Composition of Volatile Components in Mineral-Hosted Fluid Inclusions at Hydrothermal Deposits. Water–Rock–Gas Systems in Ore-Forming Processes

The paper presents data on the average analyzed concentrations of volatile components (CO₂, CH₄ and other hydrocarbons, N₂, and H₂S) in natural fluids producing hydrothermal Au, Sn, W, Mo, Cu, Pb, and Zn mineral deposits. Characteristics of the gas regime at these deposits are determined. Thermodynamic simulations are carried out to model how compounds with volatile components are formed when water interacts with silicic and mafic rocks within wide P–T ranges. The speciation of volatile components determined by direct analysis is in good agreement with numerical simulations of water–rock systems (for silicic and mafic rocks). More reduced species with volatile components are formed in mafic rocks.     

Compositions of magmatic melts and evolution of mineral-forming fluids in the banska Stiavnica epithermal Au-Ag-Pb-Zn deposit, Slovakia: A study of inclusions in minerals

Melt and fluid inclusions were investigated in minerals from igneous rocks and ore (Au-Ag-Pb-Zn) veins of the Stiavnica ore field in Central Slovakia. High H₂O (7.1–12.0 wt %) and Cl (0.32–0.46 wt %) contents were found in silicate melt inclusions (65–69 wt % SiO₂ and 5.2–5.6 wt % K₂O) in plagioclase phenocrysts (An 68–36) from biotite-homblende andesites of the eastern part of the caldera. Similar high water contents are characteristic of magmatic melts (71–76 wt % SiO₂ and 3.7–5.1 wt % K₂O) forming the sanidine rhyolites of the Vyhne extrusive dome in the northwestern part of the Stiavnica caldera (up to 7.1 wt %) and the rhyolites of the Klotilda dike in the eastern part of the ore field (up to 11.5 wt %). The examination of primary inclusions in quartz and sanidine from the Vyhne rhyolites revealed high concentrations of N₂ and CO₂ in magmatic fluid (8.6 g/kg H₂O and 59 g/kg H₂O, respectively). Fluid pressure was estimated as 5.0 kbar on the basis of primary CO₂ fluid inclusions in plagioclase phenocrysts from the Kalvari basanites. This value corresponds to a depth of 18 km and may be indicative of a deep CO₂ source. Quartz from the granodiorites of the central part of the Stiavnica-Hodrusa complex crystallized from a melt with 4.2–6.1 wt % H₂O and 0.24–0.80 wt % Cl. Magmatic fluid cogenetic with this silicate melt was represented by a chloride brine with a salinity of no less than 77–80 wt % NaCl equiv. Secondary inclusions in quartz of the igneous rocks recorded a continuous trend of temperature, pressure, and solution salinity, from the parameters of magmatic fluids to the conditions of formation of ore veins. The gold mineralization of the Svyatozar vein system was formed from boiling low-salinity fluids (0.3–8.0 wt % NaCl equv.) at temperatures of 365–160°C and pressures of 160–60 bar. The Terezia, Bieber, Viliam, Spitaler, and Rozalia epithermal gold-silver-base metal veins were also formed from heterogeneous low-salinity fluids (0.3–12.1 wt %) at temperatures of 380–58°C and pressures of 240–10 bar. It was found that the salt components of the solutions were dominated by chlorides (high content of fluorine, up to 0.45 mol/kg H₂O, was also detected), and sulfate solutions appeared in the upper levels. The dissolved gas of ore-forming solutions was dominated by CO₂ (0.1–8.4 mol %, averaging 1.3 wt %) and contained minor nitrogen (0.00–0.85 mol %, averaging 0.05 mol %) and negligible methane admixtures (0.00–0.05 mol %, averaging 0.004 mol %). These data allowed us to conclude that the magmatic melts could be sources of H₂O, Cl, CO₂, and N₂. The formation of the epithermal mineralization of the Stiavnica ore field was associated with the mixing of magmatic fluid with low-concentration meteoric waters, and the fluid was in a heterogeneous state.     

Estimation of Hydrodynamic Effect on Tidal Variations in Gravity in the Transition Zone from the Continent to the Sea of Japan

Izvestiya, Physics of the Solid Earth - Abstract—The residual vector В (B, β) calculated from the difference of the observed tidal variations in gravity Аobs(А, α)...     

