The Konduyak gold–quartz–sulfide deposit is one of the most promising gold mines in the Ayakhta gold ore cluster on the Yenisei ridge. This article is devoted to the study of the composition of the volatile compounds in the ore-forming fluid, since this is one of the key aspects in understanding the conditions of deposit formation. The compositions of the fluids that formed quartz and pyrite in the deposit ore zone were determined using Raman spectroscopy and pyrolysis-free gas chromatography–mass spectrometry. The study of the fluid inclusions in the minerals showed that complex C-H-O-S-N multi-component fluids formed the quartz–sulfide ore zones. A range of 232 to 302 various volatile compounds were found in the fluids. The mineralizing fluids mainly consist of H2O (14.25–96.02 rel. %) and CO2 (2.07–54.44 rel. %). A high SO2 content (14.60–44.95 rel. %) is typical of fluids trapped by pyrites. Moreover, a wide range of hydrocarbons (oxygen-free aliphatic, cyclic, heterocyclic, and oxygenated) and nitrogenated and sulfur compounds were found among the volatiles in the fluid. The variable H/(H + O) ratios, from 0.51 to 0.81, and CO2/(CO2 + H2O) ratios, from 0.02 to 0.56, indicate changes in the redox conditions during ore formation.

Определен изотопный состав C и O в кальците и в (CO3)-группах карбонат-силикатов Ca(спуррита, тиллеита и скаполита) из пород Кочумдекского контактового ореола (Восточная Сибирь). Малые диапазоны различий между величинами δ13C и δ18O, характеризующие кочумдекские мраморы и их протолиты (Δδ13C ≤ 1.5 ‰ и Δδ18O ≤ 2.0 ‰), согласуются с низкой степенью высокотемпературной метаморфической декарбонатизации исходных мергелисто-карбонатных осадков (0.1—0.2) и отсутствием выраженных метасоматических изменений в породах ореола. Существенное обеднение изотопом 18O присуще только жильному скаполиту (δ18O от + 17.0 до + 17.3 ‰ V-SMOW) и кальциту из рекристаллизованных прослоев в известняках (δ18O от + 18.9 до + 20.6 ‰), что доказывает ограниченную инфильтрацию магматогенных водных флюидов из остывающего траппа внутрь вмещающей толщи. Определен изотопный состав C и O (CO3)-групп спуррита и тиллеита, которые обогащены изотопом 18O и могут быть несколько обеднены изотопом 13C относительно кальцита. Этот эффект максимален в наиболее высокотемпературных мервинитовых парагенезисах (Δδ18OSpu–Cal = + 3.3 ‰; Δδ13CSpu–Cal= –0.8 ‰). С применением метода беспиролизной газовой хромато-масс-спектрометрии (ГХ-МС) определены соотношения H2O и CO2 во флюиде при пиковых параметрах спуррит-мервинитового метаморфизма. Установлено, что флюидная фаза, законсервированная в кальците из мервинитовых мраморов, была богата CO2 (XCO2 = 0.4—0.6). Carbon and oxygen isotope compositions have been determined in (CO3)-groups of Ca carbonate–silicate minerals (spurrite, tilleyite, and scapolite) and calcite from samples of the Kochumdek contact aureole (East Siberia). The observed small δ13C and δ18O difference between the Kochumdek marbles and their protoliths (Δδ13C ≤ 1.5‰ and Δ?δ18O ≤ 2.0‰) is consistent with moderate high-temperature metamorphic decarbonation of the protolith (0.1–0.2) and with almost absent metasomatic alteration in the aureole. Significant 18O depletion was inferred only for vein scapolite (δ18O from +17.0 to +17.3‰ V-SMOW) and calcite from recrystallized limestone layers (δ18O from +18.9 to +20.6‰), which is evidence for limited infiltration of magmatic aqueous fluids from the cooling sill into the host sediments. The C and O isotope compositions of (CO3)-bearing spurrite and tilleyite show lower 18O depletion and insignificant 13C depletion relative to calcite, especially in highest-temperature merwinite marble (Δδ18OSpu–Cal = +3.3‰; Δ?δ13CSpu–Cal = –0.8‰). Gas chromatography-mass spectrometry (GC-MS) provided constraints on the relative percentages of H2O and CO2 in the fluid at highest-temperature spurrite-merwinite metamorphism. The fluid phase entrapped in calcite from merwinite marble is rich in CO2 (XCO2 = 0.4–0.6).

