Głębsze podłoże geologiczne okolicy Poznania w świetle badań z lat 1973-1975
Abstract
DEEPER GEOLOGICAL SUBSTRATUM OF THE POZNAŃ AREA IN THE LIGHT OF THE STUDIES FROM THE YEARS 1973-1975
Summary
Numerous boreholes and intense geophysical surveys markedly contributed to the knowledge of deeper substratum of the capital of Wielkopolska. A progress in recognition of the substratum made since the publication of K. Wójcik's sketch in 1929 (18) till 1975 is discussed. The stratigraphic profile of borehole P from the Upper Cretaceous to Lower Permian is given (Fig. 1). Variability of Triassic and Permian rocks of the Poznań area is discussed and attention is paid to the occurrence of Triassic salts. The palynological datings have shown the occurrence of Carboniferous (Tournisian - Namurian) rocks at the depths from 2438 to 4153 m in 5 boreholes. The lists of sporomorph assemblages are given. Stratigraphic gaps in the Upper Zechstein and Triassic resulted from either halokinetic movements (borehole Si; Fig. 1) or tectonic agents (Fig. 2). The Paleozoic substratum is inclined to NE. It is differentiated into elongated regional blocks WNW-ESE oriented in result of formation of deep dislocations. Local network of diagonal faults facilitated development of step-wise blocks lowering in the stepwise way, horsts and tectonic troughs of the lower order. The network of orthogonal faults is less clear. Young-Variscan alkaline volcanism is related to Permian formation and Dolsko deep dislocation zone. Thick series of rocks salts, gas fields and single oil fields are known from the Permian rocks of this area. The stratigraphy and tectonics of the Carboniferous is the subject of recent studies.
Summary
Numerous boreholes and intense geophysical surveys markedly contributed to the knowledge of deeper substratum of the capital of Wielkopolska. A progress in recognition of the substratum made since the publication of K. Wójcik's sketch in 1929 (18) till 1975 is discussed. The stratigraphic profile of borehole P from the Upper Cretaceous to Lower Permian is given (Fig. 1). Variability of Triassic and Permian rocks of the Poznań area is discussed and attention is paid to the occurrence of Triassic salts. The palynological datings have shown the occurrence of Carboniferous (Tournisian - Namurian) rocks at the depths from 2438 to 4153 m in 5 boreholes. The lists of sporomorph assemblages are given. Stratigraphic gaps in the Upper Zechstein and Triassic resulted from either halokinetic movements (borehole Si; Fig. 1) or tectonic agents (Fig. 2). The Paleozoic substratum is inclined to NE. It is differentiated into elongated regional blocks WNW-ESE oriented in result of formation of deep dislocations. Local network of diagonal faults facilitated development of step-wise blocks lowering in the stepwise way, horsts and tectonic troughs of the lower order. The network of orthogonal faults is less clear. Young-Variscan alkaline volcanism is related to Permian formation and Dolsko deep dislocation zone. Thick series of rocks salts, gas fields and single oil fields are known from the Permian rocks of this area. The stratigraphy and tectonics of the Carboniferous is the subject of recent studies.