Microbial processes and the origin of the Úrkút manganese deposit,Hungary

The Transdanubian Range (Hungary, ALCAPA Unit) preserves a series of black shale-hosted Mn-carbonate deposits and cherty, Fe-rich Mn-oxide mineralized rocks associated with varicolored metalliferous claystones. Coccoid clumps (spherules), oval, tubular, and filamentous morphologies were observed by petrography, SEM-EDS, and TEM studies and are interpreted to be mineralized cellular materials. Local selective enrichment of bioessential elements (Mn, Fe, S, As, P, Mg, Ba, Sr, Co, Ce) occurs, and together with low δ¹³C values of the Mn carbonates also supports microbial mediated reactions. The results strongly suggest that the formation of Mn–Fe and Si minerals was associated with microbial metabolic processes. The role of aerobic chemolithoautotroph bacteria was essential in sequestering metal ions (Mn^2 +, Fe^2 +) from solution, which were deposited in the sediment pile and serve as a paleoenvironmental indicator of oxic conditions. These deposits are examples of, and therefore provide important criteria for identifying, non-sulphidic, oxic, microbial mineral processes. We provide a new genetic model for giant black shale-hosted Mn-carbonate deposits that involves episodic aerobic microbial processes.Although a part, if not the whole of the black shale-hosted Mn-carbonate deposits is of biogenetic-bacterial sedimentary origin, a hydrothermal/exhalative source of metals may have contributed to the formation of the deposits. An Fe–Mn-oxide chimney system is proposed to be a proximal facies to geofluid vents that occurred along fracture systems, which may have provided metals from deep-seated sources.     

Fe-Mn oxide indications in the feeder and mound zone of the Jurassic Mn-carbonate ore deposit, Úrkút,Hungary

The Úrkút manganese deposit, one of the World's largest, is located in the central part of the Transdanubian Range, western Hungary. The deposit is interbedded with Mesozoic limemarlstone. The Fe-Mn-oxide indications of a feeder and mound zone embedded in limemarlstone at the footwall of the Mn-carbonate ore deposit were studied using 45 samples (Úrkút Mine, Shaft III, deep level). Microstructural and textural (optical microscopy, SEM-EDS) observations, mineralogy (XRD-μXRD), and geochemistry (ICP, C and O by IR-MS) were used to characterize the host marlstone and the Fe-Mn oxides of the feeder and mound zone. High-resolution in situ and bulk organic matter analyses were performed for the first time using GC–MS, FTIR-ATR, and Raman spectroscopy. Stromatolite-like, filamentous and coccoid microstuctures built up of Fe-Mn-oxides (ferrihydrite, goethite, manganite, pyrolusite, hollandite, birnessite, hausmannite) and silica occur in the micritic marlstone host rock among common calcite biodebris (microfossils and Echinozoa fragments) and rare detrital clasts (quartz, feldspar). The clay minerals occur as greenish patches in the limemarlstone and show boring traces. The calcite matrix of the limemarlstone and idiomorphic dolomite are authigenic. δ¹³C_PDB values of the carbonate in the host limemarlstone reflect greater organic matter contributions approaching the mineralized areas (0.64 to − 21.35‰). Temperature calculation based on δ¹⁸O_SMOW values of the carbonate, assuming equilibrium conditions, show elevated temperatures toward the mineralized areas (9.93 to 29.87‰). In places, the Mn oxides appear with Fe oxides in laminated, micro-stromatolite-like structures. In these oxide zones, variable kinds of organic compounds occur as intercalated microlaminae identified by FTIR and Raman line-profile analyses as aromatic hydrocarbons. Results indicate that metal-bearing fluids infiltered the unconsolidated micritic limemarl. Fe-oxide enrichment occurred most probably through iron oxidizing microbes under suboxic, neutrophilic conditions, while Mn oxide formed most probably by active surface catalyses. At the sediment/water interface, Fe-Mn-oxide stromatolite mounds (chimneys) formed in rift zones from the discharge of fluids of elevated temperature. The host marl itself may have originated by microbially mediated reactions (clay minerals and calcite micrite).     