Synthesis of diamond from anthracene in an Fe,Ni-melt at 5.5 GPa and 1450 °C.

Based on analysis of the results of the synthesis and growth of diamonds in metal-sulfide melts at a high pressure, the cause of the crystallization of low-nitrogen diamond crystals is substantiated. The introduction of sulfur into an iron melt leads to a decrease in the solubility of nitrogen, which, in turn, leads to a decrease in the content of nitrogen atoms in the melt and the probability of their capture by growing diamond crystals in the form of a structural impurity. The addition of nickel reduces the melting point of the growth system, increases the amount of melt, and, accordingly, facilitates the dissociation of molecular nitrogen into separate atoms, which are captured as a structural impurity by diamonds during their growth.

Polycrystalline aggregates of diamonds, known as bort, framesite, diamondite, are densely cemented aggregates of small (<1 mm) crystals of both transparent and dark color. The study of fluid inclusions in three samples from the Mir and Udachnaya kimberlite pipes (Yakutia) by IR spectroscopy and GC-MS methods for the first time showed the hydrocarbons and their derivatives contained in them. A total content (from 25.7 to 57.3 rel.

Experiments conducted in the olivine–serpentine–anthracene–metal (FeNi) system have shown that the recrystallization of olivines occurs under substantially reduced conditions with active participation of hydrocarbons, especially paraffins; moreover, their amount increases with increasing pressure and temperature. During the decomposition of serpentine, a large amount of water is released; therefore, the fluid at relatively low P-T parameters (2 GPa, 1100 °C) has mainly water–hydrocarbon composition. With an increase in pressure up to 3–4.5 GPa and temperature up to 1300–1400 °C, the composition of the fluid changes greatly towards an increase in the relative amount of hydrocarbons, while the main share is occupied by light (C1–C4) aliphatic hydrocarbons. Therefore, a biogenic material with a carbon–hydrogen composition can make a certain contribution to the carbon budget in subduction processes when falling into the subduction zones and may affect the oxygen fugitivity in the subducted slab.

The Dobroe deposit with 10 t gold reserves is one of the gold mines located within the Yenisei Ridge Orogenic Belt. The ore-forming conditions of orogenic gold deposits are have recently been widely discussed. A comprehensive study of fluid inclusions revealed that the Dobroe gold deposit was formed by water–carbon dioxide and carbon dioxide–hydrocarbon fluids within a temperature range of 180 to 360 °C, a pressure range of 0.8 to 1.3 kbar, and a salinity range of 1.5 to 15.0 wt.% (NaCl-equiv.). Gas chromatography–mass spectrometry showed that ore-forming fluids consisted of H2O, CO2, hydrocarbons, nitrogenated, sulfonated, and chlorinated compounds. The distribution patterns of δ13C in fluid inclusions (−11.3‰–−3.6‰) and δ34S in sulfides (1.9‰–17‰) of the Dobroe deposit indicate a crustal source for ore-bearing fluids.

Experimental modeling of diamond crystallization is conducted in a FeNi–graphite–Ca carbonate system at 5.5 GPa and 1400°C using two scenarios of assembly configurations: layer-by-layer and mixing of all components. It is found that a Ca carbonate is decomposed with the formation of Ca, Fe oxides and release of CO2 upon interaction with FeNi melt. Magnetite can be present as an accessory mineral. Due to the formation of solid reaction products (Ca,Fe oxides) in layer-by-layer assembly configuration, the position of Ca carbonate between graphite and FeNi melt hampers the diamond crystallization in a graphite layer and carbon transport on diamond seed crystals. Mixing of components in an assembly configuration leads to diamond synthesis and growth on seed crystals. The phenomenon of segregation of diamond crystals together with Ca carbonate and oxide phases (the reaction products in metal volume) is recognized. The fluid inclusions trapped by growing diamond contain aliphatic, cyclic, and O-bearing hydrocarbons including heavy compounds (С13–С17), СО2, Н2О, and N- and S-bearing compounds. The fluid phase in these diamonds is more oxidized in comparison with that in diamonds synthesized in a carbonate-free FeNi–graphite system. Our data are consistent with data on natural diamonds, which include crystals with “significantly hydrocarbon” compositions of fluid inclusions indicating a possible involvement of crustal carbonate material in diamond formation processes upon subduction to deep mantle.

