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Nanomineralogy and nanogeochemistry of ores from gold deposits of Uzbekistan
Abstract
Gold deposits of Uzbekistan are localized in the Kyzylkum, Nurata, and Kurama ore districts of the Kyzylkum-Kurama metallogenic
belt. They comprise a consecutive series of deposit types corresponding to the series of geochemical associations: (Au-W)—(Au-As)—(Au-Te)—(Au-Ag)—(Au-Sb)—(Au-Hg),
which are arranged as a system of zones in orebodies, deposits, ore fields, and ore districts. The distribution of chemical
elements characterized by average global concentrations in the crust within the ppm-ppb (10−6-10−9 t) range was studied in ores of gold deposits using an ICP MS Elan DRC II device. Mineral nanoassemblages with a grain size
of 10−6 to 10−9 m were examined with a Jeol YXA 8800R Superprobe. The Au-W, Au-As, and Au-Te associations with Bi tellurides and maldonite
in ore dominate at hypo- and meso-abyssal gold deposits of the Kyzylkum district (Muruntau, Myutenbay). The contribution of
the Au-Sb association with Pb, Ag, and Fe sulfoantimonites and aurostibite increases at the Daughyztau, Kokpatas, and Amantaitau
gold deposits. The Au-As, Au-Te, and Au-Sb associations with Bi tellurides, maldonite, sulfoantimonites, and aurostibite dominate
at the mesoabyssal gold deposits of the Nurata district (Charmitan, Guzhumsay). The Au-Te and Au-Ag associations with Au,
Ag, Pb, Sb, Bi, and Hg tellurides and Bi selenides dominate at the hypabyssal gold deposits of the Kurama district (Kochbulak,
Kayragach). The gold-silver deposits of the Kyzylkum district (Kosmanachi, Vysokovol’tnoe) and the Kurama district (Kyzylalmasay,
Arabulak) are close in composition. They are characterized by development of intermetallides, sulfides, sulfosalts, and selenides
of Au-Ag and occasionally Au-Sb associations. Fineness of gold decreases from early to late geochemical associations, whereas
the size of gold grains increases in the same direction from nanogold to visible gold. The studies at the micro- and nanolevel
make it possible to establish the attributes of specific gold mineralization, to substantiate prospecting guides, and to estimate
the erosion level and resource potential of hidden ore objects. The greater and more diverse a set of micro- and nanominerals,
the larger a gold deposit is.
... We used a JXA Superprobe 8800R electron probe microanalyzer at the Institute of Geology and Geophysics and a Carl Zeiss electron microscope (SEM-EDX) at the Center for Advanced Technologies, Tashkent. In connection with the micro-nanosize of gold and accompanying minerals, the approaches developed for nanomineralogical studies were used [6,7]. ...
... Earlier, it was found that As-Te-Bi-Au-Sb-Ag-Se-W-Pb-Hg are the geochemical leaders in the ores of the Zarmitan, Urtalik, Guzhumsay deposits in terms of concentration clarkes [6,7]. Gold ores are distinguished, Au: Ag -2: 1, Te: Se -1: 2 and gold-silver, Au: Ag 1:12, Te: Se -1: 5. ...
... The fineness of gold in an ensemble with bismuth minerals is 850-980 ‰, with impurities of Bi, Hg, Se, Te (Bi and Hg up to 1%); with antimony -750-850 ‰, Hg impurities up to 1.4%, rarely Cu. Values from 700 to 350 ‰ are associated with Au-Ag mineralization, petcite, hessite, naumanite, and aguilarite [6,7]. Microanalyzer studies have shown that, in addition to native gold, maldonite (Au2Bi) and aurostibite (AuSb2) are found. ...
