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ABSOLUTE AGE, PETROLOGY, GEOCHEMISTRY AND ORE MINERALIZATION OF TIMOFEEV MASSIF OF GORNY ALTAI

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

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

The paper gives new data on the geological structure, ore mineralization, composition, petrography, absolute age, petrology and geochemistry of Timofeev stock of Gorny Altai. The absolute age of monzogabbroes of the stock intrusion lower phase is defined as 397 Ma, that corresponds to the Lower Devonian. Nd-model age of protolith during melting of gabbroids composes 893 Ma, that is characteristic of transit zone from the Middle Paleozoic consolidation to the Altai – Mongolian terrain. According to the chemistry, the Timofeev stock rocks belong to the lime-alkali and shoshonite series. The geodynamic aspect of melt generation is interpreted by mixing alkaline oceanic basalts of the plume setting and normal oceanic basalts of mid-oceanic ridges that took place in the Paleo-Asian Ocean evolution in the Early Paleozoic. Samarium-neodymium isotopic labels of gabbroids indicate the proximity of their values to chondrite meteorites. The ratio of neodymium isotopes with gabbro age indicates that the isotopically varying earth’s crust, close to the depleted mantle, existed under the Korgon trough in the Early Paleozoic. The skarn-iron-ore deposit of the same name is spatially and paragenetically connected with the Timofeev stock.

Keywords: Gorny Altai, Korgon trough, Timofeev stock, gabbro, monzogabbro, syenite, quartz syenite, skarns, iron ores.

DOI 10.20403/2078-0575-2023-4b-186-195

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