Structure and geological history of the Carboneras Fault Zone, SE Spain: Part of a stretching transform fault system

The Carboneras Fault Zone (CFZ), is a major NE–SW trending tectonic lineament in SE Spain. Active from upper-Miocene to Recent times, it separates the volcanic Cabo de Gata terrain to the SE (accumulated over 18–6 Ma BP) from the tract of uplifted Alpine metamorphic basement blocks and post-orogenic basins that comprise the Betic Cordilleras lying to the NW. New geological mapping and age determinations have been used to constrain the geometry and geological history of the fault zone. Z consists of left-lateral strike-slip faults bearing fault gouge formed in the uppermost 5 km of the crust. The faults cut metamorphic basement and folded post-orogenic sediments and volcanic rocks, and acted as a conduit for calc-alkaline volcanic rocks rising to the surface. NW of the CFZ, a series of unconformities and deformation episodes affect successive sedimentary formations of upper Miocene age. The CFZ is interpreted as part of a transform fault system separating NE–SW stretched and NW–SE shortened crust deformed above a south-westward retreating subducted slab, from a less deformed terrain lying to the south-east. Total offset on the CFZ may be up to 40 km but is at least 15 km.