Boundary zones of activated platforms and their metallogeny |
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| Abstract: | The Chadobets uplift is located in the southwestern part of the Siberian platform (Lat. 59° 10′ N, Long. 99°29′–100° 11′ E). It is a brachyanticline with two domes, the Terinovskiy (19 × 16 km) and the Chuktukon (7 × 6 km). The Central and Chuktukon deposits situated on the domes were derived from laterized Proterozoic quartz-mica-feldspar slates and sandstones and Triassic alkaline ultramafic rocks (picrite, pyroxenite, kimberlite, and carbonatite). The laterite profiles attain a thickness of 600 m on slates, 300 m on carbonatites, and 80 km on kimberlites. The final weathering products are bauxites, Al-Ti-Fe laterites, and Fe-Mn ochres enriched in REE (up to 50% Ln2O3 and 1% Y2O3), Nb (up to 5% Nb2O5), Ti (up to 32% TiO2), Th (0.1–0.4% ThO2), as well as Ba, P., Zn, and V. The laterites contain gibbsite; goethite; hematite; anatase after perovskite; oxyhydroxides of Mn; supergene monazite; rhabdophane; florencite; churchite; Ce-, Ba-, and Sr-pyrochlores; cerianite; barite; francolite; etc. Cretaceous-Paleogene sedimentary bauxites accumulated all these minerals, plus boehmite, diaspore, corundum, berthierine, siderite, calcite, marcasite, and pyrite. The bauxites contain 9.5% TiO2, up to 4% TR2O3 (LREE), 0.8% Nb2O5, and 0.31% ThO2. Because of their geologic setting, number of parent rocks, and mineral and chemical composition, the Central and Chuktukon deposits are unique complex deposits of bauxite, rare elements, and rare-earth elements. |
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