Subjects -> MINES AND MINING INDUSTRY (Total: 81 journals)
Showing 1 - 42 of 42 Journals sorted alphabetically
American Mineralogist     Hybrid Journal   (Followers: 16)
Applied Earth Science : Transactions of the Institutions of Mining and Metallurgy     Hybrid Journal   (Followers: 4)
Archives of Mining Sciences     Open Access   (Followers: 3)
AusiMM Bulletin     Full-text available via subscription   (Followers: 1)
BHM Berg- und Hüttenmännische Monatshefte     Hybrid Journal   (Followers: 2)
Canadian Mineralogist     Full-text available via subscription   (Followers: 7)
Clay Minerals     Hybrid Journal   (Followers: 9)
Clays and Clay Minerals     Hybrid Journal   (Followers: 5)
Coal Science and Technology     Full-text available via subscription   (Followers: 3)
Contributions to Mineralogy and Petrology     Hybrid Journal   (Followers: 14)
Environmental Geochemistry and Health     Hybrid Journal   (Followers: 2)
European Journal of Mineralogy     Hybrid Journal   (Followers: 14)
Exploration and Mining Geology     Full-text available via subscription   (Followers: 3)
Extractive Industries and Society     Hybrid Journal   (Followers: 2)
Gems & Gemology     Full-text available via subscription   (Followers: 2)
Geology of Ore Deposits     Hybrid Journal   (Followers: 5)
Geomaterials     Open Access   (Followers: 3)
Geotechnical and Geological Engineering     Hybrid Journal   (Followers: 9)
Ghana Mining Journal     Full-text available via subscription   (Followers: 3)
Gold Bulletin     Hybrid Journal   (Followers: 2)
Inside Mining     Full-text available via subscription  
International Journal of Coal Geology     Hybrid Journal   (Followers: 4)
International Journal of Coal Preparation and Utilization     Hybrid Journal   (Followers: 2)
International Journal of Coal Science & Technology     Open Access   (Followers: 1)
International Journal of Hospitality & Tourism Administration     Hybrid Journal   (Followers: 15)
International Journal of Mineral Processing     Hybrid Journal   (Followers: 8)
International Journal of Minerals, Metallurgy, and Materials     Hybrid Journal   (Followers: 11)
International Journal of Mining and Geo-Engineering     Open Access   (Followers: 4)
International Journal of Mining and Mineral Engineering     Hybrid Journal   (Followers: 8)
International Journal of Mining Engineering and Mineral Processing     Open Access   (Followers: 6)
International Journal of Mining Science and Technology     Open Access   (Followers: 4)
International Journal of Mining, Reclamation and Environment     Hybrid Journal   (Followers: 6)
International Journal of Rock Mechanics and Mining Sciences     Hybrid Journal   (Followers: 9)
Journal of Analytical and Numerical Methods in Mining Engineering     Open Access  
Journal of Applied Geophysics     Hybrid Journal   (Followers: 17)
Journal of Central South University     Hybrid Journal   (Followers: 1)
Journal of China Coal Society     Open Access  
Journal of China University of Mining and Technology     Full-text available via subscription   (Followers: 1)
Journal of Convention & Event Tourism     Hybrid Journal   (Followers: 6)
Journal of Geology and Mining Research     Open Access   (Followers: 10)
Journal of Human Resources in Hospitality & Tourism     Hybrid Journal   (Followers: 9)
Journal of Materials Research and Technology     Open Access   (Followers: 2)
Journal of Metamorphic Geology     Hybrid Journal   (Followers: 17)
Journal of Mining Institute     Open Access  
Journal of Mining Science     Hybrid Journal   (Followers: 5)
Journal of Quality Assurance in Hospitality & Tourism     Hybrid Journal   (Followers: 6)
Journal of Sustainable Mining     Open Access   (Followers: 3)
Journal of the Southern African Institute of Mining and Metallurgy     Open Access   (Followers: 6)
Lithology and Mineral Resources     Hybrid Journal   (Followers: 4)
Lithos     Hybrid Journal   (Followers: 12)
Mine Water and the Environment     Hybrid Journal   (Followers: 5)
Mineral Economics     Hybrid Journal   (Followers: 2)
Mineral Processing and Extractive Metallurgy : Transactions of the Institutions of Mining and Metallurgy     Hybrid Journal   (Followers: 14)
Mineral Processing and Extractive Metallurgy Review     Hybrid Journal   (Followers: 5)
Mineralium Deposita     Hybrid Journal   (Followers: 5)
Mineralogia     Open Access   (Followers: 2)
Mineralogical Magazine     Hybrid Journal   (Followers: 1)
Mineralogy and Petrology     Hybrid Journal   (Followers: 5)
Minerals     Open Access   (Followers: 2)
Minerals & Energy - Raw Materials Report     Hybrid Journal   (Followers: 1)
Minerals Engineering     Hybrid Journal   (Followers: 14)
Mining Engineering     Full-text available via subscription   (Followers: 7)
Mining Journal     Full-text available via subscription   (Followers: 4)
Mining Report     Hybrid Journal   (Followers: 3)
Mining Technology : Transactions of the Institutions of Mining and Metallurgy     Hybrid Journal   (Followers: 4)
Mining, Metallurgy & Exploration     Hybrid Journal  
Natural Resources & Engineering     Hybrid Journal  
Natural Resources Research     Hybrid Journal   (Followers: 4)
Neues Jahrbuch für Mineralogie - Abhandlungen     Full-text available via subscription   (Followers: 1)
Physics and Chemistry of Minerals     Hybrid Journal   (Followers: 4)
Podzemni Radovi     Open Access  
Rangeland Journal     Hybrid Journal   (Followers: 4)
Réalités industrielles     Full-text available via subscription  
Rem : Revista Escola de Minas     Open Access  
Resources Policy     Hybrid Journal   (Followers: 4)
Reviews in Mineralogy and Geochemistry     Hybrid Journal   (Followers: 5)
Revista del Instituto de Investigación de la Facultad de Ingeniería Geológica, Minera, Metalurgica y Geográfica     Open Access  
Rock Mechanics and Rock Engineering     Hybrid Journal   (Followers: 9)
Rocks & Minerals     Hybrid Journal   (Followers: 5)
Rudarsko-geološko-naftni Zbornik     Open Access  
Transactions of Nonferrous Metals Society of China     Hybrid Journal   (Followers: 9)
Similar Journals
Journal Cover
Geology of Ore Deposits
Journal Prestige (SJR): 0.54
Citation Impact (citeScore): 1
Number of Followers: 5  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 1555-6476 - ISSN (Online) 1075-7015
Published by Springer-Verlag Homepage  [2626 journals]
  • The Dudica Epithermal Cu–Au Deposit (Republic of North Macedonia)
    • Abstract: — The Dudica deposit is located in the southern part of the Republic of North Macedonia (RNM), not far from the border with Greece in the Kozuf–Aridean volcanic region. The deposit is genetically associated with the Neogene igneous event (≥6 Ma, K/Ar), which is manifested at the intersection of northeast trending faults with the northwest trending Vardar fault zone. The REE spectrum of volcanic rocks here is characterized by a weak negative Eu anomaly and enrichment in light REE (LREE) relative to heavy REE (HREE). Mineralization is found in veins, veinlets, and dissemination; Cu concentration is around 0.5%; Au, up to 1 g/t. The principal ore minerals are chalcopyrite, bornite, enargite, covellite, chalcocite, and digenite; pyrite, galena, sphalerite, marcasite, and native gold are less frequent. The δ34S isotope composition falls within a narrow interval of +1.00 to +2.50‰, indicative of the igneous origin. The data obtained suggest that the Dudica deposit belongs to the class of the high-sulfidation epithermal deposits.
      PubDate: 2020-09-01
       
