Tectonic evolution of the southern margin of the Amazonian craton in the late Mesoproterozoic based on field relationships and zircon U-Pb geochronology

Abstract

New U-Pb zircon geochronological data integrated with field relationships and an airborne geophysical survey suggest that the Nova Brasilândia and Aguapeí belts are part of the same monocyclic, metaigneous and metasedimentary belt formed in the late Mesoproterozoic (1150 Ma-1110. This geological history is very similar to the within-plate origin of the Sunsás belt, in eastern Bolivia. Thus, we propose that the Nova Brasilândia, Aguapeí and Sunsás belts represent a unique geotectonic unit (here termed the Western Amazon belt) that became amalgamated at the end of the Mesoproterozoic and originated through the reactivation of a paleo-suture (Guaporé suture zone) in an intracontinental rift environment. Therefore, its geological history involves a short, complete Wilson cycle of ca. 40 Ma. Globally, this tectonic evolution may be related with the final breakup of the supercontinent Columbia. Mafic rocks and trondhjemites in the northernmost portion of the belt yielded U-Pb zircon ages ca. 1110 Ma, which dates the high-grade metamorphism and the closure of the rift. This indicates that the breakup of supercontinent Columbia was followed in short sequence by the assembly of supercontinent Rodinia at ca. 1.1-1.0 Ga and that the Western Amazon belt was formed during the accretion of the ArequipaAntofalla basement to the Amazonian craton.

Zircon U–Pb ages of rocks from the Rio Apa Cratonic Terrane (Mato Grosso do Sul, Brazil): New insights for its connection with the Amazonian Craton in pre-Gondwana times

“…The available geological data raise two other possibilities: (i) the RACT is a prolongation of the Paraguá or Jauru Terranes, or (ii) the RACT was juxtaposed with the Paraguá and Jauru Terranes along the Sunsás Belt as an allochthonous terrane. The first two hypotheses are favored by the models where the Sunsás, Aguapeí and Nova Brasilândia Belts are interpreted as intracontinental features (Santos et al, 2000Rizzotto et al, 2014). In contrast, the third hypothesis is favored by models where the Sunsás and/or Nova Brasilândia Belts are inferred as collisional suture zones (Sadowski and Bettencourt, 1996;Loewy et al, 2004;Tohver et al, 2004;Boger et al, 2005;Tohver et al, 2005aTohver et al, ,b, 2006Teixeira et al, 2010).…”

“…In contrast, Boger et al (2005) interpret the two structures as segments of a continuous collisional belt. Geological and geochronological data (Saes, 1999;Geraldes et al, 2001;Matos et al, 2004;Tohver et al, 2004Tohver et al, , 2006Ruiz et al, 2005;Rizzotto et al, 2013Rizzotto et al, , 2014 suggest that the Paraguá and Jauru Terranes behaved as a single continent after ca. 1300 Ma, favoring an intracontinental origin for the Aguapeí Belt.…”

“…In this scenario, the role of prominent structures related to the Grenvillian Orogeny (1200-1000 Ma) (the Sunsás, Aguapeí and Nova Brasilândia Belts; Sadowski and Bettencourt, 1996;Geraldes et al, 1997Geraldes et al, , 2001Loewy et al, 2004;Tohver et al, 2004;Boger et al, 2005;Tohver et al, 2005aTohver et al, , b, 2006Teixeira et al, 2010;Geraldes et al, 2014;Rizzotto et al, 2014) and the Rondonian-San Ignacio Orogeny (1560-1300 Ma) (the Guaporé Belt; Bettencourt et al, 2010;Rizzotto et al, 2013Rizzotto et al, , 2014 are key issues that need to be addressed to securely establish the relationship between the RACT and the Amazonian Craton in pre-Gondwana times. Most authors consider the Sunsás Belt as a major suture zone related to the collision between the proto-Amazonian Craton and the Arequipa-Antofalla Terrane (Sadowski and Bettencourt, 1996;Loewy et al, 2004;Boger et al, 2005;Cordani et al, 2010b;Teixeira et al, 2010;Rizzotto et al, 2014), while others interpret it as an intracontinental belt (Santos et al, 2000. The role of the Nova Brasilândia Belt is also contentious, being inferred as the collisional suture zone between the Paraguá Terrane and the proto-Amazonian Craton (Tohver et al, 2004(Tohver et al, , 2005a(Tohver et al, ,b, 2006Boger et al, 2005) or as an intracontinental belt (Santos et al, 2000Teixeira et al, 2010;Rizzotto et al, 2014).…”

“…Most authors consider the Sunsás Belt as a major suture zone related to the collision between the proto-Amazonian Craton and the Arequipa-Antofalla Terrane (Sadowski and Bettencourt, 1996;Loewy et al, 2004;Boger et al, 2005;Cordani et al, 2010b;Teixeira et al, 2010;Rizzotto et al, 2014), while others interpret it as an intracontinental belt (Santos et al, 2000. The role of the Nova Brasilândia Belt is also contentious, being inferred as the collisional suture zone between the Paraguá Terrane and the proto-Amazonian Craton (Tohver et al, 2004(Tohver et al, , 2005a(Tohver et al, ,b, 2006Boger et al, 2005) or as an intracontinental belt (Santos et al, 2000Teixeira et al, 2010;Rizzotto et al, 2014). Rizzotto et al (2013Rizzotto et al ( , 2014 interpret the collage between the Paraguá Terrane ( Fig.…”

“…The role of the Nova Brasilândia Belt is also contentious, being inferred as the collisional suture zone between the Paraguá Terrane and the proto-Amazonian Craton (Tohver et al, 2004(Tohver et al, , 2005a(Tohver et al, ,b, 2006Boger et al, 2005) or as an intracontinental belt (Santos et al, 2000Teixeira et al, 2010;Rizzotto et al, 2014). Rizzotto et al (2013Rizzotto et al ( , 2014 interpret the collage between the Paraguá Terrane ( Fig. 1) and the proto-Amazonian Craton to have occurred between 1430 and 1340 Ma along the Guaporé Belt.…”