The Pleistocene glaciolacustrine sediments in the Bełchatów mine (central Poland): Endogenic and exogenic controls

The Quaternary overburden of Bełchatów outcrop contains five glaciolacustrine units. The three most widespread are presented. They originated during the advance of the Sanian (= Elsterian), Odranian (= Drenthian) and Wartanian (= Warthian) ice sheets. The following lake environments are distinguished: lake-bottom plain, tectonically active subaqueous slope, subaqueous fan, terminoglacial subaqueous fan and prodelta fan. The lakes formed under changing conditions; the most significant tectonic activity of the graben took place during the Odranian and the lake deposits from this glaciation represent terminoglacial conditions. The Wartanian lake deposits are the only ones that show a shallow-water facies that has not been eroded, because it has not been overridden by an ice sheet.Sedimentation conditions changed during the succeeding glaciations. Endogenic factors affecting sedimentation (i.e. tectonic activity of the graben) complemented some exogenic controls, such as the distance from the ice sheet, the thermal conditions of the lake, and the type of sediment supply. Tectonics changed the style of deposition so much that the lakes, although situated in a lowland area, displayed characteristics of deep valleys.