Modern methods of nanomineralogy (electron microscopy, electron probe microanalysis) were used to study the ores of one of the largest industrial facilities of Uzbekistan - the Zarmitan gold zone, which includes the Zarmitan, Urtalik, Guzhumsay deposits, which are located in the Koshrabadgranosyenite massif. The development of / Au-W / Au-Bi-Te / Au-As / Au-Ag-Te / Au-Ag-Se / Au-Sb-Ag / Au-Hg / types of ores. Productive mineral-geochemical types of ores are Au-Bi-Te gold-bismuth-telluride, represented by maldonite, tellurides, and sulfosalts of bismuth: hedleyite, joseite, tsumite, tetradymite, matildite, treasure, and also Au-Sb-Ag gold-silver-sulfoantimonide type represented by aurostibite, sulfoantimonidesPb, Fe, Ag: plagionite, jamsonite, boulangerite, goodmundite, ovichiite and gold-pyrite-arsenopyrite with nanogold, lellingite, gersdorfite. The main industrial resource of gold is provided by Au-Bi-Te, Au-Sb-Ag, and partially Au-As types. The objects of the Zarmitan zone belong to the orogenic gold deposits associated with the intrusion. The established mineral and geochemical features of ores are direct signs of prospecting, typification, and assessment of hidden gold mineralization of orogenic belts.
... On the territory of the Republic of Uzbekistan, a large amount of geological exploration and case studies have been carried out on all issues of the geology of uranium deposits [1]. During their implementation, the main attention was paid to the study of productive formations of the Proterozoic-Paleozoic basement and the Mesozoic-Cenozoic crust for gold, ferrous, non-ferrous metals and uranium [2]. ...
... Based on the results of these works, maps of tectonic zoning, structural maps for various horizons, seismogeological sections, an atlas of specialized maps of the Tien Shan uranium ore province on a scale of 1: 500,000, as well as more detailed forecast maps for uranium, etc. The results of their research led to the discovery of a number of gold and uranium deposits in the Central Kyzyl Kum [1,2,5,6]. ...
... At the same time, the issues of formational and geochemical typification of newly discovered sandstone-type uranium deposits over the past 20 years remain unresolved [4,7]. Prediction within their limits of new positions of complex uranium-rare-metal-rare-earth mineralization, which requires a detailed mineralogical and geochemical characteristic of the productive horizons of the Cretaceous-Paleogene crust of both the entire region and newly identified individual ore occurrences and deposits [1]. ...
The mineralogical and geochemical study of the productive horizons of the Dzhengeldy site was carried out from 2016 to 2020. It should be noted that each horizon has ore-bearing rocks with similar mineralogical and geochemical characteristics. We studied 2 horizons of the Dzhengeldy site (Maastricht and Lyavlyakan). Below are the results of studying the material composition and geochemical features of rocks and ores from deposits of the productive horizons of the Maastrichtian and Lavlyakan selected for various geochemical subzones: oxidized (oreless, selenium dispersion aureoles, uranium and selenium dispersion aureoles, uranium dispersion aureoles, selenium ores) and unoxidized (selenium dispersion aureoles, uranium and selenium dispersion aureoles, selenium ores, uranium ores, uranium dispersion aureoles, uranium and molybdenum dispersion aureoles, molybdenum dispersion aureoles) parts of zoning. It should be noted that the subzones of uranium-selenium, uranium-molybdenum and molybdenum mineralization localized in the grey part of the section have not been studied due to the lack of samples. The subzone of the uranium-molybdenum dispersion aureoles is represented by only one sample, the subzone of the molybdenum dispersion aureoles is represented by three samples (1 sample from the Lavlyakan horizon, 2 samples from the Maastrichtian horizon).
... The deposit "Shirotny" with gold-tungsten mineralization is located in the southern part of the Kyzylturuk ore field. In structural terms, this area belongs to the Zarafshan-Alai structural-formational zone of the Southern Tien Shan [1,2]. Ordovician, Devonian and Carbon sediments take part in the geological structure of the deposit. ...
... Ordovician, Devonian and Carbon sediments take part in the geological structure of the deposit. Ordovician ones are developed in the north-eastern part of the deposit, belong to the middle-upper section and are represented by poly-and oligomictic, micaceous-argillaceous sandstones, mica-clay schists and schistose porphyrite [2]. The thickness of the Ordovician sediments is characterized by the ubiquitous presence of lenticular interlayers of limestones and dolomites. ...
... The mineralization of the ore field is attributed by previous researchers to the quartz-sulfide-gold ore formation. However, the Shirotny deposit is considered to be a non-traditional apo carbonate type [1,2,7]. ...
