Details of the Abstract
| Title of paper | Joint inversion of Time-Domain Moving Loop EM and Electrical Resistivity Data: Athabasca Basin case-study |
| List of authors | Mohand-Said, A., Marquis, G., Girard, J.F., Williard, E., Harrison, G. |
| Affiliation(s) |
University of Strasbourg/CNRS ITES UMR-7063, University of Strasbourg/CNRS ITES UMR-7063, University of Strasbourg/CNRS ITES UMR-7063, Orano Mining, Orano Canada Inc. |
| Summary |
The Athabasca Basin is a world-class uranium mining province with several high-grade and high-tonnage deposits. The development of mineralization is driven by hydrothermal fluid flow at the unconformity between basin sediments and basement metamorphic and magmatic rocks. This massive fluid flow is channelized by crustal faults in which graphite later precipitated. Graphite-bearing faults are highly conductive, and their host-rock is resistive, thus they are goods targets for electromagnetic (EM) inductive surveys. Fluid flow also led to the alteration of basin and basement rocks modifying their mineralogy and petrophysical properties, including resistivity. The resistivity contrast between fresh and altered rocks is recorded in the signal of galvanic direct-current (DC) resistivity methods. Exploration of Uranium deposits in the Athabasca Basin therefore relies on localizing graphitic conductors and alteration halos, closely related to mineralization, using EM and DC methods. To evaluate the benefits of joint inversion of EM and DC data we inverted a line of Time Domain EM Moving-Loop survey, and a line of Pole-Dipole electrical resistivity survey. Inversion of EM data alone succeeds in identifying the location of graphitic conductors, while inversion of DC data alone is not able to recover information of resistivity contrasts close to the unconformity. Indeed, the signature of the graphitic conductors overprints the signal of objects nearby. Joint inversion led to a single geo-electric model fitting both datasets. The model obtained shows the conductive features identified with inversion of EM data, and resistivity contrasts unseen on separate inversions have been revealed down to 500m. |
| Session Keyword | 3.0 EM methods for exploration (geothermal, mineral resources, etc.) |
| File upload |
3.0_joint_inversion_of_time-d_mohand-said_01.pdf
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