DE RODINIA A GONDWANA: FRAGMENTOS SUDAMERICANOS DE UNA HISTORIA PALEOGEOGRÁFICA COMPLEJA

RAPALINI, AUGUSTO E.

San Miguel de Tucumán

Congreso; 20 Congreso Geológico Argentino; 2017

Asociación Geológica Argentina

The Neoproterozoic paleogeographic evolution of the South American main cratonic nucleii, i.e. Amazonia, Sao Francisco and Río de la Plata, is scarcely known and subject of major controversies. This is further complicated by the poorly known role played by other minor blocks, like Río Apa, Borborema, Pampia, Nico Perez, Arequipa, etc. during Gondwana assembly. The available paleomagnetic data supports the model of (Congo-) Sao Francisco and Río de la Plata blocks being of ?African? affinity and Amazonia (plus Western Africa) of ?Laurentian? affinity. Location of Rio de la Plata in Rodinia is unconstrained and there is paleomagnetic evidence that by late Mid-Ediacaran (ca. 580 Ma) was far-away from the remaining parts of Rodinia, while already assembled to Congo-Sao Francisco. The simplest model to account for paleomagnetic and geological evidence suggests, on the other hand, that Amazonia remained attached to Laurentia until the Late Ediacaran and did not join other Gondwanan forming blocks, perhaps until the Cambrian. This leads to a wide late Ediacaran (Clymene) ocean in South America between the ?Laurentian? and the ?African? blocks.