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The paper presents new isotope geochronological data for several mineral deposits, ore occurrences, and related igneous bodies (plutons and dikes) in the Verkhoyansk–Kolyma folded area, eastern Yakutia. Twenty-one 40Ar/39Ar mica and four U–Pb zircon dates provide the first age constraints on key metallogenic units in the area. The dating results allow correlation between tectonic, magmatic, and metallogenic events. The sampled mineral deposits within the Adycha–Taryn fault zone in the southeastern Verkhoyansk–Chersky orogen apparently formed at the Jurassic–Cretaceous boundary during the final phase of the collision between the Siberian (North Asian) craton and the Kolyma–Omolon microcontinent (Kupol’noe deposit and the early metallogenic pulse of the Malotarynskoe deposit, ~ 143–144 Ma) and in the latest Early Cretaceous, in the beginning of the orogen collapse (Tallalakh and Dora-Pil’ deposits and the Malotarynskoe late metallogenic pulse, ~ 126 Ma). According to the suggested new classification of metallogenic units, these deposits belong to the Late Jurassic–Early Cretaceous Yana–Kolyma metallogenic belt. The Kyuchus deposit (~ 106 Ma), the Deputatsky ore cluster (~ 106–113 Ma), and the Khotoidokh deposit (~ 116 Ma) in the northern Verkhoyansk–Kolyma folded area belong to the North Verkhoyansk metallogenic belt. Their origin was associated with accretional and collisional processes that produced the Novosibirsk–Chukotka orogen in the middle Cretaceous. The Mangazeya ore cluster (~ 100 Ma, Early–Late Cretaceous boundary) in the southwestern end of the North Tirekhtyakh magmatic transverse belt belongs to the West Verkhoyansk metallogenic belt. The Nezhdaninskoe, Zaderzhnoe, Kurum, and Kuta deposits of the South Verkhoyansk area (~ 125–120 and ~ 100–95 Ma) can be joined into a single Verkhoyansk–Okhotsk metallogenic belt. The belt resulted from accretion and collision along the East Asian active continental margin and the related formation of the South Verkhoyansk orogen in the Early Cretaceous.

The increased demand for indium has made it necessary to revise prospects of In-bearing tin ore deposits in the Russian Far East on the basis of geological data and results of recent analytical methods (X-ray fluorescence with synchrotron radiation, atomic absorption, and ICP-MS). The average In contents in ores of the Tigrinoe and Pravourmiiskoe deposits vary from 55 to 70 ppm, which allows tin ore deposits with Sn‒sulfide mineralization to be considered as quite promising with respect to In production from ores of Russian deposits. By their estimated In reserves, the Tigrinoe and Pravourmiiskoe deposits may be attributed to large ore objects.

Fe-rich carbonatites with a mineral assemblage of ankerite-calcite or siderite are widespread in southern Siberia, Russia. The siderite carbonatites are associated with F-Ba-Sr-REE mineralization and have a 40Ar/39Ar age of 117.2 ± 1.3 Ma. Melt and fluid inclusions suggest that the carbonatites formed from volatile-rich alkali- and chloride-bearing carbonate melts. Ankerite-calcite carbonatites formed from carbonatite melt at a temperature of more than 790 °C. The ferrocarbonatites (the second phase of carbonatite intrusion) formed from a sulfate-carbonate-chloride fluid phase (brine-melt) at >650 °C and ≥360 MPa. The brine-melt fluid phase had high concentrations of Fe and LREEs. A subsequent hydrothermal overprint contributed to the formation of economically important barite-Sr-fluorite-REE mineralization in polymict siderite breccia.

The authors have studied melt-fluid and fluid inclusions in quartz and fluorite of sideritic and ankerite-calcitic carbonatites of the Karasug ore field, as well as melt inclusions in apatite from granosyenites. The content of salt and fluid components in brine-melt inclusions was evaluated on the basis of the thermodynamic data, the calculations of volumes and densities of the solid phases, a solution of about 50% concentration, and the gas phase of the inclusions, as well as the results of the LA-ICP-MS analysis. The content of salt phases, the solution, and the gas phase amounted to 85–70, 10–25, and about 5% of the inclusion substance, respectively. The total percentage of salt and fluid components (H2O and CO2) amounted to 90–80 and 10–20 wt %, respectively. The fraction of a carbonate constituent in the inclusions was as high as 45–50% and over in ankerite-calcite carbonatites and about 15 wt % in sideritic carbonatites. The 117.2 ± 1.3 Ma age of these carbonatites by 40Ar/39Ar, along with other datings for this area, shows that their formation was associated with a manifestation of the Cretaceous alkaline-mafic magmatism (117–120 Ma). The presented model of the formation of carbonatites is in agreement with the sequence of the development of magmatic processes and mineralization in this area. The model is also confirmed by the results of the studies of melt and fluid inclusions in minerals.

