Seismic Expression of the Cenozoic Mass Transport Complexes, Deepwater Tarfaya-Agadir Basin, Offshore Morocco

摘要

The Tarfaya-Agadir Basin in offshore Morocco is a frontier exploration area with no deepwater industry well penetrations and limited well control in the updip shelfal equivalent. Recent detailed 3D seismic mapping and study by Shell has identified the presence of two large mass transport complexes (MTCs) in the Tertiary interval, in addition to a number of smaller and younger MTCs. The large MTCs, named Tejas A and Tejas B, exhibit distinct seismic characteristics that may be significant to understanding the evolution of the basin during the Tertiary. The basal Tejas A is characterized by numerous kilometer-scale, coherent transported blocks. The size and quantity of transported blocks observed in Tejas A is unique in Morocco and the Atlantic Margin. The MTC in the younger Tejas B is a thick chaotic unit with distinctive downdip erosional lobes. This deposit is overlain by high amplitude, parallel seismic facies. The chaotic seismic facies is often sharp-edged, with well-defined pressure ridges. Only a few small transported blocks and erosional remnants have been observed in Tejas B. Failure deposits account for a significant percentage of the Tertiary stratigraphic interval in the 3D survey area.