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1. Mediterranean–Atlantic Gateway Exchange

   Flecker, R; Ducassou, E; Williams, T (July 2025, Proceedings of the International Ocean Discovery Program Expedition reports)

   Marine gateways play a critical role in the exchange of water, heat, salt, and nutrients between oceans and seas. Changes in gateway geometry can significantly alter both the pattern of global ocean circulation and climate. Today, the volume of dense water supplied by Atlantic–Mediterranean exchange through the Gibraltar Strait is among the largest in the global ocean. For the past 5 My, this overflow has generated a saline plume at intermediate depths in the Atlantic that deposits distinctive contouritic sediments and contributes to the formation of North Atlantic Deep Water. This single gateway configuration only developed in the Early Pliocene. During the Miocene, two narrow corridors linked the Mediterranean and Atlantic: one in northern Morocco and the other in southern Spain. Progressive restriction and closure of these corridors resulted in extreme salinity fluctuations in the Mediterranean and the precipitation of the Messinian Salinity Crisis salt giant. International Ocean Discovery Program (IODP) Expedition 401 is the offshore drilling component of a Land-2-Sea drilling proposal, Investigating Miocene Mediterranean–Atlantic Gateway Exchange (IMMAGE). Its aim is to recover a complete record of Atlantic–Mediterranean exchange from its Late Miocene inception to its current configuration by targeting Miocene offshore sediments on either side of the Gibraltar Strait. Miocene cores from the two precursor connections now exposed on land will be obtained by future International Continental Scientific Drilling Program (ICDP) campaigns. 

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2. Expedition 401 Scientific Prospectus: Mediterranean–Atlantic Gateway Exchange

   https://doi.org/10.14379/iodp.sp.401.2023  

    Flecker, R.; Ducassou, E.; Williams, T. (April 2023, Scientific prospectus)

   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 because 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 5 My, 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 giant. Investigating Miocene Mediterranean–Atlantic Gateway Exchange (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 during International Ocean Discovery Program (IODP) Expedition 401 and recovering Miocene core from the two precursor connections now exposed on land with future International Continental Scientific Drilling Program (ICDP) campaigns. 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 oceanographic hypotheses for extreme high-density overflow dynamics that do not exist in the world today on this scale. 

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3. Data report: X-ray fluorescence scanning of sediment cores, IODP Expedition 401 Site U1609, SW Iberia Atlantic margin (Portugal)

   https://doi.org/10.14379/iodp.proc.401.201.2026  

   Teixeira, M; Chin, S; Standring, P; Zhang, Y; Billy, I; Feakins, SJ; Li, Z; Mulligan, M; Noto, D; Raad, F; et al (January 2026, Proceedings of the International Ocean Discovery Program Expedition reports)

   International Ocean Discovery Program Expedition 401 recovered 983 m of sediment from Portugal’s southwest margin in the northeast Atlantic Ocean at Site U1609 (37°22.6259′ N, 9°35.9120′ W; 1659.5 m water depth). This site was designed to recover the distal contourites deposited by the Mediterranean Overflow Water contour current from the late Miocene to the Pleistocene. We report semiquantitative elemental results from X-ray fluorescence scanning of sediment cores from Site U1609 (Holes U1609A and U1609B) scanned at a 4–5 cm resolution from ~202 to 509 m core depth below seafloor, Method A, equivalent to ~4.52 to ~7.8 Ma. Raw element intensities (in counts per second) for Al, Si, Ca, Ti, Mn, Fe, Rb, Sr, Zr, and Ba are presented here and correlated with lithofacies variations. We also identify biogenic-terrestrial input proportions and illustrate downcore cyclicity and correlation patterns between terrigenous components (Al, Si, Ti, Mn, and Ba), as well as their anticorrelations with biogenic (Ca and Sr) inputs. The cyclical variations in elemental ratios may help stratigraphic correlation between Holes U1609A and U1609B, astronomical tuning of the spliced record, and sedimentary interpretations of changes to the Mediterranean–Atlantic gateway and the bottom current circulation along the Atlantic margin of Portugal before, during, and after the Messinian Salinity Crisis. 

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4. Teleconnection between the Atlantic Meridional Overturning Circulation and Sea Level in the Mediterranean Sea

   https://doi.org/10.1175/JCLI-D-18-0474.1  

   Volkov, Denis L.; Baringer, Molly; Smeed, David; Johns, William; Landerer, Felix W. (February 2019, Journal of Climate)

   null (Ed.)

   The Mediterranean Sea can be viewed as a “barometer” of the North Atlantic Ocean, because its sea level responds to oceanic-gyre-scale changes in atmospheric pressure and wind forcing, related to the North Atlantic Oscillation (NAO). The climate of the North Atlantic is influenced by the Atlantic meridional overturning circulation (AMOC) as it transports heat from the South Atlantic toward the subpolar North Atlantic. This study reports on a teleconnection between the AMOC transport measured at 26.5°N and the Mediterranean Sea level during 2004–17: a reduced/increased AMOC transport is associated with a higher/lower sea level in the Mediterranean. Processes responsible for this teleconnection are analyzed in detail using available satellite and in situ observations and an atmospheric reanalysis. First, it is shown that on monthly to interannual time scales the AMOC and sea level are both driven by similar NAO-like atmospheric circulation patterns. During a positive/negative NAO state, stronger/weaker trade winds (i) drive northward/southward anomalies of Ekman transport across 26.5°N that directly affect the AMOC and (ii) are associated with westward/eastward winds over the Strait of Gibraltar that force water to flow out of/into the Mediterranean Sea and thus change its average sea level. Second, it is demonstrated that interannual changes in the AMOC transport can lead to thermosteric sea level anomalies near the North Atlantic eastern boundary. These anomalies can (i) reach the Strait of Gibraltar and cause sea level changes in the Mediterranean Sea and (ii) represent a mechanism for negative feedback on the AMOC. 

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5. Expedition 388 Scientific Prospectus: Equatorial Atlantic Gateway

   https://doi.org/10.14379/iodp.sp.388.2019  

   Dunkley Jones, T.; Fauth, G.; LeVay, L.J. (June 2019, Scientific prospectus)

   null (Ed.)

   International Ocean Discovery Program (IODP) Expedition 388 seeks to answer first-order questions about the tectonic, climatic, and biotic evolution of the Equatorial Atlantic Gateway (EAG). The scheduled drilling operations will target sequences of Late Cretaceous and Cenozoic sediments offshore northeast Brazil, just south of the theorized final opening point of the EAG. These sequences are accessible to conventional riserless drilling in the vicinity of the Pernambuco Plateau, part of the northeastern Brazilian continental shelf. This region was chosen to satisfy two key constraints: first, that some of the oldest oceanic crust of the equatorial Atlantic and overlying early postrift sediments are present at depths shallow enough to be recovered by riserless drilling, and second, Late Cretaceous and Paleogene sediments preserved on the Pernambuco Plateau are close enough to the continental margin and at shallow enough paleowater depths (<2000 m) to provide well-preserved organic biomarkers and calcareous microfossils for multiproxy studies of greenhouse climate states. New records in this region will allow us to address major questions in four key objectives: the early rift history of the equatorial Atlantic, the biogeochemistry of the restricted equatorial Atlantic, the long-term paleoceanography of the EAG, and the limits of tropical climates and ecosystems under conditions of extreme warmth. Tackling these major questions with new drilling in the EAG region will advance our understanding of the long-term interactions between tectonics, oceanography, ocean biogeochemistry, and climate and the functioning of tropical ecosystems and climate during intervals of extreme warmth. 

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