This paper considers geological, mineralogical, and geochemical features of the epithermal Au‒Ag mineralization at the Televeem volcanic dome uplift (VDU) which complicates the Verkhne-Pykarvaam volcano-tectonic depression (VTD) in the Central Chukchi sector of the Okhotsk–Chukchi volcanogenic belt (OCVB). The structure of this ore occurrence is due to its localization within the eponymous VDU. The main vein zone (MVZ) of the Televeem ore occurrence, as wide as 500 m, extends for 2.5 km in the north–south direction. Along the MVZ direction, en-echelon proximal quartz–adularia veins are successively replaced with zones of thin streaks and brecciation in secondary quartzites and argillisites. The gold concentrations in these rocks vary between 1.4 and 17.3 g/t, that of gold is between 7.6 and 144.6 g/t. The ores contain abundant brecciated, framboidal lamellar, geode, and fine streaky structures. The more frequent ore minerals are pyrite, arsenopyrite, acanthite, grey ores of the freibergite–tetrahedrite series, stephanite, polybasite, low-fineness native gold (fineness varies in the range 249–532‰), and titanite. The amount of ore minerals in veins does not commonly exceed 0.5

Copper mineralization in the Magadan region (North-East of Russia) has been established in quartz-chloritoid and chlorite shales of the middle and upper Riphean of the Prikolymsky terrane. Compared to the upper crust, copper shales of the Oroek deposit are noticeably enriched in a narrow range of trace elements: Cu, Ag, Au, Rh, and Se, with enrichment factors ranging from 10-fold (Se, Rh) to 100-fold (Ag, Au) and even 1000-fold (Cu) suggesting, apparently, their synchronous involvement in ore formation. In addition, the studied samples are slightly enriched in Cd, Li, Co, Zn, V, U, Sc, Y, and REE. Copper shales show relatively flat rare earth element (REE) patterns similar to the chondrite-normalized pattern having no distinct positive or negative Eu anomalies and dominated by light lanthanides. The Ce/Ce* and Eu/Eu* values indicate that ore formation proceeded under oxidizing conditions. The obtained geochemical data show that the Riphean host rocks could serve as a source of trace elements and REE ore-forming fluids. In the ores, covellin and chalcocite are the main copper minerals; less common are roxbyite, idaite, nukundamite, spioncopite, chalcopyrite, silver-bearing (Ag about 1 wt. %) bornite and yarrovite, as well as native gold. Fluid inclusions in quartz suggest that copper mineralization was formed at temperatures of 212–190 °C and a pressure of 1 kbar, from hydrothermal solutions of medium salinity (from 13.8 to 12.4 wt. % eq. NaCl) and high density (0.95–0.98 g/cm3) saturated with chlorides of Ca, Mg, and K. The copper shales of the Prikolymsky terrane differ from sedimentary copper and copper shales of the African Belt by low Co and Ni contents and from the Kupfershifer by low concentrations of Pb and Zn. The obtained results can be used for prognosticating new deposits.

The Birkachan deposit in the Middle Paleozoic Kedonsky Volcanic Belt (KVB) is unique in Northeast Russia for its stockwork epithermal Au–Ag ores. The deposit is located in the northeastern part of the Gurnik volcanotectonic depression, in the Kedonsky segment of the KVB. The deposit is localized in the lying side of a large sublatitudinal thrust fault, due to which it was overlain in the Jurassic–Early Cretaceous by allochthon rocks and, therefore, was slightly eroded, as evidenced by the preserved fragments of the argillisite cap. The ore-bearing Gurnik sequence is composed of felsic tuffs and lavas with intercalations of ignimbrites. The main ore-bearing zone of the Birkachan deposit is 4.5 km long and 200–300 m wide consists of several echelon-like vein zones of northeast strike, falling to the southeast at angles of 55°–70°. Most of the ore bodies are linear stockworks. Single, lenticular rich ore bodies represented by mineralized breccias have been found at deep horizons. In the section, the system of ore bodies of the Birkachan deposit forms a fan-shaped structure. The main textures of ores are vein-disseminated, breccia, and rhythmically banded. The ores are enriched in comparison with the upper continental crust in a rather narrow range of elements (Au, Ag, Sb, As, Mo, W, and Li) and are poor in rare-earth elements, among which light lanthanides predominate. The sulfide grade of ores is 0.1–0.5%. The vein minerals in ores are dominated by quartz, sericite, and siderite. Among the ore minerals, pyrite dominates, with fahlore, native gold and chalcopyrite, and minerals of the series acanthite → Se–acantite → naumannite, pearceite, and Se–pearceite being less common. The average fineness value of native gold is 643‰. The parameters of mineral-forming solutions correspond to typical medium-temperature fluids of epithermal low-sulfidized deposits: homogenization temperature of 93–291°С, salt concentration of 0.2–7.0 wt % eq. NaCl, and fluid density of 0.71–0.99 g/cm 3 . The main indicators of fluid composition are CO 2 /CH 4 = 15.8–23.6, Na/K = 2.3–4.3, and K/Rb = 2007. The prospects for increasing the reserves of Au and Ag are associated with further study and exploration of the flanks and deep horizons of the deposit.