  • Sulfur Isotope Fractionation During Sulfide Generation in the Hydrothermal
           Submarine Systems: The Case of Logatchev, Krasnov, and Rainbow
           Hydrothermal Fields, Mid-Atlantic Ridge
    • Abstract: — The sulfur isotope composition of single sulfide grains has been studied taking into account their paragenetic sequence in the samples collected from three hydrothermal fields (Logatchev, Krasnov, and Rainbow), located in the northern part of the Mid-Atlantic Ridge. The δ34S values of sulfides are +3.9 to +6, +7.1 to +9.8, and +2.1 to +8.4 ‰ in the Logatchev, Krasnov, and Rainbow fields, respectively. Late-generation sulfides within the studied domains (1–10 mm) of the samples are enriched in 34S isotope relative to early generations, and the sulfur isotope composition shows no relationship with the composition of sulfide minerals. In single grains of hydrothermal barite, the δ34S values exceed the generally accepted range for modern seawater sulfates. A model of the sulfur isotope fractionation in the hydrothermal system is proposed, based on the assumption of thermogenic sulfate reduction during fluid–rock interaction in the system, which is closed with respect to fluid. The model also takes into account simultaneous sulfur leaching from host rocks, the proportion of released sulfur from which depends on the progress of thermogenic sulfate reduction. Application of this model explains some well-known contradictions found in studying the sulfur isotope composition of sulfides from other hydrothermal fields in the World Ocean.
      PubDate: 2020-09-01
       
  • Research of the Uranium, Niobium, and Tantalum Behavior in the Granite
           Melt–Chloride Fluid System at 750°C and 1000 Bar
    • Abstract: — The major objective of the study investigation was to find the physicochemical conditions for U, Nb, and Ta mobilization into the solution from acidic melts similar in composition to rhyolitic inclusions in quartz at the unique Streltsovka Mo–U field (Eastern Transbaikalia). The experiments were performed with model homogeneous leucogranite glass (wt %): 72.18 SiO2, 12.19 Al2O3, 1.02 FeO, 0.2 MgO, 0.33 CaO, 4.78 Na2O, 3.82 K2O, 1.44 Li2O, and 2.4 F (LiF, NaF, KF, CaF2, and MgF2); synthetic uranium dioxide; and natural columbite in solutions containing from 1 to 8 mol kg–1 chlorides (Na, K, and Li) at 750°C, 1000 bar, with an O2 (H2) fugacity set by the Ni–NiO buffer. The selected T–P parameters and solutions corresponded to the homogeneous and fluid immiscibility regions in the NaCl–KCl–H2O solutions. The Nb and Ta contents in the Cl–F solutions in equilibrium with F-bearing melts are very low. The U content is much higher and reaches about 1 × 10–4 wt % in the low-density fluid phase and n × 10–3 wt % in the dense aqueous saline phase (brine). The U content in the glass was tenths of a percent. Despite the very high chlorine content in the studied solutions, its content did not exceed 0.5 wt % in the glass. In the course of the experiments, columbite dissolved incongruently in the glass melt to form F- and U-bearing pyrochlores. According to the investigation results, the predominantly chloride fluid with the studied T–P parameters should not be considered an active medium for mobilization of U from Li–F granite melts in the formation of unique hydrothermal U (Mo–U) deposits.
      PubDate: 2020-09-01
       
