Ore-magmatic System Research Articles

New results of the U/Pb dating of cretaceous igneous rocks of the Komsomolsk ore district (Middle Amur River area)

The Komsomolsk tin ore district is located at the Miaochan Ridge in the Middle Amur River area (Khabarovsk territory) within the Badzhal accretionary terrane of the Sikhote-Alin orogenic belt. The paper presents new results of U-Pb zircon dating of tonalite of the Miaochan complex of the Silinka granitic pluton (99.7±1.1 Ma) and two rhyolites of the lower part of the Kholdami Formation (98.4±1.0 and 98.7±1.2 Ma) from the north-eastern part of the Komsomolsk district. The geochemical characteristics of rocks were also studied, which show that granitoids of the Miaochan complex are I-type granites, and coeval rhyolites of the Kholdami Formation are very peraluminous S-type rocks. New data on the geochemistry and early Cenomanian age of the igneous rocks allows us to consider the ore-magmatic system of the Komsomolsk ore district as part of the previously identified Albian-Cenomanian igneous province of Pacific Asia.

USE OF DIGITAL MODELS OF GEOLOGICAL STRUCTURE TO IDENTIFY PALEOVOLCANIC STRUCTURES CONTROLLING PORPHYRY ORE OBJECTS

The article is devoted to the implementation of the methodology for paleovolcanic structure analyzing using 3D visualization of the model of the geological territory structure based on the relief digital model. The approach used made it possible to identify two paleovolcanic apparatuses and their structural elements: cone fragments, explosive domes, porphyritic stocks, ring fault zones with localization of dike belts in them. This, within the framework of the evolution model of porphyry ore systems, made it possible to identify promising areas for prospecting on ore objects of a given type. The procedure was checked on the basis of geochemical survey results. The regular control by the selected structural elements of geochemical fields was shown. The analysis of the spatial position of the selected structural blocks with a certain geochemical characteristic rather well into the evolution model of the porphyry ore systems. In all cases the control of geochemical halos by porphyry stocks is noted, the material rock complexes that are fragments of the zonal stone hat of the porphyry ore object, are quite clearly distinguished. Within the area of work, three ore-magmatic systems can be identified at a low level of erosion shear, potentially accompanied by porphyry-type ore mineralization.

Modern Lines in Geochemistry: Anniversary Conference

Abstract —On 21–25 November, 2022, Vinogradov Institute of Geochemistry, Siberian Branch of the Russian Academy of Sciences (Irkutsk), organized and held an All-Russian conference celebrating the 65th anniversary since the foundation of the Institute and the 105th anniversary since the birth of its first director, Academician Lev Vladimirovich Tauson, who headed the Institute from 1961 to 1989. The results reported at the conference encompass a wide range of research fields in modern geochemistry, including isotope geochemistry of igneous, metamorphic, and sedimentary rocks in various geodynamic settings; chemistry of ore-magmatic systems and modern methods of mineral exploration; environmental geochemistry, geoecology, and paleoclimate; laboratory modeling and thermodynamic calculations of natural and production-related processes and materials; advanced analytical methods and information technologies for geosciences. The conference presentations pay tribute to Lev Tauson whose academic carrier, as well as all creative activity, had been closely related with the development of the Institute of Geochemistry. The preface paper provides a review of topics discussed at the conference concerning various geodynamic and geochemical problems, including sources of material, petrogenesis, and metallogeny.

СТРУКТУРЫ ЦЕНТРАЛЬНОГО ТИПА В ЮЖНОМ СИХОТЭ-АЛИНЕ В ВЕРОЯТНОСТНЫХ ГРАВИТАЦИОННЫХ МОДЕЛЯХ: ГЛУБИННОЕ СТРОЕНИЕ, РЕОЛОГИЯ, ИЕРАРХИЯ, ФРАКТАЛЬНОСТЬ И МЕТАЛЛОГЕНИЯ

