Structural style of the Languedoc Pyrenean thrust belt in relation with the inherited Mesozoic structures and with the rifting of the Gulf of Lion margin, southern France

Abstract

The E-trending Pyrenean orogen results from the inversion of the mid-Cretaceous rift structures responding to an overall N-S extension, as suggested by the balanced and restored cross-sections oriented normal to the orogen. However, oblique convergence/divergence that involve strain partitioning and arcuate segments of the orogen prevent simple tectonic restorations. The Languedoc region (southern France) provides a case study of a complex polyphase deformation involving a range of reactivated structures and cross-cutting relationships, acquired in response to varying tectonic stresses with different orientations. We analyze and correlate the onshore-offshore structures of the Languedoc region, based on reassessment of existing and newly acquired subsurface data. New results in the poorly documented coastal area point to the existence of unrecognized major structures that improves onshore-offshore correlations. Our results show: (i) the part played by the Mesozoic (Early Jurassic, then mid-Cretaceous) extensional phases in the development and the localization of Pyrenean-related contractional structures; (ii) the control of inherited crustal structure on the later Oligocene rifting of the Gulf of Lion. This restoration of the Pyrenean shortening and Oligocene rifting, constructed along sections (approximately perpendicular to each other) indicates minimum shortening of 28 km and extension of 14 km, respectively, in the Languedoc foreland. Integration of the Pyrenean structural framework of Languedoc reveals a wide, NE-trending transfer zone linking the eastern Pyrénées to Provence.