Journal of

GEOsciences

  (Formerly Journal of the Czech Geological Society)

Original Paper

Koverdynský

The Ponikev Formation and associated units in the Devonian of the Silesicum

Journal of the Czech Geological Society, volume 38 (1993), issue 1-2, 95 - 100

The Ponikev Formation is a typical stratigraphic unit of the Drahany (basinal) Facies of the Devonian in Moravia-Silesia. As is also the case in the Moravský Beroun and Bradlo (siliciclastics) and Jesenec or Vitošov (carbonates) Formations, the Ponikev Formation is between the pre-flysch and flysch (or similar) deposits. Lithologic analogies of the Ponikev Formation ("Kieselschiefer") have a similar position in the Rhenohercynicum, Saxothuringicum and elsewhere within the Hercynides.
The Ponikev Formation consists of siliceous shales with chert interbeds which are locally tuffaceous. The formation is found especially in the Šternberk-Horní Benešov Zone (Nízký Jeseník Mts.) and in the Devonian near Konice (Drahany Upland). It was until recently unknown in the Silesicum.
According to the author's mapping, the Ponikev Formation is also developed within the metamorphics of the Silesicum. It underlies the Janovice Formation between the volcanic Horní Město Complex and the Oskava Dome. The Janovice Formation is marked by alternation of metapsammites and metapellites along with common dolerite bodies. Lithologic analogues of the Ponikev Formation occur also in the western part of the Silesicum. They also underlie the Mírov Formation near Svinov, within the upper part of the Svinov-Vranov Crystalline Complex. This is consistent with close relationships of the Mírov Formation with the underlying sequence. A similar lithostratigraphic development is near the upper part of the Velké Vrbno Group at Branná (=Kolštýn) where the equivalent of the Ponikev Formation underlies the Ramzová Quartzite.
The Ponikev Formation at the eastern border of the Silesicum is mostly of Late Devonian age, while its analogues at the western margin are older. This is in agreement with the general basin development, eastward shift of volcanic belts and the maximum subsidence during sedimentation (see figs. 2, 3).