CIG   05423
CENTRO DE INVESTIGACIONES GEOLOGICAS
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
A post-Pampean Middle to Late Cambrian siliciclastic platform on the proto-Andean margin of Gondwana and its palaeogeographical implications
Autor/es:
CASQUET, C.; RAPELA, C.W.; PANKHURST, R.J; BALDO, E.G; GALINDO, C.; VERDECCHIA, S.; DAHLQUIST, J.A.; MURRA, J.A.
Lugar:
Buzios
Reunión:
Simposio; Gondwana 14; 2011
Institución organizadora:
Universidad de Río de Janeiro
Resumen:
Laurentia broke away from an ephemeral South American Proterozoic megacraton (Amazonia + Rio Apa + Arequipa + Western Sierras Pampeanas) in the early Cambrian at ca. 545Ma, after oblique closure of the hypothetical Neoproterozoic Clymene Ocean. The latter process led to the Pampean-Paraguay-Araguaia orogeny (545?520Ma) that amalgamated the South American megacraton to other Gondwana cratons in the East, bringing to an end the assembly of Gondwana (Casquet et al., 2009). The separation of Laurentia in turn opened the Iapetus Ocean with its conjugate passive margins that persisted till the Late Cambrian?Early Ordovician, when eastward subduction started along the proto-Andean margin of Gondwana producing the Famatinian orogeny. Famatinian magmatic arcs developed between ca. 490 and 465Ma along the entire length of this margin (ca. 6000 km) accompanied by deformation and high-grade metamorphism in the middle and lower crust. The Famatinian orogeny was preceded at the latitude of the present Sierras Pampeanas of Argentina by deposition of a post-Pampean orogeny siliciclastic wedge on a continental shelf. The clastic wedge and the basement (comprising both Pampean and Western Sierras Pampeanas types) were thoroughly involved in the Famatinian orogeny. Sedimentation of the clastic wedge apparently took place in two stages: one prior to final inland dextral docking of the Rio de la Plata craton in the Middle to Late Cambrian (Verdecchia et al., 2011), and a second one, involving the provenance of detrital zircons from the craton, in the Late Cambrian. This second episode of clastic sedimentation may be correlated on the basis of detrital zircons with at least part of the siliciclastic Balcarce Formation that overlies the Rio de la Plata craton (Rapela et al., 2011).