Structure and kinematics of the South Iberian paleomargin and its relationship with the Flysch Trough units: extensional tectonics within the Gibraltar Arc fold-and-thrust belt (western Betics)

The superposition of structures observed in a selected area of the external zones of the Betic orogen, situated in the westernmost segment of the peri-Mediterranean mountain belt, reveals an alternation of compressional and extensional events during the overall convergence of the African and Eurasian plates that bound the system. An Early Miocene compressional event produced the formation of the so-called Gibraltar Arc fold-and-thrust belt, formed by the units derived from the South Iberian paleomargin and the Flysch Trough. This wedge constitutes the footwall of the Gibraltar Thrust, whose hanging wall corresponds to the Alboran Domain. The outward migration of the compressional front (W-to-NWward in the South Iberian segment) was followed by the outward migration of the extensional locus, related to the Middle Miocene rifting that led to the Alboran Basin subsidence. The tectonic inversion of the Gibraltar Thrust was accompanied by normal faulting of the innermost part of the paleomargin and the Flysch Trough units. Finally, the Alboran region underwent N–S-to-NW–SE compression from Late Miocene onwards, which caused the uplift of the Gibraltar Arc area.