Sulphur content in limestones for cement industry at the Mokrá Quarry and its source

Limestones with very high percentage of CaCO3 and a small amount of remaining oxides (principally SiO2 and SO3) are important industrial rocks. Vilémovice limestones (Macocha Fm.) in the Mokrá Quarry are widely known as best pure type not only for cement industry. However, anomalous content of sulphur above limits occurs fairly often in analyses of those limestones. Sulphur contents in limestones complicate a process of clinker firing, especially because of the increase of emissions and an absence of positive chemical reactions during the firing. The reason of their frequent occurrence in the Mokrá Quarry is a hydrotermal alteration of these limestones producing the sulphides (pyrite, sphalerite, galena) and sheet silicates (besides Si and Al containing Fe, Mg, K) together with other hydrothermal minerals.Limestones with very high percentage of CaCO3 and a small amount of remaining oxides (principally SiO2 and SO3) are important industrial rocks. Vilémovice limestones (Macocha Fm.) in the Mokrá Quarry are widely known as best pure type not only for cement industry. However, anomalous content of sulphur above limits occurs fairly often in analyses of those limestones. Sulphur contents in limestones complicate a process of clinker firing, especially because of the increase of emissions and an absence of positive chemical reactions during the firing. The reason of their frequent occurrence in the Mokrá Quarry is a hydrotermal alteration of these limestones producing the sulphides (pyrite, sphalerite, galena) and sheet silicates (besides Si and Al containing Fe, Mg, K) together with other hydrothermal minerals

PILOTNÍ STUDIUM FLUIDNÍCH INKLUZÍ V SÁDROVCÍCH ZE SEDIMENTŮ MIOCENNÍHO STÁŘÍ U KOBEŘIC

Fluid inclusions found in gypsum from Kobeřice told us lot of information about forming conditions during crystallization of crystals of gypsum and confirmed a prognosis of migration of fluids into the sedimentary basin. All microthermometric measurements performed on microthermometric stage mounted on microscope have been done on 0.05 mm thin plates. All measured temperatures including eutectic temperature and temperature of melting of last solid phase (ice) led us to very small salinity of fluids closed inside the inclusions. The salinity was calculated between 0.9 and 2.6 wt. % NaCl eq., which is very small compared to nowadays and Miocene seawater (3.5 wt. %). Parent fluids which are responsible for crystalization of gypsum crystals could be interpreted most likely as mixing sea water with a more diluted fluid (meteoric water?)

The Brno quartz lode

A large quartz vein which penetrates through granodiorite in the western zone of the Brno Batholith is described. It is composed from two bodies with different directions with a length of approximately 700 and 450 m, the thickness of vein parts varies around 2.5 m. The longer segment has E–W direction. The vein is built by massive greyish-white quartz of one generation with no traces of younger mylonitization. Its origin is spatially associated with a swarm of late Variscan amphibole diorites and porphyritic microdiorites cutting local granodiorites of the Brno Batolith. Precipitation conditions of quartz have been estimated at 170–300 °C and 400–1600 bar and depth at 1.5 up to 6 km. It represents the largest quartz vein not only within the Brno Batholith but even in the entire territory of south Moravia, so we propose to defi ne it as the Brno quartz lode.A large quartz vein which penetrates through granodiorite in the western zone of the Brno Batholith is described. It is composed from two bodies with different directions with a length of approximately 700 and 450 m, the thickness of vein parts varies around 2.5 m. The longer segment has E–W direction. The vein is built by massive greyish-white quartz of one generation with no traces of younger mylonitization. Its origin is spatially associated with a swarm of late Variscan amphibole diorites and porphyritic microdiorites cutting local granodiorites of the Brno Batolith. Precipitation conditions of quartz have been estimated at 170–300 °C and 400–1600 bar and depth at 1.5 up to 6 km. It represents the largest quartz vein not only within the Brno Batholith but even in the entire territory of south Moravia, so we propose to defi ne it as the Brno quartz lode

ZÁKLADNÍ CHARAKTERISTIKA FLUID Z HYDROTERMÁLNÍ MINERALIZACE U HRABŮVKY, NÍZKÝ JESENÍK

Preliminary results of microthermometry and isotope study of hydrothermal mineralisation in Hrabůvka have been carried out. Increasing of homogenisation temperatures has been revealed at the beginning of the mineralising stage whereas the salinity was reduced at the same period. The genetic aspects of the mineralising fluid are discussed