This paper discusses mineralogic and geochemical features of dominantly silver mineralization in secondary quartzites of the Kyplatap volcanic field (KVF) confined to the southeastern flank of the eponymous intrusive dome structure (IDS) that complicates the Palyavaam–Pykarvaam volcano-tectonic depression which is part of the Chaun zone of the Central Chukchi sector of the Okhotsk–Chukchi volcanogenic belt (OChVB). The Kyplatap IDS was formed as a large laccolite-like subvolcanic body intruded into the Alkakvun rhyolites and trachyrhyolites. The KVF contains an abundance of secondary quartzites that compose both linear zones along faults mostly northeast striking and fault-bounded isometric fields. Potential ore bodies are represented by linear zones of crushed and brecciated secondary quartzites accompanied by quartz veinlets and veins. The ore bodies are long up to 200 m and 2–5 m thick. Spotty, veinlet-impregnated, and brecciated structures predominate in the ore bodies. The ore mineralization is mostly impregnated, less frequently in veinlets. The main vein minerals are quartz (30–70%), hydromica (15–20%), sericite, kaolinite, adularia, ferrous carbonate, zircon, chlorite, and alunite. The main ore minerals are pyrite, arsenopyrite, acanthite, polybasite, pearceite, and native silver. The typomorphic feature of the mineralization is thin intergrowths of silver sulfosalts, native silver, and iron hydroxides. We note that dominantly silver mineralization in secondary quartzites within the OChVB was found for the first time ever. The results of surveys classify the Kyplatap ore occurrence as a gold-silver mineral type deposit (Au/Ag = 1 : 450 on average) of the selenium subtype because of considerable admixture of selenium in the ore minerals. The occurrence of Ag mineralization in secondary quartzites and mudstones may provide evidence that it belongs to the high-sulfidation epithermal class. These features of the KVF epithermal mineralization are largely similar to the formation of siliceous and quartz–alunite lithocaps that are formed above degassing intrusions. In such conditions, the HS-type ore-bearing fluids are either not formed in the system or did not reach the epithermal depths. The ore field is poorly or moderately eroded, what is indicated by a practically complete absence of minerals of the polymetallic association and by the dominance of acanthite and silver sulfosalts over native phases.

This study presents the typomorphic features of native gold grains from three different geological-industrial types (GIT) of gold deposits in the North-East of Russia: (1) gold–arsenic-sulfide in black shale strata (Natalka, Degdekan, Karalveem, Maldyak deposits), (2) gold–quartz veins in granitoids (Dorozhnoye, Butarnoye, Shkolnoye, Maltan deposits), and (3) gold–silver adularia in volcanogenic strata (Kupol, Olcha, Kubaka, Burgali, Primorskoe, Dalnee deposits). The reliability of the geological interpretation is directly related to mineral associations, fineness variations, its internal structure and the content of microimpurities. Native gold is a reliable indicator for identifying various GIT of gold deposits at the early geological-prospecting stages of studying gold-bearing areas. Typomorphic features of native gold for each of the considered GIT are stable and do not depend on the age and scale of mineralization. It is shown that using an integrated approach obtains genetic information about a particular ore object, which makes it possible to predict the vertical range of mineralization and outline the technology for processing ores. The information obtained can also be effectively used in the search for placer deposits in nearby watercourses. Identification of typomorphic features of ore and placer native gold opens up wide opportunities for delineating the distribution areas of placer deposits.

