Potential flare-ups and lulls in the multi-stage magmatism of the Dom Feliciano belt, southern Brazil: Evidence from geochemistry and isotopic data

Abstract

The genesis of Precambrian granitic batholiths related to supercontinent assembly is controversial, especially regarding their generating processes and tectonic settings. The present study focused on the Pelotas Batholith (Magmatic-arc domain) of the Dom Feliciano Belt, which comprises the southern segment of the Mantiqueira Province in southeastern South America. New U–Pb and Lu–Hf zircon data from plutonic rocks with evidence of magma mixing and mingling, as well as assimilation of wall rocks, suggest multi-stage magmatism related to flare-up episodes of intense magmatism, potentially triggered by changes in the tectonic setting. U–Pb zircon analyses yielded crystallization ages of granodioritic gneiss xenolith at 691.5 ± 7 Ma, microgranodiorite xenolith at 645.9 ± 3.7 Ma, host monzogranite at 634.4 ± 4.4 Ma, and intrusive syenogranite at 620.1 ± 4.7 Ma, all intruded by syenogranitic pegmatite at 606.9 ± 1.7 Ma. Other analyses were performed on calc-alkaline granite (633 ± 4 Ma) and peraluminous granite (609.6 ± 2.2 Ma). The Lu–Hf data highlights a model age interval ranging from 1.7 to 1.3 Ga with εNd values between −4 and 1, except for the pegmatite sample which also includes Paleoproterozoic and Archean model ages (3.3-1.6 Ga) and εNd values between −33 and −1. Furthermore, the acquired data, together with the gathered dataset Dom Feliciano Belt granites, emphasizes a contribution from slightly juvenile to crustal sources, with model ages ranging primarily from Statherian-Orosirian to Mesoproterozoic. Signature patterns are consistent with sources from African basement rocks.