Geochemistry and ore formation

3-13

Authors: Stepanyuk L.M., Kurylo S.І., Dovbush T.І., Grinchenko O.V., Syomka V.O., Bondarenko S.M., Shumlyanskyy L.V.

Several massifs of biotite uneven-grained, porphyric, pegmatite and aplite-pegmatite granites of the Kirovohrad Complex, and of hypesthene-bearing (charnockites) granites, monzonites and black-quartz granites of the Novoukrainka Complex are distributed within the eastern part of the Inhul region. The ages of granite crystallization were determined by U-Pb isotope method on multigrain fractions of monazite. Granites of the Pavlivka, Verblyuzhka, and Krynytchuvatska massifs were formed within the age interval of 2038-2046 Ma (within the error of measurement). Monazites sampled from aplite-pegmatite granites that widely crop out a long the right bank of the Bokovenka River (northwards of the Novooleksandrivka village) yielded a younger age of 2030.0 ± 0.3 Ma.Granitoids located in other parts of the Inhul region, i. e. Novoukrainka, Voznesensk, Lisohirska and some other smaller granite massifs, were formed during the same time interval.

32-49

Authors: Mihalchenko I.I., Andreev O.V.

In this paper, we present new result, that the crystals of relict magmatic monazite of initial granite, which tested hydrothermal metasomatism transformations, are included in mineral composition of thorium-uranium ore-bearing albitites Novooleksiivka ore deposit and hydatogenesis monazites of hydatogenesis. Chemical composition of hydrothermal monazites in «ore»albitites differs in the large values of measuring of C(La2O3) and C(Ce2O3) and considerably less C(Pr2O3), C(Nd2О3), C(ThO2), what in magmatic monazites of initial granite and the least changed magmatic monazites х of albitites. Monazites were unsteady minerals during hydrothermal metasomatism transformations. By the main factors of decomposition of magmatic monazites and, accordingly, dissociating from him, in particular, Th at formation of albitites appears: resaturation of fluid of P (PO43-(?)), saturation of Са and speed of infiltration of fluid. Exposure of hydrothermal monazite with anomalous C(La2O3) and correlation of C(La2O3)/C(Ce2O3) in «ore» albitites х with the signs of increase-diminishing of mass parts of rare-earth elements in hydrothermal relict monazites testifies to the them lixiviating, migration, partial fractionating and separate besieging. At mineral level of organization of geological substance a previous conclusion is confirmed about the division of geochemical history to thorium from history of lanthanum and cerium during formation of thorium-uranium ore-bearing albitites of the Novooleksiivka ore deposit. Formation of enhanceable concentrations to thorium with uranium, which together enter in the complement of hydrothermal-metasomatism minerals-concentrators of these chemical elements in albitites testifies to migration of uranium at the degree of oxidization of U4+.

58-69

Authors: Kryvdik S.G.

Apofenitic albitites were discovered in the Azov Sea area (the Chernigivka carbonatite massif, the fenites of Dmitrovka village, Tunikova ravine), in the western part of the Ukrainian shield (Proskurivska massif of alkaline rocks, Beryozovaya Gat’s fenites) and in the Middle Dnieper region (Mala Tersa alkaline massif). These albitites form on pyroxene fenites (more often as vein-like bodies), whereas in the Chernigivka massif they occur in the endocontact of carbonatite bodies. During formation of apofenitic albitites process, such metasomatic alteration of fenites occur most often: instead of alkaline perthite feldspars a granoblastic aggregate predominantly with albite and subordinate amount of microcline and calcite is formed, and alkaline pyroxene is replaced by Fe-Mg biotite. Sometimes the Ca-Al-amphibole of the edenite-hastingsite composition crystallize. In comparison with initial fenites these albitites have lower alkalinity ((Na + K)/Al), because the alkaline pyroxene is replaced by biotite, and instead of aluminumless and alkaline amphiboles (richterites, riebeckites, arfvedsonites) Ca-Al-amphiboles (edenite-hastingsite series) are crystallized. The most interesting feature of apofenitic albites is increased in or high Zr, Nb and U concentration (in comparison with fenites or even carbonatites) which are concentrated in zircon, columbite, pyrochlore group minerals the formation of apofenitic albitites is due to the increasing acidity (and water enrichment) of the primary ultralkalinity fluids at the early stages the fenitization of granitoids caused, and at the final stages (during cooling, lowering of alkalinity and water enrichment) led the alteration of the fenites with the formation of ore-bearing albitites. The enriched in Zr and Nb apofenitic albitites in the geochemical aspect are similar to the mariupolites, but they differ significantly from the latter. The nepheline as main mineral of mariupolites is absent in albitites, but the latter have Fe-Mg-micas and amphiboles. The secondary micas from mariupolites are presented by strongly enriched in Fe and Mn biotites. Marioupolites in comparison with albitites are enriched in REE and depleted in Sr. Apofenitic albitites are the original metasomatites for Ukraine and they can be considered as new type of ore-bearing rocks for such rare metals as Nb, Ta and Zr.