As a result of the analysis of 3D-distributions of density contrast in the crust of the South Sikhote-Alin, connections are established between ore districts, ore clusters, and ore fields, on the one hand, and hierarchically subordinate structures of the central type of three taxonomic levels, on the other. Based on the coincidence of the areas of spatial distribution of ore mineralization with the projections of deep density heterogeneities, the probable depth of occurrence of fluid-magmatic sources of ore mineralization and vertical extent of ore-magmatic systems of different specialization were determined: tin (depth of 2‒6 km), tin-polymetallic (4‒12 km), polymetallic (6‒20 km), and gold-tungsten (14‒24 km). The spatial distribution of central-type structures and the associated areas of ore mineralization are coincident with viscous shear zones, within which subsidence of the crustal upper layer is observed (Samarkinsky terrane, Kavalerovsky district and Soboliny ore cluster), as well as displacement of the contours of density heterogeneities in different depth sections (Dalnegorsky region). Deep boundaries of the ancient continental crust and Mesozoic island-arc wedges subducted under accretionary-fold complexes were determined. The joint of these structures is characterized by distinct features of a transform fault.

A «necklace» of large clusters of strategic raw materials over a stagnant oceanic slab in East Asia

<p>An analysis of geological-geophysical, metallogenic, geochronological, and seismic tomographic studies in territories joining Southeast Russia, East Mongolia, and Northeast China led to the conclusion that deep geodynamics significantly influenced the formation of highly productive ore-magmatic systems in the Late Jurassic-Early Cretaceous. This influence was likely manifested through the initiation of decompression processes around stagnant slab boundaries in the Late Mesozoic. Decompression and advection, which are particularly active near the natural boundaries of the slab, act as triggers for the intense interaction of under and over subduction asthenospheric fluids with adjacent sections of the mantle and for the directed upwelling of powerful flows of matter and energy into the lithosphere. These flows determine the locations of intermediate and peripheral magma chambers: Primary chambers in the lower lithosphere among the metasomatized mantle and lower crust and associated chambers in the middle and upper cratonized parts of the lithosphere. Large ore clusters containing noble metals (Au, PGE), uranium, fluorite, and Cu-Mo-porphyry deposits are associated with late- and postmagmatic derivatives of the emerging magma chambers over the frontal and peripheral (paleotransform) boundaries of a stagnant Pacific slab. These large Late Mesozoic ore clusters and districts form a distinctive "necklace" of strategic materials in East Asia.</p>

ИССЛЕДОВАНИЕ МИКРОВКЛЮЧЕНИЙ МЕТАЛЛОВ И МИНЕРАЛОВ В ГОРНЫХ ПОРОДАХ: ПРОБЛЕМЫ ИНТЕРПРЕТАЦИИ РЕЗУЛЬТАТОВ И ИХ ПРИМЕНЕНИЕ ПРИ ИЗУЧЕНИИ МАГМАТОГЕННЫХ СИСТЕМ КАМЧАТКИ И СТАНОВОЙ СКЛАДЧАТОЙ ОБЛАСТИ

The article discusses the problems of interpreting the results of studies on microinclusions of metals and minerals by scanning electron microscopy with energy-dispersive X-ray microanalysis, which are related to the influence of the matrix material. The method was shown to work well when studying “relatively large” (5-10 μm) microinclusions for the purpose of their phase identification and semi-quantitative determination of composition normalized to 100%. The possibilities of “cleaning” the analysis results from “additives” introduced by matrix elements are discussed, as well as criteria for assessing the distance from the boundaries of a micro-object at which the influence of the matrix becomes minimal. The use of the results obtained using these approaches is illustrated by the examples of studying the petrology and metallogeny of igneous rocks of Kamchatka and the Stanovoy fold belt, during which new data were obtained on petrological processes in the mantle-crustal substrate beneath the active volcanic arc and on the evolution of the ore-magmatic system beneath the ancient active continental margin.

Precious-Metal Mineralization and Formation Conditions of the Biche-Kadyr-Oos Epithermal Au-Ag Ore Occurrence (Eastern Sayan, Russia)

