Research subject. The Tessemsky granite massif is located in the North Taimyr tectonic zone, surrounded by Cambrian rocks. The Pekinsky granite massif is located within the Central Taimyr zone, surrounded by metamorphosed Proterozoic rocks. Aim. To develop a methodology for using the composition of accessory granitoid minerals when prospecting Cu-Mo-Au-porphyry mineralization on the example of the Pekinsky and Tessemsky granitoid massifs of the Taimyr Peninsula. Materials and methods. Accessory zircon and apatite contained in two granitoid samples from the Pekinsky massif (P1, P2) and two granitoid samples from the Tessemsky massif (T2, T3) were studied. Their mineral composition was examined using an EPMA Cameca SX100 instrument. The element content in minerals was determined by LA-ICPMS using an NexION 300S instrument equipped with an NWR 213 attachment. Results. Most of the zircons from the Pekinsky and Tessemsky massifs were formed at T < 738°C in oxidized magma with ΔFMQ of 0.6–2.6, which is a favorable sign for the identification of Cu-Mo-Au-porphyry mineralization. Zircons are characterized by elevated (Eu/Eu*)Y and (Ce/Nd)n/Y ratios, which is also a favorable, though not a strongly reliable, sign for identifying porphyry mineralization. The Eu/Eu* and Sr/Y ratios in the apatites from the Tessemsky massif are higher than those in the apatites from the Pekinsky massif. The rock compositions of both massifs fall within the fields of adakites on the classification diagrams. The estimates of oxygen fugacity (logfO2) calculated from Mn in apatites for four samples agree well within the error limits. Conclusion. Specific features of using the composition of accessory minerals (zircon and apatite) for prospecting the Cu-Mo-Au-porphyry mineralization associated with granitoids were considered. Accessory indicator minerals can be used to rank granitoid massifs in order to assess their ore content. The example of two granite intrusions of the Taimyr Peninsula made it was possible to show that the Tessemsky massif is more promising for the discovery of associated Cu-Mo-Auporphyry mineralization than the Pekinsky massif.

This article highlights an insufficiently studied issue of a primary source of placer gold in alluvium of the basin of the Kukulkindzha Creek (Okhotsk region, Khabarovsk krai) be means of the analysis of mineralogical and geochemical features of samples. This study provides information on mineral composition of heavy concentrates and morphological characteristics and chemical composition of native gold. Native gold with lumpy morphology is dominant in heavy concentrates. The fineness of native gold varies from very low (530–689 ‰) to medium (885 ‰); native gold contains only Ag and is characterized by high-fineness rims. The minerals of the garnet group with dominant grossular-andradite composition and the minerals of the pyroxene group (diopside–hedenbergite series characteristic of contact metamorphosed rocks) are always found in heavy concentrates. Three stable mineral assemblages of native gold are identified on the basis of statistical analysis of geochemical and mineralogical data. The first assemblage is related to the presence of heavy fraction minerals in heavy concentrates, which were sourced from the entire studied area. The second assemblage mainly consists of accessory minerals of Late Cretaceous subalkali granites, which are most widespread within the studied area, and the third assemblage contains skarn minerals. A primary source is most likely related to skarns, which is evident from specific features of native gold, as well as its presence in assemblage with Ca garnets of the grossular–andradite series and pyroxenes of the diopside-hedenbergite series. The samples with the highest amount of native gold in heavy concentrates are associated with skarn source.