We have studied the mineral composition of ores from the Pepenveem epithermal Au-Ag deposit, which is a promising new object of the Chukchi Peninsula. It has been found that the ore formation process was developed in the following sequence: Pyrite, arsenopyrite, and marcasite were deposited at the early stage, next were Pb, Zn, and Cu sulfides; at the late stage, native gold, pyrargyrite, stephanite, proustite, minerals of the pearceite-polybasite series, acanthite, and other Ag minerals were deposited. The results of fluid inclusion studies indicate that the Au-Ag mineralization formed from low-temperature (236-137 degrees C) low-concentration chloride hydrotherms (0.18-1.57 wt.% NaCl eq.). The results of calculation of thermodynamic equilibria have shown that in the temperature range from 200 to 100 degrees C, there were a decrease in the fugacity of sulfur (lg f(S2) from -10 to -21) and oxygen (lg f(O2) from <-36 to <-48) and a change from near-neutral to acidic solutions. Compared to other Au-Ag deposits on the Chukchi Peninsula (Corrida and Valunistoe), which are characterized by wide distribution of Se-and Te-bearing Au-Ag chalcogenides (naumannite, cervelleite, and hessite), ore formation with gold-silver-sulfosalt mineralization at the Pepenveem deposit took place at lower temperatures and lower selenium, tellurium, and oxygen fugacity. The data obtained permit us to refer the Pepenveem deposit to the group of epithermal low-sulfidation (LS) deposits.

Numerous epithermal Au–Ag deposits and ore occurrences of the Chukchi Peninsula are localized in the Cretaceous Okhotsk–Chukotka (OCVB) continent-marginal and Late Jurassic–Early Cretaceous Oloi (OVB) island arc volcanic belts and in Early Cretaceous postcollisional volcanic troughs. Volcanotectonic depressions, calderas, and volcanic domes control the location of the deposits. The orebodies of the deposits are quartz–adularia veins, sometimes en-echelon ones forming extending vein zones, as well as isometric and linear stockworks. The auriferous veins of most deposits display complex breccia–crustification structures. The vein ores have rhythmically and colloform–banded structures, with a predominantly fine distribution of ore mineral grains, often with banded clusters of ore minerals (ginguro). Native gold is of low fineness; the dispersion of this index varies from low to high. Acanthite is widespread in the ores. Its highest contents are specific to deposits with the repeated redistribution of substance (Kupol, Corrida, and Valunistoe). Based on the results of mineralogical studies, most of the epithermal Au–Ag deposits of the Chukchi Peninsula can be assigned to the Se type. The ores of some deposits (Valunistoe, Dvoinoe, etc.) contain both Se and Te minerals. The telluride-richest sites of the Sentyabr’skoe and Televeem deposits are far from the main orebodies. Most of the Chukchi epithermal Au–Ag deposits have many common characteristics (low and moderate temperatures of fluids, low fluid salinity, domination of carbon dioxide over methane, etc.) typical of low-sulfidation deposits. The maximum temperatures and salinity are specific to fluids in the Central Chukchi sector of the OCVB and in the Baimka zone of the OVB, and the minimum ones are typical of fluids in the East Chukchi flank zone and inner zone of the OCVB. The average salinity of mineral-forming fluids in the inner zone of the OCVB is half as high as the salinity of fluids in the East Chukchi flank zone of this belt, although the sulfate content is higher. At the same time, the fluids in the inner zone of the OCVB are richer in carbon dioxide and bicarbonate ion than the fluids in the East Chukchi flank zone of this belt. The fluid inclusion data permit the Vesennee deposit (Baimka zone) to be regarded as an intermediate-sulfidation one and suggest the presence of epithermal high-sulfidation deposits in the inner zone of the OCVB.

