Caracterização morfológica da porção norte do arquipélago de São Pedro e São Paulo a partir de batimetria multifeixe

Abstract

Mapping the seabed plays an essential role in understanding and exploiting ocean ecosystems, and is vital for various scientific, economic and environmental applications. One of the techniques used for this purpose is multibeam bathymetry, which involves the precise measurement of ocean depths and the creation of three-dimensional maps of the seabed. The relevance of this mapping is linked to the search for natural and marine resources, safety in navigation and an understanding of underwater geological processes. The research was carried out in the South Atlantic, close to the Archipelago of São Pedro and São Paulo, covering an area of approximately 1700 square kilometers. The bathymetric data were collected in 2023, during an expedition by the hydroceanographic vessel (NpqHOc) Vital de Oliveira, from the Brazilian Navy, within the scope of the QWHALES project. Bathymetry was acquired using an EM-122 multibeam echo sounder. Bathymetric processing was carried out with the CARIS HIPS and SIPS 12.0 software. Additionally, geographic information system (GIS) software ArcGis 10.5 and ArcScene 10.5 were used to create maps, elevation profiles and images with 3D visualization of the region. After processing, a map of bathymetry, slope and three terrain elevation profiles were prepared. As a result, it was possible to identify four distinct features: the São Pedro and São Paulo transform fault, an elevation with elongated geometry running N-S, bodies with topographic protrusion on the flank of the peridotite chain, abyssal sub-basins at the foot of the flank, finally the peridotite chain of São Pedro and São Paulo, which is the feature that stands out most due to its high topography. The depth of the study area ranges from 5,831 to 853 meters. The slope of the northern region of the archipelago ranges from 0 to 84 degrees, and most of the area studied has moderate to gentle slopes, reflecting a relatively stable and less rugged relief. This study made it possible to identify and correlate, with previous work, the morphology present in the submarine topography of the northern region of the São Pedro e São Paulo Archipelago.