  • Formation Environments of Metasomatites and Ores of the Epithermal
           Gold–silver Deposits
    • Abstract: Preore metasomatites of epithermal gold–silver deposits are formed by various types of hydrothermal solutions—from highly acidic and oxidized (argillization, alunitization, secondary quartzites) and moderately acid (sericitization) to rather reduced and alkaline (adularia). The possible processes creating highly acid mineralizing fluids at shallow depths are: (a) the condensation of the acid gas phase of heterogenized fluids (including also the condensation of gaseous HCl, HF and H2SO4 whose water solutions possess properties of maximum boiling azeotropic mixtures); (b) the oxidation of containing SO2 and H2S magmatogene gases by meteoric waters rich in oxygen; and also c) possible disproportionation of sulfur from SO2 to H2S and H2SO4. The epithermal gold–silver deposits of high sulfidation type form at the upper parts of heterophase fluid systems. The major gold–silver and sulfide mineralization (except small amounts of earlier generations of pyrite, enargite, and luzonite) precipitates not synchronously with the acid metasomatites, but essentially later, when the water table of liquid and less acid fluids raise into the realm of ore deposition. At zones of flat subducting ocean crust, the deposits of copper–porphyry type are quite often found beneath the epithermal Au–Ag deposits. However, the former cannot be considered the bottom of the gold–silver ore-forming systems, because they sometimes form much earlier and in closed systems; therefore, they have their own bottom part of the ore-forming system (a zone of K-feldspathization with related molybdenum ore) and the top part (a zone of sericitization with related copper mineralization). In addition, in steep subduction zones typical of the Central West Pacific region, including Khabarovsk and Primorsky krais and Japan, epithermal Au–Ag deposits have no spatial or temporal relations to copper–porphyry deposits due to the nearly complete absence of the latter. There are the alkaline metasomatites that form in the lower, bottom parts of epithermal heterophase fluid systems, creating the major bonanza gold–silver and sulfide mineralization of the adularia (low sulfidation) type in the Russian Far East, western America, and Japan. The term high sulfidation widely used now was created by the artificial combination of the terms high sulfate and high oxidation and is very ambiguous, because it really does not imply sulfidization processes. This type of mineralization would be better named acid sulfate.
      PubDate: 2020-09-01
       
  • Evolution of the Vagran Gold-Bearing Placer Cluster (Northern Urals) and
           Prospects for Revealing Bedrock Mineralization
    • Abstract: Abstract—More than 10 t of gold have been mined within the Vagran placer cluster (Northern Urals), and the identified primary sources are limited to single noneconomic ore occurrences. Our research has established the heterogeneity of placer gold, which reflects the multistage history of the cluster’s development and the diversity of bedrock mineralization owing to which placer deposits were formed. In the structure of the placers, three age stages are distinguished, reflecting the Post-Paleozoic history of the Ural fold belt’s development: (1) Mesozoic–Early Cenozoic peneplanation, formation of areal weathering crusts, disintegration of primary gold sources and formation of linear erosional–structural depressions, which accumulated material from the displaced weathering crusts; (2) orogenic Pliocene–Quaternary stage of tectonic activation and erosion of primary sources and intermediate gold accumulators; (3) the formation of the modern topography, hydronetwork, and alluvial placers. In morphology, chemical composition, and internal structure of grains, five types of native placer gold have been identified, three of which reflect the structure of the main primary source, which is now almost completely eroded; the fourth bears traces of hypergene changes that occurred at the stage of peneplanation and in the development zones of erosional–structural depressions. The fifth type, which has typomorphic features of near-provenance gold, characterizes the mineralization exposed at the final stage of development of the morphostructure of the Ural belt of tectonic–magmatic activation. Reconstruction of the stages of development of the Vagran ore-placer cluster makes it possible to assess the existing placer potential and the prospects for identifying economic primary mineralization.
      PubDate: 2020-09-01
       