Geological, structural and mineralogical facts describing the intersection of Paleozoic ore veins with carbon and Mezozoic veins in the Kubaka gold-silver deposit in the Omolon craton terrane are presented. The totality of the above observations does not allow limitation of the age mineralization by Upper Carboniferous based on isotope-geological studies, as V.V.Akinin et al. (2020) did on ore and rock samples selected in one geological exposure of ore body in opencast mine of the Tsokolny zone.

The Gol’tsovoe Ag–Pb–Zn-deposit (1600 t silver in ores with an average grade of 1025 g/t Ag) is located on the southeastern flank of the Dukat mining district, at the junction of the Balygychan–Sugoi rift trough and the Okhotsk–Chukotka Volcanic Belt (OCVB). The Dukat district is the largest silver producer in Russia. The Gol’tsovoe deposit is located 2 km north of the Pestraya granitoid intrusion, in the structurally complex zone of a fault contact of the Upper Triassic terrigenous sediments and Late Cretaceous volcanic rocks. The contact consists of a series of fault planes within a 0.5–1 km wide belt, along which the western block, composed of felsic volcanics, has been downthrown more than 1 km. The host Upper Cretaceous rhyolitic and rhyodacitic ignimbrites are intruded by subvolcanic nevadite bodies. A characteristic feature of the deposit is the occurrence of en-echelon galena veins and veinlets with high Ag grades at the upper levels of orebodies. Massive, coarsely banded, and spotted ore structures are predominant. Ore geochemistry agrees well with the mineral composition. The ores are enriched in a wide spectrum of elements: Ag, Sb, Pb, Cd, As, Zn, Bi, In, W, Sn, Mn, Cu, Li, Tl, and Cs. They are characterized by a low total REE abundance (33.34–50.69) and a negative lanthanide distribution type. Commercially significant potential by-products are Cd, In, and Bi. Galena is the main Ag mineral concentrator: the high Ag concentrations in this mineral are due to the occurrence of small inclusions of a large group of independent Ag-bearing minerals, argentotetrahedrite and pyrargyrite especially, and a small amount of myargirite, polybasite, etc. Argentite and native Ag occur in limited amounts. Tin minerals are represented by stannite, canfieldite, and less frequent cassiterite. Oxidation zone has been tracked over the entire mineralization depth and displays a pronounced linear trend. Oxidized ores are dominated by Zn, Pb, Fe, Ca, and Ba sulfates; less abundant Fe, Mn, and Zn oxides; and subordinate carbonates and clays; total sulfides and native metals (Cu, Ag) do not exceed 2%. Ore oxidation degree is 40.3%. The sulfide–quartz–chlorite veins of the Gol’tsovoe deposit formed at moderate temperatures (276–138°С) from low-concentration chloride hydrothermal fluids (4.2–0.2 wt % NaCl eq.), saturated with Na and К cations and Mg in subordinate amount. The obtained data allow the Gol’tsovoe deposit to be classified as an epithermal intermediate sulfidation deposit. A two-stage ore emplacement model is proposed. During the first stage Ag–Pb–Zn ore was emplaced as a result of the functioning of a near-surface hydrothermal system of volcanic origin. During the second stage, imprinted Sn mineralization was emplaced in the Ag–Pb–Zn ore veins as a result of tin-bearing magmatogenic fluid inflow at the lower levels of the deposit.

The Burgali deposit is located in the Paleozoic Kedon volcanic belt (KVB) within the Omolon cratonic terrane. The orebodies of the Burgali deposit are veined and stockwork-type. The studies of the wallrock metasomatites demonstrate that the erosional truncation of the deposit is close to minimal. The ores of the deposit are enriched in the chalcophile elements (Au, Ag, As, Sb, Te, W, Mo, and Bi) and poor in the rare earths. The rare-earth element (REE) spectra are dominated by light lanthanides. The ores are characterized as very low-sulfidation with finely disseminated mineralization, widespread occurrence of chalcedony, and widespread colloform-banded, often combined with brecciated, structures. The late quartz veins contain Lower Carboniferous coaly siltstone fragments, filled with petrified timber remains, which indicate the Carboniferous age of the ore mineralization. The ores contain widespread Au- and Te-bearing pearceite and rare minerals such as argyrodite and the selenous petrovskaite and uytenbogaardtite. The data obtained enable the Burgali deposit to be classified as low-sulfidation epithermal. The outlook for Ag and Au reserve additions is based on the further studies and exploration of the ore-bearing stockwork.

