a b s t r a c tWe have carried out zircon U-Pb SHRIMP dating and Hf isotope determinations on a biotite paraschist and on a tonalitic orthogneiss of the Yaminué Complex, and re-evaluate this complex in the broader context of the tectonic evolution of the Patagonia composite terrane. In the metasedimentary unit (msuYC), the youngest detrital zircon dated at 318 AE 5 Ma (Mississippian/Pennsylvanian boundary) indicates a Pennsylvanian (or younger) depositional age. The three main age populations peak at 474, 454 and 374 Ma. Preliminary Hf isotope data for two detrital zircons (447 and 655 Ma) yielded ε(Hf) values of À0.32 and 0.48, indicating that their primary sources contained small amounts of recycled crustal components (of Calymmian age; T DM 1.56 Ga). Zircons from the orthogneiss (miuYC; intrusive into msuYC) show a crystallization age of 261.3 AE 2.7 Ma (Capitanian; late middle Permian) which is broadly coeval with deformation, and NeoarcheanePaleoproterozoic inheritance. Meaningful core-rim relationship between Neoarchean zircon cores and late Permian rims is well defined, indicating the occurrence of Archean crust in this sector of Patagonia. Hf T DM of Permian zircons is mainly Meso-Paleoarchean (2.97e3.35 Ga), with highly negative ε(Hf) values (ca. À33). Hf T DM of inherited Neoarchean zircon cores is also Meso-Paleoarchean (3.14e3.45 Ga) but more juvenile (ε(Hf) ¼ À0.3). Hf isotopes reinforce the presence of unexposed ancient crust in this area.Combining geological and isotope data, as well as geophysical models, we identify the Yaminué Complex within the La Esperanza-Yaminué crustal block flanked by two other, distinct crustal blocks: the Eastern block which forms part of the Patagonia terrane sensu stricto, located in the eastern Patagonian region, and the Western block forming part of the Southern Patagonia terrane. Their origins and timing of amalgamation to form the Patagonia composite terrane are also discussed.

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Integration of existing isotopic and geological data allows a reconsideration of the distribution and age of the Río de la Plata Craton within South America. The reinterpretation increases the area of the craton to about 2,400,000 km 2 with implications for the tectonic map of South America and for global reconstruction of palaeocontinents. Four areas previously considered as separate cratons (Luís Alves, Curitiba, Tebicuary, and Paranapanema) are interpreted as part of the same Río de la Plata Craton. The craton is organized into six provinces and domains: Buenos Aires-Piedra Alta, Taquarembó, Tebicuary, Luís Alves, Encantadas, and Nico Pérez. The term 'Transplatense' is proposed to replace 'Trans-Amazonian' for Rhyacian events that occurred within the Río de la Plata Craton. The craton is formed not only by dominant Rhyacian rocks and local Archaean rocks, but also by Statherian and Mesoproterozoic rocks. The domains are all partially to totally covered by Phanerozoic basins (Paraná, Chacoparanense, Claromecó, Salado, Balcarce, and Colorado) which makes their investigation difficult. The Ediacaran-Cambrian collisions of the Brasilian orogen generated tectonic mixtures of orogenic and cratonic zones. This is more evident in the eastern margin of the craton, which behaved as a metacraton.