  • Gold and Silver Minerals in Sulfide Ore
    • Abstract: Abstract—Gold and silver are capable of forming stable natural compounds with different elements. For gold 36 minerals are known: 10 in the class “Native metals, intermetallic compounds” and 26 in the class “Sulfides (selenides, tellurides, arsenides, antimonides, bismuthides).” For silver, 194 minerals are registered in the MMA, presented in 8 classes. Compared to gold in the class “Native metals, intermetallic compounds” there are far fewer silver minerals. They are widely represented in the classes “Sulfides” and “Sulfosalts” (124). Among silver minerals “halides” are also known (fluorides, chlorides, bromides, iodides), seven; simple and complex oxides, two; there is one mineral each in the classes “sulfates,” “phosphates,” “arsenates,” and “vanadates.” Both metals are in the compositions of 12 minerals: native gold, native silver, weishanite, uytenbogaardtite, petrovskaite, fishesserite, penzhinite, petzite, mutmannite, sylvanite, krennerite, and bezsmertnovite. Every year, the MMA commission registers four to six gold and silver minerals, so there are prospects for the discovery of new minerals of these precious metals in the near future. The indicator elements (fixers) that form natural compounds with gold and indicate the possible presence of gold minerals in sulfide ores include 13 elements: 7 metals (Ag, Cu, Pd, Hg, Sn, Tl, Fe), 3 chalcogens (Te, S, Se), and 3 metalloids (As, Sb, Bi). For silver, this range is wider and also includes such elements as Mn, Zn, Ge, Cd, V, O, H, F, Cl, Br, I, In, and N. This review presents and summarizes the results of studies on the composition of native gold with copper, mercury, and palladium impurities in different types of gold deposits. The article describes the gold and silver minerals established by the author together with colleagues in a study of productive mineral assemblages in some gold deposits in Russia: the Ulakhan, Yunoe, Krutoe, Dzhulietta, Dorozhnoe (Magadan region), Konechnoe (Taimyr Peninsula), Kupol, Valunistoe (Chukotka), Maletoyvayam (Kamchatka), etc. Data are presented on gold and silver minerals found in sulfide ores and of economic importance. Some of their technological properties are characterized, including solubility and behavior under the influence of various reagents. The presence of refractory minerals (calaverite, sylvanite, krennerite, petzite, aurostibite, maldonite, fishesserite, uytenbogaardtite, petrovskaite, penzhinite, weishanite, yuanjianite, hunchunite, anyuite, krynovite, nadjagite, and bogdanovite, bilibinskite, criddleite, etc.), as well as the chemical composition gold and silver, are important technological factors and should be taken into account when developing a technology for extracting precious metals from ores. The presence of increased concentrations of indicator elements (fixers) of gold and silver minerals in sulfide ores is an important indicator and argument for detailed mineralogical and geochemical studies of the source raw material. Identification of mineral (micro-, nano-) forms of gold and silver in sulfide ores is necessary for developing and improving rational dressing schemes.
      PubDate: 2020-09-01
       
  • Seismogenic Nature of Fluid-Dynamic Structural Parageneses of the Uryakh
           Gold Ore Field (Northeastern Transbaikalia)
    • Abstract: New data on the geological structure and ore-bearing structural parageneses of the Uryakh gold ore field are presented. The formation of the deposit occurred in dynamic shear regime along ore-controlling deep-seated faults of the Syulban fault system and faults of the system transverse to it. The interaction of two duplex shear systems resulted in the block structure of the ore field. Tectonophysical methods have established the individual development of tectonic blocks during the period of gold-bearing fluid input in a seismically active regime. The specific features of the formation of ore-bearing fracture–fault structural parageneses in the blocks resulted from the change in the seismic regime under the action of pressure and gas-saturated fluids. The parameters of the fluid system were determined by fluid inclusion studies in quartz. An unstable variable compression–extension regime of the early phase of seismic activity led to the formation of hybrid structural parageneses under the influence of stresses of damping shear and injective hydrodynamic stress. Variations in the stress–strain state of the medium in this phase correspond to a transient seismic regime and are consistent with variations in the thermobarometric parameters of the fluid system. In the late phase of seismic activity, a stable uniaxial tension regime with a superlithostatic fluid pressure occurred, which caused brittle deformations independent of slip along the fault. The centroid mechanism of such deformations, which is rarely found in the dynamic regimes of hydrothermal deposits, ensured the formation of structural parageneses unusual for shear zones, which resulted in a different combination of structural and morphological types of orebodies in the blocks.
      PubDate: 2020-07-01
       
  • The Varvarinskoye Complex Copper–Gold Deposit in Northern Kazakhstan:
           Mineral Types and Ore Composition
    • Abstract: The Varvarinskoye copper–gold deposit, large in terms of Au and small in terms of Cu, was discovered in 1979 in the western part of the Torgai trough in Kazakhstan. It is composed of Devonian volcanosedimentary and intrusive rocks. Ore zones with a thickness from a few meters to a few tens of meters have been identified against a background of disseminated ore mineralization. They are composed of densely disseminated (porphyry) up to massive ores. The ore zones are localized in the thermal metamorphism band of volcanosedimentary and intrusive rocks, while disseminated mineralization is widespread beyond it. Ten ore mineralization types can be distinguished. The Au–Cu mineralization type is common in volcanosedimentary rocks and diorites, while the Au–Cu–Ni ores occur in serpentinites formed after thermally metamorphized intrusive rocks. Densely disseminated and massive magnetite ores are confined to skarns. Sulfide and sulfide–arsenide mineralization can also be observed. Each type of Au–Cu mineralization (pyrrhotite, chalcopyrite–marcasite–pyrite, pyrite, and gold–sulfide–arsenopyrite) can be correlated to an analog of Au–Cu–Ni mineralization (pentlandite–pyrrhotite, chalcopyrite–pentlandite–pyrite, pentlandite–pyrite, and gold–nickeline–gersdorffite). This indicates the uniform ore-forming process in serpentinites and volcanosedimentary rocks with diorites and borrowing of ore material from host rocks, at least, partially. The gold–chalcopyrite mineralization type, synchronous to the thermal metamorphism and analogous to mineralization of the alkali stage at porphyry copper deposits, has no analog in the Au–Cu–Ni mineralization. Gold is present in all mineralization types, but gold–chalcopyrite and sulfide–arsenide are the most enriched in Au. Eighty ore minerals have been found at the studied deposit. Pyrrhotite disulfidization and chalcopyrite pyritization are universal in occurrence. These processes likely led to the formation of chalcopyrite–marcasite–pyrite and chalcopyrite–pentlandite–pyrite mineralization after pyrrhotite and pentlandite–pyrrhotite types, respectively. Invisible gold present in chalcopyrite was enlarged during these processes.
      PubDate: 2020-07-01
       