The Biche-Kadyr-Oos epithermal Au-Ag ore occurrence is a prospective object in the Ak-Sug porphyry copper ore cluster (Eastern Sayan) in the northern part of the Central Asian orogenic belt (CAOB). The mineralization consists of gold-sulfide-quartz and gold-polysulfide-carbonate-quartz veins with argillic zones in the Lower Cambrian volcanic-sedimentary rocks. The origin of the Au-Ag ore occurrence is still debatable. To determine the origin, we examined the mineralogical and geochemical features, conditions of formation, and fluid sources of the Biche-Kadyr-Oos ore. A mineralogical and geochemical investigation outlines three stages of mineral formation: early argillic stage; gold-sulfide-quartz stage with pyrite, marcasite, pyrrhotite, arsenopyrite, chalcopyrite, less frequently sphalerite, hessite, gold, and electrum; and late gold-polysulfide-carbonate-quartz stage with gold, electrum, Hg-electrum, Se-acanthite, Se-galena, bornite, tennantite, tetrahedrite, hessite, tellurobismuthite, bismuthinite, matildite, jamesonite, ourayite, native Bi, and barite. Fluid inclusion study (thermometry, Raman spectroscopy) in quartz and mineral thermometry (electrum and sphalerite paragenesis) determined that ore veins were formed at P~0.5 kbar from CO2-water Na-K-chloride fluid (4.9–9.6 wt % NaCl eqv) and temperatures from 300 to 200 °C (early gold-sulfide-quartz veins at 300–230 °C, and late gold-polysulfide-carbonate-quartz veins at 290–200 °C) and variations in fO2, fS2, fSe2 and fTe2. The S isotopic composition in sulfides and δ34SH2S values of the fluid are +1.3‰ and +4.7‰, respectively, (T = 300–275 °C) indicating magmatic S in ore formation. The oxygen isotope data indicate that during the formation of veins, the magmatic fluid mixed with meteoric water (δ18Ofluid is from +3.4 to +6.4‰). The isotopic data that were obtained combined with mineralogical and geochemical features and conditions of ore formation indicate the similarity of Biche-Kadyr-Oos ore occurrence with epithermal Au-Ag deposits of intermediate sulfidation (IS) type. The presence of epithermal Au-Ag mineralization of the Biche-Kadyr-Oos IS type in ore cluster of the Ak-Sug Cu-Au-Mo porphyry deposit indicates the existence of a single porphyry-epithermal ore-magmatic system.

Complex porphyry copper ore-magmatic systems of the andesitoid and basaltoid volcano-plutonic belts

A division of the porphyry copper family ore deposits into formational types associated with the basaltoid and andesitoid volcano-plutonic belts is proposed. It is shown that differences in the structure of the basement of these belts and in the composition of the ore-bearing magmatic chambers are reflected not only in the productive plutonogenic association petrology, alteration-mineralization zonality, and mineral composition of the mineral deposits, but also in the metallogenic zonality of the complex ore-magmatic systems centered by these deposits. The established differences should be taken into account for elaboration of the forecasiting and prospecting models of potential porphyry copper ore regions and clusters.

Generation and alteration conditions, fluid regime features of the ore-magmatic system of the South Saryshagan granite intrusion (Western Balkhash region)

Research subject. For the first time, the mineral composition, petro- and geochemical features, generation and metasomatic alteration conditions, fluid regime (based on the behavior of F, Sl, and S in apatites), and ore-generating potential of granitoids from the South Saryshagan intrusion (Western Balkhash) were studied. Materials and methods. X-ray fluorescence and atomic emission methods of rock analysis (drilling well core), as well as microprobe (polished sections) studies of mineral composition. Results. The rock composition was found to correspond to moderately alkaline granites, formed at a generation pressure of about 2 kbar and T = 670°C. Subsequent metasomatic transformations were mediumtemperature (313–350°C) and multistage, i.e., phyllitization followed by chloritization. The ferrous composition of chlorite and the confinement of its development area to fracture zones indicate the local scale of the process. Ore mineralization is mainly represented by chalcopyrite, occasionally containing Au. According to the morphology and composition features, apatites from granites can be divided into two groups, i.e., magmatogenic grains and products of their transformations. In a diagram of F-Cl-S ratios, most points of their composition lie in the fields of rocks productive of Cu-porphyry mineralization. Conclusions. Mineral associations and the analysis of F, Cl, and S behavior in apatites indicate changes in the composition of the fluid phase over time under the conditions of an open system. In apatites, sulfur accumulates to the maximum level (0.012 wt % S) simultaneously with an increase in the amount of Cl and a decrease in the amount of F. After S reaches this level, the Cl content in apatites decreases followed by a notable increase in F; as a result, the late portions of the fluid become depleted of F, but enriched with Cl and S. In general, the content of the latter two components is low, compared with that typical of rich Cu–porphyry systems. Since the amount of mobilized copper depends on both the contents of Cl and S in the fluid and the volume of this fluid (determined by the size of the intrusion itself; in our case, it is a small body), the predicted copper reserves in the upper horizons of the South Saryshagan intrusion are small.

