Semi-airborne electromagnetic exploration of deep sulfide deposits with UAV-towed magnetometers — Part 1: Processing and modeling

Le résumé fourni par la source

ABSTRACT In recent decades, global technological expansion, alongside significant shifts in information technology, energy supply, and mobility, has dramatically increased the demand for certain raw materials, especially minerals. To meet future demand, new strategies and solutions are being sought. Semi-airborne electromagnetics (SAEM), an emerging method to sense conductive subsurface structures, holds high potential for mineral exploration and can be applied to uncover untapped ore deposits or re-evaluate exploited ones. This technique has been successfully implemented in multiple studies and is a core part of the Deep Electromagnetic Sounding for Mineral Exploration joint project. To date, promising sites are being surveyed using either crewed aircraft or ground-based methods, both of which come with limitations concerning site access, survey period, achievable resolution, and cost. By using uncrewed aerial vehicles (UAVs), some constraints and expenses can be overcome. Taking advantage of a battery-powered 25 kg maximum takeoff weight octocopter and two complementary magnetometers, an optically pumped total-field magnetometer and an induction coil triple, we surveyed the Hope deposit, a known, unexploited massive sulfide mineralization in Western Namibia. Time-varying EM fields, excited by grounded electric-dipole transmitters, are measured and evaluated discretely in the frequency domain. Based on 2D inverse modeling, we are able to image the Hope ore body and trace it down to a depth of more than 300 m. Combined sensor data inverted along adjacent profile lines reveal an imposing, contiguous dipping conductor that can be clearly assigned to the Hope structure. To assess the significance of our results, we invert data from the two sensor systems individually as well as jointly and carry out detailed modeling studies. Our findings are supported by available resistivity models based on audio magnetotelluric data and yield an excellent match to existing borehole probes.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.