U-Pb zircon age of the Krásné Loučky tuffite: the dating of Visean flysch in the Moravo-Silesian Paleozoic Basin (Rhenohercynian Zone, Czech Republic)

The only pre vi ous U-Pb zir con date for the the Early Car bon if er ous flysch se quence of the Moravo-Silesian Pa leo zoic Ba sin was pub lished in 1987 from tuffogenic ma te rial from Kobylí Quarry at Krásné Louèky near the town of Krnov (Silesia, Czech Re pub lic). The mea sured age of 319 Ma did not agree with its strati graphic po si tion, and was used as the ba sis for a hy poth e - sized block of Late Car bon if er ous paralic molasse in cor po rated dur ing a later tec tonic event. Dur ing a sur vey of the still-ac - tive quarry in 2010, volcaniclastic ho ri zons were iden ti fied and sam pled. Di rect cor re spon dence of the tuff units to those sam pled in 1987 can not be proved but is likely. High pre ci sion chem i cal abra sion – ther mal ion iza tion mass spec trom e try (CA-TIMS) U-Pb dat ing of zir con from this new ma te rial has yielded an age of 340.05 ± 0.22 Ma, which cor re lates to the pre vi - ously in ferred strati graphic age of the lo cal ity and the cur rent cal i bra tion of the Early Car bon if er ous geo logic time scale. The newly es tab lished age cor re sponds to the Visean stage and dates the bound ary be tween the Horní Benešov and Moravice for ma tions that can be cor re lated with other foredeep bas ins of the Culm in the Eu ro pean Variscides. A pop u la tion of de tri tal Cambro-Or do vi cian zir cons and a sin gle 2.0 Ga old zir con crys tal from the same volcaniclastic layer dated by la ser ab la tion in duc tively cou pled plasma mass spec trom e try (LA-ICPMS) are con sis tent with the known age of source ma te rial in the Variscan orogenic front.Web of Science58467265

The radioisotopically constrained Viséan onset of turbidites in the Moravian-Silesian part of the Rhenohercynian foreland basin (Central European Variscides)

The Březina Formation represents the initiation of siliciclastic flysch turbidite sedimentation at the eastern margin of Bohemian Massif or within the Rhenohercynian foreland basin. Its deposition started after drowning of the Devonian carbonate platform during Viséan (Mississippian) times, resulting in a significant interval of black siliceous shale and variegated fossiliferous shale deposition in a starved basin. Near the top of the Březina Formation an acidic volcanoclastic layer (tuff) of rhyolitic composition has been dated with high precision U-Pb zircon chemical abrasion isotope dilution method at 337.73 +/- 0.16 Ma. This new radiometric age correlates with the previously inferred stratigraphic age of the locality and the current calibration of the Early Carboniferous geologic time scale. Shales of the Březina Formation pass gradually upwards into the siliciclastics of the Rozstání Formation of the Drahany culm facies. Thus our new age offers one of the few available radioisotopic constraints on the time of onset of siliciclastic flysch turbidites in the Rhenohercynian foreland basin of the European Variscides.Web of Science107272771

Effect of Chemical Composition and Temperature on Viscosity and Structure of Molten CaO-Al2O3-SiO2 System / Wpływ Składu Chemicznego I Temperatury Na Lepkość I Strukturę Ciekłego Układu Cao-Al2O3-SiO2

The effects of the change of chemical composition and temperature on the viscosity of CaO-Al2O3-SiO2 oxide system with basicity from 0.78 to 1.63 were investigated in this paper. Experimental measurements of viscosity were performed with use of the high-temperature viscometer Anton Paar FRS 1600. Viscosity was measured in a rotational mode during heating at the rate of 2.2 K/min in the temperature interval from 1673 to 1873 K. Viscosity is often sensitive to the structural changes in molten oxide systems, which implies that the analysis of viscosity is an effective way to understand the structure of molten oxide systems. Exact clarification of the change of structure of the oxide system caused by increased content of CaO was performed by Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy and X-ray diffraction (XRD)