Biostratigraphy of the Devonian-Carboniferous passage beds from some selected profiles of NW Poland

Abstract

The results are here presented of the biostratigraphic and lithological investigations of the uppermost Devonian and Lower Carboniferous from the Chojnice region. They are based chiefly on a detailed analysis of brachiopod and conodont assemblages. The Upper Famennian (Fa2) with deposits equivalent to the Etroeungt beds of France and BeIgium (Tn1a), also the proper Touraisian (sensu Heerlen 1935) have been distinguished. The stratigraphic position of the Devonian/Carboniferous passage beds of Europe are discussed in the light of paleontological studies. Consideration is given to the sediments of this age in Poland. A description is given of the facial-paleogeographic development in the sedimentary basin of the Chojnice region at the Devonian/Carboniferous turn, two sedimentary zones being differentiated there. All the faunal remains here worked out have been figured, but descriptions are given only of forms whose generic or specific assignment is controversial.
A survey of all the phenomena noted on the Devonian/Carboniferous passage beds, also the exceptionally great depth of the sediments – the age equivalents in the Chojnice area of the Etroeungt beds (Tn1a) – reasonably suggest that this area is of essential all-European importance for the clearing up of the problems of the Dewonian/Carboniferous passage beds and the boundary between these two systems.