Genesis of garnet-bearing rocks at the Berezitovoe deposit, Upper Amur Region, Russia

Autor: O. V. Avchenko, Konstantin V. Chudnenko, V. O. Khudolozhkin, A. S. Vakh
Rok vydání: 2014
Předmět:
Zdroj: Geology of Ore Deposits. 56:15-34
ISSN: 1555-6476
1075-7015
DOI: 10.1134/s1075701514010024
Popis: The geological position, composition of mineral assemblages, and typomorphism of major minerals from garnet-bearing rocks at the Berezitovoe gold-base-metal deposit in the Upper Amur Region have been studied in detail. These are ore-bearing metasomatic rocks and metamorphosed porphyritic dikes. The garnet-bearing metasomatic rocks reveal zoning, which is caused by various degrees of metasomatic transformation of the Paleozoic porphyritic granodiorite that hosts the ore zone. The metasomatic replacement of granodiorite was accompanied by loss of Na, Ca, Ba, Sr and gain of K, Mn, and Rb. Garnet-bearing metamorphosed intermediate dikes occur within the metasomatic zone. The PT conditions of metamorphism and metasomatism are similar and estimated at 3.9 kbar and 500°C from various mineral equilibria. The results of physicochemical simulation of garnet-bearing mineral assemblages carried out by minimizing the Gibbs free energy and the geological data show that garnet-bearing mineral assemblages arose at the Berezitovoe deposit as a result of local high-temperature thermal metamorphism of previously formed low-temperature metasomatic rocks close in composition to classic beresite. In this connection, we propose considering garnet-bearing metasomatic rocks as high-temperature metamorphosed beresites.
Databáze: OpenAIRE
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