Исследован минеральный состав руд эпитермального Au-Ag месторождения Пепенвеем, которое представляет собой новый перспективный промышленный объект Чукотского полуострова. Установлено, что процесс рудоотложения развивался в следующей последовательности: на ранней стадии отлагались пирит, арсенопирит, марказит, далее сульфиды Pb, Zn и Cu; в завершении произошло отложение самородного золота, пираргирита, стефанита, прустита, минералов пирсеитполибазитового ряда, акантита и других минералов Ag. По результатам термобарогеохимических исследований Au-Ag минерализация месторождения формировалась из низкотемпературных (236– 137oС), низко концентрированных хлоридных растворов (1.57–0.18 мас. % экв. NaCl). Согласно результатам расчетов термодинамических равновесий в интервале температур от 200 до 100°C происходило снижение фугитивностей серы (log ƒS2 от -10 до -21) и кислорода (log ƒО2 от < -36 до < -48), а также смена близнейтральных растворов на кислые. По сравнению с другими Au-Ag месторождениями Чукотки (Коррида, Валунистое), для которых характерно широкое распространение халькогенидов золота и серебра с Se и Te (науманнита, кервеллеита, гессита), рудоотложение на Пепенвееме происходило при более низких температурах и фугитивностях селена, теллура и кислорода, что привело к образованию золото-серебро-сульфосольной рудной минерализации. Проведенные исследования позволяют отнести Пепенвеем к золотосеребряным эпитермальным месторождениям адуляр-серицит-кварцевого типа (по международной классификации low-sulfidation).

The relationship among the orebody, volcanic rocks, and a rhyolite dike in the large epithermal Kupol deposit (Western Chukotka) is considered. Almost throughout its entire length (more than 3000 m), the orebody of the deposit is intersected by rhyolite dikes. In the studied profiles in the mine excavations at the horizons 425, 455, 470, 515 m, a rhyolite dike clearly intersects and bisects the orebody, which is a 20-m-thick dominantly quartz vein with some adularia. The rhyolite has a porphyritic structure. The groundmass is devitrified with the formation of an aphanite quartz-feldspar aggregate with a mosaic microstructure. Some patches are fluidized. The rhyolites contain from 72.96 to 74.97 wt % SiO2, and the composition corresponds to biotite granites of the low-alkaline series. The following criteria have been identified to indicate the post-mineralization age of the dike: a clear intersection of a thick ore vein by the dike; vitrification of the dyke material at the contact with the vein; rhyolite cementing the crushed quartz vein material; the emergence of some small tongues from the dike that penetrate the quartz vein; xenoliths of quartz vein material in the dike body; the orebody tongues do not penetrate the dike; increased concentration of vein and ore minerals on the contact surface of the dike or in cracks of the endocontact zone. The formation of obsidian (vitrophyre) in rhyolite at contact with the orebody indicates that the dike was emplaced in a cold system. Preservation of the productive vein thickness, its morphological features, and the Au and Ag contents at the cabs of the rhyolite dike; identical textures and repeated rhythms in the areas of rhythmic-banded layering in the vein on both sides of the dike shows that in the Kupol deposit, post-mineralization dikes do not replace or impoverish the productive vein system, which is probably due to their dilatation nature and the infilling of separation cracks.

