Lithium pegmatites of the Kalba-Narym Belt, East Kazakhstan: Geological overview

The Kalba-Narym Belt is part of the Central Asian Orogenic Belt (CAOB) and formed due to thecontinental collision between Kazakhstan and Siberian plates in the Late Paleozoic. Severalplutons comprising the Kalba-Narym granitic batholith are considered post-orogenic. Thecommonly accepted theory claims that these intrusive bodies might have been formed due tothe far-spreading influence of the Tarim mantle plume (Khromykh et al., 2019). However, thevolcanic facies, that are normally associated with plume-related activities are present onlysporadically in the Kalba-Narym area, which may imply that the heat source is plume-unrelatedand instead linked to mafic underplating and uplift processes of the crust. Amongst the variableintrusive rocks formed in this region, highly-fractionated pegmatites are particularly importantbut nevertheless remain poorly understood with origin controversially discussed. Themineralized pegmatites are associated with Phase 1 granites of the Kalba complex, with a40Ar/ 39Ar age of 297 to 290 Ma (Kotler et al., 2021). The formation of pegmatites, driven eitherby the differentiation of granitic melts or by anatectic melting processes, was likelysupplemented by the inputs of volatiles and rare metals with fluids. The rocks of the best-known pegmatite occurrences located near Asubulak village, such as Yubileynoye and KrasnyKordon deposits, can be categorized as LCT pegmatites, including three main zones based onmineralogical and geochemical assemblages of a) microcline-albite with pollucite and petalite(Ta, Cs, Be, Sn), b) microcline-albite with spodumene (Ta, Nb, Cs, Li, Be, Sn), and c) spodumene-albite (Li, Ta, Nb, Sn) (D'yachkov et al., 2021).Apart from the mineralized pegmatites, there are known occurrences of barren pegmatites,which creates an opportunity for comparison with the mineralized pegmatites specifically viacontrasting geochemical signatures. Aiming at a proper understanding of the pegmatitegenesis, mineralization mechanisms and geochemical approach on a bigger regional scale of theGreater Altai may open up unique perspectives for the future exploration of the region.Therefore, this presentation provides an overview and re-evaluation of the detailed geologicalcharacteristics of the Kalba-Narym Belt, continuous into Chinese Altai, and the processesinvolved in rare-metal pegmatite mineralization.References:D'yachkov, B. A., Bissatova, A. Y., Mizernaya, M. A., Zimanovskaya, N. A., Oitseva, T. A.,Amralinova, B. B., Aitbayeva, S. S., Kuzmina, O. N., & Orazbekova, G. B. (2021). SpecificFeatures of Geotectonic Development and Ore Potential in Southern Altai (EasternKazakhstan). Geology of Ore Deposits, 63(5), 383–408.https://doi.org/10.1134/s1075701521050020Khromykh, S. V., Oitseva, T. A., Kotler, P. D., D’yachkov, B. A., Smirnov, S. Z., Travin, A. V.,Vladimirov, A. G., Sokolova, E. N., Kuzmina, O. N., Mizernaya, M. A., & Agaliyeva, B. B.(2020). Rare-metal Pegmatite Deposits of the Kalba Region, Eastern Kazakhstan: Age,Composition and Petrogenetic Implications. Minerals, 10(11), 1017.https://doi.org/10.3390/min10111017Kotler, P., Khromykh, S., Kruk, N., Sun, M., Li, P., Khubanov, V., Semenova, D., & Vladimirov, A.(2021). Granitoids of the Kalba Batholith, Eastern Kazakhstan: U–PB Zircon Age,Petrogenesis and Tectonic Implications. Lithos, 388-389, 106056.https://doi.org/10.1016/j.lithos.2021.10605