Evolution of Rare-Metal Li–F Granite Melts in Sources of Ore-Magmatic Systems of Tigrinoe and Zabytoe Sn–W deposits (Central Sikhote-Alin, Primorye)

The present paper considers petrographic and geochemical features of rocks of the Tigrinoe and Zabytoe stocks, provides their mineral composition, the results of the detailed study of micas and mineral-forming inclusions in quartz. It is shown that the development of ore-magmatic systems (OMSs) of the Zabytoe and Tigrinoe deposits is associated with the same rare-metal Li–F melts. It is confirmed that granitoids of the Tigrinoe stock can be considered as more differentiated analogs of granitoids of the Zabytoe stock. New data concerning the differences in the history of the magmatic stage of development of the OMSs of these deposits are presented. The evolution of melts of both deposits took place at high fluid pressure. Differences in the scale of ore mineralization of the two RMSs under consideration could be due to different fluid regime of magmatic sources evolution and more significant participation of transmagmatic fluid flows in the development of the Tigrinoe OMS.

Composition, formation conditions, distribution patterns and zoning of gold mineralization in the Stadukhinsky ore-placer region (Western Chukotka)

Gold deposits associated with granitoid intrusions have long been known. Recently, a class of deposits was identified among them, called intrusion-related granite systems, IRGS (gold-rare metal formation). The standards of the geological prospecting model for them are the deposits of the Tintin metallogenic belt (Alaska, Canada). In Russia, this type has been studied less; IRGS includes the Shkolnoye and Butarnoye (Magadan region) and Kekura (Chukotka) deposits. Based on field and laboratory studies, generalization of prospecting geological and geochemical data, the characteristics and localization features of gold mineralization associated with granitoids of a large igneous uplift in the South Anyui structural-formational zone (Western Chukotka) were determined. The mineral composition of ores, the sequence of their formation were studied, homogenization temperatures and salt concentrations in gas-liquid inclusions were determined. The geochemical and mineralogical zoning of the ore-magmatic system has been identified, and criteria have been developed for assessing erosion and predicting gold mineralization to depth.

Геодинамические обстановки формирования рудно-магматических систем Восточного Донбасса по петрохимическим данным

