The Atuba Complex, Southern South American Platform: Archean Components and Paleoproterozoic to Neoproterozoic Tectonothermal Events

The Atuba Complex consists of an Archean terrane, containing rocks differentiated from the mantle and incorporated into the continental crust between 3.1-2.7 Ga. This terrane was later reworked several times. The main metamorphism occurred in the Paleoproterozoic at about 2.1 Ga and can be related to the amalgamation of the Paleoproterozoic supercontinent “Atlantica”. Ages around 1.7 Ga may be related to the break-up of Atlantica. During the Mesoproterozoic, there was little activity in the Atuba Complex and also in the entire South American Platform. Isolated U-Pb zircon ages of 1.4 Ga and Sm-Nd model ages of about 1.2 Ga may be associated to the assembly of Rodinia. The evidence from the South American Platform indicates that the Rodinia rifting pulses started as early as the latest collisional events of the Grenville Cycle, instead of at ca. 0.7 Ga as commonly believed. Finally in the Neopropterozoic at 0.52-0.65 Ga (U-Pb, Rb-Sr, Sm-Nd and K-Ar dates) there were high-grade tectonothermal events associated with Gondwana assembly.