Refinement of genetic and structural models of the úrkút manganese ore deposit (W-Hungary, Europe) using statistical evaluation of archive data

Although the úrkút manganese ore deposit in western placecountry-regionHungary has been exploited for at least 90 years, there are still numerous open questions concerning ore genetics as well as structure and geometry of the ore body. A large set of available archive data for the deposit have been reviewed and evaluated in order to solve some of the most crucial problems. For processing, besides diverse GIS approaches, univariate and multivariate statistical methods were used on the created unified database. The main aims of the mathematical treatment were giving a classification scheme for the wide spectrum of Mn-ores based on their chemical composition (Mn, Fe, Si, P) as well as evaluation of their spatial distribution. For the ore characterization and understanding the genetic processes, cluster and discriminant function analyses were used. Results of the multivariate treatment verified the existence of different ore types and provided an exact chemical definition for all of them. It alsoinferred that the main geochemical processes that took place in ore genesis were similar for all sample groups (ore types) with significantly different weights in each case. A 3D evaluation of the úrkút mine heading map system shows that the ore body covers the footwall surface as a stratiform sheet throughout the study area. Palaeo-relief studies suggest a significant difference between the footwall and hanging wall morphologies which clearly implies tectonic activity following ore deposition. The deposit was affected by an E-W compression stress field near the Aptian-Albian transition causing folding of the Mn deposit.     

Genesis of a low-grade apatite-ilmenite-magnetite deposit in the Kauhajärvi gabbro, western Finland

The Paleoproterozoic Kauhajärvi gabbro is one of several Fe-, Ti-, and P-rich mafic intrusions associated with granitoids in the Fennoscandian shield in western Finland. The gabbro is cut by the late-orogenic Lauhanvuori granite (ca.1870?Ma), whereas the surrounding area is composed of synorogenic, collision-related granitoids and calc-alkaline volcanic rocks (ca. 1890?Ma) belonging to the Mid Finland Granitoid Complex. The mafic intrusions were probably emplaced into a Svecofennian rift zone. They are characterized by a high phosphorus content; the common occurrence of ilmenite as separate grains; and the coeval crystallization of apatite, Fe-Ti oxides, and Fe-Mg silicates. The Kauhajärvi gabbro is composed of two geochemically and structurally distinct zones. The basal zone is composed of poorly-layered, fine- to medium-grained gabbro, which represents an early intrusion of tholeiitic magma, and has rather high concentrations of chromium, magnesium and silica. Typically, the concentrations of iron, titanium and phosphorus are low, except for the top that is enriched in apatite and ilmenite. During most of the crystal-liquid fractionation of the basal zone magma, low f _O2 limited the crystallization of Fe-Ti-oxides. Instead, titanium became enriched in the uppermost layer of the basal zone. The main zone represents a later injection of more evolved tholeiitic magma and makes up 80 to 90%of the total intrusion volume. Peridotite is common, along with gabbro and gabbronorite, in the lower and middle parts of the main zone, and anorthosite is common near the top of the main zone. The Mg:Fe ratio in mafic minerals and vanadium concentrations in magnetite decrease upwards. The variation within the main zone can be explained by crystal-liquid fractionation of a single batch of a parental magma under conditions of relatively high f _O2. Titanium is not progressively enriched. The ratio of titanium to iron (TiO₂/Fe₂O₃ = 0.16 to 0.20; Fe total as Fe₂O₃) is constant in the main zone and normal for mafic intrusions. Titanium is sited in separate ilmenite grains and in lamella within ilmenomagnetite (Ti-bearing magnetite). The high phosphorus content in the main zone is interpreted to result in crystallization of ilmenite and ilmenomagnetite instead of Ti-rich magnetite under relatively high f _O2 conditions. High concentrations of titanium, iron and phosphorus in rocks of the main zone can be explained by pre-emplacement crystal-melt fractionation in a deep magma reservoir and/or contamination of mantle-derived mafic magmas by granitic magmas from partial melting of crustal rocks. A low-grade Fe-Ti-P resource at Kauhajärvi consists of layers with as much as 20 wt. % combined ilmenite (usually 8 to 11 wt. %), apatite (1 to 8 wt. %) and magnetite (1 to 9 wt. %). Mineralized layers are of variable thickness (2?m to 30?m) and occur in variable host rocks (peridotite or gabbro). The Fe-Ti oxides are most abundant in peridotite and pyroxene- or olivine-rich gabbronorite within the main zone. The contact between mineralized rocks (4%TiO₂) and non- or slightly-mineralized rocks is gradual. The deposit as a whole consists of three to five mineralized layers with maximum combined thickness of 70?m. Apatite is most abundant in the oxide-rich layers, but is locally also concentrated in anorthosite with low Fe-Ti oxide contents. The weight ratio of ilmenite to magnetite is 3:2. The ratio of total Ti-Fe-oxides to apatite averages 4.0, with the range of 1.5 to >15.     

