Mineralogical Journal

19-29

Authors: V.P. Semenenko, K.O. Shkurenko,Yu.O. Litvinenko

A study of the structural, mineralogical and chemical properties of another carbonaceous xenolith (K4) occurring in the Krymka chondrite (LL3.1) was made. The xenolith does not correspond to any known chemical sub-group of carbonaceous chondrites in terms of chemical composition and certain mineralogical characteristics, although its fine-grained component is similar to that of CI chondrites. Presence of graphite microcrystals makes the xenolith K4 similar to the Krymka xenoliths K1, K3, and Gr1-Gr7. Xenolith K4 has large amounts of iron sulfide. This may possibly be due to a nonuniform distribution of mineral fractions in a dusty component of the protoplanetary nebula, which could have both a local and more widespread character. During a pre-agglomeration period, K4 accumulated on its surface partially oxidized mineral dust in the same region of the gas-dust protoplanetary nebula as other xenoliths and chondrules of the Krymka meteorite. The evolution of xenolith K4 is generally similar to that of other Krymka graphite-bearing xenoliths, but differs in the relationship among minerals in the primary dusty aggregates. These features determined its distinct chemical and mineralogical characteristics and indicate mineralogical heterogeneity in the dusty component at the micro-level during the pre-accretional period of a mineral material development of the Solar system.

40-47

Authors: O.P. Vovk, І.М. Naumko, V.I. Pavlyshyn

Topaz crystal morphology and habit distortion has been studied in various mineral-structural zones of chamber pegmatites of the Korosten pluton, which is located in north-western part of the Ukrainian Shield. It was assumed that the symmetry of the crystals obey the Curie principle. This means that only the symmetry elements common to the crystal and the medium in which it is formed will remain on real polyhedrons. The types of symmetry that contain the axes of infinite order are reduced to the following groups: 1) ∞L∞∞PC is a ball; 2) ∞L∞ is a ball filled with an optically active liquid; 3) L∞∞L2∞PПC is a cylinder; 4) L∞ПС is a rotating cylinder; 5) L∞∞P is a cone; 6) L∞∞L2 is a twisted cylinder; 7) L∞ is a rotating cone. Symmetry of the real fluid-dynamic situation of the mineral-forming medium of topaz-bearing parageneses often evolves in the following way: ∞L∞∞PC → L∞∞P → P. In this case, the flow of the mineral-forming fluid has the symmetry P. The resulting topaz crystals can have P symmetry if their symmetry plane coincides with the flow symmetry plane, otherwise they have no symmetry elements at all. In particular, it is shown for the first crystals that the upper faces grew faster, and their size is smaller than that of the lower ones. Growth was limited by the supply of the necessary fluid to the growing crystal faces. Hence, it follows that the fluid flow was in the direction from top to bottom. If the planes of symmetry of the fluid flow and of the polyhedron do not coincide, then visually triclinic crystals of the second type are formed. They are much more abundant than the ones of the first type. In addition to these two types, polyhedra with external symmetry L2 are found. It is difficult to imagine an environment with such symmetry because; it is unlikely that an attached crystal would grow between two fluid streams moving in opposite directions. Nevertheless, polyhedra flattened along the faces M {110} and less often along l {120} are frequent. That is, they grew in the environment in which the fluid flow moved in a direction parallel to the {110} faces (and less often {120}), in the direction from the smaller faces of a simple forms to the larger ones. The direction of fluid flow is more difficult to establish, with more or less the same development of the faces of the simple form of the topaz crystal.

