Betic–Rif arc

Betic–Rif arc
Name	Betic–Rif arc
Location	Iberian Peninsula, North Africa
Type	Orogenic arc

Betic–Rif arc is a arcuate orogenic system formed by the contractional and extensional interaction between the Iberian Peninsula and African Plate across the western Mediterranean Sea. It spans southern Spain and northern Morocco and links major physiographic provinces including the Baetic System, the Rif Mountains, the Alboran Sea basin, and adjacent coastal plains. The arc records Neogene to Quaternary tectonic events that involved collision, subduction reversal, and continental escape linked to plate reorganizations near the Alpine orogeny, Atlas Mountains, and the Strait of Gibraltar.

Geography and extent

The arc extends from the western end of the Gibraltar Arc near the Strait of Gibraltar eastwards through the Betic Cordillera across Andalusia and westwards into the Rif region of Morocco, encompassing the Alpujarras, Sierra Nevada (Spain), Penibetic System, Subbetic Zone, and the Prebetic Zone. Coastal features include the Gulf of Cádiz, the Alboran Sea, and the Mediterranean coast of Morocco, while offshore structures involve the Iberian Abyssal Plain and the Torres Strait Spur. Major urban centers within the arc’s influence include Málaga, Granada, Almería, Seville, Tangier, Tetouan, and Ceuta.

Geological setting and tectonic evolution

The setting is controlled by convergence between the Eurasian Plate and the African Plate and interactions with microplates such as the Alboran Domain and the Iberian microplate. Tectonic stages include late Mesozoic rifting related to the opening of the Central Atlantic, Cenozoic subduction beneath the Alboran domain, slab rollback and retreat documented in the Alpine orogeny context, and Neogene to Quaternary compressional reorganization tied to the closure of the Tethys Ocean and the plate kinematics that followed the Messinian Salinity Crisis. Models invoke continental collision, slab tearing, and lateral extrusion similar to processes described for the Carpathians, Apennines, and Hellenides.

Stratigraphy and lithology

Stratigraphic architecture comprises Mesozoic carbonate platforms, Permian to Triassic detrital sequences, and Cenozoic marine successions including Miocene turbidites and Pliocene–Quaternary continental deposits. Units include the Malaguide Complex, Alpujárride Complex, Nevado-Filábride Complex, and ophiolitic fragments correlated with the Betic ophiolites and the Rif ophiolites. Lithologies range from Jurassic limestones and Cretaceous marls to Eocene flysch, Miocene evaporites associated with the Messinian Salinity Crisis, and Plio-Quaternary conglomerates related to uplift and erosion affecting basins such as the Guadalquivir Basin and the Rif Basin.

Structural features and deformation mechanisms

The arc exhibits nappes, thrust belts, strike-slip faults, extensional metamorphic core complexes, and folded foreland basins; prominent structures include the Alboran block, the Nevado-Filábride Complex thrust stack, and the lateral shear zones accommodating the westward displacement of crustal blocks. Deformation mechanisms involve thin- and thick-skinned thrusting, crustal shortening, extensional collapse driven by slab rollback, and oblique collision producing transpressional faulting analogous to systems like the North Anatolian Fault and the San Andreas Fault in their strike-slip components. Metamorphic gradients reflect subduction-related HP–LT conditions and exhumation comparable to belts such as the Dinarides.

Seismicity and geohazards

Seismicity is concentrated along active faults and the plate boundary, producing damaging earthquakes historically recorded in events affecting Lisbon, Málaga, Almería, and Tetouan. Major regional seismic sources include the Gulf of Cádiz thrust system, the Alboran extensional faults, and strike-slip structures near the Strait of Gibraltar. Associated geohazards include tsunamis, as evidenced by historical accounts around the 1755 Lisbon earthquake and sedimentary tsunami deposits in coastal basins; also relevant are landslides in the Sierra Nevada (Spain) and coastal subsidence in deltaic zones such as the Guadalquivir River mouth and the Marrakech plain.

Paleogeography and uplift history

Paleogeographic reconstructions trace the arc’s evolution from Mesozoic passive margin settings along the Tethys Ocean to Neogene back-arc and foreland basin configurations influenced by the Messinian Salinity Crisis and the opening of the Alboran Sea. Uplift episodes in the Pliocene–Quaternary produced the present topography of the Sierra Nevada (Spain), the Penibetic ranges, and the Rif, driven by isostatic rebound, slab rollback, and regional shortening tied to plate reorganization after the Oligocene. Fluvial terraces, marine terraces, and thermochronology data from minerals like apatite record episodic exhumation correlated with climatic shifts such as Pleistocene glaciations.

Economic resources and land use

The arc hosts mineral occurrences including polymetallic ore deposits, ancient and modern mining in the Iberian Pyrite Belt, metalliferous veins exploited near Ronda, and chromite in ophiolitic complexes studied in the Rif. Hydrocarbon potential exists in adjacent basins like the Gulf of Cádiz and the Guadalquivir Basin with exploration targeting Miocene reservoirs and turbidite systems. Soils and geomorphology support agriculture in the Andalusian plain, vineyards near Jerez de la Frontera, and olive groves around Jaén; tourism and urban development concentrate in coastal cities such as Málaga and Tangier, while conservation efforts involve protected areas like the Sierra Nevada National Park and marine reserves in the Alboran Sea.

Category:Geology of Spain Category:Geology of Morocco