Mt William is subject to Exploration License application E70/2338 and is located near Waroona, 100km south of Perth, in the South West Yilgarn Terrane (Fig 1). The main target at Mt William is a 3.5km long, very prominent magnetic feature that is interpreted to be a layered mafic complex with potential for Ni-PGM mineralisation.
The 2020 discovery of Ni-Cu-PGM mineralisation at Julimar in the Gonneville layered mafic complex has further highlighted the prospectivity of the Mt William magnetic complex, as both of these intrusions are situated in similar geological settings within the South West Yilgarn Terrane.
A comparison of airborne magnetic surveys over Gonneville and Mt William is shown in Fig 2. Mt William shows a very similar style of magnetic anomaly with discrete layering clearly visible and a character consistent with the chonolith style of intrusion at Gonneville. The Mt William intrusion is substantially larger than the Gonneville intrusion with over 3.5km of strike length compared to around 1.5km at Gonneville.
Mt William Instrusive
Fig1. Comparison of airborne magnetics at Mt William
Fig 2. Gonneville intrusives at the same scale
SOURCE: TMI Magnetic Image, Geological Survey of Western Australia
Fig 3. Schematic geology map of the South West Yilgarn Terrain (modified after Porter, 2017) showing the location of the Julimar/Gonneville intrusion in the Jimperding Metamorphic Belt and the Mt William intrusion in the Balingup Metamorphic Belt
The prospect area is dominated by deep laterite weathering profiles typical of the Darling Plateau, with no outcrops present in the area to indicate basement geology and the source of the magnetic anomaly. There is no recorded previous exploration or drilling in this area other than shallow drilling for bauxite exploration to the north.
Although no ages have been determined for the layered intrusions, the Gonneville intrusion lies within the Jimperding Metamorphic Belt which is considered to be of similar age and origin to the Balingup Metamorphic Belt that hosts the Mt William intrusion (Fig 3). Both belts are believed to have similar origins and histories and have metamorphic ages dated around 3.2 to 2.8 billion years old (Cassidy et al., 2006).
The Mt William prospect is located in a cleared forest area and within Alcoa’s Mineral Lease 1SA which was granted to Alcoa under the Alumina Refinery Agreement Act 1961 pertaining to Alcoa’s mining and refining interests. Caravel is actively working to resolve an objection to application E70/2338 made by Alcoa.