Timing and Duration of the Calc‐Alkaline Arc of the Pampean Orogeny: Implications for the Late Neoproterozoic to Cambrian Evolution of Western Gondwana

Zircon ages delimit the provenance of a sand extrudite from the Botucatu Formation in the Paraná volcanic province, Iraí, Brazil

“…Late Neoproterozoic to Cambrian ages are widespread in the Pampia terrane as magmatic and metamorphic ages; e.g. Schwartz et al (2008), Chernicoff et al (2012, Collo et al (2009), and, Lork et al (1989. Metamorphic peaks in the Brasiliano/Pan-African cycles (Silva et al 2005) are five: 840-800 Ma; 730-700 Ma; 640-620 Ma; 590-560 Ma; 520-500 Ma.…”

Mid- to Late Cambrian docking of the Río de la Plata craton to southwestern Gondwana: age constraints from U–Pb SHRIMP detrital zircon ages from Sierras de Ambato and Velasco (Sierras Pampeanas, Argentina)

“…In this interpretation, the final stage is represented by the oblique co11ision in Cambrian times of a large, probably a11ochthonous, Mesoproterozoic to Palaeo proterozoic terrane in the west that embraced the Western Sierras Pampeanas (Sierra de Pie de Palo and Sierra de Maz), the Arequipa block (southern Peru; Ramos 2008, and references therein;Casquet et al 2010) and Amazonia among other continental blocks (Rapela et al 2007;Casquet et al 2009). This co11ision resulted in the Pampean orogenic belt (545 510 Ma, Rapela et al 1998;Schwartz et al 2008) in the Eastern Sierras Pampeanas, juxtaposed with the Rio de la Plata craton across a major fault (Fig. 1).…”

“…Alternative models for the Pampean orogeny involve either Late Neoproterozoic to Early Cambrian orthogonal co11ision or ridge subduction against the Rio de la Plata craton (Ramos & Vujovich 1993;Escayola et al 2007;Schwartz et al 2008;Ramos et al 2010). Folding and the development of foliation took place in the Early Cambrian and were accompanied by low to high-grade regional metamorphism under low to medium pressure between 530 and 520 Ma.…”

“…Folding and the development of foliation took place in the Early Cambrian and were accompanied by low to high-grade regional metamorphism under low to medium pressure between 530 and 520 Ma. Intrusion of ca1c-alkaline 1-type plutons and S-type granites (magmatic arc) started at c. 545 Ma (Lira et al 1997;Rapela et al 1998Rapela et al , 2002Schwartz et al 2008;Martino et al 2009 Casquet et al 2008) This work is focused on the southern tip of the Sierra de Ambato and eastern tip of Sierra de Velasco in the Eastern Sierras Pampeanas (Fig. 2), which underwent Famatinian defor mation and metamorphism.…”

“…Historica11y, this craton -was considered the upper plate in co11isional models for the Neoproterozoic to Early Cambrian Pampean orogeny (545 510 Ma) during the amalgamation of Gondwana (Escayola et al 2007;Schwartz et al 2008;Ramos et al 2010). However, according to Schwartz & Gromet (2004) and Rapela et al (2007) the pre-Pampean sedimentary Puncoviscana Formation (largely Late Neoproterozoic to Early Cambrian turbidites; see Zimmer mann 2005), does not contain the 2.05 2.25 Ga detrital zircons expected in the case of orthogonal co11ision with the craton.…”