The results of the study of the platinum group minerals of the Baimka gold placer cluster, Western Chukotka, Russia, are presented. Platinum group minerals belong to the iridium-platinum and platinum miner- alogical-geochemical types with the Late Jurassic cumulative pyroxenite-gabbro complexes as a probable source. Platinum group minerals came to alluvial gold placers primarily from intermediate reservoirs, which is the Volgian volcanic-sedimentary sequence. Rounded silicate glass inclusions are a specific feature of platinum minerals from the Baimka placer cluster.

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.

The results of 190 Pt– 4 He dating of placer-forming minerals of platinum (PMP) from the Baimka gold placer cluster (Western Chukotka, Russia) are reported. PMPs are represented by isoferroplatinum with a composition of Pt 3 + x Fe 1 – x and Pt 3 Fe. The concentrations of 190 Pt and 4 He in 14 PMP samples were obtained. The results of 190 Pt– 4 He dating showed the existence of two age clusters of PMP (148 ± 6 and 188 ± 4 Ma) for the first time. The primary sources of PMP, which are similar in their genetic type, but have different ages, are assumed: (1) later, 148 ± 6 Ma of the Baimka Complex (J 3 b) and (2) earlier, 188 ± 4 Ma. PMPs enter alluvial gold placers mainly from the intermediate PGM reservoir, which is composed of rocks of the Volgian stage J 3 v 2–3 (Tithonian). Thus, sedimentary rocks or explosive breccia of andesite–basalt of the Volgian stage could be the PMP source reservoir.

Relevance of the work is due to the need to study the mineralogy of gold deposits in the Russian Far East, information about which is extremely scarce. Purpose of the work: study of the chemical composition of tourmaline from Mnogovershinnoe ore deposit, Khabarovsk Krai (Far East). Methodology of research: The chemical composition of minerals and BSE images were obtained using a Jeol JSM-6480 electron microscope equipped with an Inca Energy-350 EDS (analyst is N. N. Koshlyakova, Department of Petrology, Lomonosov Moscow State University). Electron microscope shooting environment: accelerating voltage is 15 kV, measuring current for the sample is 30 ± 0.1 nA. XPP corrections were used for the adjustment procedure (INCA program, version 17a). Results. The obtained data show that tourmalines of the Mnogovershinnoe deposit differ in their chemical composition and type of substitution. All studied tourmalines by these parameters can be divided into two groups. Group 1 includes schorl, foitite, and pegmatoids feruvite, as well as schorl and foitite of the first generation, tourmaline-muscovite-quartz veinlet in sandstones. Group 2 includes schorl of the second generation, tourmaline- muscovite quartz veinlet, schorl and foitite of quartz-tourmaline metasomatites, and cement dravite of quartz breccia. Conclusions. Tourmalines of the post-ore mineral associations of the Mnogovershinnoe gold deposit are divided into two groups characterized by different chemical composition and substitutions. Tourmalines of the first group with substitutions Fe ↔ Mg and X-vacancy + Al ↔ Na + R2+ are confined to pegmatoids and were formed in reducing or weakly oxidative conditions. Later tourmalines of the second group with substitutions Fe3+ ↔ Al and Al + O2– ↔ R2++ OH– indicate a possible porphyry-style mineralization and its formation during lowering oxidative potential.

В работе представлены результаты исследования каталитической активности калий-титанатных наноматериалов, допированных различными металлами (Ni, Mg, Al, Fe, Cr), в реакциях окисления водорода и монооксида углерода. Показано, что наилучшие характеристики по окислению исследуемых газов показали нанотрубки, допированные алюминием (0.3 · 10 моль Н/(г X с) при 250 °C; 0.125 · 10 моль СО/(г X с) при 350 °C).

MoO3/ZrO2 catalysts were prepared either by wet impregnation or tableting dry mechanical mixtures of corresponding zirconium hydroxide and molybdenum containing precursors. It was shown that synthesis parameters influence the phase composition, structure, nature and strength of the acid sites. The structural and textural properties of MoO3/ZrO2 catalysts were characterized by a range of techniques including DTA, XRD, N-2-physisorption, pH-measurements, selective adsorption of a series of acid-base indicators and FTIR spectroscopy of adsorbed pyridine. It is shown that an increase in the concentration of MoO3 gave a rise to Bronsted acidity concomitant with an increase of 1-butene conversion in isobutane alkylation and butene dimerization. Introduction of up to 6.6% of MoO3 resulted in sharp changes in physico-chemical properties as well as in catalytic behaviour allowing generation of products with an increased content of C-8 compounds because of alkylation and dimerization. A further increase of MoO3 content to 13.2% predominantly led to isomerization of 1-butene to 2-butene which can be related to elevated Bronsted acidity.

The paper reports data obtained in the course of a comprehensive physicochemical study of Li-tosudite, a mixed-layer mineral from hydrothermally altered rocks in western Chukotka, Russia, whose formula was reliably established. The enthalpy of formation of Li-tosudite from Chukotka, Ca0.15(Li0.9Mg0.2Al6.0)[Si6.4Al1.6O20](OH)10 · 3.3H2O, from elements was experimentally determined by melt solution calorimetry in a high-temperature Calvet microcalorimeter: ΔfH el o (298.15 К) =–15087 ± 26 kJ/mol. The standard entropy and Gibbs free energy of formation of this mineral were evaluated.

В верховьях р. Илирнейвеем (Водораздельный золоторудный узел) в измененных андезитах установлены жилы эпидот-кальцит-пренитового состава с медной минерализацией. Минералы меди представлены самородной медью, домейкитом, халькозином и спионкопитом. Формирование жил связывается с процессами низкоградного метаморфизма пренит-пумпеллиитовой фации, захватившими вулканиты тытыльвеемской свиты.

