Application deadline: 24 March 2023

Expedition 401: Mediterranean-Atlantic Gateway Exchange
10 December 2023 – 9 February 2024

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. 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 giant.

IODP Expedition 401 is one part of an amphibious drilling proposal that also includes coring on land as part of the International Continental Drilling Program (ICDP). The Investigating Miocene Mediterranean-Atlantic Gateway Exchange (IMMAGE) drilling proposal is designed to recover a complete record of Atlantic-Mediterranean exchange from its Late Miocene inception to its current configuration. This will be achieved by coring Miocene offshore sediments and borehole logging at three sites on either side of the Gibraltar Strait during IODP Expedition 401 and from the two precursor connections now exposed on land in southern Spain and northern Morocco with ICDP. 

Ichnological content and Bioturbation Index (BI) based on high-resolution treated image from core section U1385A_5H_5. Ch, Chondrites; Pl, Planolites; Th, Thalassinoides; Th-l; Thalassinoides-like; Zo, Zoophycos.

IMMAGE has three primary scientific objectives which will be met through drilling the three IODP holes during Expedition 401 and the two ICDP holes:

  1. To document the time at which the Atlantic first started to receive a distinct overflow from the Mediterranean and to evaluate quantitatively its role in Late Miocene global climate and regional environmental change.
  2. To recover a complete record of Atlantic-Mediterranean exchange before, during and after the Messinian Salinity Crisis and to evaluate the causes and consequences of this extreme oceanographic event, locally, regionally and globally.
  3. To test our quantitative understanding of the behavior of ocean plumes during the most extreme exchange in Earth’s history.

Click here for more information on the expedition science objectives. This page includes links to the individual expedition web pages with the original IODP proposals and expedition planning information. 


We encourage applications from all qualified scientists (including graduate students) specializing in sedimentology (ichnology). The JOIDES Resolution Science Operator (JRSO) is committed to a policy of broad participation and inclusion, and to providing a safe, productive, and welcoming environment for all program participants. Good working knowledge of the English language is required.


Applications for participation must be submitted to the appropriate IODP Program Member Office (PMO). For PMO links, see