USE OF ILLITE FOR K/AR DATING OF HYDROTHERMAL PRECIOUS AND BASE METAL MINERALIZATION IN CENTRAL SLOVAK NEOGENE VOLCANIC ROCKS
Abstract: In all important stages of hydrothermal precious and base metal mineralization in the central Slovak Neogene volcanic rocks the characteristic assemblages of clay minerals can be distinguished, in which illite and mixed-layer illite/smectite of various polytypes play an important role. Our study has confirmed that the illite polytypes can provide information on the thermodynamic conditions that prevailed during the formation of precious and base metal mineralization in the Central Slovak Neogene volcanic area. The results of K/Ar dating of illites from hydrothermally altered zones, such as those observed in most hydrothermal precious and base metal mineralizations in the Central Slovak Neogene volcanic area are reported for the first time. They bring new information on the time interval of the hydrothermal mineralization. The main stages took place 12.4±0.1–11.3±0.1 Ma in all the important ore districts within the Central Slovak Neogene volcanics.
ILLITE CRYSTALLINITY AND VITRINITE REFLECTANCE IN PALEOZOIC SILICICLASTICS IN THE SE BOHEMIAN MASSIF AS EVIDENCE OF THERMAL HISTORY
Abstract: The thermal maturity of Paleozoic rocks in the SE part of the Bohemian Massif is characterized by clay minerals and organic matter. The expandability of illite-smectite (S in I-S), illite crystallinity index (IC) and reflectance of (Rr) were measured and their regional distribution was evaluated. The mutual correlation of IC and Rr from diagenesis to very low-grade metamorphism is compared with the published data and used to distinguish data with more reliable paleogeothermal information from those affected by other factors. In the SE part the Paleozoic units have illite-smectites with an expandable component of 15–35 % S. The reflectance values (Rr of 0.55–1.1 %) are in good agreement with the expandability and suggest the oil window range of catagenesis with paleotemperature close to 100 °C. In the NNW part of the area the clays contain no expandable layers in illite. The illite crystallinity (IC of 0.36–0.24 Δ°2Θ) and vitrinite reflectance (Rr from 3.17 to 5.23 %) indicate very low-grade metamorphic conditions with probable maximum paleotemperatures of 240–300 °C. The systematic change in both clay and organic parameters shows the gradual decrease in thermal exposure towards the front of the Variscan orogenic zone in the S and SE and suggest extensive erosion in the NNW.
ACIDITY OF PROTON SATURATED AND AUTOTRANSFORMED SMECTITES CHARACTERIZED WITH PROTON AFFINITY DISTRIBUTION
Abstract: Potentiometric titration of proton saturated fine fractions of three bentonites were used to characterize the acid centre at the smectite-water interface in dispersions. The H-forms were prepared by H+->OH-->H+ ion exchange with resins. The obtained titration data were used in a thermodynamic calculation of proton affinity distribution. Numerical solving of an integral adsorption equation revealed a continuous distribution of proton interaction sites. Proton affinity distributions clearly detected up to 5 different proton interaction sites in all the smectite-water systems, within accessible experimental range of pH’s between 2 and 12. The amount of the strongest acid sites, i.e. those with the lowest pK values, decreased on aging, while the amounts of all weaker acid sites increased with the progress of autotransformation. The strongest acid sites are connected with free protons present in the dispersion, while the weaker acid sites are connected with the titration of released structural Al3+, Fe3+, Mg2+ cations and/or their hydrolyzed species, and deprotonation of SiOH groups. These results indicate the sources of acidity in acid activated bentonites.
CONVERSION OF SMECTITE TO AMMONIUM ILLITE IN THE HYDROTHERMAL SYSTEM OF HARGHITA BĂI, ROMANIA: SEM AND TEM INVESTIGATIONS
Abstract: Random and ordered mixed-layer smectite-ammonium illite (NH4-I/S) were identified by XRD analysis in the fossil hydrothermal system of Harghita Băi (Eastern Carpathians, Romania). Morphologies of NH4-I/S were studied by SEM and TEM. SEM image of random NH4-I/S displays a cellular or cornflake texture. Ordered NH4-I/S (R=1) exhibits a scalloped morphology with curled edges. Ribbon crystals of illite rise from the surfaces of plate aggregates. Two generations of NH4-I are distinguished: one developed from a smectite precursor and another from a kaolinite precursor. Hairy illite and illite pseudomorphs after book-like aggregates of kaolinite are present.TEM images show the evolution of morphology from flake to lath habit during the smectite to illite conversion. Particles with veil characteristics and flake particles are observed in random mixed-layered NH4-I/S. Diffuse lath shaped illite developed on the previous morphology in the expandability range 70–20 % S is observed. Euhedral lath shaped illite is present in NH4-I/S, below 10 % S. The reaction of smectite-to-illite is continuous, leading to lath shaped illite.
