Mineralogical Journal

12-28

Authors: N.М. Lyzhachenkо, S.I. Kurylo, S.M. Bondarenko, R. Milovsky, S. Milovska

This study presents results of an investigation of metamorphic rocks of the Inhul-Inhulets series located in the north-western border of the Lypniazhka granite-migmatite massif (the Inhul domain, the Ukrainian Shield). The rocks were studied petrographically and mineralogically and carbon isotope, Raman spectroscopic and microprobe measurements were made. Graphite and calcite were given special attention. Metapelites and quartz-rich graphite-biotite-garnet rocks were investigated. The former consist of biotite, graphite-biotite, amphibole-bearing graphite-biotite gneisses. Graphite in them is evenly distributed through the rock groundmass. The δС13 values of graphite lie between –39.4 and –33.6 ‰ (relative to PDB). The graphite is considered to be of biogenic origin. Quartz-rich graphite-biotite-garnet rocks are less common, but they also contain graphite. The latter occurs as inclusions in the major minerals either forming clusters. Its δС13 values fall between –28.45 and –22.2 ‰ (relative to PDB). Based on the Raman spectra, carbon from the gneisses has an ordered graphite structure. The temperature of graphite crystallization was estimated to be between 554 and 630° С and corresponds to the amphibolite facies.

40-48

Authors: O.V. Mytrokhyn, V.G. Bakhmutov

A new occurrence of igneous rocks with an orbicular structure was discovered by the authors in West Antarctica. The place of finding is Hovgaard Island in the Wilhelm Archipelago located near the Graham Coast of the Antarctic Peninsula. Until now, not a single manifestation of these rare rocks was known in this region. Usually orbicular rocks are formed under the condition of local "coincidence" of many geological and petrogenetic factors. The study of the geological position, texture features and mineral composition of the orbicular rocks on Hovgaard Island was carried out in order to create their primary petrographic description. It was found that orbiculites are exposed in a small area, about 200 m2, in the field of amphibolized gabbroids and their intrusive breccias. The occurrence and textures of the orbiculites indicate that their crystallization occurred at the hypabyssal depth. Probably, this occurrence is a marginal facies of a small gabbroid intrusion, some parts of which are exposed on the adjacent coastal areas of Hovgaard Island. The studies performed have shown that the orbiculites of Hovgaard Island belong to the rarest petrographic representatives of these rocks namely orbicular gabbroids. In their petrographic feature, they differ markedly from the famous French napoleonites (corsites) exposed on the Corsica Island. The mineral composition of the orbicules is represented by calcium plagioclase (An88-97), hornblende (#Mg = 0.77-0.81), clinopyroxene (Wo48-50En43-47Fs5-8), spinel (Sp62-72Hrc14-20Mt12-17), actinolite, phlogopite, chlorite, magnetite and apatite. The interorbicular matrix has a gabbroid composition and a porphyritic texture. It differs from orbicules in somewhat less calcium plagioclase and less magnesian hornblende, as well as in the absence of spinel. In view of the rarity of orbicular gabbroids and the specificity of the described manifestation, it is proposed that the orbicular gabbro on Hovgaard Island be considered as a new petrographic variety of the gabbroid family. The name "hovgaardite" is recommended for the name of this variety of orbicular gabbro.

58-73

Authors: I.V. Kuraieva, T.O. Koshliakova, K.V. Vovk, K.S. Zlobina

We investigated the impact of the urban environment on the park ecosystems in Kyiv. As representatives of vegetation the species Taraxacum officinale Wigg. and Tilia cordata Mill., were chosen. The content of heavy metals (Cu, Pb, Zn, Ni, Mn, Cr, and Cd) in soil and leaf samples within the ecosystems of the parks Feofaniya, Kyiv Polytechnic Institute, Mariyinsky, Pushkin, and Nyvky was measured. The highest level of soil contamination with heavy metals was found in the areas of parks located near highways and public transport stops. The most polluted park was the Kyiv Polytechnic Park, and the least polluted Feofaniya Park. High levels of metals found in soil samples did not always coincide with their highest levels in the biomass of the studied plants leaves. We found that, according to the phytotoxicological classification of metals by the biological absorption coefficient (BAC) by plants within the studied park ecosystems, Cu, Pb, Zn, Ni, Mn, and Cr belong mainly to the elements of low absorption (hazard class IV) except for Mariyinsky Park, where Zn according to the BAC value belongs to the elements of moderate absorption (hazard class III). The order of amount of metal bioaccumulation in plants obtained by us show a fairly wide range for different park ecosystems, which confirms the principle of ecological congruence (compliance), according to which the living components of an ecosystem have developed appropriate adaptations coordinated by the abiotic environment. In order to identify additional ways of migration of heavy metals to the ecosystem of Feofaniya Park, hydrochemical data from the surface of the first aquifer, circulated within the study area, were involved. It has been suggested that the increased concentrations of Cu, Pb, Zn, Ni, and Mn in the soils of Feofaniya Park are connected with the Pirogivsky landfill, and the groundwater discharged into the park ponds serves as the main way of migration of pollutants to the natural environment, in particular to the soil-plant system. Our results confirm the need to involve biogeochemical data for ecological assessment of the urban environment and early diagnosis of negative influence, when the plants have not yet manifested morphological and anatomical abnormalities.