Stan znajomości pokrywy permomezozoicznej na Pomorzu Zachodnim i obszarach sąsiednich

Abstract

STATE OF KNOWLEDGE OF THE PERMO-MESOZOIC COVER IN THE WEST POMERANIA AND ITS ADJACENT AREAS Summary The present paper deals with the realization of seismical measurements and geological drill works carried on to penetrate the Permian deposits and their basement in the area situated along the Baltic sea coast, from Szczecin to Koszalin. 1. A dislocation zone is found to run along the Mielno-Koszalin line. At various periods this zone of a deep foundation (escarpment of deep basement) must also have influenced the palaeogeography of the area under study. East of this line the geological section is as follows: Silurian deposits of great thickness – carbonate-sulphate-clastic Upper Permian deposits (probably cyclothem Z1 only) – Lower Triassic deposits – Middle Cretaceous deposits). These beds are tectonically almost undisturbed. West of this zone the section is different: Upper Carboniferous deposits – fairly complete salinary Permian deposits – complete Triassic deposits up to 1500 m in thickness – almost complete Jurassic deposits up to 1100 m in thickness. In most cases these beds are tectonically disturbed. 2. An increase in thickness of the Triassic and Jurassic deposits toward the west leads to a formation of the eastern “limb” of the apparent Kołobrzeg anticline; under the Mesozoic anticlinal form, the Zechstein rest almost horizontally. The western limb of this anticline (the Trzebiatów flexure) was formed on a dislocation characteristic of a deep foundation. This, however, did not influence the palaeogeography of Permo-Mesozoic. Similarly, the structural difference existing between Trzebiatów syncline (Turonian) and the structures occurring in the vicinities of Swidwin (Keuper) originated only due to an increase in thickness of Permo-Mesozoic toward the south, for the lower part of the Upper Permian rests in the area horizontally. 3. The northern boundary of the basin and the zone of marginal facies of the Upper Permian may stretch in an east-west direction from the northern Rügen through southern Baltic Sea as far as the vicinities of Darłowo. 4. In the Upper Permian, found in the vicinities of Kołobrzeg, there are zones of wedging out, in the area of which the individual cyclothems thin out from S toward N successively: Z3, Z4, Z2 and again Z3. The development of the Plattendolomit and that of the Hauptdolomit horizons seams to be, in certain parts of the area under consideration, greatly promising in search for bitumens (this zone probably continues toward the southern area of Rügen and toward the sector Usnam-Grimmen). In the cyclothem Z2 potassium salts occur. The cyclothem Z1 is of considerable thickness and contains salts which are not found to occur in the eastern area of Mecklenburg. 5. Deeper foundations of two known transverse faults in the Kamień anticline occur here at relatively small depth, its top resting deeper than 2400 m. 6. Near Szczecin, classical forms of salt pillows have been found to consist mainly of salts belonging to the cyclothem Z2; for the most part these were formed at Upper Cretaceous time. The area characteristic of the forms under consideration stretches from south-western Mecklenburg and embraces the Szczecin trough and the peripheral part of the Pomeranian paranticlinorium.