Basic-ultrabasic magmatic bodies of SiO2-undersaturated affinity from the Brazilian platform: study of sources and open-system evolution processes in complex plumbing systems using microanalytical approach

• Grant number: 23/11675-0
• Support Opportunities: Regular Research Grants
• Start date: December 01, 2023
• End date: May 31, 2026
• Field of knowledge: Physical Sciences and Mathematics - Geosciences - Geology
• Principal Investigator: Rogério Guitarrari Azzone
• Grantee: Rogério Guitarrari Azzone
• Host Institution: Instituto de Geociências (IGC). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated researchers: Elisa Soares Rocha Barbosa ; Excelso Ruberti ; Luanna Chmyz

Abstract

The present project aims to conduct a petrological study on specific SiO2-undersaturated basic-ultrabasic magmatic bodies of the Brazilian Platform, with a particular focus on in situ microanalytical techniques for compositional analyses of major, minor, trace elements, and isotopes of selected key minerals. Such punctual compositions of key minerals will, in the case of mantle xenocrysts, enable the study of sources and their complexities, such as calculating intensive parameters (P, T, fO2), and possible influences of metasomatic processes; in the case of antecrysts and phenocrysts, they will facilitate a better understanding of open-system evolution processes, such as interactions between magmas of contrasting compositions and/or crustal assimilation processes. This detailed type of study has proven to be of fundamental importance in investigations of kimberlite-affinity bodies, which invariably exhibit a significant load of mantle xenocrysts and various types of interactions with crustal materials, as well as in the examination of porphyritic rocks with mesocratic to melanocratic character, such as basalts, alkaline basalts, alkaline lamprophyres, and intrusive types associated with mafic-ultramafic cumulate bodies of alkaline affinity. In the occurrences of Brazilian platform, most of these magmatic types are representative of complex, multi-intrusive systems, with evolution in interconnected deep-seated fossilized chambers (complex plumbing systems), composed of different crystal populations with distinct genetic significance. Even for carbonatites, processes of assimilation of silicate host rocks are only identified through detailed studies. The project will seek to encompass specific topics that are still relatively unexplored for Cretaceous SiO2-undersaturated occurrences, employing novel concepts, such as: 1) identification and characterization of the different crystal populations present in heterogeneous and hybrid rocks (e.g., phenocrysts vs. antecrysts, cognate crystals vs. xenocrysts), 2) detailed study of zoning patterns and textures associated with major minerals, specially those more extensive crystallization history in each system, whether found in hypabyssal to volcanic varieties or crystallized in magma chamber environments; 3) petrological processes that can be inferred and/or evidenced by understanding the influence of such populations, thus providing robust data for (4) geochemical modeling of processes through algorithms with a compositional and thermodynamic basis (e.g. Melts, Magma Chamber Simulator). (AU)

Scientific publications

(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)

AZZONE, R. G.; PEARSON, D. G.; SARKAR, C.; CETINA, L. M. T.; CHMYZ, L.; LUO, Y.; RUBERTI, E.; GUARINO, V.; CABRAL-NETO, I.. Robust methods, tricky materials: Challenges in dating high common-Pb perovskite from Cretaceous Brazilian kimberlites. CHEMICAL GEOLOGY, v. 670, p. 19-pg., 2024-09-13. (17/21397-7, 23/12323-0, 19/22084-8, 17/03768-8, 23/11675-0)

DE SOUZA, AMANDA ANDRADE; AZZONE, ROGERIO GUITARRARI; CHMYZ, LUANNA; TARAZONA, LINA MARIA CETINA; DE ANDRADE, FABIO RAMOS DIAS; MARTINS, JOSE VINICIUS; RUBERTI, EXCELSO; GOMES, CELSO DE BARROS. Genesis of Fe-Ti-(V) Oxide-Rich Rocks by Open-System Evolution of Mafic Alkaline Magmas: The Case of the Ponte Nova Massif, SE Brazil. MINERALS, v. 14, n. 7, p. 26-pg., 2024-07-01. (19/22084-8, 23/11675-0)

CHMYZ, LUANNA; AZZONE, ROGERIO GUITARRARI; RUBERTI, EXCELSO; GUARINO, VINCENZA. Wall rock assimilation in carbonatite magmas: Textural, mineral and whole-rock geochemical signatures in the Jacupiranga complex, Brazil. CHEMIE DER ERDE-GEOCHEMISTRY, v. 85, n. 1, p. 16-pg., 2025-04-25. (23/12323-0, 18/15731-4, 19/22084-8, 23/11675-0)