Hydrothermal mineralization in rock of teschenite association near Nový Jičín (Silesian Unit, Outer Western Carpathians)

Studied locality is situated in western part of the Silesian Unit of the Outer West Carpathians. Hydrothermal veins up to 1.5 cm thick are present in igneous rock of the teschenite association. The studied mineralization is composed of calcite, chlorite (pennine) and dolomite. Hydrothermal veins are apparently undeformed. Homogenization temperatures of primary and secondary aqueous fluid inclusions present in calcite vary between 90 and 150 °C. The fluids have generally low salinities (0.5 to 3.1 wt. % NaCl equiv.), positive δ18O values between +5.4 and +8.8 ‰ SMOW and δ13C around -9.5 ‰ PDB. Hydrothermal veins originated from fluids causing the pervasive post-magmatic hydrothermal alteration of the host rock. The parent fluid was most probably a mixture of seawater with diagenetic waters, which have been released during thermal alteration of sediments occurring in the surroundings of the teschenite-association rock body.Studied locality is situated in western part of the Silesian Unit of the Outer West Carpathians. Hydrothermal veins up to 1.5 cm thick are present in igneous rock of the teschenite association. The studied mineralization is composed of calcite, chlorite (pennine) and dolomite. Hydrothermal veins are apparently undeformed. Homogenization temperatures of primary and secondary aqueous fluid inclusions present in calcite vary between 90 and 150 °C. The fluids have generally low salinities (0.5 to 3.1 wt. % NaCl equiv.), positive δ18O values between +5.4 and +8.8 ‰ SMOW and δ13C around -9.5 ‰ PDB. Hydrothermal veins originated from fluids causing the pervasive post-magmatic hydrothermal alteration of the host rock. The parent fluid was most probably a mixture of seawater with diagenetic waters, which have been released during thermal alteration of sediments occurring in the surroundings of the teschenite-association rock body

HYDROTERMÁLNÍ MINERALIZACE V JÍLOVCÍCH LHOTECKÉHO SOUVRSTVÍ U CHORYNĚ (SLEZSKÁ JEDNOTKA, VNĚJŠÍ ZÁPADNÍ KARPATY)

Studied locality Choryně is situated in the Silesian Unit of the Outer Western Carpathian’s flysch. Hydrothermal veins up to 1.5 cm thick are present in greyish blue Lower Cretaceous claystones belonging to the Lhota Formation. The studied mineralization is mineralogically very simple, being composed only of calcite. Hydrothermal veins are apparently deformed. Homogenization temperatures of primary aqueous fluid inclusions present in calcite vary between 110 and 147 °C. The fluids have generally low salinities (0.5 to 3.1 wt. % NaCl equiv.), positive δ18O values between +3.5 and +7.0 ‰ SMOW and δ13C around –8 ‰ PDB. Chondrite-normalized REE pattern of calcite is different from those of the host claystone (MREE-enriched calcite vs. LREE-enriched claystone) and shows a negative Eu and Ce anomalies. The origin of the mineralization was probably related to the diagenetic processes that took place in the host rocks

Ferrierite-Mg from calcite vein hosted by monchiquite at Žilina near Nový Jičín (Silesian Unit, Outer Western Carpathians)

Studied locality is situated in western part of the Silesian Unit of the Outer Western Carpathians. In an abandoned monchiquite quarry at Žilina village near Nový Jičín NW–SE -trending calcite veinlet containing ferrierite-Mg has been found. Ferrierite-Mg forms colorless to red aggregates of acicular crystals about 400 μm in size. Fluid inclusions hosted by younger vein calcite showed low both homogenization temperatures (90–130 °C) and salinities (0.5–2.6 wt. % NaCl eq.). These data are consistent with vein formation during the later stage of postmagmatic hydrothermal alteration. The hydrothermal solutions represented mixed heated seawater and diagenetic water pointing to an open-system hydrothermal circulation during this stage.Studied locality is situated in western part of the Silesian Unit of the Outer Western Carpathians. In an abandoned monchiquite quarry at Žilina village near Nový Jičín NW–SE -trending calcite veinlet containing ferrierite-Mg has been found. Ferrierite-Mg forms colorless to red aggregates of acicular crystals about 400 μm in size. Fluid inclusions hosted by younger vein calcite showed low both homogenization temperatures (90–130 °C) and salinities (0.5–2.6 wt. % NaCl eq.). These data are consistent with vein formation during the later stage of postmagmatic hydrothermal alteration. The hydrothermal solutions represented mixed heated seawater and diagenetic water pointing to an open-system hydrothermal circulation during this stage