The Piaoak tin-bearing granite-leucogranites located in the Caobang Province of Northern Vietnam compose a stock-like hypabyssal body. Host rocks are represented by Early Devonian carbonate sequences and Early Triassic “black” shales. The geochronological age of the Piaoak granite-leucogranites corresponds to the Late Cretaceous: T = 83.5 ± 6.2 Ma, 87Rb/86Sr method; T = 89.7 ± 1.0 Ma, 39Ar/40Ar method. The massif has a simple basic to acid order: two-mica and muscovite granite-leucogranite → raremetal aplites, pegmatites → tin-bearing greisens and hydrothermal veins. The petrographic and microstructural studies revealed a sharp change in crystallization conditions of the granite-leucogranite magma at the late magmatic stage and formation of muscovite via incongruent melting of protolithionite. The study of melt and coexisting fluid inclusions showed that solidus crystallization occurred under fluid-saturated conditions at 635–600°C. In composition, the granite-leucogranites of the Piaoak Massif correspond to the raremetal-plumasite geochemical type (according to L.V. Tauson), and reach Li-F facies in terms of their rare-element composition. The composition of aplites and pegmatites demonstrates that granite-leucogranite magma did not accumulate lithophile and volatile components in the residual melt during differentiation, but was initially enriched in rare-metals. It is most probable that the melt was generated from Proterozoic lithotectonic complexes and overlaying Lower Triassic “black” shales.

The Mesozoic Chuya dike complex was recognized by R.V. Obolenskaya based on the similar mineral composition of dikes and their age characteristics. Lamprophyres occur along the large Terekta–Tolbonur and Kurai–Kobda shear zones. The Chuya complex was studied by the example of two areas, South Chuya and Yustyd, with different levels of erosional truncation. The dikes of the first area are localized in the South Chuya Ridge, where they cut Cambrian–Ordovician metamorphic rocks, and the dikes of the Yustyd area occur in the Devonian terrigenous blackshale deposits of the Yustyd trough. The dikes of these areas differ in structures, textures, the degree of carbonatization, and mineral composition. The performed studies of rocks and minerals confirmed that the dikes of both areas belong to the same complex. They helped to establish the regularities of the lithologic composition of the entire complex and its local areas and to substantiate the recognition of areas not only from their geologic position but also by the composition, structures, and textures of rocks and their mineral composition. Geochronological data show two stages of the complex formation: 236–234 and 250–242 Ma. The results of studies also demonstrate that the lamprophyres and coeval syenites of the Tarkhata massif are fractionates of the same parental melt and can be united into a hypabyssal-plutonic complex. Comparison with other Permo-Triassic lamprophyre complexes showed that the wide variations of the composition of the Chuya rocks and its trend as well as the geochemical anomalies are specific features of complexes of high-K lamprophyres.

Based on study of fluid and melt inclusions in minerals from igneous rocks and associated ore-metasomatic objects, we consider the formation conditions of oxidized fluids produced at the final stages of differentiation of alkali-basic, alkaline, lamproitic, and some granitoid melts. These fluids are characterized by wide variations in composition, concentrations, and physicochemical parameters (P, T, Eh, pH, etc.) and are of sulfate-chloride, sulfate-carbonate, sulfate-fluoride, fluoride-sulfate, essentially sulfate, and other types. The specific composition of these magmatogene fluids showing a high extractive power favors the effective removal of ore-forming elements (Fe, Mn, Co, N, Ag, Cu, Pb, Zn, Mo, W, Bi, U, REE, etc.) from melt and their trapping from the host rocks. The set of these elements is determined by P-T-X-parameters, conditions of fluid separation from melts, composition of fluid-generating magmas, and geochemical composition and metal-bearing capacity of rocks through which the fluids migrate. These factors significantly determine the metallogeny of alkaline, alkali-basic, and some granitoid complexes and associated mineralization.

