Vector Residual Magnetic Intensity (VRMI)

VRMI is an efficient method of removing the effects of remanent magnetism from Total Magnetic Intensity (TMI) data to assist in preliminary mining exploration. Remanent Magnetisation or residual magnetism is the magnetisation left behind in a ferromagnetic material (such as iron) after an external magnetic field is removed.

Figure 1. VRMI processing of magnetic data over Nebo-Babel reveals high quality fit

Traditionally associated with iron ore and gold exploration, the VRMI technique is beginning to be applied in the exploration for more niche and lucrative metals, breathing new life into previously overlooked mining projects.

VRMI uses magnetic surveying to build imaging of ore bodies, which are then refined to remove the effect of remanent magnetism to produce a superior result. These results can then be used to gauge an estimate of resource size and composition, as well as helping to identify drilling targets, allowing exploration companies like Woomera to progress more quickly to more advanced stages of exploration.

Figure 2. VRMI at the Cavanagh drill target

The utilisation of the VRMI technique has been shown to enhance the ability to focus on prospective targets in areas with complex magnetic responses, where traditional geophysical processing methods may not highlight anomalies that are typically associated with mineralisation.

As such, application of the VRMI technique can enable rapid exploration, providing exploration companies another layer of data on which to target prospective geology under cover.

Figure 3. VRMI at Labyrinth

Woomera has been pioneering in the VRMI technology, utilising the technique against known and defined resources in Australia. Results have proven surprisingly effective on a number of interpreted deposits retrospectively, which has indicated that it is a surprisingly accurate predictive tool – one that could potentially assist to fast-track Australian minerals exploration and development.

Woomera has built such a resounding case for exploration at their Musgrave Project utilising VRMI that major miner OZ Minerals (OZL) has agreed to fund further exploration and drilling activities by way of Joint Venture, in exchange for a share in potential future revenue.

Figure 4. VRMI used to predict Labyrinth body