scholarly journals NATIVE GOLD OF UKRAINE, PREREQUISITES FOR THE CREATION OF ITS CRYSTALLOGENETIC DETERMINANT

2018 ◽  
pp. 6-18
Author(s):  
V. Kvasnytsya ◽  
I. Kvasnytsya
Keyword(s):  
Native Gold ◽  
Gold Mineralization ◽  
Gold Deposits ◽  
Ukrainian Shield ◽  
Low Grade ◽  
Near Surface ◽  
Mineral Associations ◽  
Gold Mineral ◽  
Impurity Elements

The main developments in the typomorphism of native gold from various depth and uneven-aged deposits are described briefly, and the basis for creating a native gold crystallogenetic determinant of Ukraine is proposed. A significant geological material for the most known occurrences of gold mineralization in Ukraine was collected and processed, and a certain stage of studying the crystallomorphology and chemical composition of visible native gold was completed. The crystals of native gold from the occurrences and deposits on the Ukrainian Shield, the Donbass, in the Ukrainian Carpathians and the Transcarpathia have been characterized. The methods of native gold studying, such as goniometry, scanning electron microscopy, and microprobe analysis were used. The typomorphic features of native gold from the main deposits and ore occurrences of Ukraine are determined, which can be used in the practice of predictive, geological prospecting and prospecting for gold. The native gold of the Ukrainian Shield is attributed to deep mineralization, the Ukrainian Carpathians and the Donbass - to medium-deep mineralization and the Transcarpathia – to shallow mineralization. It is shown that in Ukraine, as in other gold-bearing regions of the world, the transition from an ancient deep and medium deep mineralization to a younger near-surface mineralization increases the number of well-formed crystals of native gold and their morphology becomes more complex, individuals of isometric form are replaced by distorted crystals, the role of dendrites and complex twins increases, the grade of gold becomes lower and its heterogeneity grows, the composition and concentration of impurity elements change. The crystallomorphology of the shallow low-grade native gold of the Transcarpathia is diverse (the Muzhi³ve deposit, quartz-barite ores). Unique crystals here are complex twins of cube-octahedrons of native gold. Specificity of medium-deep medium-grade native gold from some ore occurrences of the Donbass is rhombododecahedral faceting of its crystals. Crystallomorphology of deep high-grade native gold from deposits and ore occurrences of the Ukrainian Shield is monotonous. Research data on native gold from known deposits and ore occurrences of Ukraine are generalized and systematization of endogenous gold ore occurrences of Ukraine is made on this basis. A model of a crystallogenetic determinant of native gold of Ukraine is proposed, in which the following main sections are emphasized: 1) native gold mineral associations; 2) chemical-structural and other features of gold crystals; 3) gold crystals morphology; 4) gold crystals anatomy; 5) the method and mechanism of gold crystals growth; 6 ) typomorphic signs of gold crystals; 7) genesis of gold. As an example, a crystallogenetic determinant of native gold from the Proterozoic conglomerates of the Bilokorovychi structure on the Volyn megablock is given. The mineralogical criteria of gold mineralization are outlined and some general conclusions concerning genesis, forecast and searches of gold deposits in Ukraine are made.

scholarly journals Native Gold in the Chudnoe Au-Pd-REE Deposit (Subpolar Urals, Russia): Composition, Minerals in Intergrowth and Genesis

Minerals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 451
Author(s):  
Galina Palyanova ◽  
Valery Murzin ◽  
Andrey Borovikov ◽  
Nikolay Karmanov ◽  
Sergei Kuznetsov
Keyword(s):  
Native Gold ◽  
Microprobe Analysis ◽  
Electron Microprobe Analysis ◽  
Gold Mineralization ◽  
Type I ◽  
Type Ii ◽  
Subpolar Urals ◽  
Type V ◽  
Impurity Elements