Sequence of mineral formation in clastic ores of the Saf’yanovka volcanic-hosted copper massive sulfide deposit,the Central Urals

The bedded clastic ore widespread on the slopes and flanks of the deeply eroded sulfide mound at the Saf’yanovka volcanic-hosted copper massive sulfide deposit consists of products of destruction of the Paleozoic black smoker along with diverse newly formed sulfides. The size of ore clasts gradually decreases with distance from the massive ore mound, from more than tens of centimeters to a few millimeters. The clastic sediments are characterized by good preservation of sulfide material composed of hydrothermal sedimentary colloform pyrite, chalcopyrite with lamellae of relict isocubanite, and concentrically zoned sphalerite. Numerous pyrite framboids, nodules, and euhedral crystals; chalcopyrite segregations; and twinned sphalerite are typical of sulfide-bearing black shale. Enargite, tennantite, and galena were formed after pyrite, filling interstices between nodules or partially replacing and corroding the previously formed minerals. The interrelations between minerals show that the fine-clastic sulfide-bearing black shale underwent diagenesis in the presence of organic matter.     

Uranyl molybdates in fluorites and uranium-carbonate ores from the Strel’tsovskoe ore field of the Argun deposit

Microprobe research was performed on transparent polished plates (thin sections) of samples of fluorite and uranium ore from the Argun deposit in Zabaikal’skii Krai, Russia. The composition of minerals was determined at the Center for Isotopic Study of the Russian Geological Research Institute using a Cam-Scan MX 2500 scanning electron microscope equipped with a Link Pentaflet energy-dispersion spectrometer. Certified natural and synthetic samples were used as the standards.     

First discovery of high-mercury silver in ores of the Rogovik gold–silver deposit (Northeastern Russia)

New data on mercurial mineralization are presented, and a detailed characteristic is given for the first discovery of mercurous silver in ores of the Rogovik gold–silver deposit (the Omsukchan trough, Northeastern Russia). It was found that native silver in the examined ores occurs as finely-dispersed inclusions in quartz filling microcracks and interstitions. It also occurs in associations with kustelite, Ag sulfosalts and selenides, selenitic acanthite, and argyrodite. The mercury admixture varies from “not detected” in the central parts of grains to 0.22–1.70 wt % along the edges, or, in independent grains, to the appearance of Ag amalgams containing 10.20–24.61 wt % of Hg. The xenomorph form of grains of 50 μm or less in size prevails. It is assumed that the appearance of mercurial mineralization is caused by the superposition of products of the young Hg-bearing Dogda–Erikit belt upon the more ancient Ag-bearing Omsukchan trough.

     

Genesis of the boron potential of the Taukha metallogenic zone,Sikhote Alin,and boron sources during formation of the Dal’negorsk boron deposit

It is shown that the formation of borosilicate skarn in the Taukha metallogenic zone completes a series of successive stages of the formation and transformation of the folded sequences of the Taukha accretionary wedge. The Early Cretaceous sedimentary stage, including accumulation of detrital tourmaline-rich sedimentary rocks, was implemented in the marginal sea of the Paleopacific Sino-Korean segment. In the Turonian–Campanian, the boron-bearing folded sequences of the accretionary wedge were involved in anatexis to generate siliceous S-type boron-bearing melts. The thus-formed magmatic chambers were emptied during catastrophic volcanic eruptions. At the final Middle Campanian volcanic stage, fluid-magmatic differentiation of the melt in the residual chambers generated fluid flow. The infiltration interaction of the fluids, which inherited enrichment in boron, with limestones of the olistostrome sequence resulted in the formation of a giant zone of grossular–wollastonite skarns and danburite lodes. The boron potential of the Taukha boron–lead–zinc metallogenic zone may be considered as a reproduction of the Precambrian boron metallogeny of the eastern Eurasian margin, which was implemented in the Late Mesozoic during recycling of the continental crust.     

