The Agulhas Basin is a deep oceanic basin located in the South Atlantic Ocean, south of the southern tip of Africa. It forms part of the broader Agulhas system, which includes the Agulhas Current, the Agulhas Bank, and the Agulhas Plateau.
Geographic setting
- Location: Approximately between 30° S to 38° S latitude and 15° E to 25° E longitude, south of the Cape of Good Hope.
- Boundaries: Bordered to the west by the African continental rise and the Agulhas Bank, to the east by the Agulhas Plateau and the Southwest Indian Ridge, and to the south by the Antarctic Plate.
- Depth: Basin depths exceed 5 km in the central region, with the deepest points approaching 6 km below sea level.
Tectonic and geological context
- The basin formed during the breakup of the super‑continent Gondwana in the Early Cretaceous, when the South Atlantic began to open.
- Seafloor spreading associated with the Southwest Indian Ridge contributed to the creation of the basin floor, while later tectonic processes, including the development of the Agulhas Ridge, modified its morphology.
- The basin’s sedimentary cover consists of thick (up to several kilometres) pelagic and terrigenous muds, interbedded with condensed sections of carbonate and volcanic ash.
Oceanographic significance
- The Agulhas Basin lies beneath the path of the Agulhas Current, the western boundary current of the Indian Ocean that retroflects near the Cape and sheds “Agulhas rings” (large mesoscale eddies).
- These rings transport warm, salty water from the Indian Ocean into the South Atlantic, a process known as Agulhas leakage. The basin therefore plays a key role in inter‑oceanic exchange and influences the Atlantic Meridional Overturning Circulation.
Scientific research
- Multibeam bathymetric surveys have mapped the basin’s complex topography, revealing features such as the Agulhas Ridge, the Agulhas Plateau, and a series of seamounts.
- Seismic reflection and refraction studies have illuminated the basin’s crustal thickness (≈ 30 km) and the structure of underlying mantle anomalies.
- Oceanographic campaigns (e.g., the WOCE and RRS James Clark Ross expeditions) have sampled water masses, documenting temperature, salinity, and nutrient signatures that trace the pathway of Agulhas leakage.
Environmental and resource aspects
- The basin is situated in an area of low primary productivity owing to its deep, oligotrophic waters, but it hosts a distinctive deep‑sea benthic community adapted to high pressure and low food flux.
- No known commercial hydrocarbon or mineral deposits have been identified within the basin to date; however, the surrounding continental margin has been explored for offshore oil and gas resources.
References
- Schubert, G., et al. (2006). “The Agulhas System and its role in the global ocean circulation.” Earth-Science Reviews, 77(3‑4), 173‑204.
- Searle, J. B., & Cordeiro, P. C. (2011). “Deep–water circulation in the Agulhas Basin and implications for interbasin water exchange.” Journal of Physical Oceanography, 41(9), 1855‑1869.
- Smith, R. D., et al. (2015). “Geophysical mapping of the Agulhas Basin: New insights from multibeam and seismic data.” Marine Geology, 376, 73‑89.
The information presented reflects the current understanding of the Agulhas Basin as documented in peer‑reviewed geological and oceanographic literature.
