Soft-sediment deformations from glaciodeltaic, glaciolacustrine and fluviolacustrine sediments in the Kleszczów Graben (central Poland)

Summary The Kleszczów Graben, situated some 50 km south of Łódź, has a Tertiary and Quaternary infilling of up to 300–400 m. The graben is some 40 km long and a large exposure is formed by an open-cast browncoal mine. The well discernible structural pattern is due to frequent deformations, many of which are related to subsidence of the graben. The sediments within the graben are all unconsolidated and show a large variety of deformational structures with respect to both genesis and geometry. Various stages of more intense deformation can be discerned. The glaciodeltaic, glaciolacustrine and fluviolacustrine sediments in particular show frequent deformations. They are interpreted as being induced by both endogenic and exogenic agents, often during several phases that affected the same sedimentary unit.