Density-driven deformation structures in glacigenic consolidated diamicts:Examples from Traeth y Mwnt, Cardiganshire, Wales, UK

Density-driven deformation may occur when a sediment of higher bulk wet den sity is deposited an top of one of a lower bulk wet density, and occurs com monly in glacigenic sediments. By recognizing density-driven deformation of gravels and sands embedded in diamicts, it is possible to reconstruct rela tive preconsolidation states of the diamicts, Density-driven structures ind icate that during deformation the diamict behaved as a viscous fluid, thus providing important evidence for the viscosity and physical state of diamic ts after deposition, which has implications for the depositional environmen t. The density-driven process and its implications for reconstructing depos itional environments is discussed. Criteria are given for the recognition o f density-driven deformation stages of gravels and sands deposited on top o f a viscous mud.