The paper presents the frst data on the distribution and composition of copper-noble metal mineralization in gabbroids of the Kumba intrusive (North Urals). The noble metal mineralization is associated with digenite-bornite, bornite-chalcopyrite, and pyrite-chalcopyrite ores and mainly occur minerals of precious metals. Nine noble metal mineral species are found for the frst time in amphibole and amphibole-olivine gabbro of the Kumba intrusive: native gold, Au-Ag alloys, Au, Ag, and Pd tellurides (hessite, merenskiite), Bi tellurides (kotulskite), antimonide-arsenides (isomertieite), arsenides (arsenopalladinite, sperrilite), and stannides (atokite) of Pt and Pd. Noble metal minerals from all sulfde assemblages in heavy concentrates are often accompanied by antimonides (stibnite) and Bi mineralization represented mainly by native bismuth and bismuthinite and less common sulfotellurides (baksanite) and tellurides (tsumoite). Our results make it possible to estimate the prospects of the discovery of new copper-noble metal deposits hosted in gabbro of the Uralian Platinum Belt. Taking into account the principles of occurrence of noble metal and copper mineralization, most gabbro intrusives of the Uralian Platinum Belt can be considered the promising objects for large-tonnage copper deposits with associated ore Au and Pd grades.

Native gold and garnets are described for the frst time in heavy concentrates from coarse-grained sediments of the Upper Devonian Tayaokuyakha Formation, which occurs on the eroded Upper Riphean schists with angular and azimuthal unconformity (middle reaches of the Murseyakha River, Kanin Peninsula, Nenets autonomous district, Russia). Particular attention was paid to indicators of primary source of native gold for the Upper Devonian conglomerates. The composition of weakly rounded almandine-spessartine garnets indicates their metamorphic origin and allows us to relate the primary source of native gold in conglomerates (D3tk) with underlying metamorphosed Riphean strata or intrusive rocks in them. Native gold is mainly characterized by a heterogeneous composition and contains Ag, Cu and Hg. The poorly rounded native gold grains, the absence of supergene rims and preservation of mineral inclusions in the margins indicate its proximal primary source. The presence of Cu suggests a link of native gold with mafc/ultramafc rocks: metamorphosed dikes of dolerites of the Nekhaiteyakha metagabbroid complex (m??RF3) or dolerite dikes of the Kanin-Timan complex (?D3kt), which intrude the Precambrian metamorphic schists. It is established that the Devonian conglomerates are intermediate reservoirs for the possible present-day placer formation.

This paper provides a detailed geological description of the Serebryansky Kamen gabbro massif and copper–precious metal mineralization found for the first time within it. The first data on the distribution and localization of disseminated copper–precious metal mineralization in the central part of the massif have been obtained. It was found that copper sulfides (bornite, chalcopyrite, digenite, and chalcocite) are predominantly hosted in melanocratic taxitic varieties of amphibole gabbro. Elevated precious-metal concentrations were measured and precious-metal minerals were identified for the first time in gabbro enriched in sulfides in the northern part of the Ural platinum belt. The Pd–Pt–Fe–Cu intermetallic compounds, sulfide (vysotskite), tellurides (merenskyite, Pd-melonite, kotulskite), bismuthotellurides (michenerite), arsenides, platinum and palladium arsenotellurides (sperrylite, arsenopalladinite), and native gold were identified. Based on a geochemical survey, the resources of copper and precious metals in the Serebryansky Kamen gabbro massif are 760.1 kt of Cu and 97.1 t of precious metals, dominated by Au and Pd. The identified mineralized zones are comparable to the complex Volkovsky deposit in size, structure, and composition. A geological and genetic model is proposed, which can be widely used in prospecting for copper and precious metals in the gabbroic parts of dunite–clinopyroxenite–gabbro massifs.

Comparative characteristics of gold minerals from gabbro of the Uralian Platinum Belt based on the author’s (Kumba massif, Serebryanskii Kamen massif, and Volkovskoe deposit) and literature (Volkovskoe deposit and Baronskoe ore occurrence) data are presented. The studied assemblages are dominated by native gold characterized by the following types: native gold without any impurities, copper gold, and copper–palladium gold. An unnamed phase with a composition similar to the Cu 2 PdAu stoichiometry has been found in gabbro of the Kumba massif for the first time in the Uralian Platinum Belt and Russia. The formation conditions of all types of gold minerals identified have been evaluated.

