The rio de la plata Craton and the assembly of south Gondwana

RAPELA, C.W., ; CASQUET, C.,; PANKHURST, R.J., ; BALDO, E.G, ; VERDECCHIA, S. ; IANNIZZOTTO N

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Conferencia; Gondwana 14 conferences; 2011

The Río de la Plata craton (RPC) is traditionally regarded as the oldest and southernmost in the American continent, fixed to the Amazon craton during the assembly of South West Gondwana and the source of Neoproterozoic to Early Paleozoic passive margin sequences in the west. This paleogeography is challenged in recent contributions showing that the RPC is bounded by large-scale Late Neoproterozoic to Cambrian transcurrent faults and did not undergo significant Brasiliano/Pan-African reworking. Moreover, Neoproterozoic to Cambrian sedimentary sequences do not contain significant contributions from the RPC. Late Neoproterozoic to Early Palaeozoic faults are responsible for translation of the RPC from a missing root in the (present) west and for its involvement in the closure of the southern Adamastor ocean. The effects of these faults were: a) in the northeast and east the late Neoproterozoic Sarandí del Yí fault displaced the RPC clockwise through several hundred kilometers to its present location adjacent to the reworked Nico Pérez and Mar del Plata terranes (Oyhantçabal et al., 2010; Rapela et al., 2011); b) in the west the Córdoba dextral fault juxtaposed it against the Pampean magmatic arc - displacement started in the Early Cambrian, 538?528 Ma (Iannizzoto, 2010 and references therein) and continued through the middle to late Cambrian (Verdecchia et al., 2011); c) in the south the Sierra de la Ventana fault juxtaposed the craton and the Brasiliano/Pan-African basement of the Saldania Belt, implying large right-lateral displacement. The RPC is a large allochthonous terrane, tectonically juxtaposed against the Dom Feliciano?Gariep belt in Ediacaran times, after the main orogenic events but very close to the Early Cambrian onset of the Gariep?Saldania orogeny.