THE VALENCIA TROUGH (WESTERN MEDITERRANEAN) - AN OVERVIEW

The Valencia trough, located between the Spanish mainland and the Balearic islands, corresponds to a late Oligocene to recent sedimentary basin that is characterized by a highly attenuated continental crust. Its northwestern part evolved in response to a late Oligocene to early Miocene rifting phase that was followed by a period of post-rift subsidence and a late Miocene-Pleistocene phase of renewed crustal extension and magmatism. Its southeastern part is characterized by late Oligocene to mid-Miocene compressional deformation and subsequent extension. In the axial parts of the basin the crust has been thinned by a factor of 3 whereby the lower crust is either absent or very thin. Upper crustal extension appears to be considerably smaller than indicated by the crustal configuration of the basin. A major problem in understanding the evolution of the Valencia trough is the lack of knowledge about the physical state and structure of the lithosphere before late Oligocene extension. Evolution of the northwestern part of the basin appears to be linked with the development of the oceanic Provencal Basin. Middle Miocene compressional deformation of the Balearic fold belt, forming the southeastern margin of the Valencia trough, appears to have interfered with the tensional evolution of the latter, which only resumed after crustal shortening in the Balearic domain had given way to extensional tectonics during the late Miocene.