Chemical substitution processes during the formation of deep-sea Fe-Mn oxide

• Grant number: 25/04448-3
• Support Opportunities: Scholarships in Brazil - Master
• Start date: September 01, 2025
• End date: December 31, 2026
• Field of knowledge: Physical Sciences and Mathematics - Oceanography - Geological Oceanography
• Principal Investigator: Christian Millo
• Grantee: Victoria Duarte Moreno
• Host Institution: Instituto Oceanográfico (IO). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

Deep-sea polymetallic deposits, composed of Fe-Mn nodules and crusts, are recognized as potential sources of critical elements essential for high-tech industries, particularly in the context of the energy transition. These deposits form through hydrogenetic, hydrothermal, and diagenetic processes, exhibiting extremely slow growth rates. They can precipitate and develop on various types of substrates. However, significant gaps remain in understanding the chemical role of substrates in the initial formation of these oxides. This study aims to investigate the replacement of volcanic minerals by Fe-Mn crusts in seven rock samples collected from the Tropic Seamount (North Atlantic) through quantitative and qualitative elemental and mineralogical characterization, testing the hypothesis that calcium (Ca) is the primary element facilitating the replacement and deposition of Fe-Mn oxides. The methodology will involve analyses using Optical Microscopy, Scanning Electron Microscopy (SEM) coupled with Energy Dispersive X-ray Spectroscopy (EDS), X-ray Fluorescence Spectroscopy (XRF), Raman Spectroscopy, and Electron Probe Microanalysis (EPMA). This project aligns with an internationally expanding research field and contributes to its ongoing development within the country. The expected results aim to address existing knowledge gaps regarding the formation of these crusts and the influence of the substrate on the precipitation of these oxides. (AU)