  • Ore-Forming Fluids of the Aleksandrovskoe and Davenda Deposits (Eastern
           Transbaikalia)
    • Abstract: A study of the composition of fluid inclusions in ore minerals of the Davenda Mo–porphyry deposit and the Aleksandrovskoe sulfide–quartz–gold ore deposit, as well as of fluid inclusions in minerals of igneous rocks, showed that ore-forming fluids inherit the salt and gas composition of magmatic fluids generated during crystallization of ore-bearing rocks of the Amudzhikan–Sretensky Igneous Complex, which formed simultaneously with the Au and Mo mineralization. The gold-bearing sulfide–quartz veins of the Aleksandrovskoe deposit formed with the participation of two types of hydrothermal fluids, differing in the composition of salts and the gas phase: homogeneous Ca–Na chloride fluids with CO2 and heterophasic Na–K–Fe-chloride fluids, which indicates two sources of ore-forming fluids during the formation of Au-mineralization. Na–K–Fe-chloride fluids in terms of salt and gas composition were similar to the ore-forming fluids of the Mo-mineralization of the Davenda deposit. Ore-forming Ca–Na-chloride with CO2 The fluids of the Aleksandrovskoe field are comparable in salt and gas composition with the magmatogenic fluids of quartz diorite porphyries and diorite porphyrites. Ore forming Na–K–Fe carbonate-chloride fluids of the Davenda and Aleksandrovskoe deposits show great similarity in composition to magmatic fluids of granite porphyry and emphasize the genetic identity of Mo mineralization in both deposits. The data obtained confirm the widespread opinion that a genetic relationship exists between gold mineralization and dikes of intermediate and mafic composition, and molybdenum–porphyry mineralization with granite–porphyry of the Amudzhikan–Sretensky Igneous Complex. The real agents of this genetic link are metalliferous magmatogenic fluids, the salt and gas composition of which inherit ore-forming fluids. The formation depth of productive ore mineral assemblages in veins of the Aleksandrovskoe and Davenda deposits is estimated at 7.9–7 and 8–6.3 km, respectively, which is not typical of porphyry deposits, the formation of which is characterized by shallower depths.
      PubDate: 2020-07-01
       
  • Ruby Mineralization in Murzinka–Adui Metamorphic Complex, Central
           Urals
    • Abstract: The Lipovka and Alabashka ruby occurrences in the Central Urals hosted in marble of the Murzinka–Adui Anticlinorium are considered. The field works were carried out; the chemical compositions of rocks and minerals and oxygen isotopic composition of corundum and silicates were determined; and micas were dated by the K–Ar method. These occurrences are similar in geological environment and mineral assemblages to the ruby occurrences in the South Urals and deposits in Southeast Asia. At the Alabashka occurrence, ruby was also found from brecciated mineralized granite and amphibolite. The mineralized breccia and ruby-bearing marble are enriched in K- and Cr-bearing minerals. Ruby characterized by a narrow range of the oxygen isotopic composition (δ18О = 14.2–17.8‰) corresponding to that of metamorphic and metasomatic corundum. The hydrogen isotopic composition of fuchsite ranges from –78.5 to –89.6‰, while the δD value calculated for fluid equilibrated with fuchsite varies from –48.8 to –79.7‰ that is consistent with the high-temperature equilibrium with magmatic rocks. Aluminum and Cr were mobile elements and could be inflowed by fluids during ruby formation. Corundum mineralization at both occurrenceswas dated at 280–260 Ma, which is consistent with the beginning of post-collisional relaxation. The Murzinka–Adui Anticlinorium is the most prospective area in the Urals for the high-quality ruby deposits.
      PubDate: 2020-07-01
       
  • Askold Gold Deposit (Askold Island, Primorye, Russia): Physicochemical
           Parameters and Composition of Ore-Forming Fluids
    • Abstract: Individual fluid inclusions in quartz from ore veins of the Askold gold deposit, which was previously attributed to the epithermal type, are studied for the first time. It is established that gold mineralization of Askold Island derived from ore-forming fluids of carbon dioxide–water–salt composition, with a salt concentration of 2.8–4.1 wt % NaCl equiv and a high carbon dioxide concentration, at temperatures of 280–324°C and pressures of 1240–2170 bar. The tectonic control of gold mineralization, the presence of tin and bismuth minerals in the ores, the high fineness of gold, and the characteristics of the mineral-forming fluids (primarily high pressures) indicate that the Askold deposit can be attributed to the type of gold deposits associated with granitoid intrusions.
      PubDate: 2020-05-01
       