Platinum-, palladium- and gold-rich arsenide ores from the Kylmäkoski Ni-Cu deposit

Summary The Kylmäkoski deposit consists of a disseminated primary Ni-Cu mineralization hosted by a differentiated ultramafic body. It also shows sulfide veins (tens of meters long and up to 20 cm thick) that evolve laterally to massive Ni-arsenide ores. In these sulfide/arsenide veins, three different ore assemblages can be distinguished: 1) sulfide ores (S ores) composed of pyrrhotite, pentlandite and chalcopyrite with minor amounts of cubanite, sphalerite and argentopentlandite which locally occurs intergrown with Ag-free pentlandite; 2) sulfide/arsenide ores (S/As ores) made up of the former S ores corroded and replaced by nickeline (locally with graphite), with gersdorffite filling discordant veins, abundant minute grains of sudburyite and accessory molybdenite, ullmanite, stibnite, galena and breithauptite; 3) arsenide ores (As ores) composed of nickeline, maucherite and disseminated, zoned cobaltite, with minor chalcopyrite, cubanite, sperrylite, sudburyite, electrum, galena, altaite and pilsenite. These veined ore assemblages were generated by the remobilization of primary, late magmatic arsenide-rich ores (well represented in the Vammala mine) by the intrusion of pegmatitic fluids derived from the partial melting of the metasedimentary country rocks.The early fractional crystallization of the monosulfide solid solution produced a residual As-rich melt that collected most noble metals (specially Pt, Pd and Au) leaving the primary Ni-Cu sulfide ores impoverished in these elements. In fact, late magmatic arsenide ores from Vammala contain up to 42.5 ppm Pd (in the form of extremely fine inclusions of sudburyite in nickeline and maucherite, and dissolved in trace amounts in the lattice of the latter Ni arsenides) and 9.6 ppm Au (concentrated in abundant minute inclusions of electrum in Ni arsenides). Later, during the remobilization of the primary arsenide ores of Kylmäkoski, Pd concentrated both in S/As and As ores in the form of sudburyite and in a rare PdBi compound. It also occurs in trace amounts in nickeline from S/As ores and in maucherite from As ores. Pt mainly concentrated in As ores as sperrylite and, in minor amounts in pilsenite and in cobaltite coronas around sperrylite. It occurs in trace amounts in the cores of zoned cobaltite. Gold is always present in the form of irregular grains of electrum in As ores.

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Pt- Pd- und Au-reiche Arseniderze von der Ni-Cu Lagerstätte Kilmäkoski (Vammala Nickel-Gürtel, SW Finnland)

Zusammenfassung Die Lagerstätte Kilmäkoski ist eine disseminierte primäre Ni-Cu-Vererzung, die in einem differenzierten ultramafischen Körper aufsitzt. Hier treten auch Sulfid-Gänge, die bis zu Zehnern von Metern lang und bis zu 20 cm mächtig sein können, auf; aus diesen entwickeln sich lateral massive Nickel-Arsenid Erze. Drei Erzparagenesen können in diesen Sulfid-Arsenid-Gängen unterschieden werden: 1. Sulfidische Erze mit Pyrrhotin, Pentlandit, Kupferkies und geringen Mengen von Cubanit, Zinkblende und Argentopentlandit der örtlich mit Ag-freiem Pentlandit verwachsen ist 2. Sulfid-Arsenid Erze, die aus korrodierten und durch Rotnickelkies verdrängten Sulfid-Erzen bestehen. Diese führen örtlich Graphit, Gersdorffit kommt als Füllung diskordanter Gänge vor. Außerdem gibt es verbreitet kleine Körner von Sudburyit und akzessorischem Molybdänit, Ullmanit, Antimonglanz, Bleiglanz und Breithaup tit. 3. Arsenid-Erze, die aus Rotnickelkies, Maucherit und disseminiertem, zonarem Kobaltit, mit Kupferkies, Cubanit, Sperrylit, Sudburyit, Elektrum, Bleiglanz, Altait und Pilsenit als Nebengemengteile bestehen. Diese gangförmigen Erzparagenesen entstanden durch die Remobilisation von primären, spätmagmatischen Arsenidreichen Erzen, die in der Vammala-Mine sehr gut aufgeschlossen sind, und auf die Intrusion pegmatitischer Fluide zurückgehen, die durch teilweises Aufschmelzen der metasedimentären Nebengesteine entstanden sind.Die frühe fraktionierte Kristallisation der Monosulfid Solid Solution führte zu einer residualen As-reichen Schmelze, die den Großteil der Edelmetalle (besonders Pt, Pd und Au) aufgenommen und die primären Ni-Cu Sulfiderze an diesen Elementen verarmt zurückgelassen hat. Spätmagmatische Arseniderze aus Vammala enthalten bis zu 42,5 ppm Pd (in Form von extrem feinkörnigen Einschlüssen von Sudburyit in Rotnickelkies und Maucherit, und als Spurengehalte im Gitter der späten Nickel-Arsenide), sowie 9,6 ppm Au, das hauptsächlich in den verbreiteten winzigen Einschlüssen von Electrum in Nickelarseniden vorkommt. Während der späteren Remobilisierung der primären Arseniderze von Kylmäkoski wurde Pd sowohl in S/As und As-Erzen in der Form von Sudburyit und in einer seltenen Pd-Bi Verbindung konzentriert. Es kommt auch als Spurenelement im Rotnickelkies aus S/As-Erzen und im Maucherit aus As-Erzen vor. Pt is vorwiegend in As-Erzen konzentriert, und zwar als Sperrylit, sowie in geringen Mengen in Pilsenit und in Colbaltit-Rändern um Sperrylit. Es kommt in Spurenelementen in den Kernen von zonaren Kobaltiten vor. Gold liegt stets in Form unregelmäßiger Elektrum-Körner in As-Erzen vor.