Genetic aspects of barite mineralization related to rocks of the teschenite association in the Silesian Unit, Outer Western Carpathians, Czech Republic

Barite is a relatively uncommon phase in vein and amygdule mineralizations hosted by igneous rocks of the teschenite association in the Silesian Unit (Western Carpathians). In macroscopically observable sizes, it has been reported from 10 sites situated only in the Czech part of the Silesian Unit. Microscopic barite produced by the hydrothermal alteration of rock matrix and also by the supergene processes is more abundant. We examined four samples of barite by mineralogical and geochemical methods. Electron microprobe analyses proved pure barites with up to 0.038 apfu Sr and without remarkable internal zonation. Fluid inclusion and sulphur isotope data suggests that multiple sources of fluid components have been involved during barite crystallization. Barite contains primary and secondary aqueous all-liquid (L) or less frequent two-phase (L+V) aqueous fluid inclusions with variable salinity (0.4-2.9 wt. % NaCl eq.) and homogenization temperatures between 77 and 152 °C. The higher-salinity fluid endmember was probably Cretaceous seawater and the lower-salinity one was probably diagenetic water derived from surrounding flysch sediments during compaction and thermal alteration of clay minerals. The δ34S values of barite samples range between -1.0 ‰ and +16.4 ‰ CDT suggesting participation of two sources of sulphate, one with a near-zero δ34S values probably derived from wall rocks and another with high δ34S values being most probably sulphate from the Cretaceous seawater. All results underline the role of externally derived fluids during post-magmatic alteration of bodies of rock of the teschenite association.Web of Science68212911

Fluid inclusions and chemical composition of analcimes from Řepiště site (Outer Western Carpathians)

Studied locality is situated in western part of the Silesian Unit of the Outer Western Carpathians. Analcime was found in magmatic rock of the teschenite association which was subject of extensive analcimization. Th e analcime crystals, filling the veins and cavities (amygdules, miaroles), have a size up to 5 mm and composite structure: a milky white core shows irregular shape, up to 1 mm in size, and a vitreous transparent rim showing euhedral crystals. The vitreous transparent analcime from veins forms either euhedral crystals or white-pink spherulitic aggregates (size up to 5 mm). Their composition is not close to stoichiometry, with the SiO2/Al2O3 mole ratios from 2.08 to 3.12. Increasing SiO2/Al2O3 molar ratios of analcimes are consistent with decreasing crystallization temperatures. Analcime contains abundant primary fluid inclusions, less secondary fluid inclusions. Fluid inclusions are one-phase (L-only) or two-phase (L+V) with essentially constant liquid-vapour ratios (gaseous phase takes ca. 10 vol. %). The homogenization temperatures of two-phase inclusions range between 122 and 180 °C (analcime from veins) and between 219 and 295 °C (analcime from cavities - amygdules, miaroles). Inclusions freeze at temperatures of -38 to -49 °C. The last ice melts at temperatures between -0.6 and -3.7 °C. The eutectic temperature was not possible to measure due to the small size of the inclusions. The hydrothermal analcime formed from fluids causing the pervasive post-magmatic hydrothermal alteration of the host magmatic rock. The parent fluids were low-salinity (0.7 to 3.2 wt. % NaCl equiv.) aqueous solutions that were progressively cooled during mineral precipitation. This mineral phase represents a transitional stage between the high-temperature and low-temperature stages of post-magmatic hydrothermal activity in the study area.Studied locality is situated in western part of the Silesian Unit of the Outer Western Carpathians. Analcime was found in magmatic rock of the teschenite association which was subject of extensive analcimization. Th e analcime crystals, filling the veins and cavities (amygdules, miaroles), have a size up to 5 mm and composite structure: a milky white core shows irregular shape, up to 1 mm in size, and a vitreous transparent rim showing euhedral crystals. The vitreous transparent analcime from veins forms either euhedral crystals or white-pink spherulitic aggregates (size up to 5 mm). Their composition is not close to stoichiometry, with the SiO2/Al2O3 mole ratios from 2.08 to 3.12. Increasing SiO2/Al2O3 molar ratios of analcimes are consistent with decreasing crystallization temperatures. Analcime contains abundant primary fluid inclusions, less secondary fluid inclusions. Fluid inclusions are one-phase (L-only) or two-phase (L+V) with essentially constant liquid-vapour ratios (gaseous phase takes ca. 10 vol. %). The homogenization temperatures of two-phase inclusions range between 122 and 180 °C (analcime from veins) and between 219 and 295 °C (analcime from cavities - amygdules, miaroles). Inclusions freeze at temperatures of -38 to -49 °C. The last ice melts at temperatures between -0.6 and -3.7 °C. The eutectic temperature was not possible to measure due to the small size of the inclusions. The hydrothermal analcime formed from fluids causing the pervasive post-magmatic hydrothermal alteration of the host magmatic rock. The parent fluids were low-salinity (0.7 to 3.2 wt. % NaCl equiv.) aqueous solutions that were progressively cooled during mineral precipitation. This mineral phase represents a transitional stage between the high-temperature and low-temperature stages of post-magmatic hydrothermal activity in the study area

