NERC-FAPESP: The Marine Gateway Project: quantifying the causes and climatic consequences of the opening of the South Atlantic and the formation of its salt giant

• Grant number: 22/02398-0
• Support Opportunities: Regular Research Grants
• Start date: September 01, 2022
• End date: February 28, 2025
• Field of knowledge: Physical Sciences and Mathematics - Oceanography - Geological Oceanography
• Agreement: NERC, UKRI
• Principal Investigator: Luigi Jovane
• Grantee: Luigi Jovane
• Principal researcher abroad: Rachel Flecker
• Institution abroad: University of Bristol, England
• Host Institution: Instituto Oceanográfico (IO). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated researchers: André Pires Negrão ; Dan Lunt ; Dan Valentin Palcu-Rolier ; Ian John Parkinson ; Paul Meijer
• Associated research grant: 16/24946-9 - Sea-level changes and Global Monsoon System: clues from marine cores in Brazil, AP.PFPMCG.TEM

Abstract

Ocean circulation is driven by water masses with different densities. Much of this is generated at the ocean-continent boundary, where near landlocked seas have a restricted connection with the global ocean, allowing them to evolve a different temperature or salinity. These marginal basins often form when continental plates coalesce - the Mediterranean today is a good example of this - or disaggregate - the opening of the South Atlantic around 100 million years as Gondwana broke apart ago is another. The evolution of these marine gateways therefore has a profound impact on the patterns of ocean circulation and its vigour and may play a role in the transition between greenhouse and icehouse climatic conditions. Marine gateways are unsurprisingly the focus of several upcoming international scientific drilling projects. When the marine gateway allows only very limited exchange, large volumes of evaporites may precipitate in the marginal basin. These salt giants, which are not forming in the world today, can be sufficiently large to change the salinity of the global ocean. The most recent salt giant formed around 5 million years ago in the Mediterranean. Using isotopes that respond to the different proportions of ocean and river water feeding the marginal basin integrated with box modelling and global climate simulations, it has been possible to reconstruct and quantify Mediterranean-Atlantic exchange and show that the major climate impact of this gateway precedes evaporite precipitation by several million years. In this project we propose to develop and apply these techniques to the older and larger South Atlantic salt giant where there is still controversy over the location and timing of gateway evolution and hence the climatic impact of opening the South Atlantic. To do this we are extending an existing collaboration between Bristol and Utrecht where researchers have led much of the Atlantic-Mediterranean gateway research to include researchers at University of São Paulo who have essential expertise in the palaeogeography and chronology of the South Atlantic salt-bearing successions. This is therefore a joint NERC-FAPESP international partnership application. Over two years we propose to undertake fieldwork in Brazil led by the University of São Paulo, isotope and GCM analysis at the University of Bristol and box-modelling at the Utrecht University. An early meeting in Bristol to review the initial pilot data will be followed by a mid-project model-data integration workshop in São Paulo. The workshop will be open to the wider research community in Brazil, and we will specifically support PhD students to apply for internship scholarships (FAPESP-BEPE) in order to be actively involved in the project. The last phase of this project will draw in researchers involved in marine gateway research associated with scientific drilling, three of which are led by UK scientists. The final meeting will be a forum both for presenting the scientific results of the project and for initiating an EU COST-Action application to support ongoing community-building collaborative research activities. This is designed to expand and renew the scientific community engaged with long-term scientific drilling projects focused on marine gateways. (AU)