Produção Nacional
Monazite Age and Composition from A Granite-Pegmatite System: A Link between Pegmatites of the São João Del Rei Pegmatitic Province and the Newly Defined High-K Restinga Metagranite, Minas Gerais, Brazil
2022; RELX Group (Netherlands); Linguagem: Inglês
10.2139/ssrn.4255074
ISSN1556-5068
AutoresSarah Siqueira da Cruz Guimar Sousa, Ciro Alexandre Ávila, Reiner Neumann, Fabiano Richard Leite Faulstich, Ricardo Scholz,
Tópico(s)Clay minerals and soil interactions
ResumoMonazite geochronology (U-Pb by LA-SF-ICP-MS) and chemical composition by electron microprobe were used to characterize the genetic link between a group of pegmatites from the São João del Rei Pegmatitic Province and a newly defined high-K metagranite of the younger Rhyacian-Orosirian Ritápolis arc of the Mineiro Belt. The monazite-(Ce) of four samples from the granite and ten from pegmatites yielded the REE pattern of a granite-pegmatite system, where the ∑LREE is similar, but the content of MREE, and Dy increase with the diminution of the crystallization temperature and, consequently, presenting a higher degree of differentiation. The monazite ages of 2022 ± 17 Ma and 2008 ± 8 Ma in the pegmatites corresponds to a new event of crystallization of these bodies in the São João del Rei Pegmatitic Province. These pegmatites have a remarkable amount of xenotime and monazite (and absence of cassiterite) and have been characterized as REE-enriched pegmatites. These bodies are connected to the crystallization of an Orosirian high-K metagranite, which has a monazite crystallization age of 2018 ± 31 Ma. This metagranite, proposed here as “Restinga Metagranite”, represents a new and the youngest pluton of the Mineiro Belt, increasing in 90 M.y. the evolution time of the Ritápolis arc (2.19-2.02 Ga), and the Mineiro Belt (2.47-2.02 Ga).
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