Mineralogical Journal

3-10

Authors: M.N. Taran

The synthetic high-pressure α- and β-modification of (Mg1–xFex)2SiO4, wadsleyite and ringwoodite, respectively, were studied by optical absorption spectroscopy at ambient and hydrostatic high-pressure conditions. In addition, the effects of thermal annealing on the crystals were investigated. Under hydrostatic compression up to ~13 GPa and then consequent released to atmospheric pressure there were changes in the spectra and related changes in the crystal color. This is a clear indication that some Fe2+ was oxidized to Fe3+. The spectra of both ringwoodite and wadsleyite change after annealing in air at temperatures up to 300 ºC. The intensities of electronic spin-allowed bands of Fe2+ decrease and the intensity of the charge-transfer electronic transition O2– → Fe3+, as given by the low-energy absorption edge in the UV region, increases. These crystal-chemical changes are shown by a weakening of the blue (ringwoodite) and green (wadsleyite) colors and a concomitant increase in yellowish tints. The effects of Fe2+ oxidation to Fe3+, upon decompression from high pressures as well as through annealing at relatively low temperatures, can cause the disintegration of both phases. Thus, both minerals have not yet been reliably identified at near surface Earth conditions after originating from deep-seated volcanism or deep subduction zone processes.

18-24

Authors: M.M. Bagmut, T.G. Kalinichenko, A.B. Brik, N.O. Dudchenko, M.O. Kalinichenko

The mineral components of powdered samples of cortical dense bone tissue of domestic animals (pig and cow) were studied by electron paramagnetic resonance (EPR). Bone tissue was heated in a temperature range 600-1000 ºС in an oven and then held for more than one year at room temperature. This was done to allow short-lived defects to decay and to let the mineral structures stabilize. In these heat-treated samples, within the limits of the sensitivity of the experiments, no EPR signals were detected, but after irradiation with X-rays, multicomponent EPR signals appeared. Spectra vary depending on the heating temperatures. Paramagnetic centers related to РО32–, NO42–, CO2 –, CO33– and O– groups are observed. The g-factor of spectroscopic splitting and amplitude of ultrafine interaction of the indicated paramagnetic centers in the spectra were determined. Due to different relaxation behavior of the paramagnetic centers, and hence their saturation effects, the form of the total EPR signals significantly depends on the microwave power level at which the spectra are recorded. Therefore, EPR signals were recorded at high (5 mW) and low (0.13 mW) microwave power levels. The temperature dependency of EPR signal amplitude was determined for some paramagnetic centers in the range of 600-1000 ºС. The EPR signal properties of the heated bone samples and synthetic hydroxylapatites were compared. The spectra indicate that phosphates in bone tissue have a more complex structure than simple synthetic hydroxylapatite. The results of this work can be used to create synthetic analogs of bone tissue, to help in the manufacturing of implants that are used to treat bone tissue, and to study the processes related to the assimilation of mineralogic-based implants by living bone tissue.

50-55

Authors: L.V. Shumlyanskyy, V. Kamenetsky, B.V. Borodynya

Results of a study of U-Pb and Hf isotope systematics and trace element concentrations in five zircon crystals separated from the Devonian Petrivske kimberlite are reported in the paper. Four zircons have yielded Paleoproterozoic and Archean ages, while one zircon grain gave a Devonian age of 383.6 ± 4.4 Ma (weighted mean 206Pb/238U age). The Precambrian zircons have been derived from terrigenous rocks of the Mykolaivka Suite that is cut by kimberlite, or directly from the Precambrian rock complexes that constitute continental crust in the East Azov. The Devonian zircon crystal has the U-Pb age that corresponds to the age of kimberlite emplacement. It is 14 m.y. younger than zircon megacrysts found in the Novolaspa kimberlite pipe in the same area. In addition, Petrivske zircon is richer in trace elements than its counterparts from the Novolaspa pipe. Petrivske and Novolaspa zircons crystallized from two different proto-kimberlite melts, whereas the process of kimberlite formation was very complex and possibly included several episodes of formation of proto-kimberlite melts, separated by extended (over 10 M.y.) periods of time.

