Abstract:
An extensive 3-D seismic volume covering an area of 1064 km (super 2) has been used to analyze the morphology of the lower continental slope, determine the emplacement history of allochthonous salt structures, and to examine the temporal changes in the interaction of structure and sedimentation in offshore Morocco. The survey area is located roughly 150 km west of the Moroccan coast, in Safi Haute Mer permit area, in a water depth of approximately 2000 meters. The western half of the survey lies just outside of the salt basin and is marked by relatively flat-lying strata. The eastern half of the survey lies within the salt basin and is characterized by sedimentation around salt structures and deformation of salt and sediment. At the distal edge of the salt basin, a thin salt sheet has been driven by sediment loading to extrude at least 10 km beyond the salt basin's western depositional edge. A series of structural restorations show changes in salt structure growth through time. Interval isopach maps allow examination of spatial and temporal changes in depocenters and assessment of the influence of salt mobilization on basin fill pattern. In the study area, Late-Triassic to Early-Jurassic age salt is believed to have become mobilized in the Jurassic, resulting in a number of different types of halokinetic structures including diapirs, salt sheets, salt-cored anticlines, and turtle structures. Structure development has been dominated by a combination of several tectonic processes at any given time throughout the evolution of the margin. Up to 6000 meters of sediments have been deposited in basins created by salt evacuation and around paleo-highs cored by mobile salt since Early Jurassic time. DSDP data from the deep offshore shows the Early-Jurassic to Early-Cretaceous strata to be carbonates, while the strata younger than Early Cretaceous are dominantly siliciclastic. The Moroccan continental margin has developed from a complex interaction of sediment and salt, resulting in a variety of structures attractive to hydrocarbon exploration.