As a result of the study of the mineralogical and geochemical features of gold mineralization at the Shirotny deposit, four natural ore types have been distinguished in terms of mineralogical composition, content of the main and associated components, mineralogical forms of gold finding. The main ore minerals are native gold, pyrite, scheelite, arsenopyrite, chalcopyrite, goethite, hydrogoethite, carbonaceous matter. According to the results of rational analyses, quantitative ratios of 5 forms of finding gold were revealed. The most widespread are 2 types: high-grade cyanated gold; gold finely disseminated in sulphides.
... Gold grains may be disseminated in quartz, along vein margins, or present as blebs and fracture fillings in sulfides; reported fineness measurements range from 770 to 980 (Golovanov et al., 1998b;Kempe et al., 2016). Anomalous Te concentrations in the ores (e.g., Koneev et al., 2010) and a strong spatial association of anomalous Au with Bi tellurides (Vasilevsky et al., 2004) suggest that Au-bearing tellurides are also certainly present. ...
... The quartz-calcite veins tend to host tetrahedrite and related Agand Sb-bearing sulfosalt minerals, along with base metal sulfides and a variety of telluride phases. Nevertheless, Koneev et al. (2010) indicated similar concentrations of Ag and Au at both Muruntau and Myutenbay such that the significance of a later Ag event is not clear. ...
Muruntau in the Central Kyzylkum desert of the South Tien Shan, western Uzbekistan, with past production of ~3,000 metric tons (t) Au since 1967, present annual production of ~60 t Au, and large remaining resources, is the world’s largest epigenetic Au deposit. The host rocks are the mainly Cambrian-Ordovician siliciclastic flysch of the Besapan sequence. The rocks were deformed into a broadly east-west fold-and-thrust belt prior to ca. 300 Ma during ocean closure along the South Tien Shan suture. A subsequent tectonic transition was characterized by left-lateral motion on regional splays from the suture and by a massive thermal event documented by wide- spread 300 to 275 Ma magmatism. The Besapan rocks were subjected to middle to upper greenschist-facies regional metamorphism, an overprinting more local thermal metamorphism to produce a large hornfels aure- ole, and then Au-related hydrothermal activity all during early parts of the thermal event. The giant Muruntau Au deposit formed in the low-strain hornfels rocks at ca. 288 Ma at the intersection of one of the east-west splays, the Sangruntau-Tamdytau shear zone, with a NE-trending regional fault zone, the Muruntau-Daugyz- tau fault, which likely formed as a cross fault during the onset of left-lateral translation on the regional splays. Interaction between the two faults opened a large dilational zone along a plunging anticlinorium fold nose that served as a major site for hydrothermal fluid focusing. The Au ores are dominantly present as a series of moder- ately to steeply dipping quartz ± K-feldspar stockwork systems surrounding uncommon central veins and with widespread lower Au-grade metasomatites (i.e., disseminated ores). Pervasive alteration is biotite-K-feldspar, although locally albitization is dominant. Sulfides are mainly arsenopyrite, pyrite, and lesser pyrrhotite, and scheelite may be present both in preore ductile veins and in the more brittle auriferous stockwork systems. The low-salinity, aqueous-carbonic ore-forming fluids probably deposited the bulk of the ore at 400° ± 50°C and 6- to 10-km paleodepth. The genesis of the deposit remains controversial with metamorphic, thermal aureole gold (TAG), and models related to mantle upwelling all having been suggested in recent years. More importantly, the question as to why there was such a focusing of so much Au and fluid into this one location, forming an ore system an order of magnitude larger than other giant Au deposits in metamorphic terranes, remains unresolved.
... Au-Ag tellurides are important accessory minerals, carrying a significant proportion of the gold endowment in some low to medium temperature hydrothermal vein deposits [50]. At the Kochbulak and Kairagach deposits (Uzbekistan) [51][52][53][54][55], Golden Mile in Kalgoorlie, Western Australia [56] about 20% of Au is in telluride form, Cripple Creek, [57]; Emperor, Fiji-10-50% in the form of tellurides [58]; and Sǎcǎrîmb, Romania [59], at the Bereznyakovskoye deposit (S.Ural) about 80% of gold [60], Sandaowanzi [61] more than 95% of the extracted gold occurs in the form of tellurides. We assume that the tellurides of the gold deposits of the Aldan Shield are also an additional source of at least 20% of the total gold reserve. ...
