Review of the ideas regarding the evolution of the Ventania System and its tectonic relationship with the Río de la Plata Craton and Patagonia

Abstract

The Ventania System, composed of a Tonian–middle Cambrian crystalline basement (i.e., Sauce Chico Complex, SCC) and a late Cambrian–Cisuralian sedimentary cover, has been a key region in the postulation of hypotheses on the drift of South America and the collision of Patagonia with the Río de la Plata Craton (RPC). This work compiles and statistically analyzes the U–Pb and Lu–Hf zircon data of the Ventania System. Through the application of multidimensional scaling analysis and Monte Carlo mixture modelling, results highlight the RPC, the SCC, the Eastern Pampean Ranges, and the North Patagonian Massif (NPM) as the main source areas. One of the main differences between the model presented here and that of previous authors is the greater significance of the SCC as a source, the lesser importance of the Eastern Pampean Ranges, and the role of the NPM as a source throughout the Paleozoic. The latter may be the result of age similarities of zircon populations between the SCC and the basement of the northeastern NPM. This and the isotopic data suggest a correlation between both basements as part of the southern accretionary margin of the RPC during the late Ediacaran–early Cambrian and reinforce the hypothesis of an African origin of at least part of northern Patagonia via the Sierra de la Ventana Shear Zone (SVSZ), which is located immediately south/southwest of the Ventania System and constitutes the southern border of the RPC. The SVSZ would have been decisive in the development of the Paleozoic Ventania basin, interpreted here as an episutural basin, and in the subsequent Gondwanide deformation that affected the entire system.