Krasove jevy ve slepencove poloze palkovickeho souvrstvi slezske jednotky vnejsich Zapadnich Karpat

Karst cave and landform occurrences within the Czech part of the Outer Western Carpathians and the Vienna Basin are rare. They are restricted primarily, but not exclusively, to three areas: (i) the Štramberk karst and (ii) the karst of the Pavlovské vrchy Hills, both developed in the Upper Jurassic to Lower Cretaceous limestones present as tectonic klippen or olistoliths within the flysch nappes and (iii) the Mušlov karst in the Middle Miocene limestones of the Vienna Basin. Here we report on a karst cave V Mankově skále in another area, at Myslíkovské Lurdy, locality in the southern part of the Palkovické hůrky Hills near Frýdek-Místek town. Although this cave has been known among the locals for many years, its lithology, stratigraphy, karst geomorphology and structural control have never been described in detail. This paper aims to fill in this gap. The V Mankově skále Cave is a 10 m long karst cave with an entrance located at the outcrop of conglomerate layer consisting of massive intraclasts of the Štramberk limestones. The analysed samples of conglomerate contain clasts of detrital biogenic limestone, sandstone a rarely also phyllite. Clay flow rolls found at the bottom of sandstone overburden of the conglomerate bed contain dinoflagellate assemblage indicating a material redeposition during the Upper Campanian/Lower Maastrichtian period. The newly studied landforms represent the karst within the youngest host rocks on the territory of the Outer Western Carpathians in Czechia, making part of the Late Cretaceous Palkovice Fm. within the Baška Development (Silesian Unit). Numerous wall scallops and karren forms have been identified on the cave walls, indicating genesis under phreatic conditions. However, the structural analysis and cave morphology indicate that the cave development is probably also related to mechanical effect of gravitational slope movements. Brittle deformation zones within the rock massif, manifested by steeply dipping NE-SW and NW-SE striking fractures, represent the main structural control of the cave. The results of electrical resistivity tomography suggest that other karst forms can be probably found within another fracture zone up the slope. Tracer tests revealed that the spring of about 1m long stream running through the cave is located about 20 m further to south underneath the deluvial and fluvial sediments of the Bačův creek. It flows out as four adjacent springs with individual discharge of the order of 10-2 l . s-1. It can be deduced that minimum volume of the karst conduit corresponds to 88 dm3.

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