Статья посвящена решению одной из научных проблем металлогении Восточного Донбасса, определяющей связь рудных проявлений и магматизма с геодинамическими условиями развития региона в мезозое. Цель исследования. Оценка геодинамических условий формирования на основе петрохимических данных выявленных ранее в Восточном Донбассе рудно-магматических систем (РМС). Актуальность исследования. Выявление геодинамических обстановок древних конвергентных и трансформных окраин является важной проблемой современной геологии, поскольку с такими обстановками связаны специфические магматические комплексы и месторождения полезных ископаемых. Методы исследования. Использованы петрохимические критерии выявления трансформных окраин, разработанные дальневосточными учеными, в частности тройные диаграммы, способные разделять магматические породы надсубдукционных обстановок, и магматические породы, образовавшиеся в обстановке трансформных окраин в зоне скольжения литосферных плит. Применена разработанная этими авторами тройная диаграмма для петрогенных оксидов (TiO2×10)–(Fe2O3+FeO)–MgO, основанная на процентном соотношении титана, железа и магния относительно суммы оксидов этих элементов, приведенных к 100 %. В качестве исходных материалов использованы химические анализы интрузивных пород Восточного Донбасса, заимствованные из производственных отчетов. Геодинамические обстановки формирования РМС центрального типа оценены на примере Кондаковской РМС, ареального типа – на примере Тузловской РМС. Результаты исследования. Установлено, что при формировании Кондаковской РМС центрального типа определяющей являлась надсубдукционная геодинамическая обстановка, которая со временем сменилась на обстановку скольжения плит с проявлением соответствующего магматизма и гибридизации заключительных порций магмы несветаевского комплекса за счет лампрофировой магмы. При формировании Тузловской РМС ареального типа основным источников магматизма, образующего интрузивные тела миусско-керчикского комплекса, могли являться подслэбовая астеносфера или деплетированная мантия. Интрузивный магматизм миусско-керчикского комплекса проявился при переходе надсубдукционного геодинамического режима в режим скольжения литосферных плит в результате коллизии континентальных окраин или смены направления движения, после прекращения субдукции. Resume. The article is devoted to solving one of the scientific problems of metallogeny of the Eastern Donbass, which determines the relationship of ore manifestations and magmatism with the geodynamic conditions of the development of the region in the Mesozoic. The purpose of the study. Assessment of geodynamic conditions of formation based on petrochemical data of ore-magmatic systems (RMS) previously identified in the Eastern Donbass. The relevance of research. The identification of geodynamic environments of ancient convergent and transform margins is an important problem of modern geology, since specific magmatic complexes and mineral deposits are associated with such environments. Research methods. The petrochemical criteria for identifying transform margins developed by Far Eastern scientists were used, in particular, triple diagrams capable of separating igneous rocks of suprasubduction environments and igneous rocks formed in the environment of transform margins in the zone of sliding lithospheric plates. The triple diagram developed by these authors for petrogenic oxides (TiO2×10)–(Fe2O3+FeO)–MgO is used, based on the percentage ratio of titanium, iron and magnesium relative to the sum of oxides of these elements reduced to 100%. Chemical analyses of intrusive rocks of the Eastern Donbass, borrowed from production reports, were used as starting materials. Geodynamic conditions of the formation of the RMS of the central type are estimated on the example of the Kondakov RMS, the areal type – on the example of the Tuzlovskaya RMS. The results of the study. It was found that during the formation of the Kondakov RMS of the central type, the suprasubduction geodynamic situation was decisive, which eventually changed to a plate sliding situation with the manifestation of the corresponding magmatism and hybridization of the final portions of the magma of the Nesvetaevsky complex due to lamprophyric magma. During the formation of the Tuzlovskaya RMS of the areal type, the main sources of magmatism forming the intrusive bodies of the Miusko-Kerchik complex could be the sublab asthenosphere or depleted mantle. The intrusive magmatism of the Miusko-Kerchiksky complex manifested itself during the transition of the suprasubduction geodynamic regime to the sliding regime of lithospheric plates as a result of a collision of continental margins or a change in the direction of movement, after the cessation of subduction.

Current actual issues of gold meniralization of the Central Kyzylkum

As a result of the analysis of the data available and collected in recent years, in contrast to the well-established ideas about the polygenic and poly-stage nature of the mineralization, it is indicated that the gold mineralization of the Central Kyzyl Kum is formed as a result of the formation of a single ore-magmatic system, which develops in the same type regardless of the composition and age of the host rocks; during the formation of deposits, the most important thing is the presence of a process that promoted ore formation, which should serve as the basis for judgements in problems of the genesis and forecasting of industrial facilities. Some problematic issues on the geology of ore deposits are noted.

Paleoproterozoic East Pana Layered Intrusion (Kola Peninsula, Russia): Geological Structure, Petrography, Geochemistry and Cu-Ni-PGE Mineralization

The East Pana intrusion is a part of the Paleoproterozoic Fedorova–Pana complex (FPC), which belongs to the group of Fennoscandian layered mafic–ultramafic massifs. This article discusses the magmatic stratification of the East Pana intrusion, as well as Cu-Ni and platinum-group elements (PGE) mineralization (PGE zones A, B and C) in its various parts with a total length of more than 20 km, including the East Chuarvy PGE deposit. Based on the whole-rock data on the distribution of major, trace, and ore-forming elements, it is assumed that PGE zone A belongs to the main ore–magmatic system of the FPC, while PGE zones B and C belong to the minor ore–magmatic systems. At the same time, additional magmatic injection played an important role in the formation of economic Cu-Ni-PGE mineralization (PGE zone B), characterized by high PGE concentrations and moderate palladium enrichment. On the normalized distribution spectra of trace elements, the crystallization products of this injection (Gabbronorite Zone 2) have a positive Zr-Hf anomaly, which distinguishes it from host rocks with an anomaly of the opposite sign (Gabbronorite Zone 1, Gabbro Zone). It is assumed that this portion of magma was intruded as a sill of crystal mush, the fractionation of which at depth led to its enrichment with residual liquid.

