The Cenocoiz Geodinamic Evolution Of The Valencia Trough (Western Mediterranean)

espanolLa integracion de datos del subsuelo de las areas sumergidas del surco de Valencia con datos procedentes del estudio geologico de sus margenes emergidos ha permitido distinguir dos dominios estructurales: El dominio Valenciano-catalan, que se extiende a lo largo de la costa, se caracteriza por una tectonica extensiva que persistio durante todo el Neogeno; el dominio Betico-balear, que corresponde a la prolongacion nororiental de las zonas externas de la cordillera Betica, cabalga al dominio p,reviamepte meri.cionad y sufrio una.tectonica extensiva durante el Mioceno superior. Con el fin de ilustrar esta estructura se presentan tres secciones regionales basadas en interpretaciones de lineas sismicas. · Asi, tanto los rasgos estructurales y morfologicos actuales del surco de Valencia, como las variaciones de grosor de lacorteza a traves del mismo no pueden explicarse como el resultado de un simple evento de rifting. Son el resultado, principalmente, del desarrollo de i) un sistema de horsts y grabens en el area NW de la cuenca durante el Oligoceno Superior (?)- Mioceno inferior, y ii) un sistema de cabalgamientos (la prolongacion nororiental de la cordillera Betica, activo hasta el Mioceno medio) y,. sobrepuesta a sus zonas internas, una tectonica extensiva de edad Mioceno superior. El rifting del Mioceno inferior causo un adelgazamiento cortical generalizado en el area del surco de Valencia, mientras que el apilamiento de las laminas cabalgantes betico-balearicas condujo, durante el Mioceno inferior y medio (Burdigaliense y Langhiense), a una flexion de la corteza previamente adelgazada y al engrosamiento de la misma en el promontorio balear. Por lo tanto, el surco de Valencia tiene la condicion de cuenca de antepais respecto al cinturon de pliegues y cabalgamientos betico-balear. Durante el resto del Mioceno medio y el Mioceno superior, el adelgazamiento cortical relacionado con la apertura de la cuenca argelina afecto considerablemente las partes mas sudorientales del promontorio balear, pero solo de manera atenuada el area del surco de Valencia. EnglishThe integration of subsurface data from the offshore Valencia trough areas and data obtained from geological studies carried out on its emerged margins permits recognition of two main structural domains in the Valencia trough: The Catalan Valencian domain, along the lberian coast, that is characterized by an extensional tectonics that persisted during the whole Neogene; and the Betic-Balearic domain, that represents a north-eastern prolongation of the externa! part of the Betic thrust and fold belt (emplaced in Early-Middle Miocene times). The BeticBalearic domain, overthrusts the previous domain and has undel:gone a phase of extensional tectonics during Late Miocene times. In order to illustrate this structure three regional cross-sections based on interpreted seismic lines are presented. The present day structural and morphological features of the Valencia trough, as well as the crustal thickness variations across them, can not be explained as the result of a simple rift event. These features resulted mainly from the development of i) a horst and graben system in the north-western area of the basin during the late Oligocene (?) - Early Miocene, and ii) a thrust system (the north-eastern prolongation of the Betics, active un ti! Middle Miocene) and, superimposed on its interna! zones, a phase of extensional tectonics (mainly Late Miocene in age). The Early Miocene rifting caused a generalized crustal thinning in the Valencia trough area, whereas the stacking of the Balearic-Betic thrust-sheets led to a bending of the previously thinned crust and to a thickening of the crust in the Balearic promontory during the Lower and Middle Miocene (Burdigalian and Langhian). Therefore the Valencia trough acted as a foreland basin in relation to the Betic-Balearic thrust and fold belt. During the rest of the Middle and Late Miocene the crustal thinning was caused by the opening of the Algerian basin, that affected to a considerable degree considerably the southeasternmost Balearic promontory areas but was weak in the Valencia trough area.