Paragenetic characterization of ferruginous concretions from the locality “Zukalův kopec” in the cadastral area of Mokrá-HorákovArticle PDF
Paragenetic characterization of ferruginous concretions from the locality “Zukalův kopec” in the cadastral area of Mokrá-Horákov
Origin of limonite concretions at the locality Zukalův kopec near the village of Mokrá-Horákov is connected with an intensive weathering of the specific calcareous Podolí Formation, probably in the warm climate of the Tertiary. The concretions and ferricretes are formed by hydrated oxi-hydroxides of iron alternating with zones more or less rich in clastic components, i. e. especially in quartz and feldspars. The content of Fe2O3 is relatively high: about 50–60 weight %. Angular sharp shape of clastic components and their mineralogical composition confirm our opinion that the process of ferruginization took place in situ or the concretions have been transported for only a short distance. High level of chemical alteration of original rock extraction is characterized by decreased content of lithophile elements in the limonite concretions. All these data testify for our explanation why the limonite concretions have been found just in the area of Zukalův kopec and not on other non-calcareous only siliciclastic Lower Carboniferous formations of the Drahany Highland.
Bohuslav Fojt, Antonín Přichystal, Department of Geological Sciences, Masaryk University, Kotlářská 2, 611 37 Brno, Czech Republic