N. S. Karmanov

The First Discovery of Uytenbogaardtite in Taimyr (Konechnoe Ore Occurrence)

Uytenbogaardtite has been observed when examining the ores of the Konechnoe gold ore occurrence, West Taimyr, which is the first find for the entire Taimyr-Severnaya Zemlya region. It is associated with native gold (fineness 520–560‰), pyrite, and sphalerite. Sphalerite is characterized by Fe, Cd, Ag, and Cu impurities. Zinc is present in siderite. In the ores of the Konechnoe ore occurrence, there is also native gold of the early generation with sphalerite, the latter containing chalcopyrite lamellae and being in association with arsenopyrite, pyrite, and galena. The peculiar compositions of microinclusions and impurities in sphalerite and other minerals and the presence of accessory minerals, such as monazite and apatite, reflect the specific metallogenic and geochemical characteristics of the Minina-Bol’shevik structural-metallogenic zone and serve as indicators of the potential of the North Taimyr area in terms of gold, silver, zinc, copper, lead, cadmium, strontium, thorium, and lanthanides.

Physicochemical parameters of crystallization of dunite from the Guli ultrabasic massif (Maimecha Kotui province)

On the basis of analysis of molten inclusions in chrome-spinelide, physicochemical parameters of dunite crystallization were defined. Experimental, analytical studies directly indicate that dunite was formed from high-temperature melts close in petrochemical composition and high-temperature characteristics to meimechite magmas. Successive evolution of magmatic systems compositions in a course of intra-chamber crystallization of dunite was established: from picriteâ “meimechite (with olivine formation at 1590–1415°C and chrome-spinelide crystallization at 1405–1365°C) to picrate-basalt and basalt.

Comendites and pantellerites of Nemrut volcano, eastern Turkey: Genesis and relations between the trachyte-comenditic, comenditic, and pantelleritic melts

The paper reports data on the mineralogy, geochemistry, phase composition of comendites and pantellerites from Nemrut volcano, eastern Turkey; estimates of the crystallization conditions of minerals, composition of matrix glasses and melt inclusions in anorthoclase, fayalite, hedenbergite phenocrysts. LA-ICP-MS was applied to analyze the matrix glasses and phenocryst minerals. The distribution coefficients between phases and glass were calculated for P, B, Li, Rb, Cs, Ba, Sr, Zr, Hf, Ta, Nb, Sc, V, Cr, Ni, Cu, Pb, Th, U, Y, REE. Mass balance simulations of the comenditic and pantelleritic compositions, experimental data, data on melt inclusions are utilized to analyze the processes responsible for the derivation of the magmas, accumulation of components in them and to elucidate genetic links between the trachyte-comenditic, comenditic and pantelleritic melts. The origin of the residual comenditic and pantelleritic melts is explained by variations in the crystallization conditions of anorthoclase (dominant phase), hedenbergite, fayalite, Fe and Ti oxides in the parental trachyte-comenditic magma depending on the pressure and concentration of water dissolved in the melts. The accessory phases (REEand Sr-bearing fluorapatite and zircon) were likely involved in the fractionation of the melts. The following crystallization parameters were obtained by QUILF calculations for the hedenbergite, fayalite, and ilmenite phenocrysts (minimum values for quartz-free melts): 3 kbar, 763°C, ΔFMQ = −1.27 for the Fe-comendites; 3.3–3.8 kbar, 715°C, ΔFMQ = −1.8 for the pantellerites; 2.3 kbar, 748°C, ΔFMQ = −1.16 for the low-Fe comendites. The equilibrium crystallization of anorthoclase phenocrysts in the comenditic melts proceeded at temperature ∼750°C. Data on glasses of melt inclusions indicate that the comenditic and pantelleritic melts contained 1–3 wt % H2O. Analysis of literature data and estimates of the conditions under which the Nemrut magmas were derived suggest that the local chambers with H2O-undersaturated comenditic and pantelleritic melts could occur at centers of alkaline volcanism at depths within the range of 5 to 10–15 km (lithostatic pressure of 1–4 kbar), at temperatures <750°C and oxygen fugacity below the FMQ buffer.

Genesis of mugearites and benmoreites of Nemrut Volcano, eastern Turkey: Magma mixing and fractional crystallization of trachybasaltic melt

Presents detailed mineralogical and phase characteristics of trachybasalt, mugearite, trachydacite, and comendite samples from Nemrut Volcano in eastern Turkey, estimates of mineral formation conditions, and analyses of glasses from melt inclusions in olivine and rock matrix. Based on the analysis of the mineralogy and geochemistry of the rocks and mass balance calculations, the most feasible models of mugearitic and benmoreitic magma formation were proposed. The crystallization conditions of olivine, feldspar, and Fe-Ti oxides (titanomagnetite and ilmenite) were determined. Titanomagnetite and ilmenite were formed under the following conditions: 960-922°C,

Unique Clinkers and Paralavas from a New Nyalga Combustion Metamorphic Complex in Central Mongolia: Mineralogy, Geochemistry, and Genesis

\Delta \log _{f_{O_2 } }

Immiscibility of Fluoride–Calcium and Silicate Melts in Trachyrhyolitic Magma: Data on Acidic Volcanic Rocks from the Nyalga Basin, Central Mongolia

NNO from −1.54 to −0.73 in the mugearite, 940-890°C,

Visible and “invisible” forms of gold and silver in the crystallization products of melts in the Fe–S–Ag–Au system: experimental data

\Delta \log _{f_{O_2 } }

First data on REE-bearing silicates from volcanic rocks of Kamchatka

NNO from −1.46 to −0.79 in the benmoreite, 870-845°C and

Electron probe microanalysis of minerals: Microanalyzer or scanning electron microscope?

\Delta \log _{f_{O_2 } }

Nb-rutile from eclogite microxenolith of the Zagadochnaya kimberlite pipe

NNO from −2.11 to −1.82 in the trachydacite, and 705-667°C,