This work was done in the Fe-Mn nodules and crusts collected in the Lion Seamount that is located in the Madeira-Tore Rise. The 48 samples to be studied in this project were collected during the oceanographic campaign to the MTR carried out on board the O/V Mário Ruivo. Fe and Mn crusts and nodules are important because they are a potential resource for several elements. There are three main types of Fe-Mn deposits: hydrogenetic, hydrothermal and diagenetic. To differentiate the types of deposits we use Ce and Y anomalies or a Ni+Co+Cu ternary system. Regarding the methods used it was done hand sample description, binocular magnifying glass description, transmitted and reflected light microscopy, XRF, SEM-EDS and FESEM-EDS. We learned that the most represented element in the crusts is Ca followed by Fe and Mn, respectively. There are also important concentrations of P, Ni, Si and Sr. We also found microorganisms, biofilms of bacteria and various biomineralizations. We concluded that the nodules and crusts have mainly an hydrogenetic origin, because the samples are placed in the hydrogenetic zone in the Ni+Co+Cu ternary system. However, it is necessary to do analyses on the REE in order to see anomalies in Ce and confirm this. Also, the microbial contribution to promote Fe-Mn growth were predominant, so it is suggested that the formation of the nodules can be characterized as a biologically induced mineralization process. Finally, to exploit Fe-Mn deposits it should start in the Pacific Ocean because the content in important metals is more enriched there. However, there is some potential of exploitation in the Lion Seamount. Finally, more studies are necessary, between various disciplines and industries to ensure that more places like the MTR are explored and also to characterize the biological role in the formation of these crusts and nodules.

Relatório de estágio de mestrado, Geologia (Geodinâmica e Recursos Geológicos), 2024, Universidade de Lisboa, Faculdade de Ciências