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April 6, 2022

International Ocean Discovery Program (IODP) Expedition 390 and 393
South Atlantic Transect (I, II)

As a part of International Ocean Discovery Program (IODP, *1), a research cruise of the JOIDES Resolution (*2) is set to begin on 7 April 2022 as IODP Expedition 390/393 program (see the attached schedule) targeting to oceanic crust and marine sediments on the seafloor across the South Atlantic Ocean. The purpose of this cruise is multidisciplinary and joint scientific ocean drilling project in the South Atlantic Gyre (SAG) sediment, the relationship between chemical gradients and cell density found in the surface and basement rock. It also aims to investigate how rapid climate change affected the Atlantic Ocean current circulation patterns and the Earth’s climate system. It is possible to estimate the marine environment condition, especially the increase and decrease of the temperature, from microfossils.

A total of 26 researchers from Austria, China, Germany, India, Italy, Japan, Korea, United Kingdom, and the United States are scheduled to join Expedition 390. Two onboard scientists and one shore-based science party member will participate from Japan.

A total of 25 researchers from China, France, Germany, India, Japan, Korea, United Kingdom, and the United States are scheduled to join Expedition 393. There is one participants from Japan.

*1 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 (MarE3 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 ©IODP

*2 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.


South Atlantic Transect (I, II)

1. Schedule (local time)

April 7, 2022
Expedition 390 begins
June 7, 2022
Expedition 390 finishes
June 7, 2022
Expedition 393 begins
August 7, 2022
Expedition 393 finishes
Port of departure and return: Cape Town, South Africa

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

2. Scientific Participants from Japan

Expedition Name Affiliation / position Specialized field
390 Masataka Aizawa Graduate School of Engineering and Science, University of the Ryukyus / Postdoctoral fellow Igneous Geochemist
390 Nobuhiro Doi * Division of Earth and Environmental Sciences, Chiba University / Ph.D. Student Micropaleontologist (nannofossils)
390 Mako Takada Graduate School of Frontier Sciences, The University of Tokyo / Ms. Student Microbiologist/Organic Geochemist
393 Daisuke Kuwano Division of Earth and Environmental Sciences, Chiba University / Ph.D. Student Paleontologist (nannofossils)

*Shore-based science member

3. Research Purposes and Objectives

The South Atlantic Transect (SAT) is a multidisciplinary scientific ocean drilling project that comprises two International Ocean Discovery Program (IODP) expeditions (390, April-June 2022, and 393, June-August 2022). These expeditions will recover complete sedimentary sections and the upper ~250 m of the underlying oceanic crust along a slow/intermediate spreading rate Mid-Atlantic Ridge crustal flow line at ~31°S. The sediments along this transect were originally spot cored more than 50 years ago during Deep Sea Drilling Project Leg 3 to help verify the theories of seafloor spreading and plate tectonics. Given dramatic advances in drilling technology and analytical capabilities since Leg 3, many high-priority scientific objectives can be addressed by revisiting the transect. The SAT expeditions will target six primary sites on 7, 15, 31, 49, and 61 Ma ocean crust, which will fill critical gaps in our sampling of intact in situ ocean crust with regards to crustal age, spreading rate, and sediment thickness. These sections are required to investigate the history of the low-temperature hydrothermal interactions between the aging ocean crust and the evolving South Atlantic Ocean and quantify past hydrothermal contributions to global geochemical cycles. The transect traverses the previously unexplored sediment- and basalt-hosted deep biosphere beneath the South Atlantic Gyre from which samples are essential to refine global biomass estimates and investigate microbial ecosystems’ responses to variable conditions in a low-energy gyre and aging ocean crust. The drilling operations will include installation of reentry cones and casing to establish legacy boreholes for future basement hydrothermal and microbiological experiments. The transect is also located near World Ocean Circulation Experiment Line A10, providing access to records of carbonate chemistry and deepwater mass properties across the western South Atlantic through key Cenozoic intervals of elevated atmospheric CO2 and rapid climate change. Reconstruction of the history of the deep western boundary current and deepwater formation in the Atlantic basins will yield crucial data to test hypotheses regarding the role of evolving thermohaline circulation patterns in climate change and the effects of tectonic gateways and climate on ocean acidification.

Coggon, R.M., Christeson, G.L., Sylvan, J.B., Teagle, D.A.H., Estes, E., Williams, T., and Alvarez Zarikian, C.A., 2020. Expedition 390/393 Scientific Prospectus: The South Atlantic Transect. International Ocean Discovery Program. https://doi.org/10.14379/iodp.sp.390393.2020


Figure Locations of drilling sites. The red circles represent the primary target sites.

Table List of drilling sites in the projected target

Site / borehole name Water depth (m) Target drilling depth (m) No. of scheduled working days
SATL-13A 3,047 215 7
SATL-25A 3,691 269 8
SATL-33B 4,193 303 9
SATL-43A 4,323 313 10
SATL-53B 4,985 345 11
SATL-54A 4,991 804 20

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・South Atlantic Transect
IODP Copyright Statement : https://iodp.tamu.edu/about/copyright.html


(For IODP and this scientific expedition)
Saneatsu Saito, Deputy General, Operations Department, Institute for Marine-Earth Exploration and Engineering
(For press release)
Press Office, Marine Science and Technology Strategy Department
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