For the first time, original results concerning the composition of fluids extracted from glendonite found in Japan (East) Sea continental slope bottom sediment have been obtained. We used the one-act shock-destructive extraction of volatile components from fluid inclusions and made their pyrolysis-free gas chromatography-mass spectrometry analysis, which, despite the limited amount of analytical data, are of scientific and practical interest. According to the data obtained, the fluids in glendonite represent a complex multicomponent mineral-forming system. In addition to water and carbon dioxide, representatives of 13 homologous series of organic compounds were found in the studied fluid inclusions. These include oxygen-free aliphatic and cyclic hydrocarbons (paraffins, olefins, cyclic alkanes and alkenes, arenes, polycyclic aromatic hydrocarbons-PAHs), oxygenated hydrocarbons (alcohols, ethers and esters, furans, aldehydes, ketones, carboxylic acids), nitrogen-, sulfur-, halogenated compounds. An oxidized water-carbon dioxide fluid with a reduced content of hydrocarbons and S–N–F-containing compounds 0.8 rel

—The behavior of fluids during plastic deformation is studied from the morphology and distribution of fluid inclusions in quartz grains of different microstructure types from a vein system controlled by thrusting and strike-slip faulting in the eastern Sayan–Baikal fold area. The analytical work includes electron backscatter diffraction (EBSD) for quartz microstructure and crystallography, as well as Linkam heating-and-freezing analysis and Raman spectroscopy for the composition of fluid inclusions. The studied fluid inclusions are of seven types that differ in morphology and position in the deformed quartz structure. A model is suggested to describe successive structural changes of quartz aggregates during dislocation sliding and subsequent creep-related recrystallization associated with redistribution of fluid. Fluid inclusions undergo qualitative and quantitative changes due to water leakage at all stages of plastic deformation. The changes occur by two main mechanisms: (i) mass transfer during dislocation sliding at medium temperatures and strain rates and (ii) diffusion creep at low strain rates and high temperatures. The contribution of creep increases gradually with temperature, which maintains the interaction of inclusions with migrating grain boundaries.

The problem of heat–mass transfer in the permeable areas above the asthenosphere zones was numerically studied based on an examination of the inclusion content in the minerals (olivine and clinopyroxenes) of igneous and metamorphic rocks of the lithospheric mantle and the Earth’s crust; evaluations of thermodynamic conditions of the inclusion formation; and experimental modeling of the influence of hot reduced gases on rocks in the mantle beneath the Siberian craton. The flow of fluids of a certain composition from the upper-mantle magma chambers leads to the formation of zonal metasomatic columns in the ultrabasic mantle lithosphere in the permeable zones of deep faults (starting from the lithosphere base at 6–7 GPa). When petrogenic components enter from the magma pocket, depleted ultrabasic lithospheric mantle rocks change to substrates, which can be considered as the deep counterparts of crustal rodingites. Other fluid compositions result in strong calcination and pronounced salinization of the metasomatized substrates or an increase in the garnet content of the primary ultrabasic matrix. A region of alkaline rocks forms above these areas, which changes to pyroxenes, amphiboles, and biotites. The heat–mass transfer modeling for the two-velocity hydrodynamic model shows that gas–fluid and melt percolation lead to an increase in the thermal front velocity under convective heating and a pressure drop in flow. It is also shown that grospidites are considered to be eclogites, are found in the permeable zones of the lithospheric mantle columns serving as conduits for the melt/fluids and represent the products of the carbonated metasomatic columns. The carbonization caused by proto-kimberlite melts may essentially decrease the diamond grade of kimberlites due to carbon oxidation.

