Discovery of the Eureka volcanogenic massive sulphide lens using down-hole electromagnetics

Abstract

The Eureka massive sulphide lens is the first new discovery of VMS mineralisation at the Stockman Project since 1979. The discovery was made in early 2013 through the integration of geophysical techniques, particularly down-hole electromagnetics, with a robust geological interpretation. The lens is located approximately 350m northeast of the Currawong deposit, immediately along strike and beneath the Bigfoot lens at a depth of 360m. Though surface EM methods played key roles in the discovery of the main deposits at Currawong and Wilga, airborne and fixed-loop EM surveys failed to detect the Eureka lens due to its moderate conductance and increased depth. Interpretation of subtle DHTEM responses in two exploration drill holes was a key component of the discovery. Additional geological input, including short wavelength infrared modelling and structural reinterpretation, presented a compelling drill target, which led to the discovery of the Eureka massive sulphide lens.