Salt giants which have a profound impact on the chemistry, biology and structural evolution of the basin, are formed only when the right combination of climatic and tectonic configuration occurs. Consequently evaporite deposits of this scale arise only episodically in earth history and there are none today for us to study. The most recent salt giant formed 5-6 million years ago in the Mediterranean, in response to tectonically-driven closure of its connections with the global ocean. This event, known as the Messinian Salinity Crisis (MSC), changed the chemistry of the global ocean and had a permanent impact on both the terrestrial and marine ecosystems of a huge surrounding area. The deposition of the salt layer has also been a major control on the tectonic evolution of the Mediterranean basin, including fluid flow and seafloor landscape.
Much of what is known about the processes that led to the MSC comes from the study of onshore exposures around the margins of the Mediterranean. These land-based successions equate to only ~5% of the total Mediterranean evaporite deposits. Basinal information is derived mainly from seismic data and very limited drilling typically restricted to palaeo-highs where the evaporites are thin or absent. As a result, many of the enduring questions about the cause of the MSC and the processes that led to such high amplitude environmental fluctuations persist because of the absence of a continuous core through the deep basinal MSC succession.
New drilling techniques can now overcome the technical challenges of drilling thick evaporite successions and consequently there is an opportunity to put together a proposal for IODP drilling with the MSC as its target. Recent ECORD meetings to initiate the proposal now seek to publicise the current proposal framework and ensure the widest possible input from the community at large.
This session seeks to bring together scientists from all disciplines with new results that contribute to the understanding of the MSC.