Abstract Seismic sequence interpretation, analysis of shallow boreholes and outcrop studies at Svalbard strongly indicate that the Triassic basin in the northern Barents Sea and eastern Svalbard was supplied by sediments from the south east by a large complex prograding delta system. The seismic facies interpretation suggests that the black Ladinian and Anisian shale (Botneheia Formation) is an integrated part of the prograding delta system and developed as the bottom sets of large pro-delta clinoforms. The clinoforms and their breaking points define a series of seismically detectable sequences at a shelf edge delta. Provenance areas are suggested to be Siberia, the Kola Peninsula and the Caledonides. Each sequence has a maximum thickness of 200–400 m and is interpreted to represent the water depth range in the basin. Seasonal flooding, stratified salinity and algal blooming are assumed to be important factors generating anoxic bottom conditions in a huge death zone in front of the prograding delta system. The folded and thrusted Triassic rocks in the western part of Svalbard are suggested to be part of an allochthonous nappe ejected from the Greenland region when Greenland moved northwards along the Hornsund Fault complex; their original position is suggested to be further south.