Tracking upwelling variability in Cabo Frio using grain-size and minerals distributions

• Grant number: 23/13167-2
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date until: November 01, 2023
• End date until: October 31, 2024
• Field of knowledge: Physical Sciences and Mathematics - Oceanography - Geological Oceanography
• Principal Investigator: Luigi Jovane
• Grantee: Martin Vicente Belz Fachetti
• Host Institution: Instituto Oceanográfico (IO). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated research grant: 16/24946-9 - Sea-level changes and Global Monsoon System: clues from marine cores in Brazil, AP.PFPMCG.TEM

Abstract

Sediment cores from the Southeastern Brazilian shelf have provided records of environmental changes in the Southwestern Atlantic Margin. Southward shift of the Intertropical Convergence Zone (ITCZ) average latitudinal position over the South American continent during the Holocene climatic maximum has provided changes in the wind-driven current system of the SW Atlantic margin, which modifies grain size characteristics and rock magnetic properties of the sediments deposited there. Stronger NNE trade winds off southeastern Brazil allow high discharge events, favouring SW transport of sediments from the Paraíba do Sul River to the shelf off Cabo Frio. Those variabilities occur probably due to the incorporation of material from continental crustal rocks of Ribeira Belt. As the distance from the holes increases relative to the coast, an organization in the paleomagnetic patterns, which indicates the capture of magnetization signals, is more clearly observed. These records are frequently covered up in the cores closest to the coast probably due to the influence of continental river discharge and diagenetic effects. With the recovery of cores in deeper regions we will be able to elaborate an evolutionary framework for region over time and space based on paleoceanographic studies involving integration of various multiproxy. This study in collaboration with UFF (Ana Luiza Albuquerque) will allow separating different responses to the same climatic events. The delimitation of the area where the action of increased continental sediment transport to the shelf off Cabo Frio due to strengthening of rainfall and the action of Brazil Current cover the answer of the resurgence phenomenon, as well as the variation of this balance over time. We want to undertake grain-size analysis, XRD and XRF of the sediments collected by the cores in Cabo Frio.