Delineating cobalt targets from a galvanic and inductive source Sub-Audio Magnetics (SAM) at the Carlow Castle project, Western Australia

Abstract

Summary The Carlow Castle deposit is located 40 kilometres east of Karratha, Western Australia. The deposit is shear hosted in the Ruth Well Mafic Formation, part of the Roebourne Group. It is interspersed with metagabbro intrusions and brecciated chert cataclastites. Carlow Castle contains Au, Cu and Co mineralisation. Data from a Sub-Audio Magnetic (SAM) survey was acquired in both galvanic and inductive configurations to map structural responses over known mineralisation. On-time Magnetometric Conductivity (MMC), Total Magnetic Intensity (TMI) and Off-time Galvanic Source Electromagnetic (GSEM) data were extracted from the galvanic dipole configuration. Off-time Inductive Source Electromagnetic (ISEM) data were extracted from the loop source configuration. MMC data were combined, modelled and interpreted to rank structural targets around existing Au and Cu mineralisation. This was used in conjunction with Co soil geochemistry as a vectoring tool for further cobalt mineralisation. The MMC data was successful in increasing level of detail over the project. ISEM and GSEM were also compared with previously highlighted VTEM anomalism. Five high and seven medium priority targets were identified for follow up with further drilling.