Nu mer ous fully cored bore holes com pleted in the last years in cen tral Po land (Kleszczów Graben area, south ern bor der of the Łódź De pres sion) en abled the re search ers to ob tain new sedimentological data on the Oxfordian-Tithonian con tin u ous sed i men tary re cord in the Pol ish part of the north ern Tethys shelf. Twenty-two fa cies were dis tin guished in the sedimentological suc ces sion. The fa cies rep re sent the outer-, mid-and in ner-ramp en vi ron ments, in clud ing evaporitic ep isodes and palaeosols. The fa cies doc u ment that the Oxfordian-Lower Kimmeridgian (up to Hypselocyclum) car bon ate ramp has evolved to the Up per Kimmeridgian-Tithonian car bon ate-siliciclastic ramp. Among the Kimmeridgian de pos its, nu merous hardgrounds, tidal chan nel de pos its and grav ity flow sed i ments were iden ti fied. The Kleszczów Graben sed i men tary suc ces sion is dis cussed along with the lithostratigraphical units known from the ad ja cent re gions of south ern and cen tral Poland.
Isolated stromatactis-like cavities were found in a microbial-sponge buildup exposed in the Wielkanoc quarry (eastern part of the Kraków-Częstochowa Upland). The cavities are filled with several generations of carbonate cements and with internal sediments. The top surfaces of internal sediments are flat or wavy, whereas the roofs of cavities are arcuate. The origin of cavities from the Kraków-Częstochowa Upland is difficult to constrain. It seems that the stromatactis-like cavities from the Wielkanoc quarry resulted, at least partly, from remodeling of open spaces left after dissolution of corals in incompletely lithified sediment. Dissolution of corals disturbed the primary stress field within the carbonate buildup and generated the secondary stress characterized by the appearance of compressional forces in the walls of cavities and tensional forces in their roofs. Thus, the lack of support of sediments over roofs of cavities after dissolution of corals resulted in their instability and collapse triggered by vibrations caused by various factors. One of such triggers might have been the rejuvenation of the Kraków-Lubliniec Fault Zone in the Late Jurassic or the collapse of reticular framework within the buildup. The material falling down from the roofs was deposited at the bottoms of cavities as an internal sediment.Results of experimental studies demonstrate that the arcuate shapes of the roof surfaces of cavities are related to compressional stress in the walls and tensional stress in their roofs.
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