The published and original data on the tellurium mineralization of gold ore deposits of the Aldan Shield are systematized and generalized. The gold content is related to hydrothermal-metasomatic processes caused by Mesozoic igneous activity of the region. The formation of tellurides occurred at the very late stages of the generation of gold mineralization of all existing types of metasomatic formations. 29 tellurium minerals, including 16 tellurides, 5 sulfotellurides and 8 tellurates have been identified. Tellurium minerals of two systems predominate: Au-Bi-Te and Au-Ag-Te. Gold is not only in an invisible state in sulfides and in the form of native gold of different fineness, but also is part of a variety of compounds: montbrayite, calaverite, sylvanite, krennerite and petzite. In the gold deposits of the Aldan Shield, three mineral types are distinguished: Au-Ag-Te, Au-Bi-Te, and also a mixed one, which combines the mineralization of both systems. The decrease in the fineness of native gold is consistent with the sequence and temperatures of the formation of Te minerals and associated mineral paragenesis from the epithermal–mesothermal Au-Bi-Te to epithermal Au-Ag-Te. The conducted studies allowed us to determine a wide variety of mineral species and significantly expand the area of distribution of Au-Te mineralization that indicates its large-scale regional occurrence in the Aldan Shield.
... Mineral nanoparticles have emerged into the ore mineralogy and geochemistry field (Gamaletsos et al., 2017;Liu et al., 2020), and they have revealed that nano-scale ore-processes may significantly control the large-scale ore systems (e.g., Ciobanu et al., 2014;Reich et al., 2011;Gao et al., 2019). Many ore-forming elements (Au, Ag, Pb and Te) occurred as the form of nanoparticles in minerals has recently been approved by previous research results (e.g., Palenik et al., 2004;Reich et al., 2006;Barker et al., 2009;Koneev et al., 2010;Deditius et al., 2011;Ciobanu et al., 2012;Hough et al., 2012;Pa cevski et al., 2012;Fougerouse et al., 2016). Also, mineral nanoparticles occurring in ores (e.g., nanoparticles of Zn-phases from disseminated ores in the Dukat ore field in Russia, Filimonova and Trubkin (2008), magnetite nanoparticles in ores of the Pena Colorada Fe-ore deposit in Mexico, Rivas-S anchez et al. (2009) and titanomagetite nanoparticles in the Panzhihua layered intrusion, Gao et al. (2019)) could reflects the formation stages of ore forming systems. ...
High-resolution transmission electron microscopy observations of bastnäsite from the Maoniuping rare earth element (REE) deposit at Panxi, SW China, revealed the presence of nanoparticles in the surface of bastnäsite crystal. The nanoparticles are identified as the bastnäsite nanocrystals, with 5 to 30 nm in length, by energy-dispersive spectrometry and fast fourier transform patterns. This represents the first observation of bastnäsite nanoparticle in nature, confirming a new form of migration and precipitation of La and Ce in the hydrothermal fluids. Meanwhile, we herein reveal that random attachment of small bastnäsite nanoparticles during aggregation-based growth initially produces large bastnäsite nanoparticles, driven by the tectonic stress. Subsequent evolution of the random aggregation and orientation of large bastnäsite nanoparticles result in bastnäsite crystal formation, driven by the tectonic stress and inherent surface stress. This underlines the bastnäsite crystallization by random aggregation and the significant role of tectonic stress in forming the bastnäsite crystal in REE deposit.
... Geochemical analysis was performed on an Agilent Technologies ICP MS 7500 mass spectrometer. Considering that gold in primary sulfide ores is a typical micro-nanomineral (size from 100 to 0.00n μm), micro-nanomineralogical research methods have been applied (Koneev et al. 2010). ...
Geochemical and micro-nanomineralogical methods have been used to study the high sulfidation ores of the Kochbulak deposit and low sulfidation ores of Kyzylalmasay. The high sulfidation type is defined as Au-Ag-Te, gold-telluride-polymetallic, and low sulfidation Au-Ag-Se, electrum-selenide-sulfosalt. Such an approach enhances the capabilities of geochemical and mineralogical and geochemical methods in the search for, classification and evaluation of hidden gold mineralization.
