Aubrecht R. & Bačík P., 2024: Palaeokarst with bauxite filling near Čoltovo (Slovak Karst). Acta Geologica Slovaca, 16, 1, 53–59.

Palaeokarst with bauxite filling near Čoltovo (Slovak Karst)

Roman Aubrecht^1,3 & Peter Bačík^2,3

¹Department of Geology and Paleontology, Faculty of Natural Sciences, Comenius University, Ilkovičova 6, SK-842 15 Bratislava, Slovakia; roman.aubrecht@uniba.sk
²Department of Mineralogy, Petrology and Economic Geology, Faculty of Natural Sciences, Comenius University, Ilkovičova 6, SK-842 15 Bratislava, Slovakia; peter.bacik@uniba.sk
³Earth Science Institute, Geophysical Division, Slovak Academy of Sciences, Dúbravská cesta 9, SK-845 28 Bratislava, Slovakia

Abstract

In the Slovak Karst area, three quarries are situated west of the Čoltovo Village. In the southern quarry, the Anisian carbonatic succession of the Silica Nappe is uncovered. Palaeokarst clefts and cavities were revealed in the calciturbiditic limestones of the Raming Limestone. They mostly contain yellowish to red sinter filling with flowstone draperies, small stalactites and stalagmites. The rest is filled with yellowish (ochre) material. The PXRD analysis (Powder X-Ray Diffraction) indicates that the material is represented predominantly by diaspore, which is an aluminium oxide hydroxide mineral, AlO(OH). This means that the material most likely represents a remnant bauxite deposit. By now, only several small occurrences of bauxitic ores were found in Slovakia. Diasporic bauxites were found only on Glac Plateau in the Stratenská hornatina Mts. The Čoltovo occurrence is then the second one of this type of bauxite. These occurrences share similar tectonic position, genesis and most likely also the same provenance. All these bauxitic occurrences in the Western Carpathians are invariably related to the emersion and karstification period that occurred after the main nappe thrusting phase in the West Carpathian internides, i.e., their age spans from the Late Cretaceous to Paleocene. In this period, the Western Carpathian area was in the humid tropical climate zone, which was able to promote lateritic weathering. In later periods, the climate was not suitable for such a weathering. It is not yet known, whether the bauxitic material rests in its original position or it was reworked and resedimented to younger clefts and cavities. Further research is necessary to verify the age and provenance of this new bauxite occurrence.

Key words: Silica Nappe, palaeokarst, bauxites, Cretaceous, Paleogene

Manuscript received: 2024-04-25

Revised version accepted: 2024-06-21