STARÉ DOBÝVACÍ PRÁCE U MALÉHO HRADISKA NA DRAHANSKÉ VRCHOVINĚ

Field and mineralogical investigations have been carried out at the given locality. A sense of the old mining activity and regional meaning of obtained data sets based on geochemical and microthermometry techniques is discussed. Fragments of hydrothermal quartz are believed to be associated with a regional vein system which has been formed by the Variscan dynamometamorphic events. No indications of any polymetallic mineralization suggest more prozaic meaning of old workings, e.g. an exploitation of quartz or more likely greywackes for millstones

Geochemistry and radioactivity of Palaeozoic rocks on the sheets 15-31 Bruntál and 15- 33 Moravský Beroun and their relation to a composition of the Variscan hydrothermal mineralization

This paper deals with the natural radioactivity of Palaeozoic rocks on the map sheets 15- 31 Bruntál and 15-33 Moravský Beroun in the NE part of the Bohemian Massif. Studied rocks belong to the Vrbno Group (greenschists and phyllites) and mainly to the MoravoSilesian Palaeozoic, particulary to the Andělská Hora, Horní Benešov and Moravice Fms. Potassium, uranium and thorium contents were measured in 1 596 rock samples using a laboratory gamma–ray spectrometer, values of mass activity of 226Ra equivalent (am) were calculated. The average am of analysed rock samples is 138 Bq.kg-1. This value is very close to the am value calculated for the average continental crust. Natural radioactivity of flysch sedimentary rocks of the Andělská Hora, Horní Benešov and Moravice Fms. (1 350 analysed samples, avg. am = 150 Bq.kg-1) grows from psefi tes (conglomerates) to psammites (dominating greywackes) up to the group of aleurites and pelites (siltstones, silty shales, clay shales). The highest uranium and thorium contents, along with other metals (Cs, Ga, Rb, Sn, Zr, La, Ce, Pb, Zn, As) were found in flysch rocks of the Horní Benešov Fm. in the area near Valšov: greywacke shows content up to 13 ppm U and 25 ppm Th (am = 364 Bq.kg-1) and siltstone up to 21 ppm U and 43 ppm Th (am = 624 Bq.kg-1). Low-grade metamorphic mobilization of elements is documented by hydrothermal minerals in syntectonic quartz veins which are e.g. fluorite, sulphides, REE-bearing phases, U-bearing phases.This paper deals with the natural radioactivity of Palaeozoic rocks on the map sheets 15- 31 Bruntál and 15-33 Moravský Beroun in the NE part of the Bohemian Massif. Studied rocks belong to the Vrbno Group (greenschists and phyllites) and mainly to the MoravoSilesian Palaeozoic, particulary to the Andělská Hora, Horní Benešov and Moravice Fms. Potassium, uranium and thorium contents were measured in 1 596 rock samples using a laboratory gamma–ray spectrometer, values of mass activity of 226Ra equivalent (am) were calculated. The average am of analysed rock samples is 138 Bq.kg-1. This value is very close to the am value calculated for the average continental crust. Natural radioactivity of flysch sedimentary rocks of the Andělská Hora, Horní Benešov and Moravice Fms. (1 350 analysed samples, avg. am = 150 Bq.kg-1) grows from psefi tes (conglomerates) to psammites (dominating greywackes) up to the group of aleurites and pelites (siltstones, silty shales, clay shales). The highest uranium and thorium contents, along with other metals (Cs, Ga, Rb, Sn, Zr, La, Ce, Pb, Zn, As) were found in flysch rocks of the Horní Benešov Fm. in the area near Valšov: greywacke shows content up to 13 ppm U and 25 ppm Th (am = 364 Bq.kg-1) and siltstone up to 21 ppm U and 43 ppm Th (am = 624 Bq.kg-1). Low-grade metamorphic mobilization of elements is documented by hydrothermal minerals in syntectonic quartz veins which are e.g. fluorite, sulphides, REE-bearing phases, U-bearing phases

