Structural interpretation of the salt-rich inverted Tarascon basin (north Pyrenean zone, south France)

Salt tectonics concepts may help explaining relatively complex tectonosedimentary relationships in the reinterpretation of inverted rifted margins. The objective of this study is to develop a valid model from extension to inversion for the Jurassic-Cretaceous Tarascon basin in the northern Pyrenees, considering the role of salt in the observed stratigraphy and structure, which may help to bring new light to the evolution of the Europe-Iberia plate boundary. To achieve this, a revised detailed geological map, cross-sections, and an evolutionary tectonic model have been proposed, based on an in-depth field analysis and the integration of existing and new structural and paleotemperature data. The Tarascon basin features a highly compartmentalised tectonosedimentary pattern, with synformal or steep tilted minibasins, separated by salt welds that truncate stratigraphic units, where most of the Keuper evaporites have been expelled, leaving mainly ophite or carniole bodies. Additionally, a large body of allochthonous Keuper gypsum has been described in the north of the basin. Therefore, deposition during the Jurassic and Cretaceous was controlled by both syn-extensional subsidence and salt migration. Furthermore, the development pattern of the different minibasins in the Tarascon basin appears related to the structure of the basement and the North Pyrenean massifs.