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513476 
Journal Article 
The Rio de la Plata craton and the assembly of SW Gondwana 
Rapela, CW; Pankhurst, RJ; Casquet, C; Fanning, CM; Baldo, EG; Gonzdlez-Casado, JM; Galindo, C; Dahlquist, J 
2007 
Yes 
Earth-Science Reviews
ISSN: 0012-8252 
83 
1-2 
49-82 
English 
The extent and nature of the Archaean-Palaeoproterozoic craton of Rio de la Plata of southern South America, a major but poorly understood crustal component in Neoproterozoic plate reconstructions, as well as the depositional, metamorphic and magmatic history of the surrounding orogenic belts, are reviewed and reassessed, in part through the analysis of material recovered from deep boreholes in western Argentina that penetrated Palaeozoic cover into basement. U-Pb SHRIMP zircon ages for these samples of 2162 +/- 6 Ma (diorite), 2189 +/- 14 Ma (arnpbibolitic schist) and 2088 +/- 6 Ma (granite) encompass the range of ages determined for the major Palaeoproterozoic orogenic events in the exposed parts of the craton close to the Atlantic coasts of Uruguay and Argentina. Taken together with the geochemical and Nd-isotope characteristics of these samples and an olivine gabbro from a further borehole that failed to yield zircon, these results strongly suggest that the Rio de la Plata Craton is extremely uniform in its dominant chrono-tectonic and lithological make-up, and that it extends westwards as far as the 535-520 Ma Pampean orogenic belt, against which it probably has a fault contact. U-Pb SHRIMP zircon detrital age patterns are presented for representative metasedimentary samples from the craton cover in the Tandilia belt of eastern Argentina, and from the Pampean (Cambrian) and Famatinian (Ordovician) belts to the west of the craton. Whereas the oldest cover rocks in Tandilia clearly show material derived from the underlying Craton, such detritus only appears in the younger (Ordovician) units to the west. Sedimentary protoliths in the Pampean belt were dominated by Neoproterozoic (broadly similar to 600 Ma) and late Mesoproterozoic (broadly similar to 1100 Ma) provenance, and derivation from the Rio de la Plata craton is highly unlikely. Regional considerations, including previously published zircon data, palaeocurrent and structural data, suggest that these rocks must have had an origin within Gondwana-forming blocks, for which the closest identifiable sources are 'Brazilian' and 'African' (Namaqua-Natal). Consequently, the preferred model for the Pampean orogeny is that the Rio de la Plata craton reached its present position by large-scale dextral strike-slip movement against fore-arc sedimentary sequences that had developed on the southern and western margins of the Kalahari Craton during the Early Cambrian. In the final stage the displaced sedimentary sequences outboard of the RPC collided with the Mesoproterozoic Western Sierras Pampeanas terrane, which was at the time attached to the large Amazonia craton and other smaller continental blocks, such as Arequipa-Antofalla and Rio Apa. Protracted relative displacement of the RPC after the Pampean Orogeny led to its final position. (c) 2007 Elsevier B.V. All rights reserved. 
Rio de la plata craton; gondwana assembly; palaeoproterozoic; neoproterozoic; cambrian; brasiliano orogeny; pampean orogeny; U-Pb; zircon dating; argentine precordillera terrane; sierras pampeanas argentina; u-pbshrimp geochronology; tholeiitic dyke swarms; cape granite suite; south-america; sm-nd; brazilian shield; age constraints; calc-alkaline