Project Details


An amphibious drilling project to recover Late Miocene-Pliocene record of Atlantic-Mediterranean exchange on all four sides of the Gibraltar Strait

Layman's description

Marine gateways play a critical role in the exchange of water, heat, salt and nutrients between oceans and seas. The
advection of dense waters helps drive global thermohaline circulation and, since the ocean is the largest of the rapidly
exchanging CO2 reservoirs, this advection also affects atmospheric carbon concentration. Changes in gateway geometry
can therefore significantly alter both the pattern of global ocean circulation and associated heat transport and climate, as
well as having a profound local impact.
Today, the volume of dense water supplied by Atlantic-Mediterranean exchange through the Gibraltar Strait is amongst the
largest in the global ocean. For the past five million years this overflow has generated a saline plume at intermediate depths
in the Atlantic that deposits distinctive contouritic sediments in the Gulf of Cadiz and contributes to the formation of North
Atlantic Deep Water. This single gateway configuration only developed in the early Pliocene, however. During the Miocene,
a wide, open seaway linking the Mediterranean and Atlantic evolved into two narrow corridors: one in northern Morocco; the
other in southern Spain. Formation of these corridors permitted Mediterranean salinity to rise and a new, distinct, dense
water mass to form and overspill into the Atlantic for the first time. Further restriction and closure of these connections
resulted in extreme salinity fluctuations in the Mediterranean, leading to the formation of the Messinian Salinity Crisis salt
IMMAGE is an amphibious drilling proposal designed to recover a complete record of Atlantic-Mediterranean exchange from
its Late Miocene inception to its current configuration. This will be achieved by targeting Miocene offshore sediments on
either side of the Gibraltar Strait with IODP and recovering Miocene core from the two precursor connections now exposed
on land with ICDP. The scientific aims of IMMAGE are to constrain quantitatively the consequences for ocean circulation
and global climate of the inception of Atlantic-Mediterranean exchange; to explore the mechanisms for high amplitude
environmental change in marginal marine systems and to test physical
StatusNot started