67-82

Authors: O.V. Mytrokhyn, L.I. Gavryliv, V.G. Bakhmutov

Dyke swarms that intrude Paleogene granitoids of the Argentine Islands near the Ukrainian Antarctic Station "Akademik Vernadsky" were studied. The field relations and mineralogical, petrographical and geochemical properties of the dykes allow their relative geological age and the geodynamic conditions to be clarified. The magmatic activity in the study area did not cease, at least until the end of the Miocene when the processes of orogenic uplift led to the erosive exposure of the Paleogene granitoids of the Barchans-Forge Massif. Tectonic exhumation of the latter was accompanied by the intrusion of dykes of different compositions at different depths. Cenozoic basalt and diabase dykes are the most common. Most are subvolcanic fractured intrusions formed after the complete exhumation of the host granitoids, which ended by the Miocene (11 Ma). The basaltic dykes are probably one of the youngest representatives of magmatism in the region. They have an intermediate position between high-LILE tholeiites and the calc-alkaline series. However, the nature of contamination of the basaltic dykes by crustal rocks requires additional research. Cenozoic microdiorites dykes are rarer than basaltic ones. They are hypabyssal fractured intrusions formed during the tectonic exhumation of the Barchans-Forge granitoids between the beginning of the Paleocene and the end of the Miocene (61-11 Ma). The microdiorites belong to the orogenic calc-alkaline series and they could be related to subduction processes. The discovery of only one dacite dyke indicates the rarity of acid magmatism during the Cenozoic period. It occurs as a fractured intrusion and formed after the exhumation of the host granitoids. The dacite dyke belongs to the calc-alkaline series, which, along with other compositional properties, suggests that dacite and microdiorite dykes are comagmatic.

99-110

Authors: І.М. Naumko, М.I. Pavlyuk, А.A. Loktiev, Yu.V. Khokha, Yu.A. Belеts’ka, N.H. Sava

Gases in migrating paleofluids of the Transcarpathian Basin in Ukraine proper were investigated. Their properties were analyzed using fluid inclusions in minerals and fluids occurring in closed pores of promising gas-bearing rocks. Samples were taken from wells drilled within the Mukachevo (1-Borodivsk-Novosilsk) and Solotvyno (1-Bushtyno, 4-Hrushovo, 1-Danylovo, 28-Solotvyno) depressions. According to the data from mass-spectrometric chemical analysis, methane and its homologues and carbon dioxide were found in the composition of volatile compounds, which coincides with the identified advantage of methane and its homologues, on the one hand, and carbon dioxide, on the other hand, in the natural gases of fields of the Transcarpathian gas-bearing area. Methane (98.2 vol. %), ethane (1.2 vol. %) and propane (0.6 vol. %) are found in fluid inclusions in calcite of veinlet in the rock from the well 28 of the Solotvyno structure, which includes the Solotvyno natural gas field. Only methane is found in closed rock pores. Natural gases of the Solotvyno gas field contain methane (53.86%), ethane (2.65%) and propane + butane (1.34-0.32%). СО2 contents as high as 97.3 vol. % occur in fluid inclusions in calcite of veinlets in rocks of the well 1 at Ruski Komarivtsi of the Mukachevo depression and 100 % in fluid inclusions in zeolite (?) from impregnates in rocks of the well 1 at Bushtyno of the Solotvyno depression. This can be explained by the activity of two different composition paleofluids, namely reduced or oxidating types present in bowels of the Transcarpathian Basin. They are associated with significant amount of reduced compounds (methane and its homologues) or a high concentration of oxidized compounds for their (mainly СО2). This was determined by differences in the composition of the primary high-energy abiogenic deep fluid: hydrocarbon-containing or carbon dioxide-containing. The gas composition of paleofluids indicates that two types of natural gas deposits may exist, mainly hydrocarbon or mainly carbon dioxide rich and, accordingly, the discovery of natural gas fields such as Solotvyno and carbon dioxide – such as Martovo. Hydrocarbon formation over a wide range of conditions and primary material ("oil polygenesis") allows the assessment of oil and gas resources of the region. A polygenetic approach for understanding hydrocarbon formation processes requires a changes in exploration strategy. More geochemical and thermobarometric research as well thermodynamic study of mineral-forming fluids is needed in promising geologic structures of the Transcarpathian gas-bearing area. This necessary, in order to predict possible occurrence of high-energy gas deposits and to determine areas for exploration.