Composition of native gold and minerals in intergrowth with rhyolites of the Chudnoe Au-Pd-REE deposit (Subpolar Urals, Russia) was studied using optical microscopy, scanning electron microscopy, and electron microprobe analysis. Five varieties of native gold have been identified, based on the set of impurity elements and their quantities, and on intergrown minerals. Native gold in rhyolites from the Ludnaya ore zone is homogeneous and contains only Ag (fineness 720‰, type I). It is in intergrowth with fuchsite or allanite and mertieite-II. In rhyolites from the Slavnaya ore zone, native gold is heterogeneous, has a higher fineness, different sets and contents of elements: Ag, Cu, 840–860‰ (type II); Ag, Cu, Pd, 830–890‰ (III); Ag, Pd, Cu, Hg, 840–870‰ (IV). It occurs in intergrowth with fuchsite, albite, and mertieite-II (type II), or albite, quartz, and atheneite (III), or quartz, albite, K-feldspar, and mertieite-II (IV). High fineness gold (930–1000‰, type V) with low contents of Ag, Cu, and Pd or their absence occurs in the form as microveins, fringes and microinclusions in native gold II–IV. Tetra-auricupride (AuCu) is presented as isometric inclusions in gold II and platelets in the decay structures in gold III and IV. The preliminary data of a fluid inclusions study showed that gold mineralization at the Chudnoe deposit could have been formed by chloride fluids of low and medium salinity at temperatures from 105 to 230 °C and pressures from 5 to 115 MPa. The formation of native gold I is probably related to fuchsitization and allanitization of rhyolites. The formation of native gold II-V is also associated with the same processes, but it is more complicated and occurred later with a significant role of Na-, Si-, and K-metasomatism. The presence of Pd and Cu in the ores and Cr in fuchsite indicates the important role of mafic-ultramafic magmatism.

Flake-thrust structures and their role in gold deposits formation within Trans-Baikal region

2021 ◽  
pp. 52-61
Author(s):  
Vladimir Salikhov
Keyword(s):  
Gold Deposit ◽  
Significant Role ◽  
Baikal Region ◽  
Gold Mineralization ◽  
Gold Deposits ◽  
Low Grade

The significant role of tectonometamorphic gold mineralization style thrust structures in the formation of some gold deposits (Kultuminskoye, Andryushkinskoye, Sepchugur, etc.) within Trans-Baikal region is shown. Thrust structures may present certain prospects for major relatively low-grade gold deposit prospecting, which requires a reassessment of some deposits.

scholarly journals AGE OF GOLD MINERALIZATION IN THE YANA-KOLYMA METALLOGENIC BELT, NORTHEAST RUSSIA: FIRST DATA OF RE-OS ISOTOPE GEOCRONOLOGY OF NATIVE GOLD

2021 ◽  
Vol 40 (4) ◽  
pp. 18-32
Author(s):  
V.Yu. Fridovsky ◽  
◽  
N.А. Goryachev ◽  
R.Sh. Krymsky ◽  
M.V. Kudrin ◽  
...  
Keyword(s):  
Native Gold ◽  
Gold Mineralization ◽  
Gold Deposits ◽  
Northeast Russia ◽  
Metallogenic Belt ◽  
Mantle Sources ◽  
First Results ◽  
Isotope System ◽  
Os Isotope

Presented are the first results of studying the Re-Os isotope system of native gold from the orogenic Malo-Taryny, Khangalas, and Bazovsky deposits located in the central part of the Yana-Kolyma metallogenic belt. Re concentration in the sampled gold varies from 0.168 to 6.997 mg/t while that of Os changes from 0.068 to 1.443 mg/t. The data obtained enabled calculation of the isochrone age which is consistent, within the limits of error, with 40Ar-39Ar and К-Аr dates of sericite from the above deposits. The results obtained indicate that gold deposits under study were formed in the interv of 147.8–137.1 Ma synchronously with Late Jurassic – Early Cretaceous orogenic processes in the Yana-Kolyma metallogenic belt and the eastern margin of the Siberian continent. The initial Os isotope ratios ((187Os/188Os)i= 0.1844–0.2475) in the studied samples and fractions of gold from the Malo-Tarynsky, Khangalas and Bazovsky deposits suggest a significant role of a non-radiogenic component, normally associated with mantle sources.

Gold-bismuth-telluride-sulphide assemblages at the Viceroy Mine, Harare-Bindura-Shamva greenstone belt, Zimbabwe

2008 ◽  
Vol 72 (4) ◽  
pp. 953-970 ◽  
Author(s):  
T. Oberthür ◽  
T. W. Weiser
Keyword(s):  
Native Gold ◽  
Gold Mineralization ◽  
Close Association ◽  
Shear Zones ◽  
Gold Deposits ◽  
Orogenic Gold ◽  
Main Stage ◽  
Melting Temperatures ◽  
Native Bismuth ◽  
Gold Bearing

