Proterozoic paleogeographic evolution of South American cratons
2008 (English)Conference paper, Presentation (Other academic)
The South American platform is composed of four major cratons (Amazonian, São Francisco, Rio de la Plata and São Luis) and other smaller continental blocks and terrains that may have taken part in supercontinental assemblages. Here, paleogeographic configurations from the Paleoproterozoic up to the Cambrian are tested by means of an updated paleomagnetic and geochronologic record of South America, including new high-quality poles from the Amazonian and São Francisco cratons. These poles are compared to those of other cratons thought to have interacted with South American units in the Proterozoic, such as Baltica and Laurentia. The oldest assemblage of continents to be addressed is the Paleoproterozoic Columbia (~1800 Ma), for which our data support a configuration aligning Laurentia, Baltica, North China and Amazonia through their Paleo-Mesoproterozoic belts. For Neoproterozoic times (~1200-1000 Ma) a connection between Laurentia and the Amazonian craton in an evolving configuration (with relative movement between the two units) is supported by a pole-to-pole comparison. In contrast, striking differences in Laurentia's drift history compared to São Francisco, São Luis (=West Africa) and Kalahari rule-out the effective participation of these cratons in Rodinia. The assembly of Gondwana has probably occurred in different steps, comprising first (~630 Ma) the connection between Sao Francisco, Rio de la Plata, other minor blocks and the African cratons, followed by the collision of these central Gondwanan blocks with the Amazonian craton and adjoining blocks by mid-Cambrian times (~530 Ma), after the opening of the Iapetus ocean basin between Laurentia and the Amazonian craton. In this scenario, the West Gondwana was not a coherent tectonic unit before the end of Precambrian times.
Place, publisher, year, edition, pages
Research subject Applied Geophysics
IdentifiersURN: urn:nbn:se:ltu:diva-40253Local ID: f50bec50-b0c8-11dd-9c9d-000ea68e967bOAI: oai:DiVA.org:ltu-40253DiVA: diva2:1013775
International Geological Congress : 06/08/2008 - 14/08/2008
Godkänd; 2008; 20081112 (ysko)2016-10-032016-10-03Bibliographically approved