The paper discusses the spatiotemporal and genetic relationships of hydrothermal Co mineralization in the Altai–Sayan orogen with mafic, alkaline mafic, and granitoid magmatism on the basis of isotopic, geochemical, and geochronological investigations. Four stages of Co mineralization have been distinguished for this region: Early Devonian (D1), Late Devonian–Early Carboniferous (D3–C1), Permo-Triassic (P2–T), and Early Cretaceous (K1). They correspond to periods of large-scale mafic magmatism. Isotopic (Pb, Sr, He) and geochemical studies have shown that Co mineralization is genetically related to mafic and granitoid magmatism. Also, these studies have confirmed that Co deposits are formed with the participation of mantle fluids and are related to chambers of mafic and alkaline mafic melts. Besides, it has been found that ore originated both from magmatic sources and host rocks. A pulsed facies endogenic zonation has been established for Co deposits, Co-bearing ore clusters, and zones with high-temperature Co–As and low-temperature Ni–Co–As mineralization. It has been first established that ores at hydrothermal Co deposits are rich in Pt and Pd. © 2010, V.S. Sobolev IGM, Siberian Branch of the RAS. Published by Elsevier B.V. All rights reserved.

Questions on the origin of Ag–Sb deposits are considered for several large economic ore districts in Central Asia: southeast Pamir (Tajikistan), Talas in northern Tien Shan (Kyrgyzstan), southeast Altai and northwest Mongolia, and Verkhoyansk province (Yakutia). The Ag–Sb mineralisation of Central Asia is spatially and temporally associated with alkaline mafic magmatism, and occasionally with coeval granitoid magmatism. Ag–Sb deposits have close spatial and temporal relationships with granitoid and alkaline mafic magmatism. The Ag–Sb deposits were formed in the temperature range 50–280°C, from Ag-specific reduced two-phase hydrothermal fluids containing a highly concentrated chloride solution (NaCl > FeCl2 > CaCl2 > KCl > MnCl2) and a high-density CO2+ CH4 ± N2 gaseous phase. Fluid salinities range widely from 40 to 0.1 wt% NaCl equiv. Geochemical specialisation of Ag–Sb ore is caused by chemical features of chloride brines enriched in Ag, Sb, Pb and Cu, with a relatively low Au content (≤10−6 mol/kg) wit...

Stanniferrous granite-leucogranite massifs in Vietnam to which the bedrock and placer commercial deposits of cassiterite are associated (Timtuc etc.) are of late Cretaceous age (∼85 Ma by Rb-Sr and Ar-Ar isotope dating). These massifs are presented by stocks and fracture intrusions (to 100 km2 in area) of simple homodromic structure: biotite granites ⇒ two-mica and muscovite leucogranites ⇒ topaz-containing aplites ⇒ rare-metal pegmatites.

Economic Ag–Sb deposits are located within four large ore districts of Central Asia: SE Altai–NW Mongolia, SE Pamir (Tajikistan), Talas (Kyrgyzstan) and Verkhoyansk province (Yakutia), where Ag–Sb ores are spatially associated with tin mineralization. The geology, mineral composition and geochemistry of the Ag–Sb deposits, age of mineralization, distribution and genesis are presented in this paper. Results of new studies show that Ag–Sb ores commonly occur within Sn ore provinces and can be divided into three groups according to their relationships with tin mineralization. Ag–Sb deposits of the first group are spatially isolated from Sn–W ore fields and from metamorphic haloes of Sn-bearing granitoids (pre-granitic deposits of the Mangazeisky ore cluster in Yakutia and deposits of the Asgat-Ozernoe ore zone in the SE Altai–NW Mongolia). A 240 ± 3.5 Ma 39 Ar/ 40 Ar age of Ag–Sb mineralization was determined for the Asgat deposit (SE Altai–NW Mongolia), which correlates well with the 243 ± 3.7 Ma 39 Ar/ 40 Ar age of alkaline mafic intrusions (lamprophyre dike). The Ag–Sb ore appears to be younger than Sn–W mineralization (352 ± 6.0 Ma) related with granite of the Yustid complex (355.7 ± 8.6 Ma). The second group comprises granite-hosted Ag–Sb deposits of the Bazardara ore cluster (SE Pamir) of Paleogene age (44 ± 1.5 Ma) located within a tin ore cluster, but separated in time from the Cretaceous Sn mineralization (98.5 ± 1 Ma, Ar–Ar). Ag–Sb ore veins of the third group are located within tin ore clusters and are nearly coeval with tin mineralization (post-granitic Ag rich ore of the Mangazeiskoe, Prognoz and Menkechenskoe deposits, Verkhoyansk province). A close spatial and temporal relationship of Ag–Sb deposits with Sb–Hg mineralization and alkaline mafic magmatism is observed. Helium isotope systematics from the ore-forming fluids of Ag–Sb Akjilga deposit (Pamir) confirm the role of mantle helium in the ore-forming process. Another important indicator of a mantle source in these Ag–Sb deposits is the Hg content in the ores; Hg being a typical element of mantle origin. Isotopic ( 3 He/ 4 He, 87 Sr/ 86 Sr, Pb, S) and geochronological data demonstrate that Ag–Sb deposits are polygenetic in sources of ore matter and relate to the mantle-crustal ore-magmatic systems.

