Basement morphology in the Northwest of the Alboran Sea

A detailed basement depth contour map of the NW Alboran Sea basin is performed from multichannel seismic p ro file data. The map shows a NE-SW trendin g trough as being the north e rn branch o f the West Alboran Basin. The trough opens and deeps to the SW, and is filled of lower-Mlocene to Recent sediments up to 6 seconds (twtt) in thickness. The trough corresponds to a complex half-graben with a gently dipping northern slope and a sharper southern flank which bounds the basement horst drilled at DSDP Site 121 and ODP Site 976: The northern slope mainly corresponds to low-angle normal faults crosscutted by NW-SE trending high-angle normal and strike-slip faults. The basement horst resulted form interference between several faults, NW dipping low-angle normal faults, SW-NE■ directed high-angle faults; and top of rollover structures related to the low-angle faulting. Both trough and horst axes are tilted towards the SW, probably as a result of post-Messinian subsidenc