Late Neoproterozoic granitoid magmatism in the southernmost section of the Dom Feliciano Belt, Uruguay

Late Neoproterozoic felsic magmatic rocks form part of a discontinuous chain of plutonic rocks that outcrop along 1,300 km of the South American Atlantic coast, from the departments of Lavalleja-Maldonado-Rocha in Uruguay northward to the state of Santa Catarina in Brazil. Our ongoing research project includes mapping, petrography, geochemistry and geochronology, and constitutes the first systematic regional attempt to characterize this granitoid magmatism in the Dom Feliciano Belt section of eastern Uruguay. Based on mineralogy, the granitoid rocks are granite and syeno-granite and can be subdivided into biotite-muscovite, biotite-muscovite-amphibole, biotite-amphibole and biotite-amphibole-pyroxene granites. Major element data classify them as granite, granodiorite and quartz-monzonite. This granitoid magmatism is strongly high-K to shoshonitic, calcic to alkali calcic, mostly ferroan (FeO/ (FeO+MgO) and peraluminous in character. Trace element signatures suggest a post-collision to within-plate intrusive setting forthese rocks. Results from this study include the first recognition of high barium and strontium granites west of the Sierra Ballena Shear Zone (SBSZ).