ПРОВЕДЕНИЕ ДЕТАЛЬНЫХ АЭРОГЕОФИЗИЧЕСКИХ РАБОТ В СЛОЖНОДИСЛОЦИРОВАННЫХ КОМПЛЕКСАХ СУТАМСКОГО ТЕРРЕЙНА (АЛДАНСКИЙ ЩИТ) ПРИ ИЗУЧЕНИИ ЖЕЛЕЗОРУДНЫХ МЕСТОРОЖДЕНИЙ

Magnetic exploration is the most informational and economical method of prospecting and exploration of iron-ore deposits. In rough-terrain and remote areas without any infrastructure, problems associated with ground-based methods can be avoided by using modern unmanned technologies that allow conducting geophysical surveys in a more efficient way. An unmanned aeromagnetic survey complex (aerial vehicle, UAV) Geoscan 401 was used to assess the possibility of using UAVs for aeromagnetic surveying of iron-ore deposits. Our experimental study was conducted in the well-studied area of the largest iron-ore deposit of South Yakutia. The UAV capacities were confirmed by comparing the aeromagnetic survey data with the available data obtained by ground magnetic exploration of the study area. By analysing magnetic fields, we established that the anomalies detected by the ground and aeromagnetic surveys were fully identical. Furthermore, a weak anomaly was discovered in the northeastern part of the study area (it was not reflected in the magnetic field from the ground survey data). Recalculation of the vertical gradient of the magnetic field shows that the anomaly is caused by a blind ore body. Its upper edge is located at a depth of 200–250 m from the day surface. In calculations for a data array without gradient intervals, a mean square error (MSE) amounts to 1.01 nT. An absolute error in the heights of the working and control flights did not exceed 1.5 m. Both the preliminary and control measurements were performed very efficiently. Profiles for UAV surveys were spaced by 100 m. A 1.0 km2 site was covered by one flight within approximately 20 minutes. The Geoskan-401 UAV is useful for obtaining orthophotos, topographic maps and 3D models of the surveyed territory as required for further studies consistent with the magnetic surveys. The aeromagnetic surveys were followed by trenching to verify the newly discovered anomalies. Based on the results of this experimental study, the forecast resources of the Sutam deposit should be increased by almost 250–350 million tons, i.e. plus 15 % to the previously explored and approved reserves of the Sutam field.Магниторазведка представляет собой наиболее информационный и экономичный метод при поиске и разведке железорудных месторождений. Избежать проблем с постановкой наземных методов на труднопроходимых и удаленных от инфраструктуры территориях, повысить скорость их изучения позволяют беспилотные технологии. Для оценки возможности применения беспилотной аэромагнитной съемки на железорудных объектах Якутии были выполнены опытно-методические работы на уже хорошо изученном ранее крупнейшем железорудном месторождении Южной Якутии с использованием беспилотного комплекса «Геоскан 401». Данный подход позволил установить работоспособность полетного комплекса, сопоставив имеющиеся данные наземных магниторазведочных работ с данными аэромагниторазведочных работ. Анализ магнитных полей показал полную идентичность полученных аномалий наземной и аэромагнитной съемки. Более того, на северо-востоке участка была выделена слабая аномалия, которая не отражена в магнитном поле наземной съемки. Пересчет вертикального градиента магнитного поля позволил определить, что аномалия обусловлена слепым рудным телом, верхняя кромка которого располагается на глубине 200–250 м от дневной поверхности. Среднеквадратическая погрешность, вычисленная для массива данных без градиентных интервалов, составила 1.01 нТл. Абсолютная погрешность высоты основного и контрольного полетов не превышает 1.5 м. По результатам рабочих и контрольных замеров отмечается высокая воспроизводимость измерений. За один полет по сети профилей с шагом 100 м был изучен участок площадью 1 км2. Полетное время составило немногим более 20 мин. Дополнением работы с полетным комплексом «Геоскан-401» стала возможность съемки ортофотопланов, топопланов, трехмерных моделей местности – в зависимости от потребностей – последовательно с выполнением магниторазведочных работ. Согласно результатам аэромагниторазведочных работ и последующей заверки полученных новых аномалий горно-вскрышными работами в виде канав и траншей, прирост прогнозных ресурсов Сутамской площади составил примерно 250–350 млн т – 15 % от уже опоискованных ранее и утвержденных запасов Сутамского месторождения

DETAILED AIRBORNE GEOPHYSICAL SURVEY OF COMPLEXLY DISLOCATED STRATA IN THE SUTAM TERRANE (ALDAN SHIELD) DURING STUDIES OF IRON-ORE DEPOSITS

Magnetic exploration is the most informational and economical method of prospecting and exploration of iron-ore deposits. In rough-terrain and remote areas without any infrastructure, problems associated with ground-based methods can be avoided by using modern unmanned technologies that allow conducting geophysical surveys in a more efficient way. An unmanned aeromagnetic survey complex (aerial vehicle, UAV) Geoscan 401 was used to assess the possibility of using UAVs for aeromagnetic surveying of iron-ore deposits. Our experimental study was conducted in the well-studied area of the largest iron-ore deposit of South Yakutia. The UAV capacities were confirmed by comparing the aeromagnetic survey data with the available data obtained by ground magnetic exploration of the study area. By analysing magnetic fields, we established that the anomalies detected by the ground and aeromagnetic surveys were fully identical. Furthermore, a weak anomaly was discovered in the northeastern part of the study area (it was not reflected in the magnetic field from the ground survey data). Recalculation of the vertical gradient of the magnetic field shows that the anomaly is caused by a blind ore body. Its upper edge is located at a depth of 200–250 m from the day surface. In calculations for a data array without gradient intervals, a mean square error (MSE) amounts to 1.01 nT. An absolute error in the heights of the working and control flights did not exceed 1.5 m. Both the preliminary and control measurements were performed very efficiently. Profiles for UAV surveys were spaced by 100 m. A 1.0 km2 site was covered by one flight within approximately 20 minutes. The Geoskan-401 UAV is useful for obtaining orthophotos, topographic maps and 3D models of the surveyed territory as required for further studies consistent with the magnetic surveys. The aeromagnetic surveys were followed by trenching to verify the newly discovered anomalies. Based on the results of this experimental study, the forecast resources of the Sutam deposit should be increased by almost 250–350 million tons, i.e. plus 15 % to the previously explored and approved reserves of the Sutam field