MICROPALEONTOLOGICAL AND ISOTOPIC INDICATORS OF THE GENESIS OF A SUBMARINE DEPRESSION IN THE NORTHERN SECTOR OF THE RIO GRANDE RISE (SOUTH ATLANTIC)

• Grant number: 25/08500-0
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: August 01, 2025
• Status: Discontinued
• Field of knowledge: Physical Sciences and Mathematics - Oceanography - Geological Oceanography
• Principal Investigator: Christian Millo
• Grantee: Vidda Pereira Machado
• Host Institution: Instituto Oceanográfico (IO). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated scholarship(s): 26/02346-1 - MICROPALEONTOLOGICAL AND ISOTOPIC INDICATORS OF THE GENESIS OF A SUBMARINE DEPRESSION IN THE NORTHERN SECTOR OF THE RIO GRANDE RISE (SOUTH ATLANTIC), BE.EP.IC

Abstract

The Rio Grande Rise (ERG) is a prominent submarine relief located around 1200 km off the coast of Brazil. Characterized as one of the largest topographic features in the South Atlantic Ocean, it is of great scientific, economic and ecological importance, including a claim for its incorporation into Brazil's exclusive economic zone. This growing interest in the ERG has increased the need to understand its formation and the geological features present in it. Thus, in December 2023, the ERG Petrobras 2023 scientific cruise took place, the main objective of which was to map and collect sediment samples from conical submarine depressions (pockmarks) located in the central-southern sector of the ERG. The mechanism of formation of these depressions is not yet fully understood, but it is speculated that they may be an indication of the presence of gaseous hydrocarbons in the subsoil. This scientific initiation project aims to characterize the surface sediment of one of these depressions, testing the hypothesis that its formation is the result of methane escaping from the seabed, which would corroborate the possibility that hydrocarbons are present in the region's subsoil. The research method will include: (i) characterization of the depositional environment through granulometric analysis of box corer samples; (ii) investigation of the presence of microfossils of benthic foraminifera that indicate the presence of methane, such as Pyrgo spp.; and (iii) study of the possible isotopic signature (extremely negative values of ¿13C) in the foreheads of the microfossils found. The project will provide important information for understanding the processes responsible for the formation of these enigmatic submarine depressions, as well as making a significant contribution to advancing scientific knowledge about the Rio Grande Rise. (AU)