80-94

Authors: Sheremet Ye.М., Strekozov S.N., Sietaia L.D., Аharkova N.G.

The Azov rare-earth deposit of the Ukrainian Shield, based on the characteristic features (major and minor ore minerals, accessory minerals, minerals of ore-bearing metasomatic changes, geochemical features), has been compared with similar rare earth rare-earth deposits enriched with yttrium REE, HREE and zirconium associated with subalkaline granitoids. The results of the comparison showed, that the Azov deposit does not have direct analogs of this type (with the exception of the Yastrebetskoe ore occurrence of USH) among the rare-earth deposits of the world. At the same time, the Azov rare-earth deposit is a large deposit where the reserves of useful components exceed the reserves of rare-earth ores of known industrial deposits in Canada and North America. Preliminary geological and economic assessment of the Azov deposit unambiguously showed its industrial significance. For several decades the development of the deposit, depending on the method of development and the depth of the technological redistribution, can bring an annual net profit of tens of millions,and for the entire development period of several hundred million dollars.

101-106

Authors: Rozko A.M., FedorenkoYu.G., Zharin I.S.

Claypolimers composites based on bentonite and sodium acrylate obtained by free radical polymerization with a long induction period after swelling in water to a maximum value, followed by drying to constant weight, with repeated contact with water, increases the degree of free swelling by an average of 2 times. In the solution of sodium tetraborate, the degree of free swelling increases on average from 1.7 times at a solution concentration of 0,03% to 1,4 times 0,3% solution. After the first swelling cycle in water and drying, the distribution coefficient of 137Cs increases almost 30-fold. The same index in solutions of sodium tetraborate decreases by 1,3–2 times. In all cases of repeated contact between the dried samples and the radioactive solution, additional sorption (active) centres occur and, as a consequence, accumulate activity on the samples. This can be used when the made to create environmental barriers, water purification from radionuclides, dehydration and liquids etc. The salt solutions and drying the swelling effect is weak.

3-14

Authors: Kryvdik S.G., Sharygin V.V., Gatsenko V.O., Lunev E.S.

