Recognising triggers for soft-sediment deformation: Current understanding and future directions

Most of the 16 papers in this special issue were presented at a session entitled “The recognition of trigger mechanisms for soft-sediment deformation” at the 27th IAS Meeting of Sedimentology in Alghero, Sardinia, Italy, which took place from 20th-23rd September 2009. They describe soft-sediment deformation structures that range widely in morphology, age, depositional environment and tectonic setting. In their interpretations, the authors have been asked to focus on identifying the agent that triggered deformation. Our aims in this introductory overview are to: (1) review the definition and scope of soft-sediment deformation; (2) clarify the significance and role of the trigger; (3) set the contributions in context and summarise their findings; and (4) discuss strategies for reliably identifying triggers and make recommendations for future study of this widespread and significant category of sedimentary structures. We recommend a three-stage approach to trigger recognition, combining the assessment of facies, potential triggers, and available criteria. This focus on the trigger for deformation distinguishes this collection of papers on soft-sediment deformation from other important collections, notably those edited by Jones and Preston, 1987, Maltman, 1994, Maltman et al., 2000, Shiki et al., 2000, Ettensohn et al., 2002b, Van Rensbergen et al., 2003, Storti and Vannucchi, 2007.