PRESSURE-TEMPERATURE CONDITIONS OF HIGH-GRADE METAMORPHISM AND MIGMATITIZATION IN THE MALA FATRA CRYSTALLINE COMPLEX, THE WESTERN CARPATHIANS
Abstract: Pressure-temperature conditions of metamorphism and migmatitization were investigated in the Mala Fatra crystalline complex, representing one of the deepest segments of the Variscan basement in the Western Carpathians. Field observations together with structural data document close relationships between migmatitization and deformation. The penetrative, syn- to post-metamorphic Variscan deformation with generally top-to-the south-southeast sense of shearing has been documented. Thermobarometric data obtained by conventional and internally consistent (TWEEQU) methods indicate the attainment of ca. 700–750 °C and 6 kbar in metapelitic migmatites and 700–750 °C and 8–10 kbar in garnet-clinopyroxene amphibolites. Migmatitization took place by partial melting during decompression, producing granitic leucosome in metapelites and tonalitic-trondhjemitic leucosome in the metabasites. Initial high-pressure stage and a "clockwise" P-T path is inferred from a) kyanite-sillimanite transformation in metapelites and b) kelyphitic and symplectitic textures in garnet-clinopyroxene metabasites, indicating the breakdown of eclogites reequilibrated at upper-amphibolite to granulite facies conditions. The proposed metamorphic evolution is consistent with considerable crustal thickening and extension of the West-Carpathian crystalline basement during the Variscan orogeny.
U-Au-Co-Bi-REE MINERALIZATION IN THE GEMERIC UNIT (WESTERN CARPATHIANS, SLOVAKIA)
Abstract: Uranium mineralization occurs in a quartz vein with gold and REE minerals. The vein cuts the Early Paleozoic rocks in the proximity of the granite body of the Humel Massif. The mineralization is represented by uraninite, brannerite, arsenopyrite, pyrite, glaucodot, gold, galena, bismuth, bismuthinite, xenotime-(Y), rutile, sericite, chlorite, apatite, monazite-(Ce) and tourmaline. Secondary minerals are represented by goethite, trögerite, zeunerite and scorodite.
THE GENESIS OF MESOZOIC RED CALCITE DIKES OF THE TRANSDANUBIAN RANGE (HUNGARY): FLUID INCLUSION THERMOMETRY AND STABLE ISOTOPE COMPOSITIONS
Abstract: Red calcite dikes with widths of 1–3 m were formed during the middle and Upper Cretaceous within Mesozoic sedimentary carbonate rocks in the Transdanubian Range of Hungary. The dikes frequently develop a complex zonation with fine-grained dark-red calcite at their margins and purer and more coarsely crystalline calcite toward their centres. The staining material responsible for their colour is amorphous Fe-oxide-hydroxide whose amount remains below 1 %. The fluid inclusions of carbonates contain rather dilute (<3.5 NaCl eq. wt. %) solutions and frequently show boiling phenomena. The evidence of boiling makes the use of Th data (100–190 °C) as estimates of formation temperatures possible. The Th-salinity plot of the microthermometric data reveals that boiling, cooling and dilution processes were operating during calcite precipitation. The stable carbon and oxygen isotope compositions of calcites and hydrogen isotope compositions of inclusion waters indicate that the formation of red calcite dikes was induced by the ascent of magmatic H2O–CO2 fluid which suffered degassing prior to and during dike formation and was contaminated by meteoric waters originating from the neighbouring rocks. The assumed movements of the magmatic fluids fit well into the results of earlier studies which have shown direct effects of magmatic fluids around lamprophyre dikes and influences of magmatic fluids in the formation of manganese oxide ores during the Cretaceous in the area of the Transdanubian Range.
LOWER BADENIAN SEA-LEVEL DROP ON THE WESTERN BORDER OF THE TRANSYLVANIAN BASIN: FORAMINIFERAL PALEOBATHYMETRY AND STRATIGRAPHY
Abstract: The marine Middle Miocene deposits from the western border of the Transylvanian Basin belong to the Gârbova de Sus Formation (Badenian), lithologically dominated by algal-bioclastic limestones. The rich and well preserved foraminiferal assemblages correspond to planktonic foraminiferal Zone M5b–M6 (Berggren et al. 1995) and the "Upper Lagenid Zone" of the Central Paratethys. The sediments are set in two sequences of about 20 m in thickness, the first mostly siliciclastic, displaying coastal onlap, and the second mainly carbonatic, with a regressive character. The sedimentary and paleontological features reflect sea level changes, the main event — recorded between the first and the second sequence — probably being correlable with a global sea-level drop in the Middle Miocene (15.5–16 Ma).
MICROMORPHOLOGICAL STUDY OF CALCRETES IN SOILS OF THE ZITNY OSTROV REGION, SOUTHWESTERN SLOVAKIA
Abstract: Calcretes have developed in soils of the Zitny ostrov region in response to the mutual interactions between the different prevailing geological and environmental conditions. The evapotranspirative climatic conditions and shallow hydrocarbonatic groundwater play a very significant role in this aspect. Different micromorphological characteristics have been described. The observed microstructures are of massive, intergrain micro-aggregate types, with occasional occurrence of the pellicular type also, in addition to the vughy, intergrain channel, and fissure microstructures. The porosity of these calcretes is dominated by vughs, channels, and planes. There is also a dominance of monic and porphyric related distribution patterns, and rarely of the chitonic type. Different pedogenic features are of special interest, they represent mainly void coating and infilling, in addition to pedofeatures of pseudomorphic, textural and impregnative types, nodules, intercalary crystals, and recrystallization.
UPPER JAW FRAGMENT OF THE ANANCUS ARVERNENSIS (CROIZET & JOBERT 1828) (MASTODONTIDAE, PROBOSCIDEA, MAMMALIA) FROM THE VILLAFRANCHIAN OF HAJNACKA, SLOVAKIA
Abstract: Remains of a representative of the family Mastodontidae (Proboscidea, Mammalia) of the Villafranchian fauna were found in Hajnacka, southern part of Central Slovakia. The upper jaw fragment of an Anancus arvernensis with preserved molars M2 sin., M2 dex., M3 sin., M3 dex. is described in this paper. Anancus arvernensis is a relatively common mastodontid in the Europaean Plio-Pleistocene deposits. Only isolated teeth and bones of mastodontids are usually found on the territory of Slovakia and more complete fossil remains such as the presented specimen are very rare.