Age of extensional detachments in the northwestern Gibraltar Arc system through onshore-offshore correlations

espanolLa evolucion tectonica del Arco de Gibraltar durante el Mioceno estuvo marcada por la formacion de un cinturon de pliegues y cabalgamientos en las zonas externas, simultanemanete con una extension de tipo retro-arco en las zonas internas. En la parte noroeste de las zonas internas la falta de afloramientos syn-tectonicos relacionados con la extension dificulta la datacion de los sistemas involucrados. Para datar estas estructuras se ha analizado la cobertera sedimentaria en mar y se ha correlacionado con las estructuras extensionales mediante cortes tierra-mar. Esto ha permitido differenciar dos grandes episodios dentro de la extension miocena en el area de estudio. El episodio Burdigaliense-Langhiense esta relacionado con el adelgazamiento y la exhumacion del Dominio de Alboran y muestra dos direcciones de transporte SW y SSE para el bloque de techo. El segundo episodio (Langhiense- Tortoniense temprano) se corresponde con la formacion de la Cuenca de Malaga y se caracteriza por un transporte hacia el NW. EnglishThe Miocene tectonic evolution of the Gibraltar Arc system is characterized by the simultaneous formation of a fold-and-thrust belt in the external zones while a back-arc basin was formed in its hinterland.At the northwestern part of the internal zones of the arc, the lack of syn-tectonic Miocene deposits onshore prevents to constraint the age of the extensional systems involved in the rifting. In order to better constraint the age of these structures we focus on the analysis of the sedimentary cover offshore and correlate them with the extensional structures through onshore-offshore cross-sections. This has allowed to differentiate two main episodes within the Miocene rifting. The Aquitanian-Burdigalian episode is related with the major thinning and exhumation of the Alboran Domain with two mayor transport directions of the hanging wall block towards the SW and SSE, respectively. The Langhian-early Tortonian episode corresponds with the opening of the Malaga Basin and was characterized by transport towards the NW.