STRATYGRAFIA I ZRÓŻNICOWANIE FACJALNE JURY GÓRNEJ NA PRZYKŁADZIE PROFILI OTWORÓW WIERTNICZYCH CIANOWICE 2 I TROJANOWICE 2 (POGRANICZE WYŻYNY OLKUSKIEJ I ROWU KRZESZOWICKIEGO)

Abstract

UPPER JURASSIC STRATIGRAPHY AND FACIES VARIABILITY – A CASE STUDY OF THE CIANOWICE 2 AND TROJANOWICE 2 BOREHOLES (OLKUSZ UPLAND AND KRZESZOWICE GRABEN BORDERLAND

Abstract. We present the results of research in two Upper Jurassic drill core sections that have been conducted in the frame of the „Integrated research program of shallow drillings to solve the major problems of geology of Poland“. The sections represent the Upper Jurassic sponge megafacies. The Trojanowice 2 core records the biohermal Oxfordian facies (from the Lower Oxfordian to the lowermost part of the Bimammatum Zone of the Upper Oxfordian). The Cianowice 2 section is characterized by a facies typical of the interbiohermal basins (Korzkiew Basin) area and shows a nearly complete Oxfordian stratigraphy. Significant differences of the sea bottom relief shown by the precise biostratigraphy, evoked various types of mass movements. Rocks representing the effects of such movements have been recognized in the upper part of the Cianowice 2 core. The differences between the two regions mentioned above are evident from the beginning of the Late Callovian.Wehave determined the density of the sponge mummies in the Trojanowice 2 core. It evolves from a few to 63 mummies per 1meter of the section. In the 201 m long profile a total 2199 “generations” of siliceous sponges were found. In the same profile we calculated the shortening of the limestone thickness as a result of pressure dissolution (along a horizontal plane). The  minimal shortening, calculated as the stylolite amplitude, was averagely 11.6%.