Próba korelacji wydzieleń stratygraficznych i litostratygraficznych trzeciorzędu zachodniej części Niżu Polskiego i śląskiej części Paratetydy w nawiązaniu do projektu IGCP nr 25
Abstract
AN ATTEMPT TO CORRELATE STRATIGRAPHIC AND LITHOSTRATIGRAPHIC UNITS OF THE TERTIARY IN WESTERN POLISH LOWLANDS AND SILESIAN PART OF THE PARATETHYS WITH REFERENCE TO THE WORKS OF THE IGCP NO. 25
Summary
The paper presents an attempt to correlate Polish lithostratigraphic units with references to the new stratigraphic subdivision of the Tertiary of the Paratethys (47, 51). Up to the present, different subdivisions are used for two structural-paleogeographic provinces of Poland: Paratethys and that of the Polish Lowlands. Correlation of these subdivisions appears possible in south-western Poland (4, 18, 20-22, 44).
The changes in stratigraphic subdivision of marine successions of the Paratethys basin make it also necessary to modify stratigraphic interpretation of continental successions from the Polish Lowlands (including brown coal seams - the Lusatian Series), correlated with those of the Paratethys. The paper presents our relation to these changes and a correlation table for the Tertiary of western Poland, compiled on the basis of results of our earlier geological and paleobotanic studies (Table 1). The table also shows some fractors responsible for climatic changes, i.e. tectonic movements, volcanic activity, and generał paleogeographic changes. The factors were especially active in the Late Oligocene, Sarmatian and Pliocene, leading to changes in the vegetational cover, reflected by pollen spectra. Some of the changes in stratigraphic subdivision seem justified from the point of view of palynology, whereas the others remain more or less disputable or even difficult to accept. For example, the Głogów brown coal layer (IV Lusatian Series) should be further correlated with the uppermost Oligocene as it is characterized by subtropical pollen flora, clearly different of that of lower members of the Ścinawa coal layer (III Lusatian Series), indicative of marked deterioration of climate due to movements of the Savic tectonic phase. In turn, assignation of the Ścinawa and Lusatian coal layers (Il Lusatian Series) to the same stratigraphic stage seems supported by similarities in pollen spectra of the layer (Table). Differences in the nature of vegetation of the Henryk coal layer (I Lusatian Series) and the Kędzierzyn one, situated within the Green Clay horizon of the Poznań Series, support the hitherto accepted interpretation in which upper part of the Sarmatian is assigned to the Upper Miocene. In the corresponding time interval there took place a change in character of Miocene vegetation from swampy to forest, resulting from a change of climate to more arid and cooler.
The latter may be explained by with drawal of the Paratethys sea from the Polish part of the Carpathian Foredeep (21, 22). So radical change in vegetational cover should be taken into account in the stratigraphic subdivision. The subdivision of the Pliocene into two substages seems supported by marked differences in Pliocene flora from the top parts of the Poznań and Gozdnica series, known from localities in western Poland (27, 45, 48, 50).
The table presented here may appear useful in attempts to establish more uniform scheme of further studies and compilation of final stratigraphic subdivision of the Polish Tertiary.
Summary
The paper presents an attempt to correlate Polish lithostratigraphic units with references to the new stratigraphic subdivision of the Tertiary of the Paratethys (47, 51). Up to the present, different subdivisions are used for two structural-paleogeographic provinces of Poland: Paratethys and that of the Polish Lowlands. Correlation of these subdivisions appears possible in south-western Poland (4, 18, 20-22, 44).
The changes in stratigraphic subdivision of marine successions of the Paratethys basin make it also necessary to modify stratigraphic interpretation of continental successions from the Polish Lowlands (including brown coal seams - the Lusatian Series), correlated with those of the Paratethys. The paper presents our relation to these changes and a correlation table for the Tertiary of western Poland, compiled on the basis of results of our earlier geological and paleobotanic studies (Table 1). The table also shows some fractors responsible for climatic changes, i.e. tectonic movements, volcanic activity, and generał paleogeographic changes. The factors were especially active in the Late Oligocene, Sarmatian and Pliocene, leading to changes in the vegetational cover, reflected by pollen spectra. Some of the changes in stratigraphic subdivision seem justified from the point of view of palynology, whereas the others remain more or less disputable or even difficult to accept. For example, the Głogów brown coal layer (IV Lusatian Series) should be further correlated with the uppermost Oligocene as it is characterized by subtropical pollen flora, clearly different of that of lower members of the Ścinawa coal layer (III Lusatian Series), indicative of marked deterioration of climate due to movements of the Savic tectonic phase. In turn, assignation of the Ścinawa and Lusatian coal layers (Il Lusatian Series) to the same stratigraphic stage seems supported by similarities in pollen spectra of the layer (Table). Differences in the nature of vegetation of the Henryk coal layer (I Lusatian Series) and the Kędzierzyn one, situated within the Green Clay horizon of the Poznań Series, support the hitherto accepted interpretation in which upper part of the Sarmatian is assigned to the Upper Miocene. In the corresponding time interval there took place a change in character of Miocene vegetation from swampy to forest, resulting from a change of climate to more arid and cooler.
The latter may be explained by with drawal of the Paratethys sea from the Polish part of the Carpathian Foredeep (21, 22). So radical change in vegetational cover should be taken into account in the stratigraphic subdivision. The subdivision of the Pliocene into two substages seems supported by marked differences in Pliocene flora from the top parts of the Poznań and Gozdnica series, known from localities in western Poland (27, 45, 48, 50).
The table presented here may appear useful in attempts to establish more uniform scheme of further studies and compilation of final stratigraphic subdivision of the Polish Tertiary.