A history of Proterozoic terranes in southern South America: From Rodinia to Gondwana

Abstract

The role played by Paleoproterozoic cratons in southern South America from the Mesoproterozoic to the Early Cambrian is reconsidered here. This period involved protracted continental amalgamation that led to formation of the supercontinent Rodinia, followed by Neoproterozoic continental break-up, with the consequent opening of Clymene and Iapetus oceans, and finally continental re-assembly as Gondwana through complex oblique collisions in the Late Neoproterozoic to Early Cambrian. The evidence for this is based mainly on a combination of precise U-Pb SHRMP dating and radiogenic isotope data for igneous and metamorphic rocks from a large area extending from the Rio de la Plata craton in the east to the Argentine Precordillera in the west and as far north as Arequipa in Peru. Our interpretation of the paleogeographical and geodynamic evolution invokes a hypothetical Paleoproterozoic block (MARA) embracing basement ultimately older than 1.7 Ga in the Western Sierras

Identifying Laurentian and SW Gondwana sources in the Neoproterozoic to Early Paleozoic metasedimentary rocks of the Sierras Pampeanas: Paleogeographic and tectonic implications

“…The two continents eventually collided to produce the Pampean orogeny (e.g., Rapela et al, 2007;Casquet et al, 2012a). We ascribe these to a large continent embracing Laurentia on one side and Kalahari-Adamastoria (see Rapela et al, 2011) and the East African orogen on the other.…”

“…In the southern part of ESP, e.g., Sierras de Córdoba, Sierra Norte de Córdoba and Ancasti, widespread greenschist, amphibolite and granulite facies metasedimentary rocks are considered higher-grade equivalents of the lower part of the Puncoviscana Formation, more intensely affected by the Pampean orogeny von Gosen and Prozzi, 2010;Escayola et al, 2007;Casquet et al, 2012a) (Fig. 2b).…”

“…Kalahari-detached blocks such as Adamastoria to produce the Pampean orogeny (Casquet et al, 2012a). The structural boundaries between the Neoproterozoic WSP siliciclastic and carbonate sedimentary series, i.e., the DCSS/Ancaján Series and the "Puncoviscan Series" would all be tectonic, resulting from oblique continental collision.…”

The Sierra Norte-Ambargasta batholith: Late Ediacaran–Early Cambrian magmatism associated with Pampean transpressional tectonics

“…522 Ma peak metamorphism (P ¼ 8.6 AE 0.8 kbar, T ¼ 810 AE 50 C, Rapela et al, 1998b) terminated by 515 Ma (Schwartz et al, 2008). The whole Pampean episode involved a Late EdiacaraneEarly Cambrian continental arc, followed in the Early Cambrian by a dextral oblique collision with a string of Meso-proterozoic exotic terranes located to the west (Antofalla and Western Sierras Pampeanas blocks, Rapela et al, 2007;Siegesmund et al, 2010;Escayola et al, 2011;Casquet et al, 2012). Terrane collision followed by slab break-off, may explain also the wide-spread crustal anatexis and emplacement of 520 AE 3 Ma OIB-like mafic magmas observed in the Sierras de Córdoba (Tibaldi et al, 2008), but the available geological evidence is very scarce to discriminate among different terrane collision models.…”

Geoquímica, dataciones U-Pb SHRIMP sobre circón e isótopos de Hf del magmatismo gondwánico en el NW de Argentina: petrogénesis e implicancias geodinámicas.

“…Loewy et al, 2004) and that its accretion to Amazonia would have taken place during the Grenville-Sunsás Orogeny (1.0-1.3 Ga) (Chew et al, 2007). The recorded evidence of Early Mesoproterozoic crust in its southern extension could provide additional evidence for its connection to the Maz and Río Apa blocks, constituting together the hypothetical MARA craton, following the model proposed by Casquet et al (2009Casquet et al ( , 2010. The 1.24 to 1.36 Ga crustal ages obtained are coincident with the Andean-type magmatic arc recorded from the Maz terrane at 1.26 to 1.33 Ga (Casquet et al, 2011 and references therein), as well as to the thermal episode at 1.3 Ga that affected the Río Apa block (Cordani et al, 2010), pointing to a common history for the three areas at least during the Mesoproterozoic.…”