Abstract
The offshore Alicante Basin is a late Neogene post-orogenic basin located at the northeastern end of the Eastern Betic Shear Zone of southeastern Spain. Based on the integration of legacy 2D seismic data, well data and outcrop geology, this paper provides a comprehensive review and analysis of its stratigraphy, structural geometry and tectonic evolution. The basin was formed as an extensional basin in latest Serravallian-early Tortonian time (ca. 11.5 Ma), accumulating 1500-2000m of marine sediments of Tortonian-Recent age. The basin overlies the tectonic boundary between the low-grade metamorphic Alpujarride units of the Internal Zone, and the non-metamorphic Mesozoic to Middle Miocene sedimentary rocks of the External Zone of the Betic Cordilleras. This Internal-External Zone Boundary is formed by a north-dipping backthrust that was reactivated in Tortonian as extensional basin bounding fault. Active extensional faulting ceased at around 8 Ma, followed by a phase of compression that resulted in basin inversion and basin margin uplift in Late Pliocene-Pleistocene time. Strike-slip tectonics related to the Crevillente Fault and the Eastern Betic Shear Zone appear to have played a minor role in the structuration of the basin, but may have shaped the structure of the Tabarca Ridge and Mazarron Escarpment at the southern margin of the basin. The basin appears to form a boundary zone separating predominantly strike–slip faulting to the south and southwest from predominantly normal faulting to the north, accommodating recent compression at the northern end of the EBSZ.