Seria poznańska w Polsce zachodniej

Abstract

THE POZNAŃ SERIES IN WEST POLANDSummaryThe analysis of the development of the Late Tertiary deposits, the data on their lithological character, palaeogeographical relations and tectonic evolution allowed the present author to distinguish, within these deposits, two large sedimentary units. The older one is called by the author the Late Tertiary coal-bearing basin of the Lowland area, the younger one is called the Poznań series basin.In its near-Sudetic part the older unit may be subdivided as shown in Fig. 1. The Late Tertiary basin of the Lowland area is built of the deposits from the Lubuska series to the Mużaków series inclusive  (Fig. 2). They include also marine or brackish formations (Figs. 3 and 4), resembling deposits that fill in the so-called Middle-European furrow. Influences of marine transgressions, begun in the area of a northern sea, are here particularly distinct. The range of the individual series within the Fore-Sudetic portion are parallel arranged, and oblique to the present-day edge of the Sudetes, expressed as the marginal Sudetic fault. The parallel tectonic directions are determined by K. Bayer (1933) to be of Hercynian origin.The Poznań series shows different extent, different palaeogeographical relations and different tectonic evolution from those of the deposits in the above coal-bearing basin. In the south, it rests transgressively on the Sudetic block, reaching partly as far as the Sudetic area and the watershed     pre-Upper Miocene zone. Thus, it connects two different basins: the Late Tertiary coal-bearing basin of the Lowland area - in the west, and the Carpathian foredeep - in the east. The relations with the Carpathian foredeep are proved by microfauna found to occur in the Poznań series (Fig. 5). Moreover, there is observed here a relation between the tectonic development of the Poznań series basin and the tectonic movements in the Carpathian foredeep. New tectonic lines are produced, characterized by a SE - NW direction, determined within the Sudetes as Late Saxonian. Here belongs also the marginal Sudetic fault. At that time, an important morphological element, i.e. the watershed zone between the Carpathian foredeep and the Late Teriary coal-bearing basin of the Lowland area disappeared, and the principal geomorphological elements of the Sudetes and of the Lower Silesian part of the Lowland area were formed.