E-catalog        

Библиогр.: 9 назв.

The geological position and ore content of the granitoids of the Kalba-Narym zone of East Kazakhstan, which is part of the general structure of the Hercynides of the Greater Altai, is considered by the modern mobilistic geotectonic concepts. At the regional level, the position of the geo-structure of the Greater Altai is noted on the north-western flank of the Altai-Alashan mobile zone of the Central Asian mobile belt, characterized by the powerful development of Permian granitoid magmatism. According to geological and geophysical data, the belt distribution of rare-metal granitoid massifs and their spatial confinement to tectonically weakened zones with a sialic type of the crustal section are emphasized. Kalba-Narym granitoid belt of the north-western direction (more than 500 km long) formed in the post-collisional (orogenic) environment, is the main rare-metal structure of East Kazakhstan, uniting many deposits and ore occurrences of rare metals pegmatite, greisen, hydrothermal and other types. Leading importance is attached to the deposits of rare metal pegmatites (Ta, Nb, Be, Li, Cs, Sn), concentrated mainly in the Central Kalba block of increased tectonic activity (Bakennoe, Yubileynoye, Belaya Gora, Verkhnyaya Baymurza, etc.). The main pegmatite fields (Ognevsko-Bakennoe, Asubulakskoe, Belogorskoye, etc.) are controlled by the regmatic system of latitudinal regional faults of the intrusion activation. The most productive for rare metals is the granite formation (Kalba complex P1), represented by two intrusive phases. The main rare metal-pegmatite mineralization is spatially genetic due to medium-coarse-grained low porphyry biotite granites of the first phase of the Kalba complex, characterized by an increased basicity of the petrochemical composition, the small-scale potassium of the low agpaitic complex (K = 0.59), and the Permian age, exposed to new radio chronological studies (283.9 and 286.4 million years). As a result of mineralogical and geochemical studies using electron microscopy, new data are presented on the material composition of rare-metal pegmatite deposits of microcline-albite and albite-spodumene types with the determination of typomorphic minerals (clevelandite, spodumene, lepidolite, colored tourmalines, etc.) and geochemical elements-indicators of rare-metal pegmatite formation (Ta, Nb, Be, Li, Cs, etc.). Revealed geological, structural, petrological, and mineralogical and geochemical criteria are recommended to be taken into account when conducting further forecast metallogenic work in the Kalba region