New classification system formass transport complexes in offshoreTrinidad

This paper delineates our use of10 708 km of three-dimensional (3D) seismic data from the continental margin of Trinidad and TobagoWest Indies to describe a series of mass transport complexes (MTCs) that were deposited during the Plio-Pleistocene.This area, situated along the obliquely converging boundary of the Caribbean/SouthAmerican plates and proximal to theOrinoco Delta, is characterized by catastrophic shelf-margin processes, intrusive/extrusive mobile shales and active tectonism. Extensive mapping of di¡erent stratigraphic intervals of the 3D seismic survey reveals severalMTCs that range in area from11.3 to 2017 km.Three types ofMTCs are identi¢ed: (1) shelf-attached systems that were fed by shelf-edge deltas whose sediment input is controlled by sealevel £uctuations and sedimentation rates; (2) slope-attached systems, which occur when upperslope sediments catastrophically fail owing to gas-hydrate disruptions and/or earthquakes and (3) locally detached systems, formedwhen local instabilities in the sea£oor trigger relatively small collapses. Such classi¢cation of the relationship between slope mass failures and sourcing regions enables a better understanding of the nature of initiation, length of development history and petrography of suchMTCs. 3D seismic enables more accurate calculation of deposit volumes, improves deposit imaging, and, thus, increases the accuracy of physical and computer simulations of mass failure processes.