Neogene tectonic evolution of the southwestern Alboran basin as inferred from seismic data off Morocco

The southwestern part of the western Mediterranean Alboran Basin, including part of the Alboran ridge (Xaouen Bank), was investigated through the analysis of 28 intersecting multichannel seismic lines, The seismic stratigraphy is tied to the Amoco well El-Jebha 1. Five seismic units or subunits are described from the Quaternary to the middle (and lower?) Miocene. The acoustic basement is interpreted to be mainly Paleozoic and Triassic metamorphic rocks of the Alboran Domain nappes, and, in places, middle Miocene-Messinian calc-alkalic volcanics, In the depocenters, the thickness of the sedimentary infill (mostly clays and turbidites) exceeds 9 km, Normal faults of middle Miocene-Tortonian age are broadly parallel to the coast, and dip either seaward or landward. They were mostly inverted during pre- and post-Messinian episodes of compression, which formed a set of en echelon, north-verging faulted folds in the Alboran ridge area, in relation with sinistral movement along the offshore projection of the Jebha fault. After Pliocene subsidence, a final episode of compression reactivated the earlier folds and pushed the Alboran ridge onto the Moroccan slope. The complex structural history suggests many structural and stratigraphic potential hydrocarbon traps. A high-resolution seismic survey could lead to the definition of new exploration plays.