MICROBIAL ACTIVITY IN SOILS UNDER THE INFLUENCE OF PYRITE WEATHERING
Abstract: The chemical and microbial characteristics of soils at seven research sites - four affected by an acid sulphate weathering and three intact, undisturbed have been investigated. The extremely low soil pH, the increased electrical conductivity and high exchangeable aluminium contents are characteristic features of the affected soils. These chemical changes were accompanied by the inhibition of the soil respiration and enzyme activities denoted the microbial activity in soils. The small microbial biomass and the abundance of bacteria and microscopic fungi indicated the worsening of living conditions for the soil microorganisms. In spite of this some representatives of microscopic fungi (Euteromycotina) isolated from the damaged soils gave evidence of their adaptability to the extreme conditions.
MINERALOGY AND GEOCHEMISTRY OF ACID MINE FE-PRECIPITATES FROM THE MAIN SLOVAK MINING REGIONS
Abstract: The Fe ochre precipitates from three mine districts of Slovakia (Smolnik, Banska Stiavnica and Pezinok) were studied. The X-ray diffraction, electron microscopic methods (TEM, SEM) with elemental X-ray analyses and the selective dissolution method were used to make mineralogical phase characteristics of Fe-ochre precipitates. Many fresh precipitates are X-ray amorphous, but in the extremely fine-grained material it is possible to identify some Fe-mineral phases like schwertmannite and ferrihydrite. In the strongly acid degraded and artificial soils mainly amorphous ferric oxyhydroxide is found. Unstable oxyhydroxides, oxyhydroxysulphate and amorphous Fe-phases were dissolved by acid ammonium oxalate solution (pH 3) and by 1M HCl. All free iron (Al, Mn) compounds of the samples were extracted by dithionite-citrate-bicarbonate solution. The extracts were analyzed for Al, Fe, Zn, Pb, Cu, As, Cd, Mn by the AAS, AES-ICP methods. Samples with different contents of Fe-phases (10–99 wt. % of samples) and formed over a wide pH range (2 to 7) were analyzed. The ochres formed under strongly acid conditions contain mainly high concentrations of Al. The ochres formed in slightly acidic or neutral conditions are enriched in Cu, Pb, Zn, Mn and As. Such conditions were found in the drainage of inactive tailing impoundments. The element attenuation by Fe-ochres are controlled to a great extent by pH and by sulphate concentrations. The comparison of oxalate and HCl extracts concentration show that analyzed elements are attenuated by the active or poorly crystalline Fe-phases to a great extent.
QUANTIFICATION OF SALTS IN EXTRACTS FROM BRICKS („WALL OF BRICKS” AT THE WAWEL CASTLE IN CRACOW)
Abstract: The concentration of soluble salts in the retaining wall of the Wawel Castle was estimated. This wall bears the pressure of a steep, earthen slope of medieval fortifications. The analyses have shown that the samples contain mainly sulphate, nitrate, chloride, calcium, sodium and potassium. The concentration of the ions increases distinctly from the inner side of the wall toward the outer, exposed part. Due to the specific position of the wall and in contrast to most other buildings, water penetrates the retaining wall from the side abutting the scarp, while capillary suction from the foundations is of minor importance.
MINERALOGICAL AND CHEMICAL IMPACT OF ANTHROPOGENIC EMISSIONS ON SOILS AND ROCKS OF THE OJCÓW NATIONAL PARK (POLAND)
Abstract: Air pollution and its influence on soil contamination and the rate of weathering of Jurassic limestone in the Ojców National Park (ONP) in Poland were studied. Phase and chemical analyses were carried out for the soils and rocks. It has been found that the components of anthropogenic origin make up over 90 vol. % of dust particles. The major phases include sulphates, spherical glass particles, unburned coal fragments and grains of metal oxides. The analyses of soils have shown elevated amounts of Cd, Pb and Zn, while the total level of hydrocarbons exceeded the permitted content in soil (samples collected along the road). The limestones are covered with black or white crusts depending on their degree of shelter from rain water. The components of crusts include aluminosilicate glass spherules, iron oxides, unburned coal particles and gypsum crystals. The outer layers of limestone are also enriched with heavy metals. The heavy metals and glass spherules found in the dust fall and in the external parts of Jurassic limestones and soil, and also the higher level of hydrocarbons in soil samples lead to the conclusion that the anthropogenic pollutants generated within and outside the ONP play a significant role in contamination of the analysed components of the environment.