The physicochemical formation conditions of Au-As, Au-Sb, and Ag-Sb ores characterized by similar paragenetic mineral assemblages and sets of major ore elements but differing in their proportions have been studied. The composition of the solutions filling fluid inclusions in minerals of Au-Sb deposits, combined with mineralogical and geochemical data, indicates that these deposits were formed from a near-neutral to alkalescent chloride-sulfide (

In the 1980s, Ag-Sb deposits were discovered in a new ore cluster of the Delyun-Yustyd back-arc rift basin in southeastern Altai and northwestern Mongolia. The Delyun-Yustyd basin is filled with up to 9 km thick Devonian volcanosedimentary and terrigenous rocks lying over Vendian-Cambrian carbonate-terrigenous strata. Volcanosedimentary rocks are intruded by D3-C1 granites of the Yustyd complex, as well as by pre-granite mafic rocks, post-granite gabbro-diabase, diabase porphyry dikes, and younger lamprophyre dikes of the Chuya complex (245–236 Ma Ar-Ar biotite age). Ag-Sb ores in the Yustyd cluster formed at the Early Mesozoic stage at 240±1.6 Ma (Early-Middle Triassic boundary) and were thus nearly coeval with the Chuya lamprophyre intrusion. The age of Cu-Ag-Sb-Hg mineralization is about 234.4±1.0 Ma (Ar-Ar, sericite). Sb-Hg mineralization is the latest in the province (231.5±1.0 Ma, Ar-Ar, sericite). Gradual change of Ag-Sb (siderite-tetrahedrite) ores to complex Cu-Ag-Sb-Hg (Hg-Ag-tetrahedrite) and Sb-Hg (cinnabar with Sb sulfosalts and stibnite) mineralization along the Kurai-Kobdo and Terekta-Tolbonur large faults is interpreted as development of stage metallogenic zoning along major ore-controlling faults.

Based on data on the composition of ore-bearing hydrothermal solutions and parameters of ore-forming processes at various antimony and antimony-bearing deposits, which were obtained in studies of fluid inclusions in ore minerals, we investigated the behavior of Sb(III) in the system Sb–Cl–H2S–H2O describing the formation of these deposits. We also performed thermodynamic modeling of native-antimony and stibnite dissolution in sulfide (mHS− = 0.0001−0.1) and chloride (mCl− = 0.1−5) solutions and the joint dissolution of Sb(s)0 and Sb2S3(s) in sulfide-chloride solution (mHS− = 0.01; mCl− = 1) depending on Eh, pH, and temperature. All thermodynamic calculations were carried out using the Chiller computer program. Under the above conditions, stibnite precipitates in acid, weakly acid to neutral, and medium redox solutions, whereas native antimony precipitates before stibnite under more reducing conditions in neutral to alkaline solutions. The metal-bearing capacity of hydrothermal solutions (200–250 °C) of different compositions and origins has been predicted. We have established that the highest capacity is specific for acid (pH = 2–3) high-chloride solutions poor in sulfide sulfur and alkaline (pH = 7–8) low-chloride low-sulfide solutions.

