Table of Contents for the Journal of GEOsciences. List of articles from the latest print issue.https://www.jgeosci.orgen-US https://www.jgeosci.org/img-system/jgeosci_cover.jpghttps://www.jgeosci.org Coşkuner B, Eren Yş; Vol. 69, issue 4, pages 199 - 212
Turkey, mostly composed of continental fragments from Gondwana, contains important clues about the evolution of the Palaeotethys and Neotethys oceans. Different tectonic models have been produced by various researchers for Palaeotethys and Neotethys evolution. An issue of debate is whether the region was affected by pre-Alpine orogenic events, including the Taurides of Turkey. To address this controversy, structural features were investigated within Palaeozoic-Mesozoic units in the northwestern part of the Central Taurides to identify pre-Alpine orogenic structures. Detailed structural analyses have shown that the Palaeozoic and Mesozoic rocks in the study area experienced together at least three phases of deformation during the Alpine Orogeny, resulting in predominantly NW-SE oriented folding, regional-scale cleavage development, folded cleavage, nappe-thrust structures and low-grade metamorphism. In addition, mesoscopic structural analyses indicate that Lower Palaeozoic rocks in the northwest of the Central Taurides were deformed, folded, and cleaved before Alpine Orogenic events. Based on deformation and metamorphism differences between Palaeozoic and Mesozoic units, we suggest that pre-Triassic deformation was associated with the Variscan or Eo-Cimmerian Orogeny. ]]> https://www.jgeosci.org/rss.php?ID=jgeosci.397 Original paper https://www.jgeosci.org/rss.php?ID=jgeosci.397 Vrtišková R, Vrtiška L, Sejkora J, Dolníček Z, Trubač J, Strnad L; Vol. 69, issue 4, pages 213 - 224
Phosphates of the plumbogummite group (kintoreite and plumbogummite) with unusually high Sn contents have been discovered in a field in the area of reclaimed mine dumps at the abandoned Ag-Pb-Zn deposit Ratibořské Hory (South Bohemia Region, Czech Republic). These phosphates form very finely dispersed microscopic grains in the hydrothermal veins penetrating altered muscovite paragneisses in association with quartz, opal, pyromorphite, acanthite and more rarely galena, sphalerite, iodargyrite, imiterite, cuprite, mimetite, coronadite and unidentified Sn silicate. The studied Sn-rich phosphates can be divided into three groups: 1. Sn-rich kintoreite with the empirical formula (mean of the 14 point analyses) corresponds to Pb_1.05(Fe_2.51Sn_0.46Zn_0.06)_Σ3.03(PO₄)_1.55(PO₃OH)_0.45(OH)_6.00; 2. Sn-rich plumbogummite with empirical formula (mean of 6 analyses) Pb_1.14(Al_2.50Sn_0.52Fe_0.04)_Σ3.06(PO₄)_1.98(PO₃OH)_0.02(OH)_6.00; 3. (Sn,Al)-rich kintoreite with mean composition (calculated from 14 analyses) (Pb_0.95Ca_0.05)_Σ1.00(Fe_1.62Sn_0.90Al_0.62Zn_0.05)_Σ3.19(PO₄)_1.69(SiO₄)_0.21(AsO₄)_0.10(OH)_6.20. To date, no primary Sn minerals have been observed in the Ratibořské Hory ore deposit. Elevated Sn contents (up to 3040 ppm) in sphalerites from the Stará Vožice - Ratibořské Hory ore district, especially from the area with the occurrence of Sn-rich phosphates detected by La-ICP-MS during this research, probably indicate a primary source of Sn entering to the supergene processes. ]]> https://www.jgeosci.org/rss.php?ID=jgeosci.398 Original paper https://www.jgeosci.org/rss.php?ID=jgeosci.398 Majzlan J, Plášil J, Dachs E; Vol. 69, issue 4, pages 225 - 229
Kaatialaite, Fe[AsO₂(OH)₂]₃·5H₂O, is a rare ferric arsenate that precipitates from strongly acidic solutions. In general, it is found associated with arsenolite, scorodite, and sulfur. In this work, we used acid-solution calorimetry and relaxation calorimetry to determine the enthalpy of formation and entropy, respectively, of kaatialaite. The experimental values are Δ_fH^o = -4223.3±7.4 kJ·mol^-1 and S^o = 559±9 J·mol^-1·K^-1. Combining these values yields Δ_fG^o -3518.4±7.9 kJ·mol^-1 and log K_sp = -65.46 for the dissolution reaction Fe(H₂AsO₄)₃·5H₂O = Fe³⁺ + 6H⁺ + 3AsO₄^3- + 5H₂O. The accuracy of the results can be tested by geochemical modeling with an aqueous solution from the Svornost mine in Jáchymov. Some of the droplets there precipitate kaatialaite actively. The modeling shows that the solution is in redox disequilibrium and is initially supersaturated with respect to arsenolite, but not to kaatialaite. Increasing the redox potential in the simulation leads to the switch of the saturation indices and explains crystallization of kaatialaite upon slow oxidation of the aqueous As(III) to As(V). The model also predicts that the stable ferric arsenate is scorodite, not kaatialaite. Considering the crystal structures of both phases, however, it shows that the assembly of the kaatialaite structure requires much less deprotonation and is, therefore, not kinetically hindered. ]]> https://www.jgeosci.org/rss.php?ID=jgeosci.399 Original paper https://www.jgeosci.org/rss.php?ID=jgeosci.399 Myšľan P, Števko M, Mikuš T; Vol. 69, issue 4, pages 231 - 249
Manganese mineralization was discovered at the Zimná Voda occurrence near Prakovce located in the Spišsko-gemerské rudohorie Mountains, eastern Slovakia. The mineralization is hosted in the Early Paleozoic metamorphic rocks of the Gemeric Unit in the Western Carpathians and it represents the only occurrence of metamorphosed manganese mineralization discovered within the Drnava Formation (Devonian). Manganese minerals are directly associated with magnetite bodies forming isolated lenses of a strata-bound oxidic Fe-ores. The manganese mineralization underwent metamorphism during the Variscan and Alpine tectonometamorphic events, resulting in two types of distinct mineral assemblages. The older assemblage includes rhodonite-ferrorhodonite series, rhodochrosite, kutnohorite, spessartine, fluorapatite and quartz with magnetite impregnations. These assemblages are intersected by younger mineral assemblages present in veins and vugs. This later assemblage consists of rhodochrosite, kutnohorite, baryte, clino-suenoite to clino-ferro-suenoite, minerals of the epidote supergroup, quartz and relatively rare sulfidic mineralization including pyrite, galena, sphalerite and cobaltite along with hübnerite. This stage also features the formation of garnets predominantly composed of the andradite molecule, with locally preserved spessartine remnants in the garnet centres. The subsequent younger post-Variscan metamorphic event is characterized by a high influx of rare earth elements (REE), leading to the formation of a rare ferriallanite-(Ce), ferriallanite-(La), ferriakasakaite-(La) and ferriakasakaite-(Ce). Allanite-subgroup minerals form a strongly zonal polycrystalline dark brown aggregates with size up to 50 μm, generated from hydrothermal fluids affecting the mineral composition of the late-stage mineral assemblage. ]]> https://www.jgeosci.org/rss.php?ID=jgeosci.400 Original paper https://www.jgeosci.org/rss.php?ID=jgeosci.400