DIAGENEZA OSADÓW CZERWONEGO SPĄGOWCA W STREFIE SZCZECINEK-BYDGOSZCZ POMORZE ZACHODNIE)

Abstract

DIAGENESIS OF THE ROTLIEGEND ROCKS IN THE SZCZECINEK-BYDGOSZCZ AREA (WESTERN POMERANIA)Abstract. The paper presents results of complex studies of the Rotliegend rocks from 22 boreholes in the Szczecinek-Bydgoszcz area obtained due to the application of different analytical methods (CL, SEM, EDS ISIS, XRD, fluid inclusions, stable isotope determinations) and sedimentological and petrophysical analyses. Several processes, which influenced the rocks, have been distinguished. They are as follows: mechanical and chemical compaction, cementation, replacement, dissolving and alteration. The effects of these processes occurred in the sediment with a differentiated intensity being dependant on its composition, degree of burial and temperature. In reference to that, three main stages have been distinguished in the history of diagenesis: eo-, meso-, and telodiagenesis. The eodiagenetical processes occurred in the sediment at temperatures not exceeding 50 degrees of Celsius, mainly due to the meteoric waters. The mesodiagenetical processes began probably at the boundary of Zechstein and Bunt Sandstein and lasted until the tectonic inversion of the axial part of the Mid-Polish Trough. Temperatures slightly exceed 100 degrees of Celsius; the pore solutions had a marine-continental character. The telodiagenetical processes started after the formation of the Mid-Polish Trough, when temperatures decreased at about 40-60 degrees of Celsius and the sediments were placed in the zone penetrated by the meteoric waters. It has been stated that the cementation and diagenetical dissolution had the main influence on the formation of the pore space of the sediments. These processes resulted in the secondary inter- and intragranular porosity. Based on the above, regions of increased reservoir properties have been distinguished: the Sokole-Czarne zone and the Unisław region.