Geophysical signature of the Sally Malay nickel deposit, Western Australia

Abstract

The Sally Malay nickel deposit has clear physical property contrasts with its host rocks and therefore lends itself to detection and mapping by geophysical methods. Conductivities as high as 30,000 S/m compared to the resistive country rock mean that electromagnetics is the best method for locating and mapping such a deposit. The magnetic susceptibility and chargeability are two orders of magnitude higher than the country rock, making magnetics and induced polarisation useful methods. Although there is a density contrast of 1 g/cm3, the gravity method was not used, largely because of the success of electromagnetics, but also because of the steep topography around the deposit. Its short strike length means that the mineralisation does not make a good airborne target using conventional line spacings.