Physicochemical parameters of the formation of hydrothermal deposits: A fluid inclusion study. I. Tin and tungsten deposits

The author’s database, which presently includes data from more than 18500 publications on fluid and melt inclusions in minerals and is continuing to be appended, was used to generalize results on physicochemical parameters of the formation of hydrothermal deposits and occurrences of tin and tungsten. The database includes data on 320 tin and tin-tungsten deposits and occurrences and 253 tungsten and tungstentin deposits around the world. For most typical minerals of these deposits (quartz, cassiterite, tungsten, scheelite, topaz, beryl, tourmaline, fluorite, and calcite), histograms of homogenization temperatures of fluid inclusions were plotted. Most of 463 determinations made for cassiterite are in the range of 300–500°C with maximum at 300–400°C, while those for wolframite and scheelite (453 determinations) fall in the range of 200–400°C with maximum at 200–300°C. Representative material on pressures of hydrothermal fluids included 330 determinations for tin and 430 determinations for tungsten objects. It was found that premineral, ore, and postmineral stages spanned a wide pressure range from 70–110 bar to 6000–6400 bar. High pressures of the premineral stages at these deposits are caused by their genetic relation with felsic magmatism. Around 50% of pressure determinations lie in the range of 500–1500 bar. The wide variations in total salinity and temperatures (from 0.1 to 80 wt % NaCl equiv and 20–800°C) were obtained for mineral-forming fluids at the tin (1800 determinations) and tungsten (2070 determinations) objects. Most of all determinations define a salinity less than 10 wt % NaCl equiv. (∼60%) and temperature range of 200–400°C (∼70%). The average composition of volatile components of fluids determined by different methods is reported. Data on gas composition of the fluids determined by Raman spectroscopy are examined. Based on 180 determinations, the fluids from tin objects have the following composition (in mol %): 41.2 CO₂, 39.5 CH₄, 19.15 N₂, and 0.15 H₂S. The volatile components of tungsten deposits (190 determinations) are represented by 56.1 CO₂, 30.7 CH₄, 13.2 N₂, and 0.01 H₂S. Thus, the inclusions of tungsten deposits are characterized by higher CO₂ content and lower (but sufficiently high) contents of CH₄ and N₂. The concentrations of tin and tungsten in magmatic melts and mineral-forming fluids were estimated from analysis of individual inclusions. The geometric mean Sn contents are 87 ppm (+ 610 ppm/−76 ppm) in the melts (569 determinations) and 132 ppm (+ 630 ppm/−109 ppm) in the fluids (253 determinations). The geometric mean W values are 6.8 ppm (+ 81/−6.2 ppm) in the magmatic melts (430 determinations) and 30 ppm (+ 144 ppm/−25 ppm) in the mineral-forming fluids (391 determinations).     

Dynamic model of accumulation of total biomass of agricultural crops

Issues concerning the growth and biological time of agricultural crops are under consideration. A closed system of equations is derived for calculating total dry biomass and biological time of plants. The model parameters are given, and the model is verified based on the experimental data of observations of the sunflower in the southern conditions of the Ukraine.     

Principal physicochemical parameters of natural mineral-forming fluids

The authors’ database (which includes data from more than 17500 publications on fluid and melt inclusions in minerals) was used to generalize information on the principal physicochemical parameters of natural mineral-forming fluids (temperature, pressure, density, salinity of aqueous solutions, and the gas composition of the fluids). For 21 minerals, data are reported on the frequency of occurrence of the homogenization temperatures of fluid inclusions in various temperature ranges, which make it possible to reveal temperature ranges most favorable for the crystallization of these minerals. Data on 5260 determinations were used to evaluate the frequency of occurrence of certain temperature and pressure ranges of natural fluids within the temperature intervals of 20–1200°C and 1–12000 bar. Within these intervals, frequencies of occurrence were evaluated for water-dominated and water-poor or water-free fluid inclusions in minerals. The former are predominant at temperatures below 600°C and pressures below 4000 bar, whereas the latter dominate at temperatures of 600–1200°C and pressures of 4000-12000 bar. Illustrative examples are presented for visually discernible magmatic water that exists as an individual high-density phase in melt inclusions in minerals from various rocks sampled worldwide (in the Caucasus, Italy, Slovakia, United States, Uzbekistan, New Zealand, Chile, and others). Attention is drawn to the fact that extensive data testify to fairly high (>1000–1500 bar) pressures during hydrothermal mineral-forming processes. These pressures are much higher not only than the hydrostatic but also the lithostatic pressures of the overlying rocks. Data on more than 18000 determinations are used to evaluate the frequency of occurrence of certain temperature and salinity ranges of mineral-forming fluids within the intervals of 20–1000°C and 0–80 wt % equiv. NaCl and certain temperature and density ranges of these fluids at 20–1000°C and 0.01–1.90 g/cm³. Information is presented on the gas analysis methods most commonly applied to natural fluids in studying fluid inclusions in minerals in 1965–2007. The average composition of the gaseous phase of natural inclusions is calculated based on more than 3000 Raman spectroscopic analyses (the most frequently used method for analyzing individual inclusions).     

