The tectonic structure of the Alboran Margin of Morocco

Abstract

We utilized a very dense seismic survey mainly performed by the oil companies completed by academic data to perform a depth to basement map of the Morocco margin of the Alboran Sea. The eastern area is characterized by several volcanic edifices that are related to the late Miocene Alboran arc. However, the volcanism persisted after the Messinian in the Gourougou volcano and the Chafarines Island. The Tortonian to Messinian activity of the Nekor fault system is characterized by normal faulting with a NE-SW trend. A tilt of the Messinian surface suggests a 1.5 km uplift of the coast since 5.33 Ma. In the Al Hoceima offshore region we identify the major left-lateral El Idrissi fault zone that probably crosses the Alboran Sea. The Xauen Bank is formed by the early Miocene sedimentary layers of the West Alboran Basin uplifted by compression with an estimated shortening of 3.5 km since the Messinian (0.65 mm/yr). The Jebha Fault was mainly active during the early Miocene. The tomography, the magmatism, and the tectonics suggest that the Alboran Arc collided with the Iberian Plate during the late Tortonian, followed by a clockwise rotation of the central Alboran basin. Although the Alboran basin is clearly affected by E-W motions we think that the eastwards subduction zone is dead since the late Miocene.