Salt-bearing sedimentary basins, preserving kilometre-thick evaporite layers, or ‘salt giants’, are frontiers for a diverse range of challenging research. Most salt giants in the geological record are old (e.g. Permian Zechstein salt or the Mesozoic salts in the Atlantic) and have typically experienced intense deformation. They are commonly the focus of applied research by the petroleum industry because of the sealing capacity of salt rock, the recurrent association with structural traps for hydrocarbon fluids, and perturbations to in situ stresses associated with salt bodies. Besides the industrial interest, salt giants are the sedimentary expression of extreme environmental events of global relevance, often resulting from a combination of deep earth- system dynamics (e.g. mantle convection and the initiation of continental break-up) and climatic forcing (evaporation-precipitation budget at the regional scale). Salt deposition impacts the structural, chemical and biological evolution of the sedimentary basins in which it accumulates, and affects global ocean salinity. Because of the variety of chemical environments, salt giants have the potential to harbour an unprecedented diversity of microbial life with exceptional metabolic activity. Finally, quantitative understanding of salt dynamics and associated fluid flow is fundamental to the assessment of submarine geohazards, and exploration or production risks.

Despite their global occurrence and general importance within the global Earth system, there is currently no complete stratigraphic record through an undeformed salt giant. Similarly, there is a significant lack of knowledge about the factors controlling salt giants deposition, their early evolution, the the evolution through time of the oceanic gateways that control salt deposition, and the impact that thick salt deposition exerts on the isostatic response of continental margins and on sub-salt formations. In the framework of the current initiative to promote scientific drilling in the Mediterranean salt giant, the youngest on Earth, and across its gateways, this session seeks to bring together scientists from all disciplines with new results that contribute to the understanding of the causes, processes and impacts on basin evolution of salt giants.