The results obtained with LA-ICP-MS by less abundant lighter 113 In isotope and EPMA show that in cassiterite of cassiterite–quartz veins the indium contents do not exceed 160 ppm, while cassiterite from Sn–sulfide veins is characterized by higher indium contents from 40 to 485 ppm; sulfides of Sn–sulfide veins unlike sulfides of cassiterite–quartz veins also have the highest indium contents: Fe-sphalerite (100–25,000 ppm), chalcopyrite (up to 1000 ppm), and stannite (up to 60,000 ppm). Indium contents in the Sn–sulfide ore of the Tigrinoe and Pravourmiiskoe deposits obtained using SR-XRF, ICP-MS and atomic absorption methods range from 10 to 433 ppm with average values of 56–65 ppm. Indium-rich Sn–sulfide mineralization in five large Sn–Ag ore districts of the Far East Russia (Khingansky, Badzhalsky, Komsomolsky, Arminsky, Kavalerovsky) provides the impetus for further exploration of deposits with Sn–sulfide mineralization as the most promising indium resources in Russia. Empirical observations from geology and geochronology of cassiterite–quartz and Sn–sulfide mineralization show that the combined contribution from granite and alkaline–subalkaline mafic sources and multistage ore-forming processes doubled indium resources of deposits being the main factors in the formation of high grade indium mineralization.

Ore forming conditions for Au-Sb and Ag-Sb deposits have been estimated using thermodynamic modeling. PTX-parameters of ore-forming fluids obtained by fluid inclusion study in the minerals were used as original data for modeling. Analysis of composition of fluid inclusion solutions in the minerals of Au-Sb deposits together with mineralogical and geochemical data show that Au-Sb deposits were formed by two types of solutions: neutral–weak alkaline (CCl < 5 wt % NaCl-eq.), and acid high concentrated chloride solution (up to 30 wt% NaCl-eq.), containing FeCl2 and CaCl2 besides NaCl. In low concentrated chloride solution Sb is transported as sulfide and hydroxide complexes, and Au and Ag as bihydrosulfide species. In acid high chloride solution of late superimposed stage, which contains Cu, Ag, Pb, and Zn, predominating Au and Ag species are chloride complexes, and for Sb chloride and hydroxy-complexes. The main factors determining geochemical specialization of Ag-Sb ore are high chloride concentration and pH = 3.5–4, determining low Au-bearing capacity of the solution. Unsaturated in Ag low concentrated chloride solutions took part in Au-Sb deposit forming that determines their specific composition.

Silver deposits of the South Pamir region of Tajikistan occur as siderite veins with sulfosalts and sulfides, and formed during a late Mesozoic-early Alpine cycle of rifting and orogenesis. Three mineral-geochemical types of ore deposits that occur in several ore districts are recognized: Ag-Sb, Ag-Pb, and Ag-Hg. The Ag vein deposits all occur in terrigenous-carbonate sedimentary rocks and in intrusive granites. The veins are controlled by late Mesozoic faults, and are the products of the last endogenous event in the region. The most significant group of Ag-Sb vein deposits is located in the Bazardara ore district. Three stages of mineralization are recognized in this region: siderite-tetrahedrite, quartz-tetrahedrite, and quartz-galena-freibergite. Most of the veins were deposited during the first stage. Tetrahedrite is the prevailing and most economically important mineral, and contains 0.2 to 15.5% Ag. Associated freibergite contains from 19.5 to 32% Ag. Fluid-inclusion studies indicate that Ag-Sb ore ...

Ag-Sb deposits of a new economic district that occurs on the boundary of the southeastern Altay Republic of eastern Russia and northeast Mongolia are herein described. Mineralization of this region is divided into two periods—(1) Late Hercynian (Mo-W deposits) and (2) Mesozoic (Sn-W, as well as Ni-Co-As, Ag-Sb, and Sb-Hg deposits). The deposits of main economic interest, silver-antimony, consist of siderite-sulfosalt veins and vein zones that occur in contact-metamorphosed coal-bearing terrigenous rocks of Devonian age. These veins occur to depths of up to 900 m, and occur along strike for 3 to 3.5 km; their thicknesses range up to 12 m. The deposits are mineralogically and geochemically similar to silver deposits of the Yakutian, Pamir, Slovakian, Coeur D'Alene (USA), and Freiberg (Germany) ore districts. The main ore minerals are quartz, carbonate, and Ag-tetrahedrite, with minor chalcostibnite, chalcopyrite, bournonite, zinkenite, arsenopyrite, and pyrite. Sulfides are characterized by widespread isomo...