AbstractGold mineralization at the Viceroy Mine is hosted in extensional veins in steep shear zones that transect metabasalts of the Archaean Arcturus Formation. The gold mineralization is generally made up of banded or massive quartz carrying abundant coarse arsenopyrite. However, most striking is a distinct suite of Au-Bi-Te-S minerals, namely joseite-A (Bi4TeS2), joseite-B (Bi4Te2S), hedleyite (Bi7Te3), ikunolite (Bi4S3), ‘protojoseite’ (Bi3TeS), an unnamed mineral (Bi6Te2S), bismuthinite (Bi2S3), native Bi, native gold, maldonite (Au2Bi), and jonassonite (AuBi5S4). The majority of the Bi-Te-S phases is characterized by Bi/(Se+Te) ratios of >1. Accordingly, this assemblage formed at reduced conditions at relatively low fS2 and fTe2. Fluid-inclusion thermometry indicates depositional temperatures of the main stage of mineralization of up to 342°C, in the normal range of mesothermal, orogenic gold deposits worldwide. However, melting temperatures of Au-Bi-Te phases down to at least 235°C (assemblage (Au2Bi + Bi + Bi7Te3)) imply that the Au-Bi-Te phases have been present as liquids or melt droplets. Furthermore, the close association of native gold, native bismuth and other Bi-Te-S phases suggests that gold was scavenged from the hydrothermal fluids by Bi-Te-S liquids or melts. It is concluded that a liquid/melt-collecting mechanism was probably active at Viceroy Mine, where the distinct Au-Bi-Te-S assemblage either formed late as part of the main, arsenopyrite-dominated mineralization, or it represents a different mineralization event, related to rejuvenation of the shear system. In either case, some of the gold may have been extracted from pre-existing, gold-bearing arsenopyrite by Bi-Te-S melts, thus leading to an upgrade of the gold ores at Viceroy. The Au-Bi-Te-S assemblage represents an epithermal-style mineralization overprinted on an otherwise mesothermal (orogenic) gold mineralization.

scholarly journals Typomorphic Features of Placer Gold from the Billyakh Tectonic Melange Zone of the Anabar Shield and Its Potential Ore Sources (Northeastern Siberian Platform)

Minerals ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 281
Author(s):  
Boris Gerasimov ◽  
Vasily Beryozkin ◽  
Alexander Kravchenko
Keyword(s):  
Native Gold ◽  
Gold Mineralization ◽  
Coarse Fraction ◽  
Gold Deposits ◽  
Primary Sources ◽  
The Arctic ◽  
Geochemical Data ◽  
Placer Gold ◽  
Anabar Shield ◽  
Tectonic Mélange

Precambrian shields and outcropped Precambrian rock complexes in the Arctic may serve as the most important sources of various types of mineral raw materials, including gold. The gold potential of the Anabar shield in the territory of Siberia has, thus far, been poorly studied. A number of primary and placer gold occurrences have been discovered there, but criteria for the prediction of and search for gold mineralization remain unclear. The main purpose of this paper was to study the typomorphic features of placer gold in the central part of the Billyakh tectonic mélange zone in the Anabar shield and to compare them to mineralization from primary sources. To achieve this, we utilized common methods for mineralogical, petrographic, and mineragraphic analyses. Additionally, geochemical data were used. As a result of this investigation, important prospecting guides were identified, and essential criteria for the prediction of and search for gold deposits were elucidated. The characteristics of the studied placer gold were specific for gold derived from a proximal provenance. These characteristics included the poor roundness of the native gold grains, a cloddy–angular and dendritic form, an uneven surface, and a high content of coarse-fraction native gold (0.5–2 mm), which was as high as 24% of the volume of analyzed native gold. In addition, we conducted a study on the mineralogical features of the gold-sulfide mineralization that was disseminated throughout a small exposure area of paleo-Proterozoic para- and orthogneisses in the Anabar shield basement. A comparison of mineral inclusions in the coarse-fraction native gold and mineral assemblages in the ore deposits showed that one of the possible primary sources for placer gold might be small bodies of metasomatically altered orthogneisses associated with large granitoid plutons.

scholarly journals DISCOVERY AND STUDY HISTORY POKROVSKY GOLD ORE DEPOSIT IN THE AMUR REGION

2020 ◽  
pp. 63-72
Author(s):  
ANTON VLADIMIROVICH MELNIKOV ◽  
◽  
VITALY ALEKSEEVICH STEPANOV ◽  
DMITRIY VALERYEVICH YUSUPOV ◽  
◽  
...  
Keyword(s):  
Native Gold ◽  
Amur Region ◽  
Near Surface ◽  
Ore Deposit ◽  
Gold Ore ◽  
Gold Silver ◽  
History Of ◽  
Typical Composition ◽  
Gold Ore Deposit

A brief history of the discovery and study of the large Pokrovsky gold ore deposit of the Amur Region, from the ores of which about 63 tons of gold were extracted, is given. The role of scientific and production organizations and individual geologists in the discovery of the deposit is shown. According to the results of almost half a century of research, the deposit is classified as a near-surface gold-silver formation with a typical composition of ores, near-ore metasomatites and native gold for deposits of this type. The closest analogue of Pokrovka is the Kubak deposit of the Omolonsky gold-silver province.

