Sergo Ordzhonikidze Russian State Geological Prospecting University, Moscow, Russia:

A. M. Portnov, Professor, Doctor of Geologo-Mineralogical Sciences, a.m.portnov@mail.ru

The author of this article participated in the surface and airborn geophysical surveys of the areas over tens thousands square kilometers within the Okhotsk–Chukotka and Beltau–Kuramin (Uzbekistan) volcanic–plutonic belts, in the North Urals, in the diamond provinces in Yakutia, in Kazakhstan, in the Kola Peninsula, Central Mongolia and other regions of the world. The investigations used data obtained by gamma spectrometers with single-crystal sensors NaI (Tl), including aerial gamma ray spectrometer manufactured by Macfar, Canada, in combination with two-level magnetometer survey. A bulk of the surface data was collected (more than 200 samples), and a huge bank of remote observation data was accumulated—over a million of observation points, and the contents of K, Тh and Bi214 (U) was calculated at each point. According to the data processing results, a majority of higher values, commonly interpreted as the ore promising anomalies of the radioactive field of the Earth, is connected with barren rocks typically characterized by a high positive correlation between K and Th. Abundance of the anomalies greatly worsened the exploration performance. The best informative in relation of live ore prospecting appeared to be the indicator functions describing mutual relations between K and Th in magmatic rocks, on the one hand, and in fluid–hydrothermal metasomatic wallrock, on the other hand. Based on these data, for the first time in the world, the high efficiency of the airborn gamma ray spectrometry has been proved in exploration of the gold and silver deposits in the Okhotsk–Chukotka volcanic–plutonic belts. The use of UAV and new geological exploration equipment makes it possible to improve efficiency of this express method of live ore prospecting.

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