The article represents new microprobe data for micas from malignites, their xenoliths and dike subalkaline gabbroids of the Pokrovo-Kyriyivo massif. Micas from gabbroids are phlogopites with moderate Al2O3 (14-16 wt. %) and TiO2 (4,3-6,3 wt.%). Malignite xenoliths contain tetraferriphlogopite, which is high in magnesian number (0,8 Mg #), low in alumina (7,9-11,2 wt.% Al2O3) and TiO2 (0,7-2,5 wt.%). Two generations of micas are documented in malignites. The first early generation includes varieties, which form single large rhomboid, rectangular or irregular grains with numerous inclusions of nepheline, clinopyroxene, titanite, magnetite and Sr-rich fluorapatite. These micas in malignites are low in Al2O3 (6.4-8.8 wt.%), high in TiO2 (up to 4.9 wt. %) and F (to 3.3 wt. %). The amount of the K cations is more than Al (K > Al), and the sum (Si + Al) is < 4. In chemical composition these micas are intermediate between tetraferriannite and tetraferriphlogopite. However, the reserve absorption scheme is rarely observed in these micas (optically tetraferriphlogopites are present only in mica-rich xenoliths from malignite). The second late generation is represented by small crystals from miarole-like minute inclusions (commonly in gцtzenite), which also contain zeolites, fluorite, strontianite and later (II generation) nepheline. Micas of second generation are characterized by low TiO2 (0.8-2.5 wt.%), MgO (1.4-10 wt.%), F (0-0.2 wt.%), and high content of Al2O3 (12.6-15.9 wt.%) which is 1.3-1.5 Al cations in the formula. They are represented by annite to siderophуllite. Annite is formed in a medium and low temperature conditions. It is assumed that complement deficiency of cations in tetrahedra (Si + Al <4) preferably Ti4+, but not Fe3+, is characteristic for micas of alkaline rocks and some carbonatites. Low Al2O3 content in early micas of malignites (K > Al) is due to agpaitic conditions of malignite formation and high K content. Alumina-understurated micas are crystallized together with such characteristic agpaitic minerals as alkaline pyroxene and amphibole, nepheline and sodalite, gцtzenite, catapleiite, Sr-rich fluorapatite. Fluorine is typical for high-magnesian micas. It decreases up to a total absence with increasing of Fe2O3. This is probably due to the decreasing temperature because fluorine is not incorporated in Fe2O3-rich annite, which crystallize in microinclusions even if fluorite is present (i.e., when the system was saturated with fluorine). It is also possible that during the formation of malignite the Fe increase in system is a division between the fluorine-rich mica and fluid – melt as determined by experiment for the system of iron-rich biotite – granite melt.

22-42

Authors: Kravchenko G.L., Rusakov N.F.

For the first time Kamyshevatsky metaultrabasite massif on the NW extension of the Sorokinska tectonic zone (STS) is revealed and mapped. Rocks of this massif are presented by apodunite and apoperidotite serpentinites, peridotites, olivine-bearing and olivine-free pyroxenites and their metamorphosed varieties, i.e. hornblendites, aktinolitites, tremolitites and phlogopite (chlorite) -tremolite-anthophyllite rocks. The primary composition of the massif corresponds to dunites, harzburgites, lherzolites and olivine pyroxenites.The massif is slightly differentiated and in the peripheral parts consist of olivine pyroxenites, and in the center of serpentinites and peridotites. Absence of distinctly displayed contact alternations in ultrabasites can evidence on injection of porridge-like magma as a protrusion or on intensive display of regional metamorphism and granitization which fully shaded these alterations. Petrographic, petrochemical and geochemical features of rocks, their rock-forming and ore minerals are described in detail. The presence of TiO2, Al2O3, CaO and alkalis, increased total iron content and low ratio of M/F and Cr/Al indicate on belonging of the studied rocks to ultraferrobasites (gabbro-peridotite association). It is suggested that these rocks are predominantly metamorphosed at the expanse of serpentine dehydration during the granitoid intrusions. The data on internal structure of the massif, its relationship with STS and some similarities and differences concerning metaultrabasite with metakomatiites that have been recently identified in the southern part of STS are presented.The similarity between these rocks consists in availability porphyraceous texture with large crystals of olivine in them, as well as practically the same chemical composition of serpentinites and komatiites with the spinifextextures in metaultrabasiteKamyshevatsky massifwere not found. As the rocks of this region have been transformed by multiple dynamic and thermal influences, the primary structure in these rocks could hardly been preserved. It is probable that the metaultrabasiteand metakomatiiteshave a secondary (metamorphogeneuos) origin at which they could have crystallized in the processes of serpentine dehydration. The latter may have a place at high contact thermal influence of granitoids or at the regional metamorphism of the moderate and low degrees. It is established that metaultrabasites of Kamyshevatsky massif are genetically closely related to those ones in STS this massif represent direct NW-continuation of layering intrusions which are spread in edge parts of STS.