Airborne electromagnetics in Pilbara manganese exploration ? a case study

Abstract

Airborne electromagnetic methods have been used for manganese exploration in parts of the Pilbara since 2002 when the first Hoistem survey was flown for Pilbara Manganese. A XTEM survey was commissioned by Montezuma Mining to test the effectiveness of the technique in a new manganese province near Kumarina, WA. A series of test lines was flown over areas of known manganese ore deposits and revealed a successful correlation between the electromagnetic conductors and the known manganese zones. In addition the test lines revealed new zones of conductivity where traces of manganese had been found but not yet drilled. Based on the preliminary results the complete Butcherbird tenement was flown in December 2010. The survey successfully mapped the extent of the known manganese zones and assisted in the identification and mapping of several new targets which were subsequently drilled and found to bear manganese oxide. The shape of the Electromagnetic (EM) anomaly maps the resource outline and the strength of the EM signal correlates strongly with the grade of the resource.