Journal of

GEOsciences

  (Formerly Journal of the Czech Geological Society)

Original Paper

Dvořák

Geology of palaeozoic sediments in the surroundings of Ostrov u Macochy (Moravian Karst, Moravia)

Journal of the Czech Geological Society, volume 42 (1997), issue 1-2, 105 - 110

The thick, chemically rather pure Vilémovice Limestones that include stromatoporoid and coral fauna of Frasnian age were overlain, during the regression of the sea, by variegated, mostly nodular Křtiny Limestones comprising abundant conodant fauna. The fauna of the Křtiny Limestones provides evidence of their Upper Frasnian and Famennian age. These limestones pass upwards into greenish, slightly siliceous Ostrov shales that are not more than 10 to 15 m thick. Their deposition started in the Uppermost Famennian and continued during the Tournaisian period.
Greywackes of the Rozstání Formation, Viséan in age, rest on the Ostrov shales with a distinct boundary. The latter formation is more than 1000 m thick and is composed of dark-coloured silty shales, siltstones and fine-grained greywackes which enclose medium to coarse-grained greywacke layers up to 200 m thick, rarely with lenticular intercalations consisting of fine-to coarse-grained petromict conglomerates.
The silicate analyses of the shales characterize the variations in the deposition of chemically strongly weathered clastic material during the Pre-Flysch period as compared with chemically non-weathered material which was deposited during the Flysch sedimentation.
The general eastward dip of the formations is disturbed only at the surface boundary between the limestones of Moravian Karst and the thick Rozstání Flysch Formation. The slight monoclinal eastward dip, existing in the south, turns to the north into an overturned fold, the latter passing to an overthrust fault of east vergency. As to its axis, the structure is dipping NNE.
A well is suggested to be drilled at Ostrov, following the successful drinking water well drilled at Křtiny. It could supply high-quality water to the locality.