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15 result(s) for "Milovský, Rastislav"
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Chemical and spectroscopic signatures of resins from Sumatra (Sarolangun mine, Jambi Province) and Germany (Bitterfeld, Saxony-Anhalt)
Fossil resins from Miocene coal deposit (Sarolangun mine, Jambi Province, Sumatra, Indonesia) have been analysed using spectroscopic methods: Raman Spectroscopy (RS), Fourier Transform-Infrared Spectroscopy (FT-IR), 13 C Nuclear Magnetic Resonance ( 13 C NMR), Fluorescence Spectroscopy (FS), and Gas Chromatography–Mass Spectrometry (GC–MS) in order to describe their diagnostic features. Simultaneously, glessite, a fossil resin from Upper Oligocene Bitterfeld deposit (Saxony-Anhalt, Germany), originating from similar botanical sources (i.e. angiosperms) was tested with the same analytical methods in order to find similarities and differences between the resins. The resins differ in colour, transparency and amounts of inclusions (resins from Sumatra—yellow, and transparent with few inclusions; glessite—brown–red, translucent with wealth of inclusions). In general, the IR and RS spectra of these resins are very similar, probably because the glessite colour-changing additives can be very subtle and non-observable in the infrared region. The RS spectra revealed also a slight difference in intensity ratio of the 1650/1450 cm −1 bands (0.56 and 0.68 for Sumatra and Germany resins, respectively), indicating a differences in their maturation process. The resins from Sumatra seem to be more mature than glessite from Germany. The excitation–emission (EM–EX) and synchronous spectra showed unique, chemical compositions of these resins, which are different one from another. The GC–MS data for Sumatran resins, dominated by sesquiterpenoids and triterpenoids (amyrin), confirmed their botanical origin (angiosperms as their biological affinities). The sesquiterpenoid biomarkers with cadine-structures suggested the glessite underwent more advanced polymerization processes, which does not correlate with its RS spectrum. The geological factors, the environmental conditions of resin deposition, and later various diagenesis processes may have influenced the maturation and crosslinking of compounds. Despite the genetic similarity of the resins from various part of the world, Sumatra and Germany, advanced techniques such as Gas Chromatography–Mass Spectrometry and Fluorescence Spectroscopy were the most useful to find the differences between them. These differences are predominantly a result of different diagenetic transformations of the resins.
Isotopic exchange of oxygen, sulfur, hydrogen and copper between aqueous phase and the copper minerals brochantite, libethenite and olivenite
Fractionation factors for the isotopes of O, H, S, or Cu (as appropriate) were determined for the minerals brochantite [Cu 4 (SO 4 )(OH) 6 ], libethenite [Cu 2 (PO 4 )(OH)] and olivenite [Cu 2 (AsO 4 )(OH)] and corresponding aqueous solutions at temperatures between 30 and 70°C. All samples used for this determination were synthetic and the degree of fractionation was expressed as 1000 ln α = ( A × 10 6 / T 2 ) + B , where A and B are empirical parameters. A few natural libethenite samples from its type locality Ľubietová-Podlipa were also analysed and compared to the prediction based on the isotopic composition of meteoric water and our fractionation factors. The hydrogen fractionation factors agreed with the prediction well, whereas those for oxygen did not. A possible explanation is the disequilibrium of aqueous phosphate (and also arsenate) species and the solution in our experiments or the interaction of meteoric fluids with the isotopically heavy (in terms of oxygen) country rocks. Because the effects of isotopic disequilibrium in our experiments cannot be ruled out, the oxygen fractionation factors should be used with caution. The determined fractionation factors can be used as an isotope geothermometer, given that it can be proven that the phases of interest precipitated from the same fluid in equilibrium. Libethenite is predicted to have slightly lower δ 65 Cu values than its parental solution, but brochantite slightly higher δ 65 Cu values than its parental solution. Simple forward models, simulating neutralisation or reduction of mine drainage, show that precipitation of these minerals and removal of the co-existing fluid, could cause isotopic variations (in δ 65 Cu) on the order of 1‰ or more.
