Composition of Hydrocarbons in Synthetic Diamonds Grown in a Fe—Ni—C System (according to Gas Chromatography—Mass Spectrometry Data)

The first data of chromatography—mass spectrometry analysis of volatiles from crystals of synthetic diamonds grown in a Fe—Ni—C system at 1350–1400°С and 5.5–6.0 GPa are presented. The composition of the fluid in equilibrium with the metal-carbon melt is determined, and a comparative estimation for the compounds of different hydrocarbons and their derivatives is made. It is shown that a significant role in these processes is played by high-molecular-weight hydrocarbons; and the total share of hydrocarbons and their derivatives in the fluid compounds can exceed 86%.     

The Composition Features of Volatile Components in Diamonds from the Placers in the Northeastern Part of the Siberian Platform by Gas Chromatography–Mass Spectrometry

The primary data are presented on gas chromatography–mass spectrometry of volatile material in diamonds from the placers in the northeast of the Siberian Platform. The new data obtained testify to the crucial role of hydrocarbons and their derivates in the processes of diamond formation within the Earth’s mantle. It was shown that the registered variations in the composition of volatile components in the treated diamonds were caused by a combination of processes including the transformation of redox conditions of the crystallization of diamonds.

     

Low-Nitrogen Diamond Growth in the Fe–C–S System

Doklady Earth Sciences - The first results on diamond growth in the Fe–С–S system with 1 wt % S (relative to Fe) at 6 GPa and 1450°C have been reported. The diamonds obtained...     

Phase Relations in the Fe–S–C System at P = 0.5 GPa,T = 1100–1250°C: Fe–S–C Liquation and Its Role in the Formation of Magmatic Sulfide Deposits

Doklady Earth Sciences - The liquid phases are represented by immiscible Fe–S and Fe–C melts under partial melting of the graphite-saturated Fe–S–C system at P = 0.5 GPa and...     

Dissolution of Natural Octahedral Diamonds in an Fe–S Melt at High Pressure

Geology of Ore Deposits - Abstract—An experimental study was carried out on the dissolution of natural octahedral diamonds from the Internatsionalnaya and Yubileinaya kimberlite pipes...     

Minerals of the Fe–Ni–Co–Cu–S System in Picrite Intrusions of the Southern Urals: Signatures of Liquation and Differentiation of the Sulfide Melt

Doklady Earth Sciences - New data on the minerals of the Fe–Ni–Co–Cu–S system in the differentiated intrusions of the Southern Urals are presented. Based on a detailed study...     

Effect of sulfur concentration on diamond crystallization in the Fe–C–S system at 5.3–5.5 GPa and 1300–1370°C

The paper presents results of experiments aimed at diamond synthesis in the Fe–C–S system at 5.3–5.5 GPa and temperatures of 1300–1370°C and detailed data on the microtextures of the experimental samples and the composition of the accompanying phases (Fe₃C and Fe₇C₃ carbides, graphite, and FeS). It is demonstrated that diamond can be synthesized after temperatures at which carbides are formed are overcome and can crystallize within the temperature range of 1300°C (temperature of the peritectic reaction melt + diamond = Fe₇C₃) to 1370°C (of thermodynamically stable graphite) under the appearance experimental pressure. The possible involvement of natural metal- and sulfur-bearing compounds in the origin of natural diamond is discussed.     

Newly formed minerals of the Fe–P–S system in Kolyma fulgurite

Newly obtained data from microscopic, geochemical, and thermomagnetic studies of the large Kolyma fulgurite are presented here: the fulgurite was formed in the Holocene as a result of lightning affected black shale alluvium. The composition is very close to that of glass formed from a melt. The glass has elevated concentrations of Y, Zr, Nb, and REEs. The newly formed mineral phases have been identified: those are Al–Si glass, α-cristobalite, moissanite, native iron with a phosphorus admixture, nickel-less shreibersite (?), troilite, and possibly cohenite. The formation of these minerals is related to the melt fractionation and the effects of element concentration and segregation of ore components under conditions of the rock melting caused by the effect of high-energy plasma (lightning strike).     

GGR Biennial Review: Key Advances in Secondary Ion Mass Spectrometry in the Geological Sciences during the Period 2008–2009

Secondary ion mass spectrometry (SIMS or ion microprobe) remains one of the most powerful techniques in the analytical geochemist’s toolkit. The key strength of SIMS is its capacity to provide trace element and isotope data at sampling sizes which are not approached by other methods. As compared with the main competing technique of laser ablation-ICP-MS, SIMS commonly provides a total sampling mass some 10 to 500 times smaller; this feature can be the deciding factor as to whether an analytical objective is technically achievable. Additional strengths of SIMS lie in the areas of depth profiling and trace element imaging. Though perhaps not as commonly used in the geosciences, these two operational modes represent unique capabilities of SIMS.     