Многочисленные эпитермальные Au-Ag месторождения и рудопроявления на территории Чукотского полуострова принадлежат меловому, окраинно-континентальному Охотско-Чукотскому (ОЧВП) и позднеюрско-раннемеловому, островодужному Олойскому (ОВП) вулканическим поясам, а также постколизионным, раннемеловым вулканическим впадинам. Вулканотектонические депрессии, кальдеры и вулканические купола контролируют размещение месторождений. Рудные тела месторождений представлены кварц-адуляровыми жилами, иногда собранными кулисообразно в протяженные жильные зоны, а также изометричными и линейными штокверковыми залежами. Для рудоносных жил большинства месторождений характерны сложные, комбинационные брекчиево-крустификационные текстуры. В жильных рудах широко развиты ритмичнои колломорфно-полосчатая текстуры, обладающие преимущественно тонким характером распределения рудных вкрапленников, нередко с полосчатыми скоплениями рудных минералов (гингуро). Самородное золото имеет относительно низкую пробность и дисперсию этого показателя от низкой до высокой. Акантит широко распространенный минерал в рудах. Наиболее высокие его концентрации характерны для месторождений с многократным перераспределением вещества (Купол, Коррида, Валунистое). В результате минералогических исследований большинство эпитермальных Au-Ag месторождений Чукотки можно отнести к Seтипу. На ряде месторождений (Валунистое, Двойное и др.) в рудах присутствуют, как селен-, так и теллур-содержащие минералы. Наиболее обогащенные теллуридами участки месторождений Сентябрьское и Телевеем находятся на удалении от основных рудных тел. Большинство эпитермальных Au-Ag месторождений Чукотки имеют много общих черт (низкие и средние температуры, низкая соленость флюида, преобладание углекислоты над метаном и др.), типичных для низкосульфидизированного класса. Максимальные величины температур и соленостей характерны для флюидов из Центрально-Чукотского сектора ОЧВП и Баимской зоны ОВП, а минимальные – для флюидов Восточно-Чукотской фланговой зоны и внутренней зоны ОЧВП. Соленость минералообразующих флюидов внутренней зоны ОЧВП в среднем вдвое меньше, чем флюидов Восточно-Чукотской фланговой зоны ОЧВП, а содержания сульфатов выше. В то же время флюиды внутренней зоны ОЧВП богаче углекислотой и бикарбонат-ионом относительно флюидов Восточно-Чукотской фланговой зоны ОЧВП. Термобарогеохимические данные позволяют месторождение Весеннее (Баимская зона) отнести к среднесульфидизированному классу и прогнозировать во внутренней зоне ОЧВП открытие высокосульфидизированных эпитермальных месторождений.

The potentially large Primorskoe epithermal Au-Ag deposit is represented by three areas: the Kholodnyi, Spiridonych, and Teplyi. It is located in the Omsukchan district of Magadan oblast, where mining is carried out at the largely similar Dukat, Lunnoe, Gol’tsovoe, Arylakh, Tidit, Pereval’noe, and other deposits. The deposit under review is located in the Kalalaga volcano-tectonic depression, where ore has been emplaced in a gently dipping sequence of Late Cretaceous ignimbrites and rhyolites more than 700 m in thickness crosscut by numerous intermediate and mafic dykes. According to drilling data, there is a leucocratic granite massif 400–500 m beneath the deposit, which is exposed on the surface in the northeastern part of the ore field. The presence of Bi-bearing galena and matildite, as well as medium- to high-temperature metasomatic facies (epidote and actinolite) and the specific physicochemical conditions of epithermal Ag-Au ore emplacement, attests to the above-intrusion position and the role of granitoids as high-temperature magmatic fluid generators responsible for supplying Bi and heating the host rock. The ore chemistry is quite consistent with its mineral composition. High Mn and Ag; elevated Au; low Cu, Pb, Zn, Sb, As, Bi, and Te; and low total REE concentrations were established, along with negative Eu and positive Ce anomalies. The high Te/Se, Sr/Ba, Y/Ho, and U/Th ratios in the ores are due to their location in the area influenced by the granitoid pluton. The physicochemical parameters of ore emplacement in the Teplyi area are unusual: high temperatures, low salt concentrations, and fluid densities typical of a “dry vapor” environment. The obtained data allow the Primorskoe to be classified as an intermediate sulfidation epithermal deposit. The data discussed below are of practical use for regional metallogenic forecasting, exploration, and economic assessment of epithermal Ag-Au deposits.