The article presents the results of studying the chemical composition of ore-bearing rocks, as well as the mineralogy of base metal sulfides and platinum group elements (PGE), of the Nyud-II sulfide PGE–Cu–Ni deposit in the southwestern part of the Nyud massif of the Monchegorsk Pluton (Monchepluton). The ores of the deposit are represented by vein-disseminated and nest-schlieren types. They are characterized by significant predominance of Pd over Pt, fractionation of low-melting PGE (PPGE subgroup) with respect to high-melting ones (IPGE subgroup), and close correlations of Ni and Cu with S in the presence of increased As, Se, Te, and Bi contents. The S/Se ratios in ore (3470−3530) correspond to the mantle values. Among the platinum group minerals (PGM), the most widespread are Pt and Pd bismuth–tellurides and tellurides (merenskyite, michenerite, and moncheite), subordinate amounts of Pt–Fe alloys and sperrylite, and native osmium and Ir, Rh, and Pt sulfoarsenides (irarsite, hollingworthite, and platarsite). The formation of ore sulfide concentrations resulted from separation of an immiscible sulfide liquid upon cooling of a sulfur-saturated silicate magma with a mafic composition. Subsequent fractional crystallization of the sulfide liquid contributed to the uneven distribution of Ni, Cu, and PGE. PGE–sulfide ore formation took place in a fairly wide temperature range, starting at 1100−1000°C and ending at 600−400°C. At an early stage, IPGE minerals (native osmium and erlichmanite) separated. Upon cooling to a temperature of 1000−900°C, the sulfide liquid fractionated with the formation of monosulfide solid solution (mss), in which compatible IPGE were concentrated, and a residual sulfide liquid enriched in Ni, Cu, PtPGE, and chalcophile elements. With a further decrease in temperature (to 600°C), Pt–Fe alloys, sperrylite, and IPGE + Pt sulfoarsenides crystallized, with separation of the residual sulfide melt enriched in Cu, PPGE and chalcophile elements. At 600−400°C, ore formation ended with the complete crystallization of base metal sulfides and the formation of Pt and Pd bismuth–tellurides and tellurides.

In this work, mineralogical and geochemical data are presented for sulfide-rich phoscorites and carbonatites in the Kovdor massif. The PGE and Ag-bearing mineralization of bornite–chalcopyrite and Ag‑bearing mineralization of pyrrhotite–chalcopyrite associations were investigated. In carbonatite stage formation of massif, the noble metal minerals occurred during evolution of alkaline–ultrabasic melt and after separation of primary sulfide melt enriched in PGE, Au and Ag. According to the observed relationships, the minerals of PGE, Au, and Ag in bornite–chalcopyrite association are crystallized sequentially from magmatic to hydrothermal stages. Crystallization of Os, Ir, Pt and Pd minerals (erlichmanite, rustenburgite, isoferroplatinum, mertieite–II, etc.) occurred at temperature close to 480°С, while further decrease in the temperature and an increase in the Cu and Fe activity in the melt leads to the crystallization of Sb, Pb, As, Bi and Te-bearing minerals (sperrylite, tatyanaite, moncheite, stumpflite, etc.). Formation of Au and Ag-bearing minerals (electrum, silver, stromeyerite, lenaite, etc.) occurred at temperatures below 300 °C with relatively low sulfur activity. In carbonatites and phoscorites of the middle and late magmatic stages enriched with magnetite, pyrrhotite–chalcopyrite association with silver-bearing minerals was formed at temperatures below 300°C. Ag-bearing minerals were produced during hydrothermal recrystallization of Cu–Fe–Ni sulfides at temperature close to 150°C.