63-72

Authors: G.V. Artemenko, L.M. Stepanyuk, I.A. Samborska, B.V. Borodynya,І.А. Shvaika, K.І. Gogolev, L.I. Proskurka

In the Saltych anticlinorium of the West Azov, small intrusions of rocks of basic and ultrabasic composition are known in the middle reaches of the Obitochna, Kiltychiya and Burtychiya rivers and in the upper reaches of the Obitochna river. They are composed from amphibolized peridotites, pyroxenites, actinolithites, tremolithites, hornblendites, amphibole and other shales. These intrusions are considered "fractured intrusions", which are rooted in the already deployed rocks of the Archean age. In the stratigraphic scheme they are referred to the Novoselytske association. Intrusions break through the veins of syenites, pegmatites and aplite-like granites. Metaultrabasites, according to I.S. Usenko and G.L. Kravchenko, these are ultrabasic rocks of the normal series, which were formed, probably, because of differentiation of basaltic magma. The main and ultrabasic rocks of these intrusions have not been studied enough yet — their age, geodynamic conditions of formation have not been determined, the potential for minerals has not been fully revealed. For this purpose, we determined the microelement composition of meta-ultrabasites, metabasites and acid rocks by the ICP MS method and determined the age of monazite from veins of aplite-like granites that break through the metapyroxenites of the Kamyshuvatka intrusion. According to the obtained geochemical and mineralogical data, the vein rocks of medium and acid composition, which break through the intrusions of the ultrabasite-basite composition at the Saltych anticlinorium, have a core genesis. Zircon in them is relict, and syngenetic monazite was found only in the veins of aplite-like granites that break through the metapyroxenites of the Kamyshuvatka intrusion. According to the dating of this monazite, it has been determined that the upper age limit for the formation of intrusions of the ultrabasite-basite composition of the Novoselytske association is 2051.8 ± 3.8 Ma. Peridotites and pyroxenites of these intrusions could be formed from melts of the depleted upper mantle, which were fractionated in intermediate magmatic chambers. In peridotites (#mg = 0.74-0.86) of the Kamyshuvatka intrusion and intrusion near the Reva farm, the Ni content (510-826 ppm) is lower than that of Clark for ultrabasic rocks, and the chromium content at the level of Clark and below it is Cr — 1250-2260 ppm. Positive anomalies of Ti and Eu indicate the processes of fractionation of the original magma of pyroxenites. The formation of intrusions of the ultrabasitebasite composition of the Saltych anticlinorium of the Azov megablock is probably connected with the activation of the Earth’s mantle about 2050 million years ago.

87-97

Authors: D.K. Voznyak, V.M. Belskyi

Various aspects of the genesis of primary fluid inclusions (0.01-1.0 sometimes up to 2 mm) with a large number of mineral inclusions in topaz crystals from chamber pegmatites of Volyn were analyzed. The data could be interpreted in two fundamentally different ways. The first argues for crystals grown in a magmatic melt; the second for an aqueous solution, with a density close to critical. The essence of the discrepancy is the reliability of the identification of the nature of mineral phases in the primary inclusions, if they are crystals captured during growth (xenogenic) or daughter crystals from the fluid. The xenogenic origin of the phases is indicated by the following observations: 1) The location of the mineral inclusions on the growing faces of the topaz crystals depends on the orientation of the crystal’s axis [001] relative to the horizontal plane. It determines the faces on which small mineral phases could be deposited from an aqueous suspension during the growth of topaz crystals. The studied crystals are dominated by individuals in which the mineral inclusions are located on the growing faces {011}, {021}, (001) (and others) of the crystal head. During growth, they were approximately in an upright position. 2) The filling of primary fluid inclusions is not constant. The volume of mineral phases in the inclusions varies from 40 to 95%, often 70-75%, the rest of the volume is gas and aqueous solution. Liquid-gas (liquids ˂40%) inclusions without or with <5 % solid phases are very rare. In addition, the ratio between the volumes of different mineral phases in the inclusions is not constant. 3) Light rims (Becke lines) around the inclusions record a change in the refractive indices (caused by a different chemical composition) of topaz when inclusions are acquiring the equilibrium form of the negative crystal. 4) The xenogenic nature of the mineral phases of the primary fluid inclusions in topaz is indirectly confirmed by the value of the fluid pressure (260-300 MPa) of the magmatic melt (determined by the method of homogenization of these inclusions), as it denies the possibility of chamber pegmatite formation at depths of 9-11 km. Thus, the peculiar mineral inclusions were deposited on the face of growing topaz crystals of small mineral phases from a turbid aqueous suspension, which boiled violently. We conclude that topaz crystals in chamber pegmatites of Volyn grew in aqueous solution at a temperature of 380-415 ºС and a pressure of 30-40 MPa.