Mineralogical Tracers of Gold and Rare-Metal Mineralization in Eastern Kazakhstan

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.

Geological History of the Great Altai: Implications for Mineral Exploration

“…Synthesis and analysis of the geological and mineralization data from the Great Altai region open new perspectives on the evolution of major metallogenic structures as a basis for exploration criteria, especially in poorly investigated and buried areas. The mineralization processes, with formation of base, rare, and precious metals and other types of mineral deposits, developed in different tectonic settings in the course of its long history (Table 2) [27,30,[48][49][50]52,61,63,67,[72][73][74][75][76][77][78][79][80]. [72,80] Au in kaolinite-sericite weathering profiles Zhanan deposit [74] During the Early Paleozoic orogenic cycle, the Great Altai territory was occupied by the Zaysan oceanic basin, a part of the Paleo-Asian ocean ([1,3-5], etc.…”

“…Ores occur as microcline-albite and albite-spodumene pegmatite veins in the phase I granites (Figure 6). The spodumene assemblage is especially rich in Ta, Nb, Be, Li, Rb, and Cs rare metals [50]. The ores contain on average 2.1 wt% Pb, 8.15 wt% Zn, 2.23 wt% Cu, 129 ppm Ag, and 1.52 ppm Au, as well as impurity elements of 80 ppm Bi, 420 ppm Cd, 39 ppm Se, 10 ppm Te, 850 ppm Sb, and 400 ppm As.…”

“…Ores occur as microcline-albite and albite-spodumene pegmatite veins in the phase I granites (Figure 6). The spodumene assemblage is especially rich in Ta, Nb, Be, Li, Rb, and Cs rare metals [50].…”

Geology, magmatism and specific features of mineralization of Bakyrchik ore field (Eastern Kazakhstan)

“…The capacity of ore bodies is up to the first tens of meters. Ore minerals of Bakyrchik de posit form five paragenetic assemblages [18][19]: early melnico vitepyritespyrrhotinemarcasite (with nickeline and pentlan dite); ore goldpyritearsenic pyrite (with cubanite and gersdorffite), goldquartzpolymetallic (fahlore, chalcopyrite, galenite, and sphalerite), and goldquartzcarbonatescheelite chalcopyrite (with breunnerite, dolomite, aikinite, free gold); late quartzcarbonateantimonitetetrahedrite (with marcasite, remanie gold). Goldpyritearsenic pyrite assemblage have "through" expansion, melnicovitepyritespyrrhotinemarca site melnicovitepyritespyrrhotinemarcasite and goldquartz carbonatescheelitechalcopyrite are developed at deep levels, goldquartzpolymetallic and quartzcarbonateantimonite tetrahedrite are inclined to upper and medium horizons.…”

Predicted resource assessment of Central Kazakhsta ore districts based on airborne geophysical methods

“…This entire group of ha los is associated with biotitecorniferous granites of the Upper Ordovician age, among which aplite dikes, granite porphyries and diorites are widely distributed [18]. As a result of the work on deep lithogeochemistry, primary halos of copper, lead, and zinc have been identified, which are confined mainly to the contact of intrusive rocks with host rocks [19].…”