This work presents the results of investigating the catalytic activity of potassium titanate nanomaterials doped by different metals (Ni, Mg, Al, Fe, and Cr) in oxidation reactions of hydrogen and carbon monoxide. It is shown that the best characteristics of the oxidation of the investigated gases have nanotubes doped by aluminium (0.3 × 10 –5 mol H 2 /(g s) at 250°C and 10 –5 mol CO/(g s) at 350°C).

The Peschanka deposit and Nakhodka ore field occurring in the Baimka Cu-Mo-Au porphyry-epithermal trend in the western Chukchi Peninsula, Russia are spatially related to monzonitic rocks of the Early Cretaceous Egdykgych Complex. Tetrahedrite solid solution (Tt(s)) was recognized at the deposit and within the ore field in the following assemblages: (1) porphyry stage bornite, chalcopyrite, and molybdenite, (2) transitional (subepithermal) stage sphalerite, galena, chalcopyrite, and As-free pyrite, (3) HS epithermal stage enargite, chalcopyrite and high-fineness native gold, and (4) IS epithermal stage As rich pyrite, galena, sphalerite, and low -fineness native gold and electrum. The porphyry and subepithermal Its crystals are oscillatory zoned because of variable contents of Sb and As. The literature data show that similar zoning has been recognized in the Tt(s) crystals in the other porphyry Cu-Mo-Au and transitional assemblages and differs from the other type deposits. Therefore, such a zoning is considered to be a guide to these two mineralization types. No zoning was found in Tts referred to the HS and IS epithermal assemblages within the Baimka trend. The porphyry stage Tts evolves from Fe-rich tennantite ((sb = Sb/(Sb + As) below 0.01, fe = Fe/(Fe + Zn) 0.60-0.80) through oscillatory zoned tennantite enriched in Sb and Zn (sb 0.19-0.37, fe 0.56-0.66) to tetrahedrite enriched in Zn (sb 0.51-0.70, fe 0.39-0.66). This trend is caused by the Sb accumulation and increased f(s2), The review of published data shows that such trend is typical of the other porphyry deposit worldwide. Therefore, it is considered to be a guide to distinguish porphyry deposits from the other type deposits containing fahlores and to distinguish porphyry stage fahlores. The composition of the transitional stage Tts evolves from Zn-rich tetrahedrite (sb 0.56-0.82, fe 0.03-0.05) through Zn-rich tennantite (sb 0.03-0.19, fe 0.11-0.13) followed by Zn-rich oscillatory zoned solid solution (sb 0.03 to 0.69, fe 0.09 to 0.11) to goldfieldite. This evolution testifies to increased f(Te2) to the end of transitional stage. The HS stage Tt(s) corresponds to Fe -rich tennantite (sb below 0.05, fe 0.65-1.00) containing high Cu-excess (1.43 apfu). The IS stage Tt(s) evolves from Zn-rich tennantite (sb = 0, fe = 0.44) to Zn-rich tetrahedrite (sb = 0.97, fe = 0.03). The latest Zn-rich tetrahedrite of this assemblage is enriched in Ag (up to 4.1 wt.%) testifying to increasing Ag activity to the end of mineralizing process. The review of literature data shows the similar trend for the transitional and IS Tts in the other porphyryepithermal systems. Therefore the Tt(s) evolution trend is a criterion to separate porphyry, transitional, IS, and HS Tt(s). (C) 2017 Elsevier B.V. All rights reserved.

The porous structure and surface acid–base properties of sulfated zirconia, alumina and alumina–zirconia applied in isobutylene alkylation were characterized using a variety of physico-chemical methods. Catalytic activity was related to catalyst physico-chemical properties.

The Kapelka Ag-Au prospect is located in the Western Chukchi Peninsula, Russia. The mineralization is hosted by Upper Cretaceous volcanic rocks of the Okhotsk-Chukchi Volcanic Belt (OChVB). Wallrock alteration and ore bodies are associated with NE and NNE trending faults.The LS and base metal types of mineralization are predominant at the Kapelka prospect. Ore bodies occur as stockwork and veinlet systems. Major alteration types are propylitic, argillic and secondary quartzite. High grades of main components were determined in ore samples: 1.5% Ag, 12% Pb, 2.2% Cu, 0.8% Zn and 27 ppm Au; gold silver ratio is from 1: 100 to 1: 3500. The anomalous geochemical field is widespread. The composition of secondary halos is corresponding to the one of primary ore.Propylites are composed of epidote, chlorite, K-feldspar, quartz. The main minerals of argillic rocks are tosudite, montmorillonite, dickite and quartz. Propylitic and argillic rocks were formed at the temperature of 330-365 and 110-300 degrees C. respectively (the Cathelineau thermometer [1]). Gangue minerals include quartz, adularia, sericite and others. Ore minerals are pyrite, arsenopyrite, galena, sphalerite, chalcopyrite, bornite, electrum, polybasite-pearceite, acanthite and tetrahedrite-tennantite. Native silver, acanthite, anilite, brochantite, anglesite, cerussite, malachite, azurite and wulfenite represent supergeneous assemblage. Homogenization temperatures of fluid inclusions vary from 167 to 353 degrees C, salinity is within the range of 0.2-1.4 wt. % NaCl equiv. Pressure estimated for fluid boiling at the temperature of 353 degrees C is 16MPa corresponding to the ore formation depth of 0.6 km.According to geology, wallrock alteration and composition of geochemical anomalies, the closest analogue of Kapelka is the Zhilny prospect nearby the large Au-Ag epithermal Valunistoye deposit, the Eastern Chukchi Peninsula. Future exploration will clarify the parameters of the ore bodies and economic prospects of Kapelka.