Carbonatite-melilitite-phosphate immiscible melts from the aragonite stability field entrained from the mantle by a Pliocene basalt
A plagioclase megacryst containing composite crystal-glass inclusions was ejected in a Pliocene basaltic diatreme in the Carpathian back-arc basin (Pannonian Basin). The megacryst grew from phonolitic melt, relics of which are preserved in the crystal-glass inclusions. Most of the pristine melt has undergone substantial compositional resetting by interaction with several batches of a low-viscosity carbonated, P-rich melilitite melt, which infiltrated and largely replaced the original inclusion content. The melilitite melt also caused partial resorption of the host megacryst and crystallisation of new calcic plagioclase forming stringers and palisades. A P-rich calcic carbonatite melt exsolved from the melilitite and later crystallised to aragonite at ~ 800 °C and 1.9 GPa. The phosphate melt fraction exsolved from the carbonatite and solidified as CO32−-rich A-B type apatite. At a very late evolutionary stage, K- and Si-rich fluids caused potassic and silicic alteration of the solidified melilitite glass along cracks and interfaces between calcic carbonate globules and glass at temperatures below 680 °C. The oxygen isotope composition of the plagioclase megacryst (6.2 ‰ V-SMOW; Vienna Standard Mean Ocean Water) and the 87Sr/86Sr isotope ratio of carbonates in the inclusions (0.7034) are consistent with a mantle-derived melt. 87Sr/86Sr isotope ratios (0.7047–0.7051) in interstitial carbonates from associated syenite and carbonatite xenoliths indicate a metasomatised mantle source contaminated with radiogenic crustal material or altered marine carbonate. The O-isotope ratios in the carbonates, 22.7 ± 0.6 ‰ V-SMOW in calcite and 23.6 ± 0.7 ‰ V-SMOW in aragonite, are also consistent with a sedimentary precursor. Contrasting δ13C values in the calcite, -12.7 ± 0.5 ‰ V-PDB (Vienna PeeDee Belemnite), and the aragonite (-4.6 ± 0.5 ‰ V-PDB) indicate low-temperature modification of calcite assisted by δ13C-depleted CO2 and preservation of primary magmatic δ13C values in aragonite. The microstructural and geochemical evidence points towards heterogeneous silicate-carbonate melt fractions generated during the metasomatism and partial melting of a supra-subduction mantle wedge.
Fossil evidence for vampire squid inhabiting oxygen-depleted ocean zones since at least the Oligocene
A marked 120 My gap in the fossil record of vampire squids separates the only extant species (Vampyroteuthis infernalis) from its Early Cretaceous, morphologically-similar ancestors. While the extant species possesses unique physiological adaptations to bathyal environments with low oxygen concentrations, Mesozoic vampyromorphs inhabited epicontinental shelves. However, the timing of their retreat towards bathyal and oxygen-depleted habitats is poorly documented. Here, we document a first record of a post-Mesozoic vampire squid from the Oligocene of the Central Paratethys represented by a vampyromorph gladius. We assign Necroteuthis hungarica to the family Vampyroteuthidae that links Mesozoic loligosepiids with Recent Vampyroteuthis. Micropalaeontological, palaeoecological, and geochemical analyses demonstrate that Necroteuthis hungarica inhabited bathyal environments with bottom-water anoxia and high primary productivity in salinity-stratified Central Paratethys basins. Vampire squids were thus adapted to bathyal, oxygen-depleted habitats at least since the Oligocene. We suggest that the Cretaceous and the early Cenozoic OMZs triggered their deep-sea specialization.A new fossil of a vampire squid bridges a 120 million-year gap in their fossil record. Vampire squid today are adapted to low oxygen, deep sea environments and this new specimen provides evidence that the deep sea specialisation of vampire squid may have been triggered during the development of oxygen minimum zones in the oceans during the Cretaceous and Cenozoic.