scholarly journals Role of the Environment in the Placement of Apocarbonate Gold Mineralization Chakylkalyan Megablock (Southern Uzbekistan)

2021 ◽  
Vol 7 (6) ◽  
Author(s):  
T. Yarboboev ◽  
Sh. Sultanov ◽  
I. Ochilov
Keyword(s):  
Carbonate Rocks ◽  
Gold Mineralization ◽  
Gold Deposits ◽  
Gold Deposition ◽  
Sufficient Detail ◽  
Available Information ◽  
Gold Bearing ◽  
Geochemical Specialization

Analysis of the available information and the results of many years of research on gold deposits in Uzbekistan made it possible to identify the main unconventional types of deposits. Among them, the most interesting are apocarbonate, crustal, sulfide-carbonaceous and apovolcanogenic quartzite (Upper-Kattakashkasai ore occurrence). The apocarbonate type is widespread in Uzbekistan, has been studied in sufficient detail and information is provided on it in this article. The article examines the existence, distribution and genesis of ores of Karlin type gold deposits. The generalizing characteristics of the Karlin type gold mineralization are given. The issues of geochemical specialization of the Paleozoic strata of the Chakylkalyan megablock are considered, the most favorable stratolevel for the localization of mineralized zones is determined, and the features of carbonate rocks in the process of gold deposition during reactions with silicic solutions are characterized. Based on the materials of regional geochemical profiling, the behavior of the main ore-forming elements in the rocks of both carbonate and volcanogenic-terrigenous strata is analyzed. As a result of the analysis, subclarkic contents of the main ore-forming elements (As, Co, Ni, Pb, Cu, Ag, V, Cr, Sc) were revealed, which create increased concentrations in gold-bearing pyrites of both apocarbonate gold mineralization and related formations.

scholarly journals Mineralogy of precious metals in ores of the Yubileinoe porphyry gold deposit (Kazakhstan)

2020 ◽  
pp. 44-53
Author(s):  
O.Yu. Plotinskaya
Keyword(s):  
Gold Deposit ◽  
Native Gold ◽  
Precious Metals ◽  
Gold Deposits ◽  
Silver Telluride ◽  
Gold Mineral

Gold and silver mineralogy is studied in ores of the Yubileinoe porphyry gold deposit (Kazakhstan). Native gold is the major gold mineral. Its fneness varies from 970‰ in magnetite-hematite assemblage to 733–860‰ in pyrite-chalcopyrite assemblage. Silver occurs as admixture in native gold and, occasionally, as silver telluride. Native gold is associated with bi and Pb minerals: rucklidgeite, galenaclaustalite, and tetradymite-kawazulite. According to chlorite geothermometry, the Au, Ag and bi minerals precipitated at temperatures of 250-230 °С. These features are typical of the porphyry gold deposits worldwide. Figures 5. Tables 3. References 17.

Chapter 17: Epithermal Gold Deposits Related to Alkaline Igneous Rocks in the Cripple Creek District, Colorado, United States

2020 ◽  
pp. 355-373
Author(s):  
Karen D. Kelley ◽  
Eric P. Jensen ◽  
Jason S. Rampe ◽  
Doug White
Keyword(s):  
Gold Mineralization ◽  
Fracture Network ◽  
Hydrothermal Activity ◽  
Gold Deposits ◽  
Igneous Rocks ◽  
Low Grade ◽  
Key Factors ◽  
Enriched Mantle ◽  
Cripple Creek ◽  
History Of

Abstract Cripple Creek is among the largest epithermal districts in the world, with more than 800 metric tons (t) Au (>26.4 Moz). The ores are associated spatially, temporally, and genetically with ~34 to 28 Ma alkaline igneous rocks that were emplaced into an 18-km2 diatreme complex and surrounding Proterozoic rocks. Gold occurs in high-grade veins, as bulk tonnage relatively low-grade ores, and in hydrothermal breccias. Pervasive alteration in the form of potassic metasomatism is extensive and is intimately associated with gold mineralization. Based on dating of intrusions and molybdenite and gangue minerals (primarily using 40Ar/39Ar and Re-Os techniques), the region experienced a protracted but intermittent history of magmatism (over a period of at least 5 m.y.) and hydrothermal activity (intermittent over the final ~3 m.y. of magmatic activity). Key factors that likely played a role in the size and grade of the deposit were (1) the generation of alkaline magmas during a transition between subduction and extension that tapped a chemically enriched mantle source; (2) a long history of structural preparation, beginning in the Proterozoic, which created deep-seated structures to allow the magmas and ore fluids to reach shallow levels in the crust, and which produced a fracture network that increased permeability; and (3) an efficient hydrothermal system, including effective gold transport mechanisms, and multiple over-printed hydrothermal events.

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