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Marian Janák, Tomáš Mikuš, Pavel Pitoňák and Ján Spišiak

Eclogites overprinted in the granulite facies from the Ďumbier Crystalline Complex (Low Tatra Mountains, Western Carpathians)

Metabasites with evidence for breakdown of former eclogites and recrystallization under granulite facies conditions occur in the Ďumbier Crystalline Complex of the Low Tatra Mountains, Central Western Carpathains. Textural relationships, phase equilibrium modelling and thermobarometry have been used to determine the P-T evolution of these rocks. Omphacite diagnostic for the eclogites facies stage is absent but its former presence is inferred from the symplectitic intergrowths of clinopyroxene + plagioclase. The re-equilibration in high-pressure granulite facies conditions is demonstrated by the assemblage garnet + clinopyroxene (< 10 % Jd) + plagioclase + quartz. The phase equilibrium modelling using THERIAK-DOMINO program and conventional geothermobarometry suggest the P-T conditions of 750-760 °C and 1.1-1.5 GPa for the high-pressure granulite stage. Orthopyroxene formed in the clinopyroxene + plagioclase symplectites and kelyphites and coronas around garnet at P-T conditions of ca. 0.7-1.0 GPa and 650-700 °C. P-T evolution of granulitized eclogites is interpreted as the result of two metamorphic events; early Variscan eclogite facies metamorphism was followed by granulite facies thermal overprint in the Carboniferous time. The second metamorphic event was crucial for breakdown of eclogites, these are only seldom preserved in the pre-Alpine basement of the Western Carpathians.

Open access

Jozef Varga, Radoslava Kanianska and Ján Spišiak

Abstract

The aim of the study was to analyse the impact of land use and altitudinal gradient including geological conditions on selected soil physical properties with subsequent effect on earthworms as important soil organisms. The research was conducted at three study sites (Očová – OC, Tajov – TA, Liptovská Teplička – LT) situated in the different climatic and natural conditions of Slovakia each with 3 plots differing in land use (arable land - AL, permanent grasslands – PG, forest land – FL). During 2014 over two periods, we measured soil penetration resistance (PR) with total depth of the measurement (DP) and soil moisture (SM). Earthworms were hand sorted counted and weighed. We found out high variability of measured parameters conditioned by time, space (altitudinal gradient) and land use. PR values of all measurements ranged from 0.19 to 5.00 MPa, DP values from 0.02 to 0.80 m and soil moisture from 2 to 50%. Paired samples test confirmed differences between different land use types mainly between AL and FL plots. There were confirmed significant differences between three ecological gradients in all observed properties with one exception. Correlations among observed variables under different altitudinal gradients and land use types were found. The earthworm density and biomass was significantly higher in permanent grasslands compared to forest and arable land. In arable land, the earthworm density and biomass negatively correlated with the penetration resistance and positively with the depth of the total measurements. In permanent grasslands earthworm biomass positively correlated with soil moisture.

Open access

Ján Spišiak, Lucia Vetráková, David Chew, Štefan Ferenc, Tomáš Mikuš, Viera Šimonová and Peter Bačík

Abstract

Calc–alkaline lamprophyres are known from several localities in the Malá Fatra Mountains. They form dykes (0.5–3 m) of varying degree of alteration that have intruded the surrounding granitoid rocks which are often incorporated xenoliths. Clinopyroxenes (diopside to augite), amphiboles (kaersutitic), biotites (annite) and plagioclases are major primary minerals of the dykes, accessory minerals include apatite, ilmenite, rutile, pyrite, chalcopyrite, and pyrrhotite. Apatite has a relatively low F, but increased Cl content compared to typical apatite from lamprophyres or magmatic apatite from granitic rocks in the Western Carpathians. The chemical composition of the lamprophyres indicates their calc–alkaline character, but affinity to alkaline lamprophyres is suggested by the Ti enrichment in clinopyroxene, amphibole and biotite. According to modal classification of the minerals, the studied rocks correspond to spessartite. The differences in the chemical composition of the rocks (including Sr and Nd isotopes) probably result from the contamination of primary magma by crustal material during magma ascent. The age of the lamprophyres, based on U/Pb dating in apatite, is 263.4 ± 2.6 Ma.

Open access

Jozef Vozár, Ján Spišiak, Anna Vozárová, Jakub Bazarnik and Ján Krái

Abstract

The paper presents new major and trace element and first Sr-Nd isotope data from selected lavas among the Permian basaltic andesite and basalts of the Hronicum Unit and the dolerite dykes cutting mainly the Pennsylvanian strata. The basic rocks are characterized by small to moderate mg# numbers (30 to 54) and high SiO2 contents (51-57 wt. %). Low values of TiO2 (1.07-1.76 wt. %) span the low-Ti basalts. Ti/Y ratios in the dolerite dykes as well as the basaltic andesite and basalt of the 1st eruption phase are close to the recommended boundary 500 between high-Ti and low-Ti basalts. Ti/Y value from the 2nd eruption phase basalt is higher and inclined to the high-Ti basalts. In spite of this fact, in all studied Hronicum basic rocks Fe2O3* is lower than 12 wt. % and Nb/La ratios (0.3-0.6) are low, which is more characteristic of low-Ti basalts. The basic rocks are characterized by Nb/La ratios (0.56 to 0.33), and negative correlations between Nb/La and SiO2, which point to crustal assimilation and fraction crystallization. The intercept for Sr evolution lines of the 1st intrusive phase basalt is closest to the expected extrusions age (about 290 Ma) with an initial 87Sr/86Sr ratio of about 0.7054. Small differences in calculated values ISr document a partial Sr isotopic heterogeneity source (0.70435-0.70566), or possible contamination of the original magma by crustal material. For Nd analyses of the three samples, the calculated values εCHUR (285 Ma) are positive (from 1.75 to 3.97) for all samples with only subtle variation. Chemical and isotopic data permit us to assume that the parental magma for the Hronicum basic rocks was generated from an enriched heterogeneous source in the subcontinental lithospheric mantle.