The Albian ammonite fauna of Poland and .its paleogeographical significance

Abstract

The·taxonomical and ecological analysis of·the ammonite assemblages, as well as the general paleogeographical setting indicate that the Albian deposits within the Polish part of the Central European Basin accumulated under shaIIow or extremely shaIIow-marine conditions, and those of the High-Tatra Swell in an open sea environment. The Boreal character of the ammonite faunas in the epicontinentaI area of Poland, and the Tethyan one in the Tatra Mts are well displayed by the composition of the anaIyzed assemblages. During Middle Albian time the Boreal hoplitids migrated to the Polish areas from the west or north-west, and they gradually spread, through the western Ukraine, towards the High-Tatra Swell located far within the Tethyan Realm (Alpino-Carpathian geosyncline). In the Upper Albian, in spite of an increasing marine transgression, a distinct provincialism became evident both in the Boreal and in the Tethyan ammonite assembIages. This distinction apparently resulted from the depth/distance filter which bad separated the High-Tatra Swell from the platform areas of Poland, a filter which worked more efficiently than . it had during Middle Albian time. This event was of regional character in Europe, and was caused by change in climatic and bathymetrical conditions rather than by the development of physical barriers (lands or cordilleras).