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PETROLOGY AND GEOCHEMISTRY OF INTRUSIVE ROCKS OF THE SINYUKHINSKOYE DEPOSIT (GORNY ALTAI)

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

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

New data on phase relationships, petrology and geochemistry of the Sinyukhinskoye rocks and dikes of the same deposit are presented. Five phases of rock intrusions formed in a homodromic-antidromic sequence are found. The Sinyukhinskoye rocks fall in the oxidized type. In the depth, a source of melting was garnet lherzolites, and, to a lesser extent, spinel lherzolites of an enriched mantle source of the lithospheric slab with a degree of partial melting from 0.2 to 0.4 and low pressure. The formation of intrusive rocks of the deposit took place in the post-collisional environment. The magmatite fluids of the massif and dikes were characterized by high partial pressures of such volatile components as H2O, Cl, F, CO2, which were the main carriers of metals. The rocks exhibit the tetrad effect of the W-type REE fractionation. The dependences of the values of the latter and the concentrations of copper and gold in igneous rocks and fluids were determined by different regimes of acidity and alkalinity of the medium. The deposit belongs to a complex family of ores of the copper-gold-skarn-porphyry type. In the Cheryomukhovaya Sopka and Chir areas, this is also confirmed by the presence of the copper-gold-porphyry type in the ore field, in addition to the gold-copperskarn mineralization.

Keywords: Gorny Altai, intrusive magmatism, gabbro, diorite, granodiorite, granite, monzonite, monzodiorite, tetrad effect of REE fractionation.

DOI 10.20403/2078-0575-2020-3-100-109