From Rodinia to Western Gondwana: An approach to the Brasiliano-Pan African cycle and orogenic collage

Abstract

The basement of the South American platform displays the lithostructural and tectonic records of three major orogenic collages: Middle Paleoproterozoic (or Transamazonian), Late Mesoproterozoic/Early Neoproterozoic and Late Neoproterozoic/Cambrian, the Brasiliano-Pan African collage. The first two collages have their records in the basement of the Syn-Brasiliano cratons and Brasiliano Fold Belts. The development of the Brasiliano-Pan African collage started in Early Neoproterozoic times, with the first events of breakup of the Rodinia Supercontinent, and it has been characterized by diachrony since their early beginnings. The processes of break up and fission took place in different time intervals (ca. 1000-950 Ma, ca. 750 Ma, ca. 600 Ma) from one part to another. Different lithospheric segments were then generated as large (cratons), intermediate and small (terranes, massifs) blocks and, at the same times, different kinds of basins were formed among them, floored by continental, proto-oceanic and oceanic rock units. The subsequent interactions among these blocks, descendants of Rodinia, have occurred all over the Neoproterozoic, since the Tonian up to the Cambrian period, according with local tectonic circumstances, from one province to another, until the complete (collision) closure of all basins due to different phases of tectonic convergence. Diachronism was a characteristic of the basin-forming tectonics and also of the subduction and collisional processes that have formed the Brasiliano-Pan African orogenic systems. So, the basement of the South American platform is recording all the steps of the development of a complete, wide and complex Wilson Cycle, from the disarticulation of the former Mesoproterozoic supercontinent (Rodinia) to the amalgamation of a newer one (Western Gondwana), following a very diachronic history of evolution. For descriptive purposes, four structural provinces have usually been recognized for those domains where these orogenic systems sharing the Brasiliano collage are better cropping out: Borborema (Eastern northeast), Tocantins (Central-eastern, part of the Central-western), Pampean (Central-southwestern) and Mantiqueira (East-southeast).