The Petřkovice Member (Ostrava Formation, Mississippian) of the Upper Silesian Basin (Czech Republic and Poland)

Abstract

The Petřkovice Member (Carboniferous, Mississippian, Early Namurian) is in many ways the most interesting lithostratigraphic unit of the paralic part of the Carboniferous coal-bearing Upper Silesian Basin (described as the Ostrava Formation in the Czech part or as the Paralic Series in the Polish part). Petřkovice Member represents a transition between the non-coal-bearing Carboniferous flysch sedimentation of the Moravian-Silesian Basin and the coal-bearing sedimentation of the Upper Silesian Basin. The paper includes maps of the basic sedimentological parameters of this unit — thickness, sand content and coal-bearing capacity. The thickness of the Petřkovice Member ranges from approximately 50 m in the east of the basin to around 770 m in the west and has a clear polarity in the NNW-SSE direction. Sand content ranges from 23% in the west of the basin to more than 90% in the east. Its polarity is approximately the same as its thickness. The greatest coal-bearing capacity, expressed as total thickness of the coal layers with a thickness greater than 10 cm, is known from the Czech part of the basin, where it exceeds 25 m in places. In the majority of the Polish part of the basin the Petřkovice Member's total coal content is less than 5 m, at times up to 7 m. However, in this part of the basin their level of recognition is very low. On the basis of the above parameters 3 assumed zones of differing mobility in the basin's bedrock are defined in the Petřkovice Member's area.