Acta Musei Moraviae

The discovery of chert-bearing limestone in the Boskovice Furrow

The paper deals with a new finding of peloidal/oolitic micritic limestone in the Bohemian Massif. Limestone outcrops was recently discovered in the vicinity of Malhostovice village, Brno-venkov distrikt (GPS: 49.338250 N; 16.516177 E; WGS 84). The rock is characterised by the presence of cavernous holes of spherical shape after the weathered carbonate particles. These particles, that morphologically correspond to peloids and/or recrystallised ooids, are interpreted as in-situ formed microbial peloids. Within the matrix were identified semi- rounded to rounded sand-sized clasts of quartz. The limestone is also prominent by the presence of calcite rosettes or clusters representing pseudomorphs after the supposed Ca-sulphates. Another typical feature is the occurrence of several stages of silicification leading up to the formation of dark-colored chert bands. Micropaleontological research has revealed that the samples examined are unfossiliferous. Regarding the mentioned features, we conclude that the limestone was formed within a sabkha environment characterised by (1) hot and arid climate, (2) sea-marginal location with adequate supply of both terrigenous clastic material and saline water to develop the evaporites. Although we cannot completely exclude the possibility of Neogene age and genetic relationship with transgression in the Carpathian Foredeep, we prefer the concept of a genetic link with other chertbearing Jurassic limestones in Moravia containing the silica geodes with anhydrite and barite inclusions. Additionally, we have found field evidences for using of described silicified limestone as a primary source of raw material for lithic chipped artefacts in prehistoric times.