The results of the study, the relationship of regional faults with the processes of formation and mixing of gold ore occurrences in Western Uzbekistan are presented. According to researchers, the gold deposits of the region were formed under the influence of regional northwestern and transverse northeastern faults. So that the results of their research could serve as search signs and predictive criteria, they have not been studied enough to date. It is shown that the analysis of data on the location of gold ore occurrences in the network of regional faults in the region showed that 32% of gold ore objects were formed in the zones of northwestern faults. It is noted that the inter-fault space plays an important role in the placement of gold ore manifestations. Another important feature of the relationship between gold manifestations and regional faults has been revealed - this is the morphological feature (curvature area) of the faults, which determines the saturation of the inter-fault zone with manifestations of gold mineralization. The identified features of the relationship between regional faults and ring structures with gold occurrences are recommended to be used in forecasting and prospecting for gold.
The evolution of ideas in the last few decades on the duration and sequence of the development of mineral parageneses (epochs, megastages, and stages) during the mineral deposit formation is reviewed. The author concluded that the prolonged period of the prehistory of the formation of economic ore accumulations is very important. This is also very important for understanding the nature of metallogenic specialization, the extent of ore-bearing potential, and for distinguishing evolutionary series of ore deposits. By the example of gold deposits, the relations between the megastages and stages of the evolution of postmagmatic solutions and megastages and stages of ore mineralization reflecting pulsation in the course of ore genesis are discussed. The main sequence in the development of mineral parageneses, steadily preserved in various types of ore deposits, is regarded as an instrument for the analysis of the megastage and stage of ore formation and evolutionary systematics of mineral deposits.
At first glance, nano and Earth seem about as far apart as one can imagine. Nanogeoscience seems to be a word connecting opposites.
But to a growing number of Earth scientists, this term makes sense. Although relatively difficult to detect and study, natural
nanomaterials are ubiquitous in nature. Their properties are often different (sometimes dramatically different) from those
of the same material at a larger size. In many cases, larger equivalents do not even exist. By understanding natural nanomaterials,
we can acquire another perspective from which to view Earth's chemical and physical properties. Important insights into local,
regional, and even global phenomena await our understanding of processes that are relevant at the smallest scales of Earth
science research.
Nanoscience is a relatively new field of research that primarily involves the discovery and exploration of the properties of matter in the size range of roughly one to 100 nanometers, the so-called nanoscale. Mechanical, electrical, thermodynamic, and other types of properties are strongly modified as the physical dimensions of a material enters the nanoscale, and researchers in the field are just beginning to catalog and understand these property modifications in this fuzzy area between the classical (bulk) and quantum domains. It is also becoming more and more apparent that many earth materials exist in the nanodomain as minute particles or thin films, especially in low-temperature environments, but also in mid- to high temperature environments. As examples, this article describes how nanoscience has started to be applied to mineral weathering, mineral-bacteria interaction, and metal transport in acid mine drainage systems, but this is only the beginning. The future directions of nanoscience in geochemistry will include a determination of the identity, distribution, and properties of nanosized particles in aqueous and soil systems, thin films in both low and high temperature systems, and nanosized features on mineral surfaces.
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- Koneev
Nanogeokhimiya zolota. Trudy simpoziuma (Proceedings of Symposium on Nanogeochemistry of Gold), Vladivostok: Dal'nauka, 2008. Nanomineralogiya. Ul'traa i mikrodispersnoe sostoyanie minn eral'nogo veshchestva (Nanomineralogy. Ultraa and Microo dispersion State of Mineral Substance), St. Petersburg: Nauka, 2005. Nanotekhnologii v blizhaishem desyatiletii. Prognoz napravv leniya poiskov (red. M.K. Roko i dr.) (Vision for Nanotechh nology: Research and Development in the Next Decade), GEOLOGY OF ORE DEPOSITS Vol. 52 No. 8 2010 KONEEV et al.
Samorodnoe zoloto mestorozhdenii Zapadnogo Uzbekistana (Native Gold at Deposits of Western Uzbekistan)
- N V Kotov
- L G Poritskaya
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Ul’tra- i mikrodispersnoe sostoyanie mineral’nogo veshchestva (Nanomineralogy. Ultra- and Micro-dispersion State of Mineral Substance)
- Nanomineralogiya