Deciphering the origin of iron oxide-copper-gold deposits in the Carajás Mineral Province from the chemical signature of magnetite and apatite

• Grant number: 21/13414-4
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: April 01, 2022
• End date: December 31, 2023
• Field of knowledge: Physical Sciences and Mathematics - Geosciences - Geology
• Principal Investigator: Lena Virginia Soares Monteiro
• Grantee: Ligia Stama
• Host Institution: Instituto de Geociências (IGC). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

The Carajás Province, located in the Amazonian Craton, stands out worldwide for its metallogenetic diversity, giant iron ore reserves, and large amounts of iron-copper-gold oxide (IOCG) deposits. The IOCG deposits had a complex geological evolution and record the superposition of at least four hydrothermal events in the Neoarchaean and Paleoproterozoic (ca. 2.70 Ga; ca. 2.57 Ga; ca. 2.05 Ga; ca. 1.88 Ga). However, the significance of each event for the formation of the largest mineral reserves still needs to be better understood. In particular, the relationship between metallogenetic, tectonic and magmatic events has yet to be established. Aiming to contribute to determining physicochemical parameters important for understanding the genesis of the IOCG deposits in the Carajás Province and its possible relationship with magmatism, this study focuses on the AQW2 deposit, located in the Aquiri region, in the westernmost portion of the Carajás Province. This region represents a frontier for mineral research, about which knowledge is still incipient. The study aims to recognize: (i) the paragenetic evolution of the hydrothermal alteration zones and the types of copper-gold ore in the AQW2 deposit; (ii) mode of occurrence and magnetite and apatite textural and paragenetic relationships in the AQW2 deposit; and (iii) chemical composition (major and minor elements) from different generations of magnetite and apatite and interpretation of their implications for the evolution of the IOCG system in Carajás. Thus, this project will provide critical physicochemical parameters (e.g., fO2, temperature) to understand the evolution of superimposed hydrothermal events in the Aquiri region and their correlations with the IOCG deposits in the Carajás Province.(AU)