A reappraisal of the Carboniferous macrofloras of the Zonguldak - Amasra Coal Basin, north-western Turkey
The Zonguldak – Amasra Coal Basin in north-western Turkey has Carboniferous terrestrial deposits ranging in age from Arnsbergian to late Asturian or possibly early Cantabrian. They yield macrofloras that allow detailed biostratigraphical correlations with sequences in Europe. These correlations suggest there are substantial gaps in the Zonguldak – Amasra succession, with middle to upper Namurian, upper Langsettian, Duckmantian and lower Asturian strata apparently being missing. This in turn suggests the area was subjected to significant tectonic instability during Pennsylvanian (late Carboniferous) times and that this might have been instrumental in initiating the progressive change in composition and eventual collapse of the coal swamp biome across Variscan Euramerica during Westphalian times.
Early Pennsylvanian ombrotrophic mire of the Prokop Coal (Upper Silesian Basin); what does it say about climate?
Abstract The Lower Pennsylvanian (Kinderscoutian) Prokop Coal (Coal No. 40), the erosional remnant of which covers about 5000 km 2 , is the thickest seam of the Upper Silesian Basin situated along the Czech – Polish border. This basin-wide coal is unusual in its thickness and high inertinite and very low ash contents. In the Czech sector, this coal merges with the overlying Coal No. 39 into a single 9 to 15 m thick seam. Maceral analyses of an approximately 11 m thick section of these two merged coals show changes in the proportion of vitrinite (24.7 – 88.0 %) and inertinite (8.5 – 56.8 %) in cycles between 50 and 190 cm thick. The increase of inertinite in the lower part of coal cycles coincides with a dulling-upward trend, which records a drying-upward succession due to a slowing of accommodation rate relative to plant biomass productivity. This succession is interpreted as a transition from rheotrophic to ombrotrophic conditions. The brightening-upward succession in the upper part of coal cycles records a wetting-upward trend due to water table rise, resulting in restoration of rheotrophic conditions that supported humification under the regional ground water table. The sudden shift from inertinite-rich to vitrinite-rich coal at the base of brightening-upward successions points to a period of degradation and lowering of the peat dome. The coal cycles within the studied seam section probably preserve a succession of spatially overlapping but genetically independent mires bounded by degradation surfaces. The alternation between mires with contrasting hydrological regimes is interpreted as a record of base-level fluctuations of climatic causation of sub-Milankovitch periodicities. Early Pennsylvanian climate for various stages of mire development is inferred from analogy with modern tropical mires in SE Asia.
Geological, mineralogical and chemical characterization of Devonian kaolinite-bearing sediments for further applications in the ceramic (tiles) industry in La Paz, Bolivia
Clay minerals are widely distributed in Bolivia; among them, illitic clays are most common in the Altiplano where they are mined for use in the ceramic industry that has been growing in the last few years. In addition to illitic sediments, kaolinitic sediments have been recently discovered in sedimentary units in the Bolivian Altiplano. Residual ball clay occurrences in Devonian sedimentary units were studied as part of this work. Geological mapping and geophysical studies (ERT and GPR) were done for better understanding the origin of the deposits and were part of a preliminary study of the mineral potential to define the relationship with the host rock. Chemical and mineralogical techniques such as X-Ray Diffraction, Scanning Electron Microscopy and Inductively Coupled Plasma analyses were performed in samples from the studied area to verify the presence of kaolinite. Atterberg limits and behaviour of the raw material in ceramic specimens supported by chemical analyses show that this material is suitable for manufacturing tile ceramics. This study provides fundamental knowledge for deposit exploitation and future generation of an alternative source of employment for the inhabitants of Micaya.