Comparison of geophysical inversion programs run on aeromagnetic data collected over the Highland Valley Copper district, British Columbia, Canada

ABSTRACT

As part of the Natural Sciences and Engineering Research Council of Canada–Canada Mining Innovation Council (NSERC-CMIC) Mineral Exploration Footprints project, three selected magnetic inversion programs (VPmg, MAG3D and VINV) were used to process the same aeromagnetic data set from the Highland Valley Copper district, British Columbia, Canada. In each case, the inversion was constrained using available geological and physical property constraints. Analysis of magnetic susceptibility data suggests that the observed aeromagnetic anomaly pattern includes effects associated with boundaries between lithological units and fault zone alteration resulting from removal of magnetite. Susceptibility contrast associated with alteration is greater than that associated with changes in lithology. The inversions seek to define the three-dimensional geometry of geological boundaries and the fractures are treated as high-frequency noise. Results from the three programs, although similar, are sensitive to attributes of the different algorithms. VPmg emphasises physical boundaries between geological domains, MAG3D produces a more blurred image, whereas VINV produces reasonable geological images. Computer performance using the different programs ranges from reasonable for VPmg to computer intensive for MAG3D and VINV. Differences in the results reflect the inherent uncertainty in producing inversions from “noisy” aeromagnetic data.

KEYWORDS:

• Geophysical inversion
• aeromagnetic method
• geological model
• uncertainty
• porphyry copper

Acknowledgments

The Natural Sciences and Engineering Research Council of Canada (NSERC) and the Canada Mining Innovation Council through the NSERC Collaborative Research and Development Program. We acknowledge the industrials sponsors of the Footprints project and more particularly Teck. Teck Resources Limited (Teck) was neither privy to the access terms nor played any part in directing the research with respect to specific sampling areas or plans outside Teck’s tenure. On any non-Teck mineral tenure or open ground, which CMIC and its researchers elected to access, CMIC was and remains solely responsible, and Teck was not and is not responsible, for any land access, sampling, data collection and/or reporting permissions during the course of the research and for meeting any associated obligations arising from such access and data collection. We also acknowledge two anonymous reviewers. NSERC-CMIC Mineral Exploration Footprints Project Contribution Number # 158. MDRU contribution number 425.

Disclosure statement

No potential conflict of interest was reported by the authors.

ORCID

Marc A. Vallée http://orcid.org/0000-0002-0045-0920

Michel Chouteau http://orcid.org/0000-0002-8538-1775

Additional information

Funding

Funding was provided by the Natural Sciences and Engineering Research Council of Canada (NSERC) and the Canada Mining Innovation Council (CMIC) through the NSERC Collaborative Research and Development Program.