Volcanic rocks in Lower Jurassic marine carbonate successions in the southeastern Iberian Range (Spain): biochronostratigraphic dating

Abstract

The Ligurian Tethys began to open in a roughly NE–SW direction in Pliensbachian times. West of the Ligurian oceanic crust, a carbonate-platform system constituted the eastern Iberian paleomargin. Lower and Middle Jurassic marine sediments deposited in these shallow platforms are well exposed today in the southeastern Iberian Range and host multiple volcanogenic deposits, mainly volcaniclastic in nature. Regional mapping reveals that volcanic outcrops show NW and NE (or NNE) oriented lineaments following tracks of cortical weakness. Volcanic ages were estimated by using biochronostratigraphic methods and sequence-stratigraphic correlations. As a result, ten Lower Jurassic volcanic episodes have been identified. The chronostratigraphic positions of the volcanic deposits span from the early Pliensbachian (Jamesoni Zone or later) to the late Toarcian (Thouarsense Zone). The extension-dominated regime of the eastern Iberian paleomargin also affected the southern Iberian paleomargin (Betic Cordillera) as a result of the eastward prolongation of the central Pangea fragmentation. The break-up of wide platforms and the first volcanic emissions seem to be roughly coeval in the Betic and Iberian domains and synchronous with the onset of rifting and spreading events of the Ligurian Tethys Ocean.