The Rio de La Plata Craton and the Western Gondwana Assembly

Abstract

The core goal of this project is to characterize the tectonic evolution of the Rio de la Plata Craton (RPC), the development of the adjacent fold belts, and the interaction with other continental fragments during the development of W Gondwana. Two main lines of integrated action are planned: (i) the application of new geochronological-isotopic techniques using the enhanced instrumentation in USP, and (ii) new field-based geological research in the RPC. The project compiles several interlinked strands which can be summarized as follows:1) among the successful thematic project achievements (FAPESP 05/58688-1) on the South American Platform are noteworthy correlations between Brazil and Africa, e.g. the identification in Uruguay of the continuity of the Gariep Belt from Namibia-South Africa, based on the provenance patterns of detrital zircons; the 2500 km long Neoproterozoic belt from Mali (NW Africa) and Ceará (NE Brazil), with high to ultra-high pressure rocks. This project proposes to clarify the construction and dispersion of the Rodinia, Gondwana and Pangea supercontinents; 2) Contemporary Earth Sciences rely on the integration of detailed field studies with a range of laboratory-based techniques .Isotopes provide the ages of rocks and can fingerprint their crustal versus mantle origins. South America´s leading facility in the Geochronological Research Center is based at the USP (CPGeo), and its continued progress is critical to the standing of the Earth sciences research in S America. In detail the aims are: (i) to acquire a Cs source for SHRIMP (Sensitive High Resolution Ion Microprobe) oxygen microanalysis applied to geological problems; (ii) implementation of dating protocols for several novel minerals and to improve the routine LA-ICPMS (Laser Ablation - Ion Coupled Plasma Mass Spectrometer) analysis of Sr, Nd and Pb to tackle problems of crustal evolution. These advances will improve our scientific development, and allow us to continue providing essential support to the entire scientific community; 3) for the RPC geological information related to a supercontinent formation and dispersion remains limited, compared to other cratons, as its relationship with the neighboring cratonic fragments and its inferred position in the Rodínia. In part this reflects the lack of paleomagnetic surveys even though in tectonostratigraphic terms the RPC contains litho-structural representatives of most of the Archean and Proterozoic eathems. Hence, the RPC will be characterized in detail, mainly to its geological and structural and relationships with the Pâmpia (Pa), Paranapanema (Pr), Luiz Alves (LA), Kalahari (K), Angola (Ag) and Congo (Co) cratons and the surrounding fold belts. This will be achieved by coordinated geological survey in five targeted areas across the RPC. In all areas the focus will be on composition, age, tectonothermal history and crustal evolution: a) the central domain of the RPC - constitution, characterization of its basement and its extent, magmatism and paleomagnetism; b) the N-NW domain - concerning interaction between the RPC and Pr cratons and correlation of these segments with the Tocantins and Mantiqueira Provinces; c) the S Domain - characterization of the southern RPC margins and relations with Patagonia; d) W domain-relations between RPC and the Pa Terrane; e) the E domain - interaction between RPC and Co-K cratons and development of Mantiqueira southern province and related belts of the SW Africa; 4) the final goal is to improve and to ensure broader based scientific leadership and training. This project is designed to expand the scale of our thinking into questions of the search for mantle-derived rocks, the generation and evolution of the continental crust, and the resources preserved within it. Correlation problems between rock associations and processes both within and outside S America are essential issues that require similar approaches to be used by different groups working in different areas. (AU)