Paleozoic metallogeny of Precambrian massifs of the Central Asian Tectonic Belt in the Russian Far East

Abstract

This paper examines the geological structure and metallogeny of Neoproterozoic to Paleozoic basins overlying Precambrian massifs in the eastern part of the Central Asian Tectonic Belt, including the South Sinegorsk basin and the Kabarga trough of the Khanka massif, the Kimkan trough of the Jiamusi-Lesser Hinggan massif, and the Melgin trough of the Turan-Zhangguangcailing massif. The ages of these basins are dated on assemblages in the succession, the age and relationships of Paleozoic intrusive complexes are described, and the ages of the ores and associated alteration assemblages have been defined using radiogenic isotopes. The Neoproterozoic to Paleozoic basins share a number of common geological features. Their basement is composed of Archean to early Proterozoic gneisses and crystalline schists metamorphosed at granulite and amphibolite facies. The lower successions of the basins (PR2–€1) comprise highly carbonaceous siliciclastic and carbonate rocks of terrigenous origin intercalated with ferruginous quartzites and manganese ores. Middle–upper Cambrian to Ordovician–Silurian successions are composed of terrigenous rocks. The upper part of the succession reflects the wide distribution of Devonian to Carboniferous volcanogenic and sedimentary–volcanogenic assemblages, except in the Kimkan trough, where they were most likely eroded. Basin development was terminated by emplacement of granites and leucogranites of the Carboniferous Kuibyshevka, Troitsk and Tyrma–Bureya intrusive complexes to which some mineral resources are related. Two discrete metallogenic epochs are recognised. An early Paleozoic epoch is characterised by pyrite, beryllium–fluorite, tantalum-bearing and tin greisen deposits. A late Paleozoic epoch displays the wide distribution of uranium and molybdenum–uranium mineralisation in quartz–sericite metasomatites and clay alteration halo and, to a lesser degree, polymetallic vein and molybdenum occurrences, tantalum and niobium deposits in apogranites.