Geology of the Salinas De Rosío Diapir (Basque-Cantabrian Basin, Spain)

This study presents a new geological map of the Salinas de Rosío diapir (Basque-Cantabrian Basin, northern Spain), based on detailed fieldwork, interpretation of high-resolution topographic data, and integration of existing geological information. The diapir displays an elongated geometry and consists of Keuper evaporites with Upper Triassic – Lower Jurassic carbonate intrasalt blocks and dolerite bodies. It pierces a Lower Cretaceous to Miocene sedimentary sequence, including marine and continental deposits variably affected by halokinesis. Structural and stratigraphic data from the overburden and the detailed mapping of progressive unconformities, indicate a multi-episodic history linked to extensional and contractional tectonics. The last stage of this evolution took place during the Miocene, under syntectonic Alpine compression, when accelerated salt rise and extrusion led to the formation of a characteristic salt glacier. This study highlights the value of detailed geological mapping and field-based structural analysis in advancing the understanding of salt tectonics.