Constrained inversion models identify new resources at Ivanhoe's Platreef deposit

In a new Earth Explorer article, geophysicists Barry de Wet and Dr. Nick Williams explain how they utilized advanced gravity and magnetic inversion methods, and VOXI Magnetization Vector Inversion (MVI) technology, to help predict new resources at Ivanhoe Mine’s Platreef PGM Project - the Flatreef Discovery - in South Africa’s Bushveld Igneous Complex.

The two biggest challenges faced on the Platreef Project were relating the fine-scale physical rock property measurements to the large volumes of rock involved, and the limited resolution of the gravity and magnetic data sets at depth.

To extract the true magnetic structure of the geological units at depth, and create predictive models for exploration, the team needed to integrate the standard aeromagnetic data collected over the area in 2004 with other physical property data from drill logs and the literature, such as density, velocity, conductivity and chargeability.

The first models generated predicted a deep extension of the regional contact and Flatreef host rocks over an area of about four square kilometers, approximately 1.5 km west of the prior drilling. The target was drilled in 2011 and hit the contact and reef within 200 meters of the predicted 1300-meter depth.

de Wet and Williams generated three major iterations of models using Geosoft VOXI over a five-year period, updating the inversion models as new drilling and other information became available.

Read the full story on Earth Explorer. Find out more about choosing the right magnetic field inversion method for your geological situation

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