Genesis of Syntectonic Hydrothermal Veins in the Igneous Rock of Teschenite Association (Outer Western Carpathians, Czech Republic): Growth Mechanism and Origin of Fluids

Hydrothermal mineralization hosted by the Lower Cretaceous igneous rock of the teschenite association at Jasenice (Silesian Unit, Flysch Belt, Outer Western Carpathians) occurs in two morphological types - irregular vein filled by granular calcite and regular composite vein formed by both fibrous and granular calcite and minor chlorite, quartz, and pyrite. Crosscutting evidence indicates that the granular veins are younger than the composite vein. The composite vein was formed by two mechanisms at different times. The arrangement of solid inclusions in the marginal fibrous zone suggests an episodic growth by the crack-seal mechanism during syntectonic deformation which was at least partially driven by tectonic suction pump during some stages of the Alpine Orogeny. Both the central part of the composite vein and monomineral veins developed in a brittle regime. In these cases, the textures of vein suggest the flow of fluids along an open fracture. The parent fluids of both types of vein are characterized by low temperatures (Th=66-163 °C), low salinities (0.4 to 3.4 wt. % NaCl eq.), low content of strong REE-complexing ligands, and δ18O and δ13C ranges of + 0.2/+12.5 %. SMOW and -11.8/-14.1 %. PDB, respectively. The parent fluids are interpreted as the results of mixing of residual seawater and diagenetic waters produced by dewatering of clay minerals in the associ-ated flysch sediments. The flow of fluids was controlled by tectonic deformation of the host rock

Genetic aspects of barite mineralization related to rocks of the teschenite association in the Silesian Unit, Outer Western Carpathians, Czech Republic

Barite is a relatively uncommon phase in vein and amygdule mineralizations hosted by igneous rocks of the teschenite association in the Silesian Unit (Western Carpathians). In macroscopically observable sizes, it has been reported from 10 sites situated only in the Czech part of the Silesian Unit. Microscopic barite produced by the hydrothermal alteration of rock matrix and also by the supergene processes is more abundant. We examined four samples of barite by mineralogical and geochemical methods. Electron microprobe analyses proved pure barites with up to 0.038 apfu Sr and without remarkable internal zonation. Fluid inclusion and sulphur isotope data suggests that multiple sources of fluid components have been involved during barite crystallization. Barite contains primary and secondary aqueous all-liquid (L) or less frequent two-phase (L+V) aqueous fluid inclusions with variable salinity (0.4-2.9 wt. % NaCl eq.) and homogenization temperatures between 77 and 152 °C. The higher-salinity fluid endmember was probably Cretaceous seawater and the lower-salinity one was probably diagenetic water derived from surrounding flysch sediments during compaction and thermal alteration of clay minerals. The δ34S values of barite samples range between -1.0 ‰ and +16.4 ‰ CDT suggesting participation of two sources of sulphate, one with a near-zero δ34S values probably derived from wall rocks and another with high δ34S values being most probably sulphate from the Cretaceous seawater. All results underline the role of externally derived fluids during post-magmatic alteration of bodies of rock of the teschenite association