Alkaline-carbonate metasomatites of fault zones are widely distributed within all Precambrian shields. Their studying has attracted the close attention of researchers in connection with the confinement of various concentrations of ore-forming elements. In addition, a clear structural control of metasomatites, their composition and stages of development are of great importance for the predictive assessment of geological structures. Kuolayarvi zone is one of the most promising in the Republic of Karelia in terms of prospecting, evaluating and possible industrial production of gold and uranium. On its territory, the Mayskoye gold deposit has been identified, as well as a number of complex gold-uranium ore occurrences, among which Ozernoye and Lagernoye are of the greatest interest. This paper discusses the features of the ore mineralization of these ore manifestations, as well as the dependence of its composition on the primary rock that has undergone hydrothermal-metasomatic study. In the general sequence of forming ore minerals, six parageneses (rock, uranium ore, sulphide, selenide-telluride, low-temperature and hypergenic) have been revealed. It has been also established that gold mineralization is associated with the selenide-telluride paragenesis, and uranium – with the uranium ore and low-temperature ones. The interrelation of the ore parageneses with the global stages of the development of the Kuolayarvi structure (Svekofennian and Paleozoic activization) has been shown. New data on the Re-Os isotope dating of sulfide formation minerals (chalcopyrite and molybdenite), with which gold mineralization is closely associated, have been presented. The so-called "chemical" isotope age of uraninite has been calculated as well. The obtained isotopic data allow us to consider that the formation of minerals of the uranium and gold ore formations took place during the period of the Svekofennian activation of the Kuolayarvi structure.

The geology of the basal-structural Loypishnyun low-sulfide Pt–Pd deposit is characterized, including its mineral composition and the peculiarities of its PGE and chalcophile-element distribution in ore. The deposit is situated in the northeastern part of the Monchetundra basic massif and is localized in its lower norite–orthopyroxenite zone, intensely injected with late gabbroic rocks. Two ore zones are distinguished within the deposit. Ore zone 1 has been traced by drilling for about 1.5 km at a thickness from 10–15 to 120 m and incorporates from two to nine separate lenticular–sheetlike orebodies 0.5–25 m in thickness. Ore zone 2 has been traced for 550 m and is represented by one orebody 5–35 m thick. The internal structure of the orebodies is characterized by alternation of low-grade (Pt + Pd = 0.5–0.9 gpt), ordinary (Pt + Pd = 1.0–1.9 gpt), and high-grade (Pt + Pd > 2 gpt) interlayers of various thickness. The ores are spatially and genetically related to sulfide mineralization (pentlandite–chalcopyrite–pyrrhotite) in an amount of 1–5 vol %. The PGE distribution in ores normalized to primitive mantle is characterized by fractionation of easily fusible platinoids with a positive Pd anomaly. The spectra of chalcophile elements normalized to primitive mantle are notable for elevated Te, Bi, As, and Se contents with respect to Sn, Hg, and Pb, which reflects the significant contribution of Te, Bi, and As in the formation of platinum group minerals (PGM), whereas Se, which is devoid of proper mineral phases, most likely is an admixture in the composition of sulfides. The S/Se value in ore of the Loypishnyun deposit varies from 31 to 814. The platinum group elements (PGE) in ore are represented by 45 noble metal minerals. Ore zone 1 is characterized by lateral mineral zoning, which is expressed as replacement of a bismuthotelluride–sulfide PGM assemblage by an assemblage of copper–PGE compounds and alloys. In ore zone 2, a mineral assemblage of tellurides, copper–PGE compounds and alloys predominates, with native gold, silver, and palladium, as well as sulfides and bismuthotellurides, playing a subordinate role. The formation of PGM ore proceeded under variable sulfur fugacity conditions, beginning with the late magmatic stage at temperatures of 900–700°C and ending with hydrothermal transformation at a temperature of <500°C.

