The Kleszczów Graben (central Poland): reconstruction of the deformational history and inventory of the resulting soft-sediment deformational structures

Abstract

Summary There is a deep tectonic graben near the village of Kleszczów, some 50 km south of Łódź. A Mesozoic substratum has subsided in the graben. The infilling consists of unconsolidated Tertiary and Quaternary deposits that reach thicknesses of up to 300 m; locally they may be even more than 400 m thick. The equivalent deposits outside the graben area are 5–7 (or more) times thinner. The lowermost part of the graben contains the oldest infilling, probably indicating the very first moment of subsidence, and consists of late Oligocene deposits. The overlying sediments form an almost complete succession up to the Holocene and represent the best developed and most intensively studied Cenozoic section in Poland. The sections show a unique degree of exposure in continuous horizontal and vertical sections, well developed deformational structures and an exceptional thickness of the Cenozoic succession. There has been much interest in the geological history of the intensely deformed infilling of the graben. The reconstruction of the sedimentological and deformational history is the main topic of this contribution.