Gravity-constraint salt distribution and migration model in the South Pyrenean Central Salient

Upon shortening, salt distribution determines the formation of salients and reentrants in fold-and-thrust belts. Such distribution is controlled by the original sedimentary architecture of the salt basin and subsequent post-sedimentary salt tectonics. In the Southern Pyrenees, the South Pyrenean Central Salient detaches on Triassic evaporites (the regional décollement of the Pyrenees) and stands as a prominent feature bounded, to the north and to the south, by diapiric provinces. Despite its subsurface geometry has been characterized by 2D reflection seismic profiles and exploration wells, an accurate image of the distribution at depth of the Triassic evaporites remains unsolved. In this work, we present an updated observed residual gravity anomaly map of the South Pyrenean Central Salient together with three gravity-validated cross-sections that give structural meaning to gravity anomalies and therefore yields a further interpretation of them helping to interpret those areas lacking seismic images. Middle-Upper Triassic salt accumulations dominate in the western half of the South Pyrenean Central Salient. To the northwest, a prominent accumulation of Triassic evaporites is likely associated with an inherited accumulation predating the Pyrenean orogeny and associated with extensional to gravity-driven salt tectonics during the rift and post-rift stages. To the South, Triassic rocks core salt-detached anticlines. Along the southernmost (and youngest) thrust sheet of the salient, diapirs and evaporite accumulations are associated to an inflated area resulting from the north-coming migration of evaporites during the middle to late stages of the Pyrenean orogeny.