Measurement of air-fluorescence-light yield induced by an electromagnetic shower

For most of the ultra-high-energy cosmic ray (UHECR) experiments and projects (HiRes, AUGER, TA, JEM-EUSO, TUS, …), the detection technique of extensive air showers is based, at least, on the measurement of the air-fluorescence-induced signal. The knowledge of the fluorescence-light yield (FLY) is of paramount importance for the UHECR energy reconstruction. The MACFLY experiment was designed to perform absolute measurements of the air FLY and to study its properties. Here, we report the result of measurement of dry-air FLY induced by 50 GeV electromagnetic showers as a function of the shower age and as a function of the pressure. The experiment was performed at CERN using a SPS-electron-test-beam line. The result shows the air FLY is proportional to the energy deposited in air (E_d). The ratio FLY/E_d and its pressure dependence remain constant independently of shower age, and more generally, independently of the excitation source used (single-electron track or air shower).     

Chemical composition and crystallization conditions of trachybasalts from the Dzhida field, Southern Baikal volcanic area: Evidence from melt and fluid inclusions

Melt and fluid inclusions have been studied in olivine phenocrysts (Fo 81–79) from trachybasalts of the Southern Baikal volcanic area, Dzhida field. The melt inclusions were homogenized, quenched, and analyzed on an electron and ion microprobe. The study of homogenized glasses of nine inclusions showed that basaltic melts (SiO₂ = 47.1–50.3 wt %, MgO = 5.0–7.7 wt %, CaO = 7.1–11.1 wt %) have high contents of Al₂O₃ (17.1–19.6 wt %), Na₂O (4.1–6.2 wt %), K₂O (2.2–3.3 wt %), and P₂O₅ (0.6–1.1 wt %). The volatile contents are low (in wt %): 0.24–0.31 H₂O, 0.08 F, 0.03 Cl, and 0.02 S. Primary fluid inclusions in olivines from four trachybasalt samples contain high-density CO₂ (0.73–0.87 g/cm³), indicating a CO₂ fluid pressure of 4.3–6.6 kbar at 1200–1300°C and olivine crystallization depths of 16–24 km. Ion microprobe analyses of 20 glasses from melt inclusions for trace elements showed that the magmas of the Baikal rift were enriched in incompatible elements, thus differing from oceanic rift basalts and resembling oceanic island basalts. A comparison of our data on melt and fluid inclusions in olivine from trachybasalts of the Dzhida field with preexisting data on the Eastern Tuva volcanic highland in the Southern Baikal volcanic area showed that they had similar contents of volatiles, major, and trace elements.     

硅酸盐-盐（硫酸盐）流体不混溶：蒙古南部Mushugai-Khuduk含火成碳酸岩杂岩体矿物中的熔体包裹体研究

Crystalline and melt inclusions were studied in garnet,diopside,potassium feldspar,and sphene from the garnet syenite porphyry of the carbonatite-bearing complex Mushugai-Khuduk,southern Mongolia.Phlogopite,clinopyroxene,albite,potassium feldspar,spheric,wollastonite,magnetite,Ca and Sr sulfates,fluorite,and apatite were identified among the crystalline inclusions. The melt inclusions were homogenized at 1010～1080℃and analyzed on an electron microprobe.Silicate,salt,and combined silicate- salt melt inclusions were found.Silicate melts show considerable variations in SiO_2 concentration(56 to 66wt% ),high Na_2O K_2O (up to 17wt% ),and elevated Zr,F,and C1 contents.In terms of bulk rock chemistry,the silicate melts are alkali syenites.During thermometric experiments,salt melt inclusions quenched into homogeneous glasses of predominantly sulfate compositions containing no more than 1.3wt% SiO_2.These melts are enriched in alkalis,Ba,Sr,P,F,and C1.The investigation of the silicate and salt melt inclusions in minerals of the garnet syenite porphyries indicate that these rocks were formed under influence of the processes of crystallization differentiation and magma separation into immiscible silicate and salt(sulfate)liquids.