Doklady redepozice křídových sedimentů do uloženin spodního miocénu mezi Černou Horou a Závistí

Abstract

Many boreholes have been drilled between Černá Hora town and Závist village to evaluate geohazards that may affect the construction of a new road. The core material from boreholes was studied for translucent heavy minerals and microfossil content. Translucent heavy mineral assemblages from sands are often dominated by the staurolite. Cyanite, tourmaline, rutile and andalusite, typical for Cenomanian sediments of Moravia are common. Relatively important share of garnet (20–30 %) in two samples reflects most probably the source in Turonian sediments. Those heavy minerals typical for granitoids of the Brno Massif, surrounding and underlying the sediments, are very rare. Agglutinated foraminifera reworked from Turonian or younger Cretaceous sediments, represent the most frequent microfossils. Single find of Pleurostomella gr. alternans may be the only autochthonous element indicating the Miocene age. Both microfossils and translucent heavy mineral assemblages correspond with those from previously studied sites of broader area including Brno surroundings. Sediments are characterised by a high susceptibility to sliding, which was particularly evident during the high rainfall totals in spring 2006.