Episodios de deformación de la Cordillera Bética y su entorno próximo (España): problemas no resueltos

• Autores: Wenceslao Martínez del Olmo
• Localización: Revista de la Sociedad Geológica de España, ISSN 0214-2708, Vol. 31, Nº. 1, 2018, págs. 49-66
• Idioma: español
• Títulos paralelos:
  • Modalities and deformation phases of the Betic Ranges: overlooked problems
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• Resumen
  • español

    La Cordillera Bética ha sido tradicionalmente dividida en tres conjuntos con significado tectónico y paleogeográfico: Zonas Internas (Complejos Nevado-Filábride, Alpujárride y Maláguide), Zonas Externas (Prebético, Subbético y Flysch de Gibraltar) y Cuencas miocenas sin- y post-orogénicas. Recientemente el Subbético ha sido subdividido en Olistostrómico, Caótico y Subbético s.s., diferenciaciones que junto a una ordenación de ocho episodios estructurales, hacen objeto de este trabajo. Dichos episodios son: 1) Sedimentación (Triásico-Mioceno Inferior) en el Margen Suribérico, tiempo hacia el final del cual el diapirismo salino ya había producido la primera estructuración del Subbético; 2) Rampas laterales E-O y frontales N-S, producto de la colisión E-O de las Zonas Internas con el paleomargen; 3) Apertura y subsidencia del Mar de Alborán; 4) Inversión tectónica de las rampas laterales y deslizamientos gravitacionales del Subbético; 5) Compresión NO-SE y diapirismo en todo el paleomargen; 6) Deslizamiento gravitacional de los olistostromas del Guadalquivir y del Golfo de Valencia; 7) Sistema extensional de Mecina-Filabre; 8) Compresión en el segmento más oriental; 9) Basculamiento y subsidencia diferencial en el Guadalquivir. Finalmente, se significan problemas, aún no resueltos, tales como: taludes de origen y medio de transporte de los olistostromas, cizallas basales de olistolitos o cabalgamientos, y significado regional del llamado Triásico de Antequera ya que podría ser interpretado como la brecha de base de un olistostroma que contendría la totalidad del Subbético Externo y gran parte del Subbético Medio.

  • English

    The Betic Mountain Chain has been the subject of geological works that have traditionally divided it into three main tectonic and palaeogeographic domains: Internal Zones (Nevado-Filábride, Alpujarride, Malaguide complexes), external platform facies units of the Prebetic, and mixed and deep waterfacies units of the Subbetic, also divided along a N-S section in External, Middle and Internal. This division is completed by the Miocene basins (Guadalquivir marine foreland basin) and numerous post-orogenic basins filled by marine and continental sediments. Recent studies have established three mayor divisions in the Subbetic (Olistostromic, Chaotic and Subbetic s.s) whose evolution is related to eight structural events: 1) Triassic to Early Miocene sedimentation over the south of the Iberian margin in a long thick Atlantic-type margin. The Triassic salt diapirism originated the first structures of the Subbetic causing the olistolith falls, canopies and toe thrusts; 2) The E-W collision of the internal zone (AlKaPeCa, Alboran tectonic plate) with the sedimentary paleo-margin pile during the Aquitanian-Burdigalian that produced W-E, long lateral ramps and N-S short frontal ramps; 3)Burdigalian-Langhian opening and subsidence of the Alboran Sea and the surrounding Balearic islands Miocene basins; 4) During Serravallian and Tortonian, many W-E lateral ramps underwent tectonic inversion. Massive propagation of gravitational landslides of Triassic salt and shales-rich Subbetic materials also took place at this stage. The new NW-SE compressional phase caused the Chaotic Subbetic, the former first olistostrome, to move towards the W-NW, and the disappearance of many N-S frontal ramps; 5) The NW-SE Tortonian compression, still active all along the Betic paleo-margin, stimulated new olistostrome slides from the uplifted relief towards the Guadalquivir and Gulf of Valencia foreland basins; 6) The extension episode (Mecina-Filabres system) during the latest Miocene penetrated inside the Alboran Sea and generated a low-angle fault system towards the S-SW; 7) Compression and transpression of the easternmost segment can be noted at the Alhama, Carrascoy, Palomares and Carboneras faults; 8) Margin tilting and Guadalquivir Basin east to west differential subsidence. Finally, some issues still remain open, including: i) the tectosedimentary process (turbiditic or gravitational) that generated the olistostromes and the talus location which caused them; ii) abnormal contacts attributed to thrusting that can be interpreted as olistoliths; and iii) the meaning of the Triassic of Antequera as the exponent of the large Triassic outcrops of the Subbetic, which we have interpreted as a an olistostrome scar that includes the totality of the External Subbetic and a big segment of the Medium Subbetic.