Sergo Ordzhonikidze Russian State University for Geological Prospecting, Moscow, Russia:

P. A. Ignatov, Head of Department, Professor, Doctor of Geological and Mineralogy Sciences, petrignatov@gmail.com
R. U. Eremenko, Student

Diamond and Precious Metal Geology Institute, Siberian Branch, Russian Academy of Sciences, Yakutsk, Russia:
A. V. Tolstov, Chief Researcher, Doctor of Geological and Mineralogy Sciences

Vilyuisk Exploration Expedition, ALROSA, Mirny, Russia:
I. M. Ovchinnikov, Head of Department

Prerequisites and signs of scandium deposits in the ancient weathering crusts and in the oxidation zones in the Upper Paleozoic strata in West Yakutia are defined and substantiated. The prerequisites include: the presence of scandium sources—basic rocks, kimberlites and carbonatites; the spread of the ancient formation and ground oxidation which conditions migration of scandium; the presence of weathering crusts of the Carboniferous and Mesozoic ages, with alkaline and adsorptive barriers which concentrate scandium; good prospecting at depths up to 100 m. These prerequisites govern the relevance of the research as there is a possibility of scandium recovery from ore by in-situ leaching. Ancient oxidation in the strata and in the fractures in the gray-colored Сarboniferous–Permian formations and in the underlying weathering crusts is detected in the Ulakhan-Kurung-Yuryakh area of the Malaya Botuoba region in the Yakutian Diamond Province. Ancient epigenetic processes are confirmed by zonal limonitization and clarification of primary gray-colored rocks, and by redistribution of uranium, vanadium and gallium with the increased background contents of V and Sc. The X-ray fluorescence analyses performed in the Malaya Botuoba, Middle Markha and Ygyatta diamond-bearing regions revealed areal concentrations and promising scandium ore occurrences in the ancient weathering crusts and in the Late Paleozoic formations. In the weathering crust, in Suldyukar kimberlites, scandium concentrations exceed 100 ppm and feature high (up to 0,n%) contents of V, Co, Ni, La and Ce. The outstanding concentrations of scandium are found in the Triassic–Jurassic Dyakhtar clayey rocks representing a derivative weathering crust in the Nakyn diamondiferous field.

1. Ignatov P. A., Tolstov A. V., Protsenko E. V., Kolesnik A. Yu., Maltsev M. V. Vilyui-Markha interfluve of Yakutia: a region prospective for Cu-Ni-PGM mineralization. Otechestvennaya geologiya. 2021. No. 5. pp. 51–64.
2. Bykhovskiy L. Z., Potanin S. D., Kotelnikov E. I. et al. Rare earths and scandium in Russia. Mineral Raw Materials. Moscow : VIMS, 2016. No. 31. 216 p.
3. Volkova N. M., Levchenko E. N. Scandium—From the past toward the future. Mineral Resources for High-Tech Metals. Extraction, Reproduction, Use : Proceedings of the Second Conference with International Participation. Moscow : VIMS, 2021. pp. 72–81.
4. Polikashina N. S. Quality requirement imposed on mineral raw materials contacting rare metals and rare earths. Scandium. Moscow : VIMS, 2016. 65 p.
5. Polikashina N. S., Torikova M. V. Rare metals deficit in Russia: causes emergence and ways of eliminating. Ratsionalnoe osvoenie nedr. 2019. No. 5. pp. 26–43.
6. Chassé M., Griffin W. L., O`Reilly S. Y., Calas G. Scandium s peciation in a world-class lateritic deposit. Geochemical Perspectives Letters. 2017. Vol. 3. pp. 105–114.
7. Williams-Jones A. E., Vasyukov O. V. The Economic Geology of Scandium, the Runt of the Rare Earth Element Litter. Economic Geology. 2018. Vol. 113, No. 4. pp. 973–988.
8. Zhenchao Wang, Yan Hei Li M., Ze-Rui Ray Liu, Mei-Fu Zhou. Scandium: Ore depos its, the pivotal role of magmatic enrichment and future exploration. Ore Geology Reviews. 2021. Vol. 128. 103906. DOI: 10.1016/j.oregeorev.2020.103906
9. Zinchuk N. N. Comparative characteristics of weathering crust composition of kimberlite rocks in the Siberian and East-European platforms. Russian Geology and Geophysics. 1992. Vol. 33, No. 7. pp. 99–109.
10. Nikulin I. I., Savko A. D. Lithology of the Low Jurassic diamondiferous deposits in the Nakyn kimberlite field, West Yakutia. Transactions of the Geological Institute at the Voronezh State University. Voronezh : Voronezhskiy gosudarstvennyi universitet, 2009. No. 56. 134 p.
11. Korobkov I. G. Tectonics, paleogeography and basic volcanism of diamondiferous regions of Tungusska syneclise eastern edge. Irkutsk : IZK SO RAN, 2015. 353 p.
12. Ignatov P. A., Bushkov K. Y u ., Novikov K. V., Tolstov A. V. Basite breccia areal in Nakyn kimberlite field. Izvestiy a vuzov. Geologiya i razvedka. 2010. No. 2. pp. 31–35.
13. Ignatov P. A., Zaripov N. R., Tolstov A. V., Kolesnik A. Yu., Maltsev M. V. Hydrotermal mineralization hosted by Cambrian sedimentary rocks as evidence of kimberlite-hosting structure, Syuldyukarskoye field, Yakutia. Rudy i metally. 2021. No. 1. pp. 93–105.
14. Teitler Y., Cathelineau M., Ulrich M., Ambrosi J. P., Munoz M. et al. Petrology and geochemistry of scandium in New Caledonian Ni-Co laterites. Journal of Geochemical Exploration. 2019. Vol. 196. pp. 131–155.
15. Simonenko V. I., Tolstov A. V., Vasileva V. I. New approach to geochemicai search for kimberlite at the overburden areas. Razvedka i okhrana nedr. 2008. No. 4-5. pp. 108–112.
16. Grakhanov O. S. Structure, composition and formation of the Early Mesozoic buried diamond placers in the Middle Markha area in West Yakutia : thesis of inauguration of Dissertation … of Candidate of Geologo-Mineralogical Sciences. Mirnyi, 2010. 24 p.
17. Drozdov A. V., Iost N. A., Lobanov V. V. Cryohydrogeology of diamond deposits in West Yakutia. Irkutsk : IrGTU, 2008. 507 p.
18. Kiselev A. I., Yegorov K. N., Chernyshov R. A., Chashchukhin A. V., Yanygin Yu. T. The nature of basic explosive breccias within the Nakyn kimberlitic field (Yakutian diamondiferous province). Russian Journal of Pacific Geology. 2004. Vol. 23, No. 1. pp. 97–104.
19. Tomshin M. D., Kopylova A. G., Konstantin ov K. M., Gogoleva S. S. Basites of the Vilyui paleorift: geochemistry and sequence of intrusive events. Russian Geology and Geophysics. 2018. Vol. 59, No. 10. pp. 1204–1216.
20. Kiselev A. I., Yarmolyuk V. V., Egorov K. N., Chernyshov R. A., Nikiforov A. V. Middle Paleozoic Basic Magmatism of the Northwestern Vilyui Rift: Composition, Sources, and Geodynamics. Petrology. 2006. Vol. 14, No. 6. pp. 588–608.