Data on gold ore objects in the Strelna Greenstone Belt in the southeastern Kola Peninsula are presented in the paper. The studied Vorgovy and Sergozero ore occurrences are localized in the zone of tectonic contact of the Neoarchean complexes making up the greenstone belt and the volcanic–sedimentary sequences of the Paleoproterozoic Imandra–Varzuga Zone. The Vorgovy gold occurrence is related to stockwork of carbonate–quartz veins and veinlets hosted in a biotite gneiss transformed into chlorite–sericite–quartz metasomatic rock with pyrrhotite–arsenopyrite dissemination. The Sergozero occurrence is localized in amphibolites corresponding to komatiitic and tholeiitic basalts hosted in biotite gneiss (metapelite). Mineralization is confined to the zone of tectonized contact between komatiitic and tholeiitic basalts, where it is controlled by a strip of metasomatic biotite–calcite rock with gersdorffite–arsenopyrite dissemination. The native gold grains medium to high in fineness are up to 0.1 mm in size and mainly localized at the contact of arsenopyrite and gersdorffite with gangue minerals. Gold mineralization is of superimposed character, and, as indicated by isotopic geochronology, was formed at the retrograde stage of the Svecofennian regional metamorphism. Comparison of ore occurrences localized in the Strelna Greenstone Belt with gold deposits in greenstone belts of the western Fennoscandian Shield and the Superior Province in Canada allows us to suggest a high perspective of the entire Strelna Belt for gold.

The Djamgyr gold deposit is located within the Neoproterozoic basement of the Middle Tien Shan terrane immediately west of the Talas-Fergana fault. The deposit comprises a system of auriferous quartz veins cross-cutting the Beshtor plagiogranite. The veins are surrounded by hydrothermal alteration aureoles and are oriented parallel to the Talas-Fergana fault. The Beshtor granite sampled in the vicinity of the deposit yielded a Neoproterozoic (Tonian) U-Pb zircon age of 815 +/- 6 Ma, which is the first single grain zircon age of the Middle Tien Shan basement west of the Talas-Fergana fault. Ar-Ar dating of two muscovite fractions from the alteration aureoles of the auriferous quartz veins yielded ages of 804 +/- 3 and 805 +/- 3 Ma suggesting that the mineralization in the Djamgyr deposit occurred during the Neoproterozoic ca. 10 m.y. after emplacement of the Beshtor granite. The structural pattern of the auriferous quartz veins and the new geochronological data, combined with the results of previous structural studies, may tentatively constrain the age of pre-existing major fault possibly marking an inherited terrane boundary in the northern part of the present-day Talas-Fergana strike-slip fault. The discovery of Precambrian gold mineralization in the Middle Tien Shan suggests re-evaluation of the metallogenic potential of its Precambrian basement that occupies significant areas west and east of the TalasFergana fault. (C) 2017 Elsevier B.V. All rights reserved.

Охарактеризовано внутреннее строение Волчьетундровского массива габбро-анортозитов, приведены данные об особенностях локализации в нем малосульфидного платинометального оруденения, его характеристика и минеральный состав. Волчьетундровский массив длиной 24 км при ширине от 500 м до 4 км слагает среднюю часть комплекса Главного хребта общей протяженностью 75 км, вытянутого в субмеридиональном направлении. Во внутреннем строении массива выделяются краевая и главная зоны. Краевая зона мощностью от 20 до 400 м протягивается вдоль всего восточного контакта массива. Она сложена, в основном, среднезернистыми мезо-лейкократовыми норитами, габброноритами, плагиоклазитами, реже ортопироксенитами. Главная зона слагает основной объем массива и представлена преобладающими крупнозернистыми лейкократовыми габбро и габброноритами с полосой анортозитов в осевой части массива. Малосульфидное платинометальное оруденение Волчьетундровского массива отчетливо делится на два типа, которые существенно различаются условиями локализации, минеральным составом, основными химическими параметрами и промышленной значимостью. К первому типу относится оруденение, локализованное в пределах краевой зоны и имеющее наибольший промышленный потенциал. Ко второму типу принадлежит платинометальное оруденение, развитое в пределах главной зоны. Оруденение, приуроченное к краевой зоне, пространственно и генетически связано с сульфидной минерализацией пирит-пентландит-халькопирит-пирротинового состава в количестве 1–5%, представленной мелкой, неравномерной интерстициальной вкрапленностью, реже более крупными вкрапленниками и гнездами. Оно локализовано в двух рудных зонах протяженностью до 2 км каждая. Мощность отдельных рудных горизонтов варьирует, в основном, от 0.5 до 3 м с отдельными раздувами до 45 м, среднее содержание Pt + Pd составляет 1.37 г/т при Pd/Pt = 3.1. Оруденение второго типа вскрыто, в основном, скважинами в отдельных подсечениях, которые не коррелируют друг с другом, имеют незначительную протяженность как по простиранию, так и по падению. Оно связано с сульфидной минерализацией пентландит-пирит-пирротин-халькопиритового состава, развитой в виде тонкораспыленного и эмульсионного, реже прожилково-вкрапленного типов. Мощность рудных тел варьирует от 2 до 7 м, среднее содержание Pt + Pd = 1.61 г/т при Pd/Pt = 1.3. Минеральный состав платинометального оруденения представлен 22 минеральными видами, среди которых преобладают сульфиды (куперит-брэггит-высоцкит, в незначительных количествах лаурит и эрлихманит), в подчиненном количестве присутствуют висмутотеллуриды (мончеит-котульскит-меренскиит) и арсениды (сперрилит, палладоарсенит, арсенопалладинит и атенеит). Кроме того, обнаружены сульфоарсениды (платарсит и холлингвортит) и теллуриды (теларгпалит, сопчеит, кейтконит, мелонит и гессит), а также паоловит и Pt-Fe-сплав, постоянно присутствует примесь самородного золота и электрума.

