Extension and general evolution of the Río de la Plata craton

CINGOLANI, C.A.,; BOSSI, J.

Neoproterozoic-Cambrian events in SW Gondwana: Developments in Precambrian Geology, Elsevier.

Elsevier

Lugar: Amsterdam; Año: 2008;

NEOPROTEROZOIC-CAMBRIAN EVOLUTION OF THE RIO DE LA PLATA PALAEOCONTINENT 9.1 EXTENSION AND GENERAL EVOLUTION OF THE RIO DE LA PLATA CRATON 9.1.1 Introduction             Origin, extension and boundaries of the Río de la Plata cratonic region. Following the fragmentation of the Rodinia supercontinent, Archaean to Mesoproterozoic cratonic blocks were amalgamated to constitute the Gondwana continent during Neoproterozoic-Cambrian times (Hoffman, 1999; Brito Neves et al., 1999; Fuck et al., 2008). One of these continental blocks of western Gondwana is the Río de la Plata Craton (Almeida et al., 1973; 1976; 2000; Cordani et al., 2000), which comprises part of southern Brazil, Paraguay, Uruguay and the central-eastern sector of Argentina (Fig. 9.1.1). However, the main exposures of the Río de la Plata Craton (RPC), are located within its eastern border and include the Asunción arch, the Taquarembó Block, and the Nico Pérez, Piedra Alta and Tandilia terranes. The Nico Pérez Terrane is the oldest and includes Paleoarchaean granite-greenstone sequences (Hartmann et al., 2001).             To the north, the RPC (Fig. 9.1.2) is bounded by the southern Amazonian craton (Bolivia-Brazil), whereas to the east it is bounded by the allochthonous Cuchilla Dionisio suspect terrane (Uruguay). The RPC is limited towards west by the Pampia terrane of Argentina (Ramos, 1988; Rapela et al., 2007). According to the basement rock geochronological studies (Cingolani and Varela, 1973; Rapela et al., 2003) and based on at least two drilling boreholes in the Claromecó basin (Lesta and Sylwan, 2005), it was deduced that the RPC was not part of the basement of the Sierra de la Ventana fold and thrust belt. It is important to note, that low-grade metapelites occurring in the Punta Mogotes borehole have been correlated to similar rocks (Rocha Formation) of the Cuchilla Dionisio terrane in Uruguay (Cingolani and Bonhomme, 1982; Ramos, 1988), showing similar detrital zircon ages (Rapela et al., 2008).