Aeromagnetic gradiometry with UAV, a case study on small iron ore deposit

Abstract

Unmanned aerial vehicles (UAVs), commonly known as drones, offer several advantages over traditional piloted aircraft. They are characterized by enhanced safety, cost-effectiveness, and the ability to operate in closer proximity to targeted sources. Consequently, magnetic sensors have been adapted or specifically designed for integration onto UAV platforms. However, existing sensors are burdened by issues such as weight, cost, and high power consumption. These challenges are particularly pronounced when employing aeromagnetic gradiometry, which necessitates simultaneous measurements from at least two sensors. In response to these limitations, we propose the implementation of a cost-effective, lightweight, and low-power magneto-inductive sensor with satisfactory resolution aboard a UAV. To evaluate its efficacy, a survey was conducted over a small iron ore deposit in Western Iran. To validate our approach, we compare the results with those obtained using only one sensor on the drone. This comparative analysis reveals that employing a gradiometry array leads to a pronounced steepening of magnetic anomaly margins. Specifically, the gradient of magnetic measurements on four selected profiles increases to 3.8, 4.6, 9.3, and 10 nT/m when utilizing the proposed magneto-inductive sensor, in contrast to the conventional method of gradient determination through mathematical derivatives in the z-direction. This research contributes to the advancement of efficient and economical methods for mineral exploration using UAV-based magnetic surveying techniques.