Geochemical characterization and geological significance of carbonate crusts in the Rio Grande Rise (South Atlantic Ocean)

• Grant number: 22/03363-6
• Support Opportunities: Scholarships in Brazil - Doctorate (Direct)
• Effective date (Start): September 01, 2022
• Effective date (End): December 31, 2026
• Field of knowledge: Physical Sciences and Mathematics - Oceanography - Geological Oceanography
• Principal Investigator: Christian Millo
• Grantee: Alexandre Henrique Ferraz
• Host Institution: Instituto Oceanográfico (IO). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

The Rio Grande Rise (RGR) is a wide oceanic rise located ~1200 km to the East of Brazil and 2000 km to the west of the Mid-Atlantic Ridge. The RGR is becoming increasingly relevant for Brazil, because in 2015 the International Seabed Authority (ISA) and the Brazilian Companhia de Pesquisa de Recursos Minerais (CPRM) signed a contract for the exploration of minerals in the region. In 2018, two oceanographic cruises of IOUSP revealed the presence of extensive carbonate crust at several sites of the RGR. Little is known about the formation mechanisms of these carbonates. This PhD project aims at 1) characterize the mineralogy, elemental and isotope composition, cement texture and microfossil content of these carbonate crusts; 2) investigate their formation mechanisms, in particular with regards to periods of potential subaerial exposure and/or occurrence of fluid vents; 3) investigate the potential genetic relationship between carbonate and FeMn crusts present in the study area; 4) interpret this information to unravel the recent geological history of the RGR. The samples for this study were collected during the scientific cruises of IOUSP in 2018, and are available at the Institute. All the analyses will be carried out at the IOUSP or in collaboration with partner laboratories at the USP. This PhD project will obtain valuable information for the understanding of the geochemical processes in the RGR, particularly with regards to the formation of minerals on the seafloor. (AU)