No abstract

Replenishment of mineral resources, especially gold and rare metals, is critical for progress in the mining and metallurgical industry of Eastern Kazakhstan. To substantiate the scientific background for mineral exploration, we study microinclusions in minerals from gold and rare-metal fields, as well as trace-element patterns in ores and their hosts that may mark gold and rare-metal mineralization. The revealed compositions of gold-bearing sulfide ores and a number of typical minerals (magnetite, goethite, arsenopyrite, antimonite, gold and silver) and elements (Fe, Mn, Cu, Pb, Zn, As, and Sb) can serve as exploration guides. The analyzed samples contain rare micrometer lead (alamosite, kentrolite, melanotekite, cotunnite) and nickel (bunsenite, trevorite, gersdorffite) phases and accessory cassiterite, wolframite, scheelite, and microlite. The ores bear native gold (with Ag and Pt impurities) amenable to concentration by gravity and flotation methods. Multistage rare-metal pegmatite mineralization can be predicted from the presence of mineral assemblages including cleavelandite, muscovite, lepidolite, spodumene, pollucite, tantalite, microlite, etc. and such elements as Ta, Nb, Be, Li, Cs, and Sn. Pegmatite veins bear diverse Ta minerals (columbite, tantalite-columbite, manganotantalite, ixiolite, and microlite) that accumulated rare metals late during the evolution of the pegmatite magmatic system. The discovered mineralogical and geochemical criteria are useful for exploration purposes.

The Great Altai region, located at the boundary of Russia, Mongolia, China, and Kazakhstan, belongs to the system of the Central Asian Orogenic Belt. It has undergone a long complex geological and metallogenic history. Extremely rich resources of base, precious, and rare metals (Fe, Cu, Pb, Zn, Ag, Au, Li, Cs, Ta, Nb, REE, etc.) maintain developed mining and metallurgical industry, especially in East Kazakhstan, which is the key metallogenic province. The East Kazakhstan province comprises the Rudny Altai, Kalba-Narym, West-Kalba, and Zharma-Saur metallogenic belts, each having its typical mineralization profiles and deposits. The reconstructed geodynamic and metallogenic history of the Great Altai province, along with the revealed relationships between tectonic settings and mineralization patterns, allowed us to formulate a number of geodynamic, structural, lithostratigraphic, magmatic, mineralogical, and geochemical criteria for exploration and appraisal of mineral potential in Eastern Kazakhstan. Geodynamic criteria are based on the origin of different mineralization types in certain geodynamic settings during the Late Paleozoic–Early Mesozoic orogenic cycle. Structural criteria mean that the location of base-metal deposits in Rudny Altai, gold deposits in the West Kalba belt, rare and base metals in the Kalba-Narym and Zharma-Saur zones is controlled by faults of different sizes. Lithostratigraphic criteria consist of the relation of orebodies with certain types of sedimentary or volcanic-sedimentary rocks. Magmatic criteria are due to the relation between mineralization types and igneous lithologies. Mineralogical and geochemical criteria include typical minerals and elements that can serve as tracers of mineralization. The joint use of all these criteria will open new avenues in prospecting and exploration at a more advanced level.

Currently the resources of rare metals, especially Ta, Nb, Be, and Li used in high-tech industries, are of great demand in Kazakhstan and worldwide. Main Ta, Nb, Be, Li, Sn, and W deposits in the Great Altai territory are hosted by Permian granitic belts that formed during the Late Paleozoic-Early Mesozoic orogeny, in a postcollisional setting. The largest metallogenic structure of the Kalba-Narym granitoid belt accommodates many genetically different deposits and occurrences. Pegmatitic rare-metal deposits have vertically and laterally zoned distribution patterns, with mineralization mostly localized in the tectonically active Central Kalba ore district. The richest spodumene and pollucite pegmatites are located in the upper parts of the ore zone. The mineralization types make up the following sequence: barren oligoclase-microcline pegmatites followed by microcline-quartz-muscovite (Nb, Be), microcline-albite (Ta, Sn, Be), albite (Ta, Nb, Be, Sn), albite-spodumene greisen (Li, Ta, Be, Sn), and cleavelandite-lepidolite-pollucite-spodumene (Ta, Li, Cs, Sn) zones. The zoned patterns of rare-metal mineralization have to be taken into account in further studies.

The certificate of registration of a periodical printed publication in the Committee of information of the Ministry of Information and Social Development of the Republic of Kazakhstan No. KZ39VPY00025420, issued 29.07.2020. Thematic scope: geology, chemical technologies for oil and gas processing, petrochemistry, technologies for extracting metals and their connections.