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Crystal chemistry of micas from České středohoří
Goll, Jan ; Skála, Roman (advisor) ; Rieder, Milan (referee)
Micas from České středohoří mts. have been studied by X-ray difractometry, ICP-MS and electron microprobe. The measurements of trace elements and REEs revealed very low tendency by normalization of chondrite reservoir and primitive mantle. The micas classifications were determined by Tischendorf (2007) and Rieder (1998) as Fe- or Fe-Ti phlogopites. The abundances of Ti are very high up to 0,46 (a.p.f.u.). X-ray powder diffraction revealed double layered polytype 2M1 with space group C/2c.
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Crystal chemistry of pyroxenes and amphiboles from the České středohoří
Kallistová, Anna ; Skála, Roman (advisor) ; Ulrych, Jaromír (referee)
Contents of major, minor and trace elements in clinopyroxenes and clinoamphiboles of basanites, volcanoclastics, essexites, sodalitic syenites, and monzodiorites of the České středohoří Mts. has been determined using an electrone microprobe and LA-ICP-MS techniques. Composition of clinopyroxenes corresponds to either diopside or augite and clinoamphiboles can be classified as kaersutite or pargasite. Some pyroxenes display pronounced sector zoning showing increased contents of Mg and Si in pyramidal sectors whereas prismatic sectors show Fe, Ti and Al enrichment. Chemical composition of both sectors corresponds to diopside. Growth zoning has been found in the samples from basanites and volcanoclastics. Grain cores display the chemistry of augite and towards the rim the chemical composition changes to diopside. Samples have also been analyzed by powder and single crystal X-ray diffraction techniques. Samples of pyroxenes appear to be either pure or they contain negligible admixtures of phlogopite. Samples of amphiboles are also either without any admixtures or they show contamination by low amounts of diopside or augite, or phlogopite may rarely be encountered. Mutual relationship between the size of the unit cell parameters b and and substitutions in M1,2,3 and A sites has been observed. Longer mean T-O...
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Ověření obsahu azbestu v horninách lomu Sýkořice : závěrečná zpráva
Skála, Roman
Zpráva je volně šiřitelná. Anotace: U pěti vzorků hornin z lomu v Sýkořici byl vyhodnocován možný obsah azbestu. Horniny byly podrobeny makroskopickému a mikroskopickému pozorování a studiu elektronovým mikroanalyzátorem a práškovou rentgenovou difrakcí. V žádném ze studovaných vzorků nebyly nalezeny významné akumulace azbestových minerálů, jak jsou definovány právními normami ČR.
Fulltext:  PDF
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Chemical composition of moldavites from the Cheb Basin and their relationship to other tektites of the Central European strewn field
Skála, Roman
Basic physical properties (weight, shape, color and sculpture) were evaluated for over 350 individual finds of tektites from 4 different localities in the Cheb Basin. They are similar to those observed for South Bohemian moldavites. Totally, 24 tektites from the Cheb Basin and 17 from the South-Bohemian and Moravian substrewnfields have been characterized chemically using EPMA. Contents of major elements overlap between the two sample sets covering a broad range; trends observed in the Harker plots, however, seem to differentiate several partial groups. Minor and trace elements have been measured with an LA-ICP-MS technique. Preliminary 40Ar/39Ar dating shows that Cheb tektites are coeval with moldavites from South Bohemia and Western Moravia. Finding of a new moldavite substrewnfield around Cheb substantiate the theory that moldavites were ejected from the Ries impact structure in a fan-shaped jet.
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