During International Ocean Discovery Program Expedition 392, three sites were drilled on the Agulhas Plateau and one site was drilled in the Transkei Basin in the Southwest Indian Ocean. This region was positioned at paleolatitudes of ~53°–61°S during the Late Cretaceous (van Hinsbergen et al., 2015) (100–66 Ma) and within the new and evolving gateway between the South Atlantic, Southern Ocean, and southern Indian Ocean basins. Recovery of basement rocks and sedimentary sequences from the Agulhas Plateau sites and a thick sedimentary sequence in the Transkei Basin provides a wealth of new data to (1) determine the nature and origin of the Agulhas Plateau; (2) significantly advance the understanding of how Cretaceous temperatures, ocean circulation, and sedimentation patterns evolved as CO2 levels rose and fell and the breakup of Gondwana progressed; (3) document long-term paleoceanographic variability through the Late Cretaceous and Paleogene; and (4) investigate geochemical interactions between igneous rocks, sediments, and pore waters through the life cycle of a large igneous province (LIP). Importantly, postcruise analysis of Expedition 392 drill cores will allow testing of competing hypotheses concerning Agulhas Plateau LIP formation and the role of deep ocean circulation changes through southern gateways in controlling Late Cretaceous–early Paleogene climatemore »
Expedition 392 Scientific Prospectus: Agulhas Plateau Cretaceous Climate
The long-term climate transition from the Cretaceous greenhouse to the late Paleogene icehouse provides an opportunity to study changes in Earth system dynamics associated with large changes in global temperature and atmospheric CO2 levels. Elevated CO2 levels during the mid-Cretaceous supergreenhouse interval (~95–80 Ma) resulted in low meridional temperature gradients, and oceanic deposition during this time was punctuated by widespread episodes of severe anoxia termed oceanic anoxic events, resulting in enhanced burial of organic carbon in conjunction with transient carbon isotope and temperature excursions. The prolonged interval of mid-Cretaceous warmth and subsequent Late Cretaceous–Paleogene climate trends, as well as intervening short-lived climate excursions, are poorly documented in the southern high latitudes. International Ocean Discovery Program (IODP) Expedition 392 aims to drill five sites in the southwest Indian Ocean on the Agulhas Plateau and in the Transkei Basin, positioned at paleolatitudes of 65°–58°S during the Late Cretaceous (100–66 Ma) and in the new and evolving gateway between the South Atlantic, Southern Ocean, and southern Indian Ocean basins. Recovery of basement rocks and expanded sedimentary sequences from the Agulhas Plateau and Transkei Basin will provide a wealth of new data to (i) determine the nature and origin of the Agulhas Plateau and more »
- Award ID(s):
- 1326927
- Publication Date:
- NSF-PAR ID:
- 10229902
- Journal Name:
- Scientific prospectus
- Volume:
- 392
- ISSN:
- 2332-1385
- Sponsoring Org:
- National Science Foundation
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International Ocean Discovery Program (IODP) Expedition 361 drilled six sites on the southeast African margin and in the Indian-Atlantic ocean gateway, southwest Indian Ocean, from 30 January to 31 March 2016. In total, 5175 m of core was recovered, with an average recovery of 102%, during 29.7 days of on-site operations. The sites, situated in the Mozambique Channel at locations directly influenced by discharge from the Zambezi and Limpopo River catchments, the Natal Valley, the Agulhas Plateau, and Cape Basin, were targeted to reconstruct the history of the greater Agulhas Current system over the past ~5 my. The Agulhas Current is the strongest western boundary current in the Southern Hemisphere, transporting some 70 Sv of warm, saline surface water from the tropical Indian Ocean along the East African margin to the tip of Africa. Exchanges of heat and moisture with the atmosphere influence southern African climates, including individual weather systems such as extratropical cyclone formation in the region and rainfall patterns. Recent ocean model and paleoceanographic data further point at a potential role of the Agulhas Current in controlling the strength and mode of the Atlantic Meridional Overturning Circulation (AMOC) during the Late Pleistocene. Spillage of saline Agulhas water intomore »
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Accepted Manuscript1.0
- Publisher's Version of Record
- https://doi.org/10.14379/iodp.sp.392.2020