Nitrogen partitioning between its main hosts is investigated using partly devolatilized natural quartz-muscovite-chlorite schist (mica schist), with NH4+-rich muscovite, under conditions corresponding to hot subduction: 3.0-7.8 GPa, 750-1090 degrees C, and oxygen fugacity (fO(2)) about the NNO (Ni-NiO) buffer. At these conditions, mica schist transforms into an eclogitic assemblage, while muscovite (C2/c) recrystallizes successively into two high-pressure white mica phases. The resulting phases are phengite (P3(1)12) and a phase intermediate between the dioctahedral and trioctahedral mica series (C2/m). During dehydration and decarbonation reactions at run P-T conditions mica schist releases an H2O-CO2 fluid containing 0.3-14 rel.% N2 and < 0.1-3.7 rel.% NH3. The contents of NH4+ determined by Fourier transform infrared spectroscopy (FTIR) decrease from 1600 to 2000 ppm in primary muscovite to similar to 1500 ppm in phengitic muscovite at 6.3 GPa and 1000 degrees C and to 610-990 ppm in the intermediate between the dioctahedral and trioctahedral mica phase at 7.8 GPa and 10701090 degrees C. Ammonium in the analyzed metapelite shows incompatible behavior (D-NH4(Mica-Fluid)=0.05-0.15) at >= 5.5 GPa and temperatures and fO(2) common to hot oxidizing slabs, which is expected to cause its efficient outgassing from subducting metasediments depleted in volatiles. Nitrogen partitioning under hot subduction conditions at sub-arc depths is generally controlled by devolatilization of measediments, phase transitions in Nbearing micas, and changes of fluid composition near the second critical point.

An experimental simulation of diamond crystallization in the system FeNi - graphite - calcium carbonate at a pressure of 5.5 GPa and a temperature of 1400℃ was carried out. Two sample assembly configurations were used. In the first one – the starting materials were put layer by layer, and in the second one - the components were mixed. It has been established that calcium carbonate, when interacting with the FeNi-melt, decomposes with the formation of Ca,Fe oxides and the release of CO2. Magnetite may be present as an accessory phase. Due to the formation of solid reaction products (Ca,Fe oxides) during layer-by-layer filling of the growth volume, the presence of calcium carbonate between graphite and FeNi-melt prevents diamond crystallization in the graphite layer and carbon transport to diamond seed crystals. When the components are mixed in the growth volume, diamond synthesis and growth onto seed crystals occur. The phenomenon of segregation of diamond crystals together with calcium carbonate and oxide phases, the products of the reaction in the bulk of the metal, has been discovered. Aliphatic, cyclic, and oxygenated hydrocarbons, including heavy compounds (C13-C17), CO2, H2O, nitrogen- and sulfonated compounds, were identified in the fluid phase captured by diamonds in the form of inclusions during growth. The composition of the fluid phase in the studied diamonds is more oxidized compared to the composition of fluid inclusions in diamonds grown in the FeNi – graphite system without carbonate. The results obtained correlate with the data on natural diamonds, among which there are crystals with “essentially carbon dioxide” compositions of fluid inclusions, which indicates the possible participation of crustal carbonate matter in the processes of diamond formation during subduction into the deep mantle.

The composition of volatile components of cordierite from the Muzkol metamorphic complex was studied using shock destruction with pyrolysis-free gas chromatography-mass spectrometry (GC-MS) with simultaneous IR and Raman spectroscopy. Applying the GC-MS procedure, the component relative concentrations (rel.%) and composition of different zones of cordierite crystals were determined. It was found that the substantially magnesian cordierite was formed with a predominantly aqueous-carbonic acid fluid (from 57.06 to 67.88 rel.% H2O, from 24.29 to 32.95 rel.% CO2). From the center towards the crystal periphery, the molar fraction of carbon dioxide (CO2/(H2O + CO2)) decreases from 0.36 to 0.26, whereas the alkane/alkene ratio increases from 0.80 to 0.88. At least 11 homologous series of organic compounds among the identified volatile components, in addition to water and carbon dioxide, were determined, including oxygen-free aliphatic and cyclic hydrocarbons (paraffins, olefins, cyclic alkanes and alkenes, arenes, polycyclic aromatic hydrocarbons (PAHs)), as well as oxygen-containing (alcohols, esters, aldehydes, ketones, carboxylic acids) and heterocyclic (furans, dioxanes) organic compounds.

