Terraces identification in the Rio Grande Rise, South Atlantic west

• Grant number: 18/12038-6
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: August 01, 2018
• End date: December 31, 2019
• Field of knowledge: Physical Sciences and Mathematics - Oceanography - Geological Oceanography
• Principal Investigator: Luigi Jovane
• Grantee: Raylla Souza Silva
• Host Institution: Instituto Oceanográfico (IO). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated research grant: 14/50820-7 - Marine ferromanganese deposits: a major resource of E-tech elements, AP.TEM

Abstract

Located in the west of the South Atlantic Ocean, the Rio Grande Rise (RGR) has been prominent due to its ferromanganese crusts that have large amounts of cobalt, among others. Its origin is uncertain, but it is known to be related to continental break up during the formation of the South Atlantic, in the mid-oceanic ridge, and with volcanic activities and the following subsidence. The RGR has already been through atmosphere exposure periods and, based on this, the presence of marine terraces was investigated in this work, since the subaerial condition may have allowed the seamount to be hit by waves, responsible for erosion and formation of such terraces. For this geomorphological interpretation and description of terraces in the region, bathymetric data were collected during RGR1 and DY094 cruises of the Marine ferromanganese deposits project - the largest resource of E-tech elements (Marine E-Tech) in 2018, on board of Alpha Crucis and Discovery Oceanographic Ships. The data were processed and depth and geomorphologic maps, three-dimensional images and bathymetric profiles of the region were generated, analyzed and compared to previous studies and publications. The data showed the influence of bottom currents on the recent geomorphology of the Rio Grande Rise, with the presence of sediment waves, erosional terraces, and channels - possibly associated with contourites - especially in the western areas, closer to the Vema Channel.