Using complex low-altitude unmanned aerogeophysical survey to refine medium-scale geological maps of Bodaibo synclinorium

The purpose of the work is to demonstrate the possibility to clarify and correct medium-scale geological maps of precursors (scale 1:200000–1:50000) using low-altitude unmanned aerial geophysical survey which is the fastest and low cost method of obtaining geological and geophysical data. A quantitative assessment is given to the more accurate identification of the location of geological boundaries and potential ore-bearing structures of the Sukhoi Log type. The first stage of geological study of the area involved obtaining the data from low-altitude unmanned gamma and aeromagnetic surveys. The survey results were prepared, interpolated, visualized, and, finally, subjected to geological and geophysical interpretation. Lineaments of the highest and lowest values, as well as the maximum gradients were identified in the magnetic field while the areas with the least variability at the lowest values and positive anomalies were identified in the gamma field. Interpretation and cross-comparison of the specified data allowed to compile new geological maps of the day surface and pre-Quaternary formations without any ground geological survey but based on the ideas about the geology of the region and characteristic differences in the physical properties of rocks. Taking into account regional stratigraphic and structural search criteria, two sites promising for gold mineralization were identi-fied in the studied area. It is shown that the known geological boundaries in these areas are shifted relative to the real ones by 100–1400 m (on average by 300 m), which is a significant error both in terms of mining and drilling operation planning and general correct understanding of the geological situation. The results obtained are typical for the projects aimed at gold exploration in the Bodaibo District of the Irkutsk region. The results of the study allow to conclude that the express and inexpensive method is useful for the specification of the position of geological and promising ore-bearing structures in the area under investigation, as well as for similar areas in nearby licensed areas and other sites of the Bodaibo synclinorium.