Porosity Development Controlled by Deep-Burial Diagenetic Process in Lacustrine Sandstones Deposited in a Back-Arc Basin (Makó Trough, Pannonian Basin, Hungary)
Deeply buried Pannonian (Upper Miocene) siliciclastic deposits show evidence of secondary porosity development via dissolution processes at a late stage of diagenesis. This is demonstrated by detailed petrographic (optical, cathodoluminescence, fluorescence, and scanning electron microscopy) as well as elemental and stable isotope geochemical investigations of lacustrine deposits from the Makó Trough, the deepest depression within the extensional Pannonian back-arc basin. The analyses were carried out on core samples from six wells located in various positions from centre to margins of the trough. The paragenetic sequence of three formations was reconstructed with special emphasis on sandstone beds in a depth interval between ca 2700 and 5500 m. The three formations consist, from bottom to top, of (1) open-water marls of the Endrőd Formation, which is a hydrocarbon source rock with locally derived coarse clastics and (2) a confined and (3) an unconfined turbidite system (respectively, the Szolnok and the Algyő Formation). In the sandstones, detrital grains consist of quartz, feldspar, and mica, as well as sedimentary and metamorphic rock fragments. The quartz content is high in the upper, unconfined turbidite formation (Algyő), whereas feldspars and rock fragments are more widespread in the lower formations (Szolnok and Endrőd). Eogenetic minerals are framboidal pyrite, calcite, and clay minerals. Mesogenetic minerals are ankerite, ferroan calcite, albite, quartz, illite, chlorite, and solid bituminous organic matter. Eogenetic finely crystalline calcite yielded δ13CV−PDB values from 1.4 to 0.7‰ and δ18OV−PDB values from –6.0 to –7.4‰, respectively. Mesogenetic ferroan calcite yielded δ13CV−PDB values from 2.6 to –1.2‰ and δ18OV−PDB values from –8.3 to –14.0‰, respectively. In the upper part of the turbidite systems, remnants of the migrated organic matter are preserved along pressure dissolution surfaces. All these features indicate that compaction and mineral precipitations resulted in tightly cemented sandstones prior to hydrocarbon migration. Interconnected, secondary, open porosity is associated with pyrite, kaolinite/dickite, and postdates of the late-stage calcite cement. This indicates that dissolution processes took place in the deep burial realm in an extraformational fluid-dominated diagenetic system. The findings of this study add a unique insight to the previously proposed hydrological model of the Pannonian Basin and describe the complex interactions between the basinal deposits and the basement blocks.
Modified electrolyte leakage method for testing the oxidative stability of Pinus mugo Turra under ozone-induced stress
Electrolyte leakage (EL) is the method commonly used to test the cell membrane integrity of plants under stress conditions. The cells of the leaf may be damaged by ozone (O ) entering the intercellular space as an oxidative stress agent. The modified EL method was used to test the oxidative stability (OxS) of plant tissue against O -induced oxidative stress. The modification includes simulation of the artificial oxidative stress by additional ozonation of plant samples in the laboratory chamber. This modified EL method was applied to Turra needle samples collected in the subalpine zone of the High Tatra Mts (Western Carpathians), in the years 2019 and 2020. Changes in the chemical composition of samples after artificial ozonation were traced by gas chromatography/mass spectrometry (GC/MS) analysis. In addition, O uptake through open stomata was estimated by calculation of the modelled ozone dose (MO D). We also conducted an inspection of visible injury (VIN) on the needle surface focused on the occurrence of O -induced symptoms and biotic harmful agents. Regarding OxS results as well as VIN indices, needles showed relatively low sensitivity to oxidative stress induced by O . Therefore MO D in a range between 14 and 16 mmol m can be considered as O3 dose with minor phytotoxic effect on growing in the mountains of central-eastern Europe.
