U–Pb geochronology of the Lagoa Real uranium district, Brazil: Implications for the age of the uranium mineralization. (March 2015)

• Record Type: Journal Article
• Authors: Lobato, Lydia Maria; Pimentel, Márcio Martins; Cruz, Simone C.P.; Machado, Nuno; Noce, Carlos Maurício; Alkmim, Fernando Flecha
• Is Part Of: Journal of South American earth sciences. Volume 58(2015:Mar.)
• Page Start: 129
• Page End: 140
• Publication Date: 2015-03
• Subjects: Lagoa Real uranium deposit -- Metasomatic alteration -- U–Pb mineralization age -- Metallogenetic implications; Geology -- Latin America -- Periodicals; Earth sciences -- Latin America -- Periodicals; Geology -- Antarctica -- Periodicals; Earth sciences -- Antarctica -- Periodicals; Geology -- Caribbean Area -- Periodicals; Earth sciences -- Caribbean Area -- Periodicals; Géologie -- Amérique latine -- Périodiques; Sciences de la terre -- Amérique latine -- Périodiques; Géologie -- Antarctique -- Périodiques; Sciences de la terre -- Antarctique -- Périodiques; Géologie -- Caraïbes (Région) -- Périodiques; Sciences de la terre -- Caraïbes (Région) -- Périodiques; Earth sciences; Geology; Antarctica; Caribbean Area; Latin America; Periodicals; 550.5
• DOI: 10.1016/j.jsames.2014.12.005
• Languages: English
• ISSNs: 0895-9811

Abstract

Abstract: The Lagoa Real uranium district in Bahia, northeastern Brazil, is the most important uranium province in the country and presently produces this metal in an open-pit mine operated by Indústrias Nucleares do Brasil. Uranium-rich zones are associated with plagioclase (dominantly albite ± oligoclase) -rich rocks, albitites and metasomatized granitic-gneisses, distributed along NNW/SSE striking shear zones. We have used the ID-TIMS U–Pb method to date zircon and titanite grains from the São Timóteo granitoid, and albite-rich rocks from the Lagoa Real district in order to assess the age of granite emplacement, deformation/metamorphism and uranium mineralization. The isotopic data support the following sequence of events (i) 1746 ± 5 Ma – emplacement of the São Timóteo granitoid (U–Pb zircon age) in an extensional setting, coeval with the beginning of the sedimentation of the Espinhaço Supergroup; (ii) 956 ± 59 Ma hydrothermal alteration of the São Timóteo granitoid and emplacement of the uranium mineralization (U–Pb titanite age on an albite-rich sample); (iii) 480 Ma metamorphism, remobilization and Pb loss (U–Pb titanite age for the gneiss sample), during the nucleation of shear zones related to the collision between the São Francisco-Congo and Amazonia paleoplates. The 956 ± 59-Ma mineralization age is apparently associated with the evolution of the Macaúbas-Santo Onofre rift. This age bracket may bear an important exploration implication, and should be included in the diverse age scenario of uranium deposits worldwide. Highlights: Lagoa Real most important uranium province in Brazil. U–Pb geochronological investigation on zircons and titanites from granitic and albititic rocks. 956 ± 59 Ma, U–Pb titanite age – hydrothermalism, albitite formation, age of uranium mineralization.