     

Geology, Geochemistry and Genesis of the Hongshijing Gold Deposit in Ruoqiang,Xinjiang

1IntroductionTheHongshijinggolddepositislocatedinthenorthofLuobupouLakeofRuoqiang ,about 30 0kmsouthwestofHamiCity ,Xinjiang .ItwasdiscoveredbytheSixthGeologicalTeamofXinjiangduringgeo chemicalexploration .TheHongshijinggolddeposit,whichoccursinthegold bearingformationcomposedofMiddleandLateCarboniferousvolcanicandpyroclasticrocks ,isabrittle ductileshearzonetypegolddepositcontrolledbyariftbelt.TheHongshijinggolddepositislocatedinthesouthwestoftheHongshi jing -Maotoushanmineralizationb…     

On the Genesis of the Super-large Baguamiao Gold Deposit in Fengxian County, Shaanxi Province

The Baguamiao gold deposit in Fengxian County, Shaanxi Province, is a recentlyexplored super-large gold ore deposit. A comprehensive and deep-going study has revealedthat it is a polygenetic deposit: early-stage mineralization due to shearing, middle-stagemineralization due to hydrothermal alteration, and late-stage mineralization due toweathering, leaching and concentration at shallow depths. Shearing played a dominant role inthe formation of gold orebodies.     

Genesis of the mineral groundwaters of the Razdol’nenskii occurrence in Primorye

Original isotopic and chemical data are reported on the groundwater and gases from the unique occurrence of mineral water in the coastal zone of southern Primorye. Results of the δ¹⁸O and δ²H analysis of the underground and surface water of the area integrated with their δ¹³C composition made it possible to solve the problem of the genesis and evolution of groundwater and gases in the coastal part of the Sea of Japan. It was established that meteoric waters penetrate into the Mesozoic terrigenous rocks and changed their chemical composition under the influence of transformation of organic matter from the host rocks. CO₂ released owing to reactions provides multiple enrichment of the water in HCO₃ and stimulates Na influx via dissolution of aluminosilicates.     

Genesis of the Nanyangtian scheelite deposit in southeastern Yunnan Province,China: evidence from mineral chemistry,fluid inclusions,and C–O isotopes

