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MINERAL AND CHEMICAL COMPOSITION OF BASITES OF THE KHATYMINSKAYA DIAPHTHORESIS ZONE AND PROSPECTS FOR THEIR ORE SPECIALIZATION (CENTRAL PART OF THE ALDAN-STANOVOY SHIELD)

A. A. Kravchenko 1, N. A. Bondar-Lunetskas 1, V. I. Beryozkin 1, N. V. Popov 2, A. I. Zhuravlev 1, A. V. Okrugin 1

1 Diamond and Precious Metal Geology Institute SB RAS, Yakutsk, Russia; 2 Trofimuk Institute of Petroleum Geology and Geophysics SB RAS, Novosibirsk, Russia

The paper deals with determined petrographical features and conditions of metamorphism of basite dikes in the Khatyminskaya diaphthoresis zone (Amginskaya melange zone of the Aldan-Stanovoy Shield), represented by metamorphosed rocks of the Precambrian Medvedev complex and non-metamorphosed dolerites. Comparative analysis of the basite chemical composition was performed. It was found that the rock metamorphism of the Medvedev complex in the diaphthoresis zone proceeded in conditions from granulite to greenschist facies, accompanied by characteristic changes in mineral associations and rock chemical composition. The transition from granulite metamorphism to amphibolite facies metamorphism was carried out along a metamorphic gradient of 10°C/km (from amphibolite to epidote amphibolite facies with its high values). Diaphthoresis zone is characterized by the presence of metamorphosed basites of the Medvedev complex with the age of 1.9 Gya and non–metamorphosed dolerites 1.87 and 1.75 Gya, probably determines the age limits of the Khatyminskaya zone 1.9–1.75 Gya diaphoresis. Metamorphic gradients and the presence of dolerite dikes indicate the formation of zone in an extension setting at the stage of transition to the platform mode.

Keywords: Aldan-Stanovoy Shield, polymetamorphic compexes, evolution, petrology, metallogeny.

DOI 10.20403/2078-0575-2024-4a-63-78

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