Geophysical Signature of the Balla Balla Titaniferous Magnetite Deposit, Western Australia

The Balia Balia titaniferous magnetite deposit is situated about 120 km southwest of Port Hedland, in the Archaean Pilbara Craton of Western Australia. The titaniferous magnetite, and associated vanadium, occurs as layers within a mafic intrusion. A detailed gravity survey was conducted over the deposit. After band-pass filtering, residual gravity highs (about 10 gu) associated with mineralisation were defined. A ground magnetic survey was also conducted over the deposit. Positive magnetic anomalies (about 4000 nT) were interpreted to be due to more massive areas of mineralisation. Offsets between these anomalies allowed faults to be mapped. Elementary modelling of the magnetic data indicates that remanent magnetisation is responsible for a significant part of the observed magnetic anomalies. Ground electromagnetic data (VLF) and resistivity data were moderately successful in mapping the contact between the mafic intrusion and underlying granitic rocks, and confirmed the location of faults inferred from the magnetic data. Induced polarisation data show that the mineralisation is chargeable.