Deciphering the source of multiple U–Pb ages and complex Hf isotope composition in zircon from post-collisional charnockite-granite associations from the Araçuaí orogen (southeastern Brazil)

摘要: Abstract Giant post-collisional magmatic systems are marked by an intricate diversity of zircon ages and Hf isotopic signatures. Granites charnockites from such in high contrast with simple composition modern granites, which often record no more than one crystallization age. Despite the complexity, assortment compositions can be explored to extract vital information understand magma histories, isotope fractionation sources. Here we focused on a charnockite-granite association (Barra do Sao Francisco pluton - BSFP) formed during stage Aracuai orogen (southeastern Brazil). The chemical these rocks points towards metaluminous slightly peraluminous character, ferroan calc-alkalic alkalic signature. Zircons extracted BSFP show large scatter U–Pb age distributions (from 614 498 Ma), indicating complex history processes wanning stages orogeny. Detailed discrimination analysis based texture, chemistry data established well-defined groups (groups I III); each reveales significant part this evolution (ca. 614-552 Ma, ca. 528-513 Ma 510-498 Ma). Zircon xenocryst cores Group have broad distribution 614-552 Ma) that mirror within inherited populations country rock (Carlos Chagas batholith). other two present all samples interpreted here as antecrysts (Group II: 528-513 Ma) autocrysts III: All charnockite negative ɛHf(t) −7.4 −0.5) Calymmian Ectasian model (TDM = 1.58-1.21 Ga), contribution heterogenous granites exhibit values −9.3 −5.9) largely older (TDM = 1.68-1.49 Ga), granite magmas were derived different crustal These isotopes robust evidence source for water activities. prolonged assemblage probably combined slow cooling orogen.