PETROLOGY AND ORE CONTENT OF THE CHINDAGATUYSKY MASSIFIN THE SOUTH OF GORNY ALTAI

A. I. Gusev 1, N. I. Gusev 2

1 Shukshin Altai State Humanities Pedagogical University, Biysk, Russia; 2 A. P. Karpinsky Russian Geological Research Institute, St. Petersburg, Russia

The paper discusses the petrogeochemistry and petrology data on the Chindagatuysky massif in the south of Gorny Altai. The massif is composed of early-phase medium-alkaline granites and late-phase leucogranites. The rocks are peraluminous type and ferrous type of androgenic monospathic hypersolvus granitoids. All rocks of the massif have Ga, Nb, Cs, Zr, and Ba increased concentrations, which is a characteristic of anorogenic granitoids. The granitoids are strontium-rich and neodymium-depleted. Canonic diagrams include the rocks to the A2-type field, which implies formation under postcollision conditions driven by plume activity. The rock generation scenario is complicated: extreme differentiation of basaltic melt, contamination with crust material represented by orthoamphibolites and metagreywacke of an ancient volcanic arc. The granitoids host a quartzgreisen-wolframite deposit, which comprises about 100 veins. Ore minerals include wolframite, molybdenite, scheelite, bismuthine, native bismuth, pyrite, arsenic pyrite, chalcopyrite, tetrahedrite, rarer beryl, wittichenite, sphalerite, tetradymite, and cassiterite. Homogenisation temperature of gas-liquid inclusions in quartz in veiny formations varies from 320 °C to 340 °C. In ore minerals (pyrite, chalcopyrite, beryl), there is the tetrad effect of REE fractionation of W type, which is a characteristic for highly aqueous fluids. Minerals were crystallized under conditions of chemical elements revealing non-CHARAC behaviour in hydrothermal solutions.

Keywords: anorogenic granitoids, granites, medium-alkaline granites, leucogranites, differentiation of basaltic magma, crust material contamination, isotopes of Sr, Nd, greisen, wolframite, molybdenite.

DOI 10.20403/2078-0575-2017-4-71-79

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