  • Oscillatory Zoning in Tennantite-(Fe) at the Darasun Gold Deposit (Eastern
           Transbaikal Region, Russia)
    • Abstract: Oscillatory zoning in tennantite-(Fe) crystals found in carbonate–sulfide aggregates at the Darasun gold deposit has been studied. Similar elements have been distinguished in zoned crystals: core, “identical oscillatory rhythm,” rhythms with crystallographic and wavy oscillatory zoning, and rim with poorly defined fine oscillatory zoning. Oscillatory zoning is due to considerable variations in the contents of semimetals (As and Sb) and formally divalent metals (Fe and Zn). Variations in As and Sb are coupled with changes in Fe and Zn, respectively. Both As and Fe contents increase in zoned crystals from the center to the edge: Sb/(Sb + As) ratio varies from 0.44 to 0.03, while Fe/(Fe + Zn) ratio varies from 0.38 to 0.75. The evolution of the composition of zoned tennantite-(Fe) crystals is similar to that of the fahlore at the deposit and to that in pseudomorphic rhythmically zoned tennantite aggregates. A negative relationship between Sb/(Sb + As) and Fe/(Fe + Zn) ratios has been revealed: it is stronger in the internal rhythms than in the external. The oscillatory zoning formed under conditions close to local equilibrium under the influence of external factors at the early crystal growth stages. The composition of zones reflects (random) fluctuations of the external parameters caused by variations in physicochemical conditions (T, fS2, fO2, and pH) and fluid composition, by fluid boiling or mixing of fluids from different sources. Subsequently, changes in the crystal morphology, irregular fluctuations in crystal compositions, and various trends in the behavior of components were caused by the appearance of a concentration gradient at the mineral–fluid boundary and kinetic phenomena on the mineral growth surface. The zoning developed under the influence of “internal” mechanisms under conditions far from equilibrium due to the interrelation between the growth of zones enriched in one component, resulting from the concentration gradient at the crystal–fluid boundary, and the incorporation of another component, in particular, as a result of the self-organization process uninfluenced by external factors. It has been concluded that the oscillatory zoning in fahlore is caused by the difference in solubility of the end-members of the tennantite–tetrahedrite solid solution due to changes in the metal and semimetal migration conditions with a decrease in temperature and fluid salinity. Hence, the oscillatory zoning in tennantite-(Fe) crystals at the Darasun deposit was related to self-organization processes complicated by random fluctuations (noise) of the external parameters.
      PubDate: 2020-05-01
       
  • Behavior of Trace Elements during Oxidation of Sphalerite of the
           Irinovskoe Hydrothermal Sulfide Field (13°20′ N, Mid-Atlantic Ridge)
    • Abstract: — The formation of present-day seafloor sulfide deposits is accompanied by their continuous oxidation and crystallization of insoluble Fe oxyhydroxides, which absorb metals (including heavy metals) (Fallon et al., 2017). Due to the high sorption ability of Fe oxyhydroxides, it is suggested that the removal of metals during submarine oxidation into ambient seawater is insignificant (Fallon et al., 2017). Quantitative data on the redistribution of trace elements between primary sulfides and their oxidation products, however, are insufficient. Recently, we revealed the enrichment of trace elements in covellite with respect to primary sphalerite, chalcopyrite, and isocubanite (Melekestseva et al., 2017). In this study, we estimate the behavior of trace elements during submarine oxidation of sphalerite from smokers at the Irinovskoe hydrothermal field (Atlantic Ocean), which is intensely replaced by Fe oxyhydroxides. As a result, it is established that Fe oxyhydroxides are enriched in many trace elements with respect to sphalerite and the mode of their occurrence is identified.
      PubDate: 2020-05-01
       
  • Gold-Bearing Rodingites of the Agardag Ultramafic Massif (South Tuva,
           Russia) and Problems of Their Genesis
    • Abstract: — The limited literature data on gold-bearing albite–pyroxene rodingites are summarized for the Agardag ultramafic massif in southern Tuva. These data are supplemented by new mineralogical, geochemical, thermobarogeochemical, and isotopic–geochemical results in order to reveal the physicochemical mineral formation conditions and sources of ore matter and fluids on gold deposition in rodingites. Rodingites and associated schistose nephritoids are near-fault metasomatites and are confined to a latitudinal tectonic zone in antigorite serpentinites. They formed in two stages. Stage I minerals (pyroxene, albite, etc.) are rodingites and stage II minerals (Na-bearing actinolite, albite, etc.) are nephritoids and veinlets that intersect rodingites. Disseminated sulfides of the Cu–S series (chalcocite, digenite, etc.) and Au minerals (tetra-auricupride and electrum) were deposited during both stages. The temperature regime (500–250°C) and low amount of CO2 in fluid ( \({{{\text{X}}}_{{{\text{C}}{{{\text{O}}}_{{\text{2}}}}}}}\) = 0.017–0.025) correspond to the formation conditions of typical bimetasomatic rodingites. The degree of oxidation of gas components in fluids CO2/(CO2 + Σreduced gases) increases from rodingites (0.189) to nephritoids (0.299) and antigorite serpentinites (0.738). The O isotopic composition of silicates and calculated O isotopic composition of the fluid during antigorite serpentinization (5.8 to 7.6‰ δ18Оfl and –66 to –69‰ δDfl) correspond to juvenile and magmatic water in contrast to metamorphic water during nephritization and rodingitization (6 to 9.9‰ δ18Оfl and –39 to –46‰ δDfl) with involvement of heavy oxygen that was subjected to the sedimentary cycle. It is suggested that the magmatic ore-bearing fluid (7.3–7.6 wt % NaCl-equiv) separated from gabbroic melts. The oxidized fluid was modified to a reduced fluid during interaction with ultramafic rocks. The mafic and ultramafic rocks were the source of Na, REE, Au, Ag, Cu, and Ni. Deformations with the formation of veins and filling of veinlets are favorable for a high local gold concentration.
      PubDate: 2020-05-01
       
