Том 56, № 7 (2018)

Experiments were carried out in hermetically sealed platinum capsules, with water saturated with silica with respect to quartz at 300°C in the lower parts of the electric furnaces, where the temperature slightly increases upward at 0.15°C/cm. Our earlier studies (Alekseyev and Medvedeva, 2017) have shown that these exactly experimental parameters are favorable for silica transfer from the liquid to vapor phase. The statistically processed experimental results show that the molal silica concentration in the liquid phase (m) exponentially decreases with time. This dependence and the fact that the newly produced opal occurs on the capsule walls above the meniscus are consistent with the distillation model. The scatter of the experimental m values turned out to be caused not by differences in the temperature gradient in different wells of the electric furnaces but by the natural roughness of the inner walls of the capsules, which differed from one capsule to another and could even change with time in any given capsule. In the capsules with roughness artificially made on their walls, m decreased much more rapidly, and not only in the bottom but also in the upper parts of the electric furnaces, where temperature decreased upward (–0.08°C/cm). This may suggest that the discovered phenomenon is spread in nature more widely than surmised previously, because this phenomenon does not strongly depend on the direction of the temperature gradient, and voids in natural rocks usually have rough walls.

Data obtained on lamprophyres from the carbonatite–volcanic unit in the lower horizon of the Tomtor Massif indicate that the rocks and zoned diopside and kaersutite phenocrysts in them are enriched in incompatible elements more significantly than is typical of alkaline ultramafic rocks of the Maymecha–Kotui and Kola provinces. The concentrations of these elements and their indicator ratios in the cores and intermediate zones of the diopside and kaersutite phenocrysts significantly vary, and this suggests that the minerals might have crystallized from different melts. This is consistent with the earlier conclusions, which were derived from studying melt inclusions, that the phenocrysts crystallized from mixing alkaline mafic melts of sodic and potassic types and different Mg–number which were enriched in the carbonatite component. The cores of the diopside phenocrysts started to crystallize from sodic mafic magma in a magmatic chamber, while the intermediate and outermost zones of this mineral crystallized from mixed sodic–potassic mafic melts. The carbonatite component was separated from the sodic mafic melt at high temperature (>1150°C) during diopside core crystallization. The bulk compositions of the alkaline lamprophyres and of the diopside and kaersutite phenocrysts contain lower normalized concentrations of HREE than LREE. This led us to conclude that the parental sodic and potassic mafic melts were derived from an enriched mantle source material under garnet–facies parameters, as is typical of continental rifts. It is noteworthy that the potassic mafic melt was derived at greater depths and lower degrees of melting of the mantle source than the sodic melt. The iron–rich sodic melt from which the cores of the diopside phenocrysts started to crystallize was enriched in V, REE, Y, and volatile components (H₂O, CO₂, F, Cl, and S). The onset of carbonate–silicate liquid immiscibility was marked by the redistribution of REE and Y into the carbonatite melt. The potassic, more Mg–rich mafic melt from which the intermediate and outermost zones of the diopside phenocrysts crystallized was enriched in Ti, Nb, Zr, and REE and always remained homogeneous when this mineral crystallized.

The paper presents the results of a long–term (52 months) monitoring of molecular hydrogen release from the rocks of the Lovozero Massif. Observations are performed in an underground mine with the help of a portable highly sensitive gas analyzer developed at the National Research Nuclear University MEPhI. The strong variability (of 0.7 to 303 ppm) of the dynamics of the volume concentration of hydrogen (φH₂) is established. The main elements of the structure of the time series obtained consist of the fact that they have quite sustained and long intervals of low background concentrations, low–amplitude excesses of various durations, and short (usually high–amplitude) bursts. Seasonal and off–season periodic and other cyclic components in the structure of the series are identified. It is shown that the most important factors determining the dynamics of φH₂ are barogenic (variation in the atmospheric pressure) and technogenic (technological explosions). Possible mechanisms of gas release are considered.

To study the migration and accumulation of Rh(III) in natural systems, we have synthesized complexes of Rh(III) and fulvic acids (FA), which are dominant organic compounds of natural waters. The composition of rhodium hydroxofulvate complexes is determined at pH 7.0, and the stability constant of these complexes is calculated. Data are obtained on interaction of FA and Rh(III) hydroxofulvate complexes with components of naturally occurring reactive barriers (ferrihydrite, quartzite, clay shale, and natural aluminosilicate suspensions) at pH 4.0–8.0. The adsorption behavior of FA and rhodium fulvate complexes at the sorbents was determined to be analogous.

Gas chromatography and gas chromatography–mass spectrometry data on oils from wells and seeps in the Eastern Kamchatka Basin indicate that, according to their composition and the distributions of biomarker molecules, these oils can be classified into three groups, which differ in the composition of the parent organic matter, litho–facies sedimentation conditions, and catagenetic transformations. Oils from the wells were determined to be produced by organic matter of the sapropel type of marine facies in the main oil window (MC₂). Condensate from the natural seep was generated at higher catagenesis grades (MC_2–3) by organic matter of the sapropel–humus type of littoral facies. Uzon oil shows are demonstrated to be formed in a continental environment by organic matter of the humus–sapropel type and were not genetically related to oil from the Paleogene–Neogene source rocks of the Bogachevka Formation.