Mineralogy and evolution of the epithermal mineralization in the Rudno nad Hronom-Brehy ore deposit, Štiavnické vrchy Mts. (Slovakia)
The Rudno nad Hronom-Brehy ore deposit in Slovakia represents an important locality of epithermal precious metal mineralization in the Central Slovak Volcanic Field. The main ore structures in the area are Anna, Goldschram, Filip, Johan de Deo and Priečna veins. In this work, we present mineralogical, paragenetic and geochemical aspects of the ore mineralization, hydrothermal alteration patterns, fluid inclusions, isotopic composition of sulfur (5 34S) and K-Ar age of ore mineralization. Four mineralization stages were recognized, the third one being split into two substages. (1) Pyrite stage with quartz, K-feldspar, arsenopyrite and pyrite. (2) Base-metal stage with sphalerite, galena, chalcopyrite, Au-Ag alloys and famatinite. (3a) Early Ag stage with tetrahedrite-(Zn), tetrahedrite-(Fe), argentotetrahedrite-(Zn), tetrahedrite-(Cd), argentotetrahedrite-(Cd) and greenockite. (3b) Late Ag stage with pyrargyrite, polybasite, pearceite, cupropolybasite, cupropearceite, acanthite and galena. (4) Late Ag-Cu stage with bornite, stromeyerite, mckinstryite, chalcocite, digenite, covellite and uytenbogaardtite. Veins are rich in silver with an average Ag:Au ratio of 85:1; in some parts of the veins, Ag content reaches up to 1950 ppm and Au up to 42.7 ppm. The neutral to alkaline style of hydrothermal alteration is represented by K-feldspar, quartz, carbonates, smectite, interstratified illite/smectite, and chlorite (clinochlore, chamosite). This assemblage indicates a low sulfidation origin of the mineralization formed at 177-224°C. The ô34S values from the base-metal stage varies from +2.8 to +3.5 %o for chalcopyrite from the northern part of the Priečna vein, from +1.9 to +2.6 %o for galena, from +4.9 to +5.2 %o CDT for pyrite from the Anna vein. These values indicate a relatively homogeneous sulfur source, most likely related to an igneous or mixed igneous and host-rock source. Fluid inclusions in quartz associated with the base-metal stage have low salinity (1.1-1.6 wt. % NaCl eq.) and homogenization temperatures of 176-250 °C. The available data suggest that the base-metal stage was accompanied by cooling and dilution owing to a meteoric fluid. The temperature estimated from the tetrahedrite thermometer of the early Ag stage is -170-205 °C. According to the paragenetic relationship and mineral stability, the deposition temperatures in the late Ag stage did not exceed 160 °C. The late Ag-Cu stage formed at temperatures of <93 °C. The results of К-Ar radiometric dating from the hydrothermal alteration returned an average age of 12.5 + 0.3 Ma. The studied mineralization is possibly related to the initial stage of resurgent horst tectonic activity and rhyolite volcanism of the fifth stage of Štiavnica stratovolcano formation.
