T. A. Bul’bak

The composition of volatile components in olivines from Yakutian kimberlites of various ages: Evidence from gas chromatography–mass spectrometry

The composition of volatiles from fluid and melt inclusions in olivine phenocrysts from Yakutian kimberlite pipes of various ages (Olivinovaya, Malokuonapskaya, and Udachnaya-East) were studied for the first time by gas chromatography–mass spectrometry. It was shown that hydrocarbons and their derivatives, as well as nitrogen-, halogen-, and sulfur-bearing compounds, played a significant role in the mineral formation. The proportion of hydrocarbons and their derivatives in the composition of mantle fluids could reach 99%, including up to 4.9% of chlorineand fluorine-bearing compounds.

Peculiarities of the composition of volatile components in picroilmenites from Yakutian kimberlites of various ages (by gas chromatography—mass spectrometry)

The composition of volatile components in picroilmenites from Yakutian kimberlitic pipes of various ages (the Olivinovaya, Malokuonapskaya, and Udachnaya–East pipes) was studied for the first time by means of gas chromatography–mass spectrometry (GC-MS). It was shown that picroilmenites and olivines from same kimberlitic pipes contained volatile components of close composition, whereas these components were quite different in these minerals from different pipes. These features point to a common source and represent the specificity of the magma chamber formed under the pronounced influence of hydrocarbons with their derivates, as well as nitrogen-, chlorine-, and sulfur-containing compounds. The fraction of hydrocarbons and derivates in the composition of volatile matter is as high as 99%, including 9.7% of chlorine- and fluorinecontaining compounds.

Primary melt and fluid inclusions in regenerated crystals and phenocrysts of olivine from kimberlites of the Udachnaya-East Pipe, Yakutia: The problem of the kimberlite melt

The primary melt and fluid inclusions in regenerated zonal crystals of olivine and homogeneous phenocrysts of olivine from kimberlites of the Udachnaya-East pipe, were first studied by means of microthermometry, optic and scanning electron microscopy, electron and ion microprobe analysis (SIMS), inductively coupled plasma mass-spectrometry (ICP MSC), and Raman spectroscopy. It was established that olivine crystals were regenerated from silicate–carbonate melts at a temperature of ~1100°C.

Stability of methane in reduced C–O–H fluid at 6.3 GPa and 1300–1400°C

The composition of a reduced C–O–H fluid was studied by the method of chromatography–mass spectrometry under the conditions of 6.3 GPa, 1300–1400°C, and fO2 typical of the base of the subcratonic lithosphere. Fluids containing water (4.4–96.3 rel. %), methane (37.6–0.06 rel. %), and variable concentrations of ethane, propane, and butane were obtained in experiments. With increasing fO2, the proportion of the CH4/C2H6 peak areas on chromatograms first increases and then decreases, whereas the CH4/C3H8 and CH4/C4H10 ratios continually decrease. The new data show that ethane and heavier HCs may be more stable to oxidation, than previously thought. Therefore, when reduced fluids pass the “redox-front,” carbon is not completely released from the fluid and may be involved in diamond formation.

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.

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%.

Synthesis of hydrocarbons by CO2 fluid conversion with hydrogen: Experimental modeling at 7.8 GPa and 1350°C

Synthesis of hydrocarbons by the interaction of a CO2 fluid with hydrogen mantle domains has been simulated in an experiment at 7.8 GPa and 1350°C. The synthesized fluid contains mainly aldehydes; lower amounts of ketones, alcohols, esters, and ethers; as well as noticeable amounts of isobutane and butane, alkenes, arenes, and polycyclic aromatic and heterocyclic hydrocarbons. The fluid is compositionally close to volatiles found in inclusions from mantle olivines and picroilmenites.