Diamonds grown by high pressure high temperature process (HPHT) are usually characterized by yellow color and high contents of nitrogen. Introduction of Ti decreases nitrogen content in diamond. Understanding the formation of nitrogen-poor diamond is very important not for the progress of HPHT process only, but because these diamond varieties represent the rare natural stones, although their crystallization conditions have not been clarified yet. Here we studied the composition of fluid phase in synthetic diamonds. The experiments were performed using a high-pressure apparatus BARS at pressures 5.5–6.0 GPa and temperatures 1350–1400 °C. It was found that introduction of metallic Ti leads to concentration of nitrogen mainly as nitrogenated hydrocarbons. The hypothesis that elucidates the formation of low-nitrogen diamond in Fe–Ni is proposed: the presence of Ti leads to an increase of hydrogen fugacity in the metal melt which drastically reduces the nitrogen solubility. As a result, nitrogen concentrates in the form of complex hydrocarbon compounds, while diamond grows colorless and characterized by very low nitrogen content. It is suggested that the proposed mechanism acts the same way in the presence of other metals which are strong reducing agents.

In this study, the composition of fluid inclusions in minerals from polymetallic sulfide deposits Ashadze-1, Semenov-2, Krasnov, Rainbow and from the Lost City carbonate structures of hydrothermal fields in the Atlantic Ocean was determined using pyrolysis-free gas chromatography-mass spectrometry. It was found out that sulfides and anhydrite from the hydrothermal ore crystallized in reducing conditions with the active participation of hydrocarbons, including high-molecular, sulfonated, nitrogenated and halogenated compounds as well as water and carbon dioxide. On the other hand, carbonate structures formed in considerably more oxidizing conditions, for which the main components of volatiles were CO2 and H2O. The amount of detected hydrocarbons, including sulfonated, nitrogenated and halogenated compounds is significantly smaller compared to sulfides of ore vent structures.

Research subject. Fluid inclusions in quartz of three vein systems associated with tectonic cracks occurred during the development of thrust and shear deformations of the Western Transbaikalia. Vein systems localized in volcanic, terrigenous and granite rocks. Methods. The composition of fluid inclusions was studied by microthermometry, Raman spectroscopy and gas chromatography-mass spectrometry. Results. The quartz under study was formed by high-density medium-temperature NaCl-KCl and a low- and medium-salinity water-carbon dioxide fluid (2-5 wt % NaCl eq.). A distinctive feature of quartz of different vein systems was found to be the gas phase composition of inclusions associated with the composition of host rocks. The minimum temperatures of vein quartz formation were determined to range from 180 to 450°C under the minimum fluid pressure values of 0.7-2.9 kbar. Conclusions. Complex vein systems of the junction zone of the Baikal-Muiskaya and Barguzino-Vitimskay SFZ, confined to different host rocks and having different structural positions, are characterized by a similar fluid composition and a common thermodynamic history reflecting the change of deformation aggregates. The metamorphogenic-hydrothermal nature of the fluid involved in the formation of quartz vein systems was established. The development of the hydrothermal system was accompanied by its influence on the host rocks, which was manifested in the variations of fluid composition. The evolution of a single hydrothermal system is associated with tectonic deformation processes, which can be described by three dynamic stages corresponding to three quartz generations.

Pyrolysis-free gas chromatography-mass spectrometry was used to determine the gas phase composition of inclusions in phenocrysts from basalts and rhyolites of the Men'shii Brat Volcano (Medvezh'ya caldera, Iturup Island). Among more than 300 compounds detected in the inclusions, hydrocarbons are predominant (52-92 rel.%). These hydrocarbons (C-1-C-17) are alkanes, alkenes, alcohols, polycyclic aromatic hydrocarbons, ethers and esters, aldehydes, ketones, and carboxylic acids as well as sulfonated, nitrogenated, and halogenated organic compounds. Inorganic substances, which are predominantly CO2, H2O, SO2, and N-2, are present in subordinate amounts. The organic compounds are interpreted as products of abiogenic synthesis of hydrocarbons in magmatic gases. This fundamentally new information about the composition of magmatic fluid suggests that mantle and crustal magmas can transport hydrocarbon substance.