Fluid evolution and mineralogy of Mn-Fe-barite-fluorite mineralizations at the contact of the Thuringian Basin, Thüringer Wald and Thüringer Schiefergebirge in Germany
Numerous small deposits and occurrences of Mn-Fe-fluorite-barite mineralization have developed at the contact of the Thuringian Basin, Thüringer Wald and Thüringer Schiefergebirge in central Germany. The studied mineralizations comprise the assemblages siderite+ankerite-calcite-fluorite-barite and hematite-Mn oxides-calcite-barite, with the precipitation sequence in that order within each assemblage. A structural geological analysis places the origin of the barite veins between the Middle Jurassic and Early Cretaceous. Primary fluid inclusions contain water vapour and an aqueous phase with NaCl and CaCl as the main solutes, with salinities mostly between 24–27 mass. % CaCl eq. measurements range between 85 °C and 160 °C in barite, between 139 °C and 163 °C in siderite, and between 80 °C and 130 °C in fluorite and calcite. Stable isotopes (S, O) point to the evaporitic source of sulphur in the observed mineralizations. The S,C,O isotopic compositions suggest that barite and calcite could not have precipitated from the same fluid. The isotopic composition of the fluid that precipitated barite is close to the sea water in the entire Permo–Mesozoic time span whereas calcite is isotopically distinctly heavier, as if the fluids were affected by evaporation. The fluid evolution in the siliciclastic/volcanic sediments (as determined by a number of earlier petrological and geochemical studies) can be correlated with the deposition sequence of the ore minerals. In particular, the bleaching of the sediments by reduced fluids (basinal brines) could be the event that mobilized Fe and Mn. These elements were deposited as siderite+ankerite within the carbonate rocks and as hematite+Mn oxides within the oxidizing environment of the Permian volcanic and volcanoclastic rocks. A Middle-Jurassic illitization event delivered Ca, Na, Ba, and Pb from the feldspars into the basinal brines. Of these elements, Ba was deposited as massive barite veins.
Structural pattern and emplacement mechanisms of the Krížna cover nappe (Central Western Carpathians)
The Central Western Carpathians are characterized by both the thick- and thin-skinned thrust tectonics that originated during the Cretaceous. The Krížna Unit (Fatric Superunit) with a thickness of only a few km is the most widespread cover nappe system that completely overthrusts the Tatric basement/cover superunit over an area of about 12 thousands square km. In searching for a reliable model of its origin and emplacement, we have collected structural data throughout the nappe body from its hinterland backstop (Veporic Superunit) to its frontal parts. Fluid inclusion (FI) data from carbonate cataclastic rocks occurring at the nappe sole provided useful information about the p-T conditions during the nappe transport. The crucial phenomena considered for formulation of our evolutionary model are: (1) the nappe was derived from a broad rifted basinal area bounded by elevated domains; (2) the nappe body is composed of alternating, rheologically very variable sedimentary rock complexes, hence creating a mechanically stratified multilayer; (3) presence of soft strata serving as décollement horizons; (4) stress and strain gradients increasing towards the backstop; (5) progressive internal deformation at very low-grade conditions partitioned into several deformation stages reflecting varying external constraints for the nappe movement; (6) a very weak nappe sole formed by cataclasites indicating fluid-assisted nappe transport during all stages; (7) injection of hot overpressured fluids from external sources (deformed basement units) facilitating frontal ramp overthrusting under supralithostatic conditions. It was found that no simple mechanical model can be applied, but that all known principal emplacement mechanisms and driving forces temporarily participated in progressive structural evolution of the nappe. The rear compression operated during the early stages, when the sedimentary succession was detached, shortened and transported over the frontal ramp. Subsequently, gravity spreading and gliding governed the final nappe emplacement over the unconstrained basinal foreland.
Hydrothermal speleogenesis in carbonates and metasomatic silicites induced by subvolcanic intrusions: a case study from the Štiavnické vrchy Mountains, Slovakia
Several caves of hydrothermal origin in crystalline limestones and metasomatic silicites were investigated in the central zone of the Stiavnica stratovolcano, Stiavnické vrchy Mountains, central Slovakia. Evidence of hydrothermal origin includes irregular spherical cave morphology sculptured by ascending thermal water, occurrence of large calcite crystals and hydrothermal alteration of host rocks, including hydrothermal clays. The early phases of speleogenesis in the crystalline limestone near Sklené Teplice Spa were caused by post-magmatic dissolution linked either to the emplacement of subvolcanic granodiorite intrusions during Late Badenian time or to the spatially associated Late Sarmatian epithermal system. Speleogenesis in metasomatic silicites in the Sobov area is related to hydrothermal processes associated with the pre-caldera stage of the Stiavnica stratovolcano in Late Badenian. Both localities are remarkable examples of hydrothermal speleogenesis associated with Miocene volcanic and magmatic activity in the Western Carpathians.