The Cawse nickeliferous laterite deposits, Western Australia ? A case study on the application of airborne geophysics in targeting zones of supergene enrichment in a complex regolith setting.

Abstract

Helicopter electromagnetic (HEM) and magnetic survey data were acquired over the Cawse district in the Eastern Goldfields of Western Australia, to help define the structural controls that influence supergene mineralisation and delineate areas favorable for further exploration. The rationale for conducting the EM survey was that previous work in the area had demonstrated that local discontinuities, represented by stratigraphic and structural variations in the regolith, or related textural and/or mineralogical changes have influenced hydrogeological process and consequently the distribution mobile elements such as Ni, Co and Mn within the profile. The observed conductivity structure in the HEM data is related to regolith heterogeneity and to the presence of hydromorphic barriers (structural, material) behind which salts and water accumulate. In places these barriers are spatially associated with Ni enrichment.