The Nanyangtian skarn-type scheelite deposit is an important part of the Laojunshan W–Sn polymetallic metallogenic region in southeastern Yunnan Province, China. The deposit comprises multiple scheelite ore bodies; multilayer skarn-type scheelite ore bodies are dominant, with a small amount of quartz vein-type ore bodies. Skarn minerals include diopside, hedenbergite, grossular, and epidote. Three mineralization stages exist: skarn, quartz–scheelite, and calcite. The homogenization temperatures of fluid inclusions in hydrothermal minerals that formed in different paragenetic phases were measured as follows: 221–423 °C (early skarn stage), 177–260 °C (quartz–scheelite stage), and 173–227 °C (late calcite stage). The measured salinity of fluid inclusions ranged from 0.18% to 16.34% NaCleqv (skarn stage), 0.35%–7.17% NaCleqv (quartz–scheelite stage), and 0.35%–2.24% NaCleqv (late calcite vein stage). Laser Raman spectroscopic studies on fluid inclusions in the three stages showed H₂O as the main component, with N₂ present in minor amounts. Minor amounts of CH₄ were found in the quartz–scheelite stage. It was observed that the homogenization temperature gradually reduced from the early to the late mineralization stages; moreover, δ¹³C_PDB values for ore-bearing skarn in the mineralization period ranged from ? 5.7‰ to ? 6.9‰ and the corresponding δ¹⁸O_SMOW values ranged from 5.8‰ to 9.1‰, implying that the ore-forming fluid was mainly sourced from magmatic water with a minor amount of meteoric water. Collectively, the evidence indicates that the formation of the Nanyangtian deposit is related to Laojunshan granitic magmatism.     

REE characteristics of the Fanshan alunite deposit in Zhejiang Province, China

1 Introduction Alunite [KAl3(SO4)2(OH)6] is a very important non-ferrous metal resource, so many countries throughout the world have made great investments in research on the mechanism of its formation, its geological characteristics and applications. O…     

Genesis of fahlore in the Tianbaoshan lead–zinc deposit,Sichuan Province,China: a scanning electron microscopy–energy dispersive spectroscopy study

The Tianbaoshan deposit, located in the southwestern part of the Yangtze Block, is a representative Pb–Zn deposit in the Sichuan–Yunnan–Guizhou Pb–Zn metallogenic province. The Pb–Zn orebodies are hosted in the upper Sinian Dengying Formation dolostone. The predominant minerals are sphalerite, galena, pyrite, chalcopyrite, quartz, and calcite with minor arsenopyrite, fahlore, and dolomite. The deposit is characterized by relatively strong Cu mineralization. However, the relationship between Pb–Zn and Cu mineralization is unknown. We analyzed the mineralogy and composition of fahlore, chalcopyrite, arsenopyrite, sphalerite, and galena using scanning electron microscopy–energy dispersive spectroscopy, with the aim of providing new evidence for the genesis of the Pb–Zn–(Cu) ore. The results show that the Cu ore in the deposit is dominated by chalcopyrite and fahlore, both of which formed before or during the Pb–Zn ore-forming stage. The fahlore showed dramatic compositional variation and was characterized by negative correlations between Ag and Cu, and between As and Sb, suggesting substitution of Ag for Cu, and that As and Sb substitute in the same site in the fahlore lattice. Based on backscattered electron images and composition, the fahlore was divided into two types. Type I fahlore crystallized early and is characterized by enrichment of Cu and depletion in Ag and Sb. Type II fahlore formed after Type I, and is rich in Ag and poor in Cu and As. Moreover, galena and fahlore are the host minerals of Ag. The variation of valence state with As host mineral—from fahlore to arsenopyrite—indicates the metallogenic environment changed from relatively oxidizing to reducing with a high pH. In the light of Gibbs energies of reciprocal reactions and isotherms for cation exchange, the composition of the fahlore implies its ore-forming temperature was lower than 220 °C, corresponding with typical Mississippi Valley-type (MVT) deposits. Based on the geologic character and geochemical data of this deposit, we suggest that the Tianbaoshan deposit belongs to the MVT deposit category.     

Explosion breccias of the Vysokogorskoe tin–porphyry deposit: Genesis and role in ore formation (Kavalerovo ore district,Primorye)

Detailed geological observations and analytical studies make it possible to distinguish two groups of fluid-explosion breccias (FEB) in the Vysokogorskoe tin deposit of the Kavalerovo ore district. These breccias are assumed to be related to different stages of geological (geodynamic) evolution and played different roles in ore formation. The earlier breccias (79–69 Ma), which were altered by boron metasomatism and subsequent main tin mineralization, were most probably formed at the Cretaceous subduction stage. The later breccias (55–51 Ma) are syngenetic to the dacite (rhyolite) porphyry dikes of the Paleocene–Eocene transform stage. They were formed after precipitation of the majority of the cassiterite, but prior to the latest quartz–fluorite–carbonate stage of ore formation. According to the Sillitoe classification, the explosion breccias of the Vysokogorskoe deposit correspond to a magmatic–hydrothermal genetic type. They are characterized by multiple brecciation and intersection by small bodies of porphyritic rhyolites.