Потенциально крупное Ag-Au эпитермальное месторождение Приморское представлено тремя участками Холодный, Спиридоныч и Теплый. Оно расположено в Омсукчанском округе Магаданской области, где разрабатываются во многом аналогичные месторождения: Дукат, Лунное, Гольцовое, Арылах, Тидит, Перевальное и др. Месторождение приурочено к Калалагинской вулкано-тектонической депрессии и локализовано в пологозалегающей толще позднемеловых игнимбритов и риолитов мощностью более 700 м, которая прорвана многочисленными дайками среднего и основного состава. Массив лейкократовых гранитов, по данным бурения, находится под месторождением на глубине 400–500 м и выходит на поверхность в северо-восточной части рудного поля. Присутствие Bi-содержащего галенита и матильдита, наличие средне-высокотемпературных фаций метасоматитов (эпидот, актинолит) и специфические физико-химические условия образования эпитермальных Ag-Au руд свидетельствуют о надинтрузивном положении и роли гранитоидов, как генераторов высокотемпературных магматических флюидов, осуществлявших привнос Bi и прогрев вмещающих оруденение пород. Геохимические особенности руд хорошо согласуются с их минеральным составом. Установлены высокие концентрации Mn и Ag, повышенные — Au, низкие — Cu, Pb, Zn, Sb, As, Bi и Te, низкая сумма РЗЭ, отрицательные Eu- и положительные Се-аномалии. Высокие значения показателей Te/Se, Sr/Ba, Y/Ho и U/Th в рудах связаны с положением месторождения в зоне влияния гранитоидного массива. Физико-химические параметры образования руд участка Тёплый необычны — характеризуются высокими температурами, низкими концентрациями солей и плотности флюида, что характерно для “сухого пара”. Полученные результаты позволяют отнести эпитермальное месторождение Приморское к промежуточному классу. Приведенная в статье информация имеет практическое значение для региональных прогнозно-металлогенических построений, поисков и оценки эпитермальных Ag-Au месторождений.

As a potentially large Ag-Au epithermal deposit, Primorskoye comprises the following three areas: Kholodny, Spiridonych, and Teply. This deposit is located in the Omsukchan district of the Magadan Region, where similar deposits, including Dukat, Lunnoye, Goltsovoye, Arylakh, Tidit, and Perevalnoye, have developed. The deposit can be attributed to the Kalalagian volcano-tectonic depression and is localized in a flat-lying rock mass in the Late Cretaceous ignimbrites and rhyolites having thicknesses of greater than 700 m, which is cut through by numerous dykes of medium and major composition. According to the drilling data, the solid mass of leucocratic granites is located in deposits at a depth of 400–500 m with outcrops in the northeastern part of the ore field. The presence of Bi-containing galena and matildite, the availability of mid and high temperature facies of metasomatites (epidote and actinolite), and the specific physical and chemical conditions during the formation of the epithermal Ag-Au ores indicate the intrusive position above and the role of granitoids as generators of high temperature magmatic fluids, which introduced Bi and heated the rocks enclosing the mineralization. The geochemical features of the ores are well correlated with their mineral compositions. The high concentrations of Mn and Ag, elevated concentration of Au, low concentrations of Cu, Pb, Zn, Sb, As, Bi, and Te, low sum of REE, and negative Eu- and positive Се-anomalies were observed. The high values of the Te/Se, Sr/Ba, Y/Ho, and U/Th indicators in the ores are associated with the deposit location in the zone of granitoid massif effect. Further, the physical and chemical parameters of ore formation in the Teply area are unusual and are characterized by high temperatures, low concentrations of salts, and fluid density, which are indicative of the typical “dry steam” conditions. The obtained results allow the Primorskoye epithermal deposit to be attributed to the intermediate class. The information present in the article is practically valuable for the regional forecast and metallogenic developments as well as for searching and assessing the epithermal Ag-Au deposits.

The mineralogical–geochemical and thermobarogeochemical features of the Teploe Ag–Au epithermal deposit are considered. The dissolution and redeposition of ore minerals are a result of thermal metamorphism. The redistribution of Ag leads to the formation of lenaite and exsolution structures in minerals of the Cu–Ag–S system; abundant stromeyerite, jalpaite, and mckinstryite compose a significant amount of ores. The atypical physicochemical parameters of the formation of ores include high (for epithermal mineralization) temperatures and low salinity and density of the fluid typical of a dry vapor. The results of fluid inclusion study ascribe the Teploe deposit to an intermediate class of epithermal deposits.