Petrogenesis of protoliths and U–Th–Pb SHRIMP ages in zircons of the Cerro Negro Paleoproterozoic mylonitic igneous suites, Tandilia belt: Adakitics local fingerprints in the Rio de la Plata craton

A dataset of 23 geochemical analyses of mylonitized igneous rocks from the Cerro Negro hill, at the northwestern-most tip of the Azul Megashear Zone of the Tandilia Belt (TB), was evaluated to characterize protoliths: mafic granulites, felsic granulites, garnet-bearing hornblende gneissic and garnet-bearing granite. The evaluation of major and trace elements points to rocks derived from an arc-related suite of metaluminous to peraluminous magmas. Felsic granulites and garnet-bearing granite displayed REE patterns with Eu/Eu* >1.5 and K/Rb ratios around 250, suggesting accumulation of plagioclase feldspars during differentiation of mafic underplated magmas. An exceptional adakite-like signature is reported based on high Sr/Y (20–100) for low Yb (