The internal structure of the Volchetundra gabbro-anorthosite massif is considered, including localization of low-sulfide PGE mineralization and its mineralogy. The Volchetundra massif 24 km long and 0.5–4.0 km wide occupies the middle part of the Main Range complex, which extends for 75 km in the nearly meridional direction. The main and marginal zones are distinguished in the massif. The marginal zone 20–400 m wide extends along the entire eastern contact of the massif and is primarily composed of mediumgrained meso- and leucocratic norite, gabbronorite, plagioclasite, and less fequent orthopyroxenite. The main zone consists of coarse-grained leucogabbro and gabbronorite with an anorthosite zone in the axial part of the massif. The PGE mineralization of the Volchetundra massif is distinctly subdivided into two types substantially differing in localization, mineralogy, geochemistry, and economic importance. Mineralization of the first type is localized in the marginal zone and characterized by the highest resource potential. Mineralization hosted in the main zone belongs to the second type. The PGE ore of marginal zone is spatially and genetically related to the pyrite-pentlandite-chalcopyrite-pyrrhotite sulfide mineralization (1–5%) in the form of fine inequigranular interstitial disseminations, and less frequent larger grains and pockets localized within two ore zones each up to 2 km in extent. The thickness of separate mineralized layers varies from 0.5 to 3.0 m and up to 45 m in bulges. The average Pt + Pd grade is 1.37 gpt at Pd/Pt = 3.1. The mineralization of the second type has been penetrated by boreholes. Separate intersections do not correlate with one another and are limited in extent both along the strike and down the dip. The PGE mineralization is related to finely dispersed pentlandite-pyrite-pyrrhotite-chalcopyrite sulfides, sulfide emulsions, and less abundant stringer-disseminated sulfide ore. The orebodies vary from 2 to 7 m in thickness. The average Pt + Pd grade is 1.61 gpt; Pd/Pt = 1.3. The PGE mineralization includes 22 mineral species. PGE sulfides (cooperite-braggite-vysotskite; laurite and erlichmanite in insignificant amounts) are predominant. Bismuthotellurides (moncheite-kotulskite-merenskyite) and arsenides (sperrylite, palladoarsenite, arsenopalladinite, atheneite) are subordinate in abundance. In addition, sulfoarsenides (platarsite, hollingworthite), tellurides (telargpalite, sopcheite, keithconnite, melonite, hessite), paolovite, and Pt-Fe alloy have been identified. An admixture of native gold and electrum occur constantly.