Low-Altitude Aeromagnetic Survey: Drones and High Frequency Magnetometers. Experiences and Perspectives

Growth of the mineral resource base requires geological and geophysical studies in difficult-access conditions. Airborne geophysical survey is usually carried out during small-scale works. Large-scale surveys are conducted on foot. Most of Russia's territory is characterized by harsh conditions for such magnetic surveys - which is one of the main tools of geological and geophysical study of the territory. That is differentiated relief, boreal forests with thick undergrowth, stone runs, marshy tundra and so on. This increases the cost of the work. The use of large-scale airborne geophysical surveys is almost impossible for several reasons. Very high cost of using the carrier use (helicopters and planes). Detailed work requires a very low areal speed — below 10 m/s, and the high frequency of the magnetometer, above 100 Hz, which in turn dramatically reduces the accuracy of the survey. We propose to designate a special kind of low-altitude surveying at extremely low altitudes using a high-frequency magnetometer. Designed specifically for this type of surveys, our magnetometer complex has a frequency greater than 1.5 kHz, and the accuracy of the measurement system of the entire field is not less than 1 nT. The surveying complex is designed on base of light and ultralight drones. Experimental work on various objects (from archaeological to geological: burial mounds, skarn deposits, kimberlite pipes, geological mapping of volcanic and sedimentary rocks, etc.) has shown high efficiency of this survey type. High performance and low cost combined with the level of details in results, comparable to surveying on foot at high altitude flights, and exceeding it at low altitudes