THE INSKOE DEPOSIT OF SKARN-MAGNETIC ORES IN GORNY ALTAI

Rich factual material was used for the first time to present a complet e picture for the geologic structure of the Inskoe deposit situated in northwestern Gorny Altai near the piedmont of the northern slope of t he Tigirek Ridge and known since 1952. The deposit is localized among Middle Devonian acid volcanites. Intrusive rocks varying in conditions , setting composition, form of occurrence and age are widespread there . They include subvolcanic formations of Middle-Upper Devonian age, Up per Devonian plagiogranites, Upper Devonian-Upper Carboniferous gabbro ids, and Carboniferous-Permian granitoids. Crossing one the other, the two latter intrusive complexes superimpose the skarn-ore zone. Plagio granites having a very complicated relief of the surface constantly un derlie mineralization thus determining its rather complicated morpholo gy. Skarn-ore deposits have distinct zoning (often concentric) express ed in successive substitution of the following formations: intact volc anites of acid composition or plagiogranites - hornfelses - skarns - p oor and, at last, rich magnetic ores. The latter usually gravitate to the central parts of the ore deposits. The Inskoe deposit refers to th e skarn contact-metasomatic type connected not only spatially but also genetically with the origin of the Upper Devonian plagiogranites of t he Inya intrusive complex.