  • The Tumannoe Gold–Antimony Occurrence (East Sayan, Russia): Mineralogy,
           Fluid Inclusions, S and O Isotopes, and U–Pb and 40 Ar/ 39 Ar Age
    • Abstract: The article discusses the features of the composition, age, and genesis of gold–antimony mineralization of the East Sayan based on the example of the largest Tumannoe ore occurrence. It is shown that objects of this type are rare in the considered region. In the course of studies, it was found that stibnite, pyrite, and arsenopyrite predominate in ores; Bi minerals (tetradymite, cobaltite, native Bi), antimonides and sulfosalts (zinkenite, chalcostibite, aurostibite, tetrahedrite, and andorite), and three generations of native gold are also present. The mineralization contains gold–bismuth and gold–antimony ore assemblages, which are the evolutionary products of a single ore-forming system, during which a sequential decrease in the PTX parameters of ore deposition occurred, where temperatures decreased from more than 380 to 180°С. Sulfur activity decreased during ore deposition, which led to the deposition of alternating ore assemblages from simple sulfides to sulfosalts, in the direction of increasing deposited components, and to the formation of different generations of native gold with a gradual increase in fineness from early to late assemblages. The results of mineralogical–genetic and isotope–geochemical studies evidence the magmatogenic nature of gold–antimony mineralization. The isotopic age of parent granitoids, obtained by LA-ICP-MS zircon dating, is Early Ordovician; age values are 491–486 Ma. 40Ar/39Ar dating of muscovite from ore veins shows a relatively young age value (439 Ma), which is due to the influence of late tectonic and thermal events associated with the Early Paleozoic orogeny occurred at that time throughout the territory of the present-day East Sayan.
      PubDate: 2020-05-01
       
  • Valunistoe Epithermal Au–Ag Deposit (East Chukotka, Russia): Geological
           Structure, Mineralogical–Geochemical Peculiarities and Mineralization
           Conditions
    • Abstract: The Valunistoe Au–Ag deposit is the third largest among epithermal deposits in Chukotka after the Kupol and Dvoinoe. It is located at the western closing of the East Chukotka flank zone of the Okhotsk-Chukotka volcanic belt. Volcanic domes (Pravogornenskaya, Zhil’ninskaya, Shakhskaya, Valunistaya, Shalaya, and Oranzhevaya, each is 3–6 km in diameter) have the main ore-controlling significance in the area; they form a chain elongated to the northeast, along the Kanchalan fault zone. Near the deposit, Upper Cretaceous volcanics are widespread: ignimbrites, lavas and tuffs ranging from rhyolite to basaltic composition, and lenses and interbeds of sedimentary rocks, subvolcanic bodies and dikes of andesites, basalts, and dacites. The structure of the deposit is caused by its localization within the limits of the eponymous (Valunistaya) volcanic dome. Twelve ore-bearing vein zones with thicknesses ranging from several to several tens of meters have been revealed at the deposit. The Glavnaya (Main) and Novaya (New) vein zones have been studied in detail; they are traced along their strikes to a distance of more than 1500 m and consist of en echelon veins 1.0 m thick on average, with lengths varying from 100 to 400 m. Based on the sampling data, Au and Ag contents in ores are 0–474.3 and 0–3794.23 g/t, respectively. Colloform-banded structures are frequently encountered, often combined with breccia structures. The main vein minerals are quartz and adularia; calcite, chlorite, fluorite, sericite, pyrophyllite, kaolinite, montmorillonite, gypsum, and epidote are less frequent. The main ore minerals are pyrite, acanthite, chalcopyrite, galena, sphalerite; secondary ore minerals are native Au and Ag and polybasite; rare ore minerals are pearceite, magnetite, hematite, marcasite, freibergite, tetrahedrite, bournonite, hessite, matildite, and others. Ores are characterized by an Au/Ag ratio from 1 : 5 to 1 : 10 and sulfidity (0.5–5%). Ores are enriched in many elements (Au, Ag, Sb, Cd, Pb, Cu, Zn, As, Se, Mo, Te, and Cr), with enrichment factors ranging from several times (Se, Mo, Te, and Cr), to tenfold (Cd, Pb, Cu, and Zn) and hundredfold (Sb) levels, reaching an excess of tens and hundreds thousand times for Au and Ag (Fig. 7). Ores are characterized by a low total REE and demonstrate positive Eu anomalies. Geochemical features are consistent with the mineral composition of ores. Full homogenization of fluid inclusions in quartz occurs at temperatures of 203–284°C and 174–237°C in calcite, while the salt concentration in both cases is from 0.2 to 0.7 wt % NaCl equiv. Fluid density changes from 0.87 to 0.56 g/cm3. The results give grounds to attribute the Valunistoe deposit to the low-sulfidized epithermal class. The data provided in the article are of practical value for regional forecast–metallogenic maps and can be used in searching for and appraising epithermal Au–Ag deposits.
      PubDate: 2020-03-01
       
