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International Ocean Discovery Program (IODP) Expedition 401 Mediterranean–Atlantic Gateway Exchange


As part of the International Ocean Discovery Program (IODP)※1, JOIDES Resolution※2 research cruise IODP Expedition 401 is set to begin on 10 December 2023 (see addendum).

IODP Expedition 401 plans to drill at three sites in the Atlantic and Mediterranean across the Gibraltar Strait with the aim of recovering a complete core record of the Atlantic–Mediterranean exchange during Late Miocene to Early Pliocene (approximately 5 to 8 million years ago).

This is the first drilling phase of the first-ever Land-2-Sea Proposal※3, called Investigating Miocene Mediterranean–Atlantic Gateway Exchange (IMMAGE), and therefore will be followed by the International Continental Scientific Drilling Program (ICDP)※4 in onshore Spain and Morocco.

Totally twenty-seven researchers from Australia, China, France, India, Japan, Morocco, the Netherlands, Norway, Spain, the United Kingdom and the United States are scheduled to join this research cruise, including three Japanese onboard research participants.

Supplemental Information

International Ocean Discovery Program (IODP)
This international scientific research cooperative project started in October 2013. By drilling deep below the ocean floors using drilling vessels provided by Japan (JAMSTEC DV Chikyu), the United States (JOIDES Resolution), and Europe (Mission-Specific Platforms), IODP promotes research aimed at elucidating the internal structure and the biosphere within and below the Earth’s crust.


JOIDES Resolution
The JOIDES Resolution Science Operator (JRSO) manages and operates the riserless drillship, JOIDES Resolution, for the International Ocean Discovery Program (IODP). The JRSO is based in the College of Geosciences of Texas A&M University.

JOIDES Resolution ©IODP


Land-2-Sea Proposals (L2S)
L2S Proposals are designed for projects that can be jointly implemented by the ICDP and IODP. L2S Proposals are those for which full achievement of the scientific objectives require scientific drilling at both onshore and offshore sites or at shallow marine sites.


International Continental Scientific Drilling Program (ICDP)
ICDP is an international scientific research project with the objective of addressing diverse challenges in earth science. It involves collecting subsurface samples through drilling on land and observing geophysical properties in boreholes to reveal various phenomena on the Earth's surface and interior. Japan joined the program in 1998, and the headquarters has been situated at the German Research Center for Geosciences since 1996.


Mediterranean–Atlantic Gateway Exchange

1. Schedule (local time)

IODP Expedition 401

10 December 2023 Research cruise begins (Port of departure: Amsterdam, Netherlands)
9 February 2024 Research cruise finishes (Port of return: Naples, Italy)

※The schedule may change depending upon the condition/inflences of COVID-19, the progress in sailing preparations, weather conditions, research activities, etc.

2. Scientists scheduled to participate from Japan

Name Affiliation / position Specialized field
Kosuke Egawa Department of Earth Resources Engineering,
Kyushu University / Associate Professor
Erika Tanaka Marine Core Research Institute, Kochi University / Assistant Professor Inorganic Geochemist
Xunhui Xu Department of Urban Management, Kyoto University / Ph.D. student Physical Properties Specialist

3 Research Purposes and Objectives

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. During the Miocene, a wide, open seaway linking the Mediterranean and Atlantic evolved into two narrow corridors: one in northern Morocco and one in southern Spain, both of which face the Gibraltar Strait today. The development of these corridors permitted the Mediterranean salinity to rise, which caused overspill of distinct dense water mass into the Atlantic for the first time. Further restriction and closure of these connections have accelerated extreme salinity fluctuations in the Mediterranean, leading to the Messinian Salinity Crisis to form salt giants. IODP Expedition 401 targets (i) to quantitatively constrain the consequences for ocean circulation and global climate by the inception of Atlantic–Mediterranean exchange, (ii) to explore the mechanisms for high-amplitude environmental change in marginal marine systems, and (iii) to test physical oceanographic hypotheses for extremely high-density overflow dynamics that never happen in the present day on such a large scale.

Flecker, R., Ducassou, E. and Williams, T., 2023, Expedition 401 Scientific Prospectus: Mediterranean–Atlantic Gateway Exchange. International Ocean Discovery Program. https://doi.org/10.14379/iodp.sp.401.2023


Figure Topographic map of the continent and seafloor in the study are with the locations of the planned drilling sites.
The orange and yellow circles represent the primary target site and alternate site, respectively (cited from IODP Exp. 401 Scientific Prospectus).

Table List of drilling sites in the projected target
Site / borehole name Water depth (m) Target drilling depth (m) No. of scheduled working days
ALM-03B 1,638 930 10
GUB-02A 558 1,464 11
WAB-03A 811 1,700 17

Note: Drilling sites may change depending upon sailing preparations, weather conditions, and/or research progress.

※Figure is cited from the IODP website with partial modification.

IODP JRSO・Expeditions・Mediterranean-Atlantic Gateway Exchange

【Reference】IODP Copyright Statement

For IODP and this scientific expedition

Saneatsu Saito, Deputy Director, Operations Department, Institute for Marine-Earth Exploration and Engineering

For press release

Press Office, Marine Science and Technology Strategy Department