Formation and growth of diapirs in contractional settings: the Mediano anticline and Clamosa diapir case study (Southern Pyrenees)

Abstract. At the northwestern termination of the South Pyrenean Central Salient, thrust imbrication, detachment folding and diapirism are structurally and genetically related. The La Fueba imbricate system has been folded by the Mediano detachment anticline, while this fold connects with the Clamosa diapir. Together, this structural-stratigraphic trinity provides an excellent example to evaluate the factors controlling purely contractional diapirs in onshore-offshore contractional fold-thrust systems. Our study integrates detailed geological mapping, a large structural dataset, new biostratigraphic data, and interpretations of well-tied depth-converted seismic lines and cross-sections. A combined evolutionary model for contractional diapir formation and evolution is presented. While less common than in extensional settings, the interplay shortening of a salt horizon along with vertical axis rotations and local stretching and erosion of the overburden can lead to purely contractional salt diapirs.