Origin of crumpled limestone in the Middle Triassic of Poland

Abstract

O pochodzeniu wapieni gruzłowych w wapieniu muszlowym Sedimentary deformational structures exhibited by the „Wellenkalk” type of limestones are explained as due to instability in density stratification. Such an instability existed in a multi-layer horizontal sequence composed of densely packed calcareous muds, interbedded with water-laden marly sediments. The sequence contained a certain amount of potential energy, which accumulated during the deposition of the layers and represented a typical trigger system. The deformational processes were preceeded by liquefaction of the marly sediments. The resulting quick conditions reduced the bearing capacity of the system and consequently brought about the collapse and fragmentation of the more cohesive and heavier limey layers. The detached and crumpled fragments of these layers accumulated at the base of the discrupted sequence to form a new bed.