Geodynamic factors in the formation of large gold-bearing provinces with Carlin-type deposits on continental margins in the North Pacific

<abstract> <p>Several similar indicators in Nevada (USA) and South Yakutia (Russia) gold-bearing provinces have been identified based on modern tectonic, geophysical and seismic tomography observations, followed by the analysis of the main geodynamic factors of the formation and distribution of large gold-bearing provinces in the North Pacific. One of the significant metallogenic peculiarities is a wide variety of formational and mineral deposits concentrated in the areas. Both provinces are situated at active margins surrounded by fold-thrust belts. In South Yakutia, a combination of sublatitudinal Baikal-Elkon-Ulkan and submeridional Seligdar-Verkhnetimpon gravity field gradient zones is recorded. In contrast, significant positive gravity anomalies of the Northern Nevada Rift and higher-order gradient zones are presented in Nevada. Large pluton and transform fault zones in both provinces support a conclusion about the fundamental role of geodynamic factors in developing ore-magmatic systems in the regions. Significant differences in the scale of the gold mineralization in the considered provinces are explained by the existence under the North American continent not only of the Mendocino transform fault zone but also of the Juan de Fuca paleo-spreading center. In contrast, the Inagli-Konder-Feklistov magmatic-metallogenic belt alone controls mineralization under the Asian continent.</p> </abstract>

Geological features, hydrothermal alterations, and cryptic mineralogical zonation of the Kyzyk-Chadr porphyry copper deposit (Tyva Republic)

The altered rocks of the Kyzyk-Cha dr deposit are predominantly composed of quartz and potassic dioctahedral micas of the phengite–muscovite series, that dominate in almost all zones of the alteration halo. Parageneses of albite with chlorite and epidote are only characteristic of peripheral sections of the halo, subjected to the propylite-type alteration. Quartz-potassium feldspar alterations are distributed in the central and deep-seated sections of the halo. Petrographic investigations of hydrothermal alterations and results of the X-ray structural analysis and infrared (IR) spectroscopy of micas from the mineralized quartz-sericite metasomatites were applied to reveal a cryptic mineralogical zonation of the Kyzyk-Chadr porphyry copper deposit. Elements of the cryptic mineralogical zonation, revealed based on results of the X-ray study and IR spectroscopy of light-colored micaceous metasomatites of the deposit, are caused by variable proportions of the phengite and muscovite components in their composition. The phengite component predominates in the central and deep-seated sections of the alteration-mineralization halo of the deposit, while the muscovite component progressively increases toward its flanks and upper sections. This tendency correlates with the general vector of the mineralogical alteration-mineralization zonation and are supposedly explained by changing PT conditions within the porphyry copper ore-magmatic system. The indicator of the cryptic mineralogical zonation by the “phengite-muscovite” relationship can be applied for prospecting and preliminary evaluation of porphyry copper type deposits, being used as an objective guide for correlation of already obtained ore-grade interceptions and forecasting the ore bodies.

Chronology of Alkaline Magmatism and Gold Mineralization in the Central Aldan Ore District (Southern Yakutia)