Fluid types in rock crystals from quartz vein close to Hutě near Bechyně

Pure quartz crystals occurred in the vein penetrating intensely altered biotite migmatites in proximity of the eclogite body located NE from Hutě near Bechyně. Optical microthermometry has been applied on fluid inclusions (FI) in quartz. Two-phase primary inclusions contain aqueous solution, vapour phase and rarely unidentified solid phase as well (type L+V±S). Medium tempered fluids (Th = 251/270 °C) contain a little amount of CO2 and eutectic temperatures (Te = -9,5/-4,3 °C) suggests presence of sulphates and/or (hydrogen)carbonates. The overall composition of trapped fluid is H2O-MgSO4 ± Na2SO4 ± K2SO4 ± KCl ± CO2. Such not common composition of aqueous phase might be a result of interaction of fluids and ultrabasic rocks containing sulphides.Pure quartz crystals occurred in the vein penetrating intensely altered biotite migmatites in proximity of the eclogite body located NE from Hutě near Bechyně. Optical microthermometry has been applied on fluid inclusions (FI) in quartz. Two-phase primary inclusions contain aqueous solution, vapour phase and rarely unidentified solid phase as well (type L+V±S). Medium tempered fluids (Th = 251/270 °C) contain a little amount of CO2 and eutectic temperatures (Te = -9,5/-4,3 °C) suggests presence of sulphates and/or (hydrogen)carbonates. The overall composition of trapped fluid is H2O-MgSO4 ± Na2SO4 ± K2SO4 ± KCl ± CO2. Such not common composition of aqueous phase might be a result of interaction of fluids and ultrabasic rocks containing sulphides

Hydrotermální karbonáty a termometrie žilné mineralizace v terciérních vulkanitech u Uherského Brodu

Hydrothermal mineralization in the Bučník quarry near Uherský Brod is the best locality for the study of this type of mineralization in the Outer Western Carpathians. The studied sulfide vein mineralization is genetically linked to Tertiary volcanics and represents a distance manifestation of the same vein type in the metallogenetic region of the Central Slovakian Volcanic Field.Study of vein structure, ore textures and structures, chemical composition of carbonates, isotope thermometry (isotopic composition of sulfur sphalerite/galena) and fluid inclusions, including microthermometry, shows that mineralization occurred under complex and variable conditions. Carbonates, defined as calcites with a proportion of Fe and Mn, dolomites and Fe- and Mn-dolomites, Mg-ankerites, show a highly variable chemical composition clearly documented as fine zones in CL-microscopy and BSE images.Fluid inclusions contain the aqueous system H2O-NaCl and H2O-NaCl + MgCl2 + FeCl2-3. Fluid salinity ranges from 2.7 to 14.7 mass% NaCl eq. whereas it is higher for sphalerite than for carbonates. The same trend is for homogenization temperatures in the range of 121-272 °C.Isotopic thermometry in combination with microthermometry shows a relatively wide probable range of temperature conditions. The younger carbonate mineralization may begin at temperatures of 125 °C and around 200 °C may overlap with a temperature of sulfide association that ranges from 170 °C to 335 °C. Isotopic thermometry also suggests possible higher temperatures up to 450 °C and above, but these highest temperatures are rather unlikely. The wide temperature range in which the mineralization originated is in accordance with the development of the hydrothermal system in a very dynamic environment in terms of tectonic, magmatic and hydrothermal. The studied hydrothermal system has a number of physico-chemical parameters similar to vein systems in the Central Slovakian volcanics region

PODMÍNKY VZNIKU HYDROTERMÁLNÍ KALCIT-KŘEMEN-SULFIDICKÉ MINERALIZACE U HRANIC

There are numerous calcite veins with quartz and little sulphides that cut through the Devonian limestones near Hranice. They are assumed to be a post-Variscan mineralization stage. Low temperature fluids (50 to 100°C), from which hydrothermal minerals precipitated, can be best interpreted as mainly basinal fluids (type H2O-NaCl-CaCl2). The fluid system has been influenced by meteoric and marine water (d18O of fluids between -7 and 0 ‰ SMOW). Highly variable precipitation conditions are indicated by zonal structures of most mineral phases. Such conditions are comparable with other vein type mineralizations in the Moravo-Silesian Paleozoic

GENETICKÉ ASPEKTY FLUORITOVÉ MINERALIZACE U RAKŠIC V BRNĚNSKÉM MASIVU

Hydrothermal fluorite mineralization is located within hydrothermally altered pegmatites near Rakšice (Brno massif). Fluorite prevails, quartz and mainly barite and calcite are minor components of the mineralization. Fluorite has been studied by the microthermometric techniques. Temperature of homogenization (TH) of primary and primary-secondary fluid inclusions ranges between 106° and 142°C. Salinity of traped aquous fluids is low between 0.0 and 3.7wt% NaCl eq. Formation conditions are discussed with other fluorite occurrences in the Bohemian Massif. Genetic aspects of the studied fluorite mineralization are compared with Tertiary fluorite mineralizations near Teplice and Jílové u Děčína