  • Geochemical Characteristics of Volcanogenic Deposits and Exhalation
           Mineralization in the Crater Part of the Active Kudryavy Volcano (Iturup
           Island of the Kuril Arc)
    • Abstract: Exhalation ore mineralization is developing in the crater part of the active Kudryavy volcano. Lithogeochemical sampling results have revealed that Re, Au, Ag, As, Bi, Cd, Cu, Ge, In, Mo, Pb, S, Sb, Se, Sn, Te, Tl, W, Zn, Rb, and Cs accumulate in solid fumarole formations. These elements are transported by high-temperature volcanic gases and are deposited in mineral phases in the near-surface horizons of fumarole fields under decreasing temperature conditions. The contents of rhenium and other metals in volcanic deposits of fumarole fields locally reach values characteristic of ore deposits. Zoning of lithogeochemical anomalies in ore element associations has been revealed, expressed by the series Re, Mo, W, Au, Cu, Ag, Zn, Cs, Ge → In → Bi, Cd, Pb, Sn, Tl → As, Sb, Se, Te, (Cu, Ag, Au) in the direction from the highest-temperature fumarole fields to less hot, reflecting their temperature zoning. It is demonstrated that lateral geochemical zoning is caused both by the ore element contents in fumarole gases, which depend on temperature, and by differences in the optimal temperature ranges in which various elements precipitate from gases. Signatures for similar exhalation mineral formation processes have been revealed that occurred in the recent geological past at the neighboring extinct Sredny volcano. This suggests the occurrence of similar processes within other volcanic systems of Iturup Island, which increases the prospects for detecting complex exhalation-related manifestations of rare, base, and noble metals.
      PubDate: 2020-03-01
       
  • Variability of Alunite Quartzite Composition as a Reflection of the
           Characteristics of Its Genesis
    • Abstract: Based on 5000 analyses of geological prospecting samples from four alunite deposits (Began’, Ukraine; Haft Sanduq, Iran; Bolshaya Kremenyukha and Kachar, Kazakhstan) and 6000 microprobe analyses of alunite, the features of changes in three parameters of alunite quartzite composition have been studied: (1) alunite content, (2) mole fraction of K in alunite, and (3) correspondence of the amount of K and Na to that of alunite sulfur. All three parameters are highly variable. A linear correlation between them has been identified in over half of the exploration workings. This correlation is sometimes very strong, approaching a functional relationship, especially for two: the alunite content and mole fraction of K in alunite. In the first three of the above-mentioned deposits, this correlation is almost always positive, and in the last, it is always negative. In other words, as alunite content increases, it becomes higher-K in the first case and higher-Na in the second case. Alunite quartzite makes up a regular zone of the infiltration metasomatic column of sulfuric acid alteration in aluminosilicate rocks under conditions apparently close to isothermal. However, the highly variable contents of the basic minerals (alunite and quartz) and alunite composition point to a difference between the alunite quartzite formation model and the theoretical model for isothermal infiltration metasomatic rock. According to the theoretical model, the solution and rock compositions mainly change at the boundaries of the metasomatic zone, whereas the rock and mineral compositions are not characterized by significant variations within the zone. During alunite quartzite formation, the solution and rock compositions change not only at the boundaries, but also within the zone due to ongoing oxidation of sulfur compounds in the solution with the sulfate formation. An increasing sulfate concentration leads to the solution becoming supersaturated in relation to alunite and causes its precipitation, with filling of voids and displacement of quartz. Cooling, heating, or a change in the composition of the hydrothermal system solutions lead to temporal variations in the K/Na ratio in precipitated alunite. Alunite formation inside the alunite zone, accompanied by changes in the mole fraction of K in deposited alunite, is the reason for the high variability of the alunite quartzite composition and for the correlation between the alunite content and its mole fraction of K. If the contribution of higher-K alunite to the variability of its total content is higher than that of higher-Na alunite, a positive correlation is likely to appear, otherwise a negative correlation is more probable.
      PubDate: 2020-03-01
       
  • The World’s Largest Fouta Djallon–Mandingo Bauxite Province (West
           Africa): Part I. Background
    • Abstract: — The recognition of the Fouta Djallon–Mandingo territory as an independent bauxite province is substantiated. It is confined to the morphostructure of the same name within a single geotectonic structure, the sedimentary cover of the Sahara Platform, in the tropical monsoon climate zone in West Africa. The bauxite exploration history, reserve and resource estimates, and production dynamics in the Fouta Djallon–Mandingo province are reviewed.
      PubDate: 2020-03-01
       
  • 90th Birth Anniversary of Academician N.P. Laverov
    • PubDate: 2020-01-01
       
 
JournalTOCs
School of Mathematical and Computer Sciences
Heriot-Watt University
Edinburgh, EH14 4AS, UK
Email: journaltocs@hw.ac.uk
Tel: +00 44 (0)131 4513762
 


Your IP address: 3.232.133.141
 
Home (Search)
API
About JournalTOCs
News (blog, publications)
JournalTOCs on Twitter   JournalTOCs on Facebook

JournalTOCs © 2009-