Coal clasts in the Carboniferous sediments of the Upper Silesian basin


Authors: Kožušníková A, Martinec P, Pešek J, Valterová P

Published in: Bulletin of Geosciences, volume 74, issue 2; pages: 109 - 114;

Keywords: coal clasts, Upper Silesian basin, palynology,

Export to RIS



Coal clasts (pebbles, fragments and coarse coalified plant remains) and coalified plant debris are common constituents of the Upper Carboniferous sediments of the Upper Silesian basin. The coal clasts were analysed in detail to determine their maceral composition, coal rank and age.
The coal rank of the coal clasts determined by mean vitrinite reflectance Ro was compared with the coal rank of the stratigraphically adjacent coal seam. The Ro values for coal clasts are lower than those for the coal seam.
In the drill cores which are about 10-20 cm long often several coal clasts can be found which differ in their maceral composition. The rank of these clasts is also often different. These differences do not appear to be regular. In some cases the Ro values for a coal clast with dominant vitrinite composition are higher than for the coal with trimacerite composition but in the other cases it is the other way round.
Both plastic and brittle deformations of coal matter occur at the contact of the coal clast and host rock. Pyrite mineralization occurs commonly at the contact between the coal clast and adjacent rock or in the marginal zone of the coal clast close to the contact.
The coal clasts were classified stratigraphically by means of palynological analysis. The majority of coal clasts were derived from the Ostrava Formation (Lower Namurian = Namurian A). One sample of coal clasts was derived from the Karvin. Formation (Saddle Member, Middle Namurian = Namurian B). All clasts with exception of one of them have been sampled from the Saddle and Lower Such. Members (Middle to Upper Namurian = Namurian B and C).