A seismite in Triassic gypsum deposits (Grabfeld Formation, Ladinian), southwestern Germany

Abstract

An approximately 1 m thick gypsum bed and its underlying < 45 cm dolomite bed with variable soft-sediment deformation structures are described from the Grundgips Member of the Grabfeld Formation (Middle Keuper, Ladinian) in southwestern Germany. The deformation structures are mainly convolutions, folds, cusps, domes and off-shooting dykes and, less common, brecciation or faulting. These deformation structures are interpreted to be caused by liquefaction and/or fluidization of the semiconsolidated sediments by a seismic shock of approximately magnitude 6-7. Palaeoseismicity is thought to be related with a nearby wrench fault system associated with a major suture zone of the Variscan basement. © 2005 Elsevier B.V. All rights reserved.