Abstract —The Central Aldan ore district (CAOD) is unique by the abundance of gold deposits associated with Mesozoic alkaline magmatism. Four types of gold deposits are established here: porphyry gold, gold–sulfide, gold–argillizite-K-feldspar–quartz, and gold–uranium. The available geochronological data on the age of igneous rocks and gold mineralization in the CAOD show that the latter formed in the period 151–120 Ma. These data also agree with the results of the U–Pb dating of the El’kon gold–uranium ore-magmatic system (143–125 Ma). Analysis of our and earlier published geochronological data showed two stages of magmatism evolution in this region. At the early stage (151–130 Ma), most of the alkali syenites, monzonites, and their analogues (sills, stocks, ring intrusions, and volcanic sequences) and ores formed. They are widespread in various deposits and massifs. In the Ryabinovyi massif, this stage is marked by the formation of most of the alkaline rocks (Aldan Complex) and ores: aegirine syenites, 151.4 ± 1.9 Ma; pyroxene–K-feldspar pegmatites, 144.8 ± 1.5 Ma; and Au–Cu ores, 137.5 ± 1.7—131.1 ± 16 Ma. The crystallization of amphibole in the syenite of the Lunnoe deposit (143.1 ± 2.0 Ma) and in the clinopyroxenite of the Inagli massif (142.4 ± 2.0 Ma) and the formation of most of the alkaline rocks of its ring framing also took place at this stage. At the Samolazovskoe deposit, this stage is marked by the formation of zircon in pseudoleucite syenite, 135.9 ± 1.9 Ma, and in different syenite porphyry phases, 141.39 ± 0.90—142.4 ± 5.0 and 134.25 ± 0.70—129.9 ± 2.6 Ma, as well as gold–skarn mineralization, 129.9 ± 2.6—134.9 ± 2.8 Ma. The same period included the formation of primary ores at the Kuranakh deposit, 136.2 ± 1.7 Ma, and the deposition of brannerite mineralization at the Lunnoe deposit, 132.4 ± 1.6 Ma. Early intrusive phases, such as potassic picrites, shonkinites, and lamprophyres, are scarce among the products of this stage of magmatism, which is possibly due to their burial beneath large volumes of later formed alkali syenites and monzonite–syenites. The second stage (128–120 Ma) was distinguished within the Ryabinovyi massif as small intrusions and dikes of olivine lamproites, shonkinite porphyry, minettes, and syenite porphyry. We revealed explosive breccias with an age of 127 Ma at the Samolazovskoe deposit. Magmatism of this stage was of limited occurrence in the CAOD and did not produce alkali syenites, monzonite–syenites, and ores. At the same time, rocks with an age of 121.1 ± 1.3—115.5 ± 1.6 Ma are widespread in the large (120 km2) Dzheltula ring massif of the Tyrkanda ore district, located east of the Central Aldan region.

СТАНОВЛЕНИЕ ГРАНИТОИДНЫХ (ГАББРО-ГРАНИТНЫХ) ПЛУТОНОВ И СВЯЗАННОГО С НИМИ ОРУДЕНЕНИЯ

Deep geological and geophysical modeling by a large number of granitoid plutons for the first time showed a completely different nature than was commonly believed. As a result, ideas about the connection of mineralization with them have changed dramatically. Many petrological contradictions and puzzles were solved logically and scientifically grounded. The complete and comprehensive review of the problem from the beginning (source of the initial magma) to the end (formation of the granite ore-magmatic system) is given. Three stages of the volatiles and ore matter concentration in the history of the plutons formation were established: the first (planetary) - during the intrachamber differentiation of the initial basalt magma with an isolation of granitoid melting; the second (regional) - during the formation of a residual leukogranite chamber the third, main (local) - during the intrusion of ore-generating apophyses from the chamber.

Formational types of porphyry copper deposits and their ore-magmatic systems

Two individual ore-formational types have been identified within the porphyry copper family: the gold-copper-porphyry and molybdenum-copper-porphyry ones. The fundamental difference between them lies in their geotectonic position that determines the origin and composition of fertile magmatic source, as well as other features the composition of ore-bearing porphyry intrusions, the mineralogical and geochemical features of ores, and the pattern of metasomatic and ore zonation. In this study, we investigated porphyry copper ore-magmatic systems with complex metallogeny, or complex porphyry copper systems (CPCS), where porphyry copper deposits constitute the core elements spatially associated with mineralization of other ore-formational types. Based on a set of conjugated and combined types of ore mineralization we established the differences between diorite-related gold-copper-porphyry CPCS, formed in basaltic volcano-plutonic belts, and granodiorite-monzonite-related molybdenum-copper-porphyry CPCS, formed in andesite belts. These differences confirm the validity of the distinction of the two ore-formational types of deposits of the porphyry-copper family.

Volcanic Massive Sulfide Complexes of the Magnitogorsk Paleoisland Arc Megazone in the Southern Urals: Models of Ore-Magmatic System and Geodynamic Reconstructions

Volcanic Massive Sulfide Complexes of the Magnitogorsk Paleoisland Arc Megazone in the Southern Urals: Models of Ore-Magmatic System and Geodynamic Reconstructions