Specific Features in the Deep Structure of the Naryn Basin–Baibichetoo Ridge–Atbashi Basin System: Evidence from the Complex of Geological and Geophysical Data

New magnetotelluric data were obtained for the Karabuk profile crossing the Naryn basin–Baibichetoo Ridge–Atbashi basin geodynamic system (Central Tien-Shan). The complex geological–geophysical cross section along the profile provides a good agreement between the surface tectonic structures and the deep geoelectric model. The electric conductivity anomalies revealed as subvertical conductors striking along the flanks of basins may be explained by the zones of dynamic influence of faults and cataclasis of granite.     

New Data on Geochronology of the Upper Quaternary Loess–Soil Series in the Terek–Kuma Lowland

Lithology and Mineral Resources - Drilling recovered the upper part (23 m) of the upland loess–paleosol series (LPS) on the right bank of the Kuma River near the Otkaznoe Settlement....     

New Data on the Chronostratigraphy of the Upper Pleistocene Loess–Soil Series in Southwestern Siberia

Doklady Earth Sciences - We have analyzed the modern status of the chronostratigraphic differentiation of the loess–paleosoil series in southwestern Siberia and the results of luminescence...     

The effect of sulfur content on density of the liquid Fe–S at high pressure

The density of liquid Fe–S was measured at 4 GPa and 1,923 K using a sink/float method with a composite density marker. The density marker consisted of a Pt rod core and an Al₂O₃ tube surrounding. The uncertainty in the density of the composite marker is much smaller than that of the composite sphere, which had been used in previous density measurements. The density of liquid Fe–S decreases nonlinearly with increasing sulfur content at 4 GPa and 1,923 K. This tendency is consistent with the results measured at ambient pressure. The molar volume of FeS calculated from the measured density gradually increases with sulfur content. The excess molar volume from ideal mixing of Fe and S at 4 GPa was negative value. The new method proposed here is applicable to the density measurement of other Fe alloys at high pressure. The tendency of the molar volume and the excess molar volume with sulfur content at ambient pressure is consistent with these at high pressure at least up to 4 GPa. The excess molar volume at high pressure is essential for estimating the amount of light elements in the outer core.     

Evidence for Granitoid Magmatism and the Composition of the Silicic Melt in the Gabbroid Assemblage of the Mid-Atlantic Ridge at 13° N: New Data on Melt Inclusions

Doklady Earth Sciences - Despite the local occurrence of silicic magmatism during the formation of the oceanic crust, the nature of felsic granitoid veins (“oceanic plagiogranite”)...     

Influence of the Sulfur Concentration in a Fe–S Melt on Diamond Preservation under P–T Conditions of the Earth’s Mantle

Doklady Earth Sciences - The results of experiments on dissolution of diamond in a Fe melt with variable concentrations of S at high P–T parameters are presented. It is established that the...     

Influence of Climate Changes in the Late Pleistocene–Holocene on Composition of Bottom Sediments of the Selenga–Buguldeika Saddle,Lake Baikal

The study of bottom sediments of Lake Baikal recovered by submarine drilling at the Selenga–Buguldeika saddle (core VER93-2 st. 24GC) allowed us to reconstruct the climatic events in the Baikal region in the last 20–25 k.y. On the basis of the data on distribution of chemical elements in the core section, the mineral composition of sediments was calculated by the physicochemical modeling method. A study of how ratios of clay minerals changed in the section allowed us to identify the Pleistocene–Holocene boundary, Bølling–Allerød postglacial warming, and Late Dryas cooling. The calculated data on mineral composition of bottom sediments from the core VER93-2 demonstrate a good fit to the X-ray diffraction analysis results. The proposed approach can be used in calculation of mineral compositions of other sedimentary sequences with known chemical composition.     

New Data on the Sm–Nd Age of Picrites in the Lysogorsk Complex,Southern Urals

Doklady Earth Sciences - This paper reports new data on the age of picrites in the Lysogorsk complex, which are common in the Taratash metamorphic complex (Bashkir Meganticlinorium, the western...     

The Position of the Wuchiapingian–Changhsingian Boundary in Northeast Russia on the Basis of Radioisotopic and Chemostratigraphic Data

Doklady Earth Sciences - The approximate position of the Wuchiapingian–Changhsingian boundary of the Upper Permian in Northeast Russia was determined for the first time on the basis of the...     

Spots on the Surface of a Star: An Influence on the Estimates of Star–Exoplanet Binary System Parameters

Astronomy Reports - We developed an algorithm to model a light curve observed in a binary system that contains an exoplanet and a host star, on the surface of which there are spots. The spot-caused...     

Interaction of an Fe–Ni Melt with Anthracene (C14H10) in the Presence of Olivine at 3 GPa: Fluid Phase Composition

Doklady Earth Sciences - The first results on the interaction between an Fe–Ni melt and anthracene (С14Н10) in the presence of olivine at 3 GPa and 1500°С and on the...