014 two AMT surveys were performed. The sulphide body was drilled extensively to a depth of 200 m, but little deep drilling has taken place. In May 2016 NRG offered to fly Sunnyside with their new Xcite heli-EM system, as a test survey. The possibility to compare a generous selection of AEM systems, makes the Sunnyside deposit a defacto test site for airborne EM in southern Africa.