The Western Sierras Pampeanas: Protracted Grenville-age history (1330–1030 Ma) of intra-oceanic arcs, subduction–accretion at continental-edge and AMCG intraplate magmatism

Early Carboniferous sub- to mid-alkaline magmatism in the Eastern Sierras Pampeanas, NW Argentina: A record of crustal growth by the incorporation of mantle-derived material in an extensional setting

“…14a) and (b) a wide zone of Late Devonian intracontinental A-type magmatism located some 600 km to the east and emplaced in a relative short period (c. 390-365 Ma, Fig. 14b) together with W-directed com pression at -380 Ma (lira and Kirschbaum, 1990;Sims et al, 1998;L6pez de Luchi et al, 2004;Rapela et al, 2008;Steenken et al, 20OS). Here both magmatic events would be linked to an initial flat-slab sub duction towards the east that caused Middle to Late Devonian litho spheric shorting, when metamorphism and deformation is recognised in the several parts of the Western Gondwana margin (Ramos et al, 1986;Basei et aI., 1998;Varela et aI., 2002;L6pez and Gregori, 2004;Willner et al, 2011).…”

“…Modem geochronological studies have demonstrated that the Western Sierras Pampeanas preserve a completely different geological history, involving an ex posed Mesoproterozoic crystalline basement (e.g., Rapela et al, 2010 and reference therein).…”

“…It is represented by small and scattered plutons, usually sub-circular, in truded mainly along prominent Ordovician shear zones fonned during the earlier Famatinian orogeny (e.g., H6ckenreiner et al, 2003;Dahlquist et al, 201 0). Host rocks to this Carboniferous magmatism formed during three main periods of magmatic and metamorphic activ ity: Middle Cambrian (Pampean orogeny), Early-Middle Ordovician (Famatinian orogeny), and Middle-Late Devonian (Achalian event) (Pankhurst et al, 1998;Rapela et al, 1998;Sims et al, 1998;Pankhurst et al, 2000;Dahlquist et al, 2008;Rapela et al, 2008;Vaughan and Pankhurst, 2008;Spagnuolo et al, 2011;Tohver et al, 2011). The geody namic setting of the Carboniferous magmatism remains controversial.…”

“…Some authors have suggested that it resulted from crustal reheating as the final phase of a protracted Famatinian orogeny extending from Ordo vician to Early Carboniferous (e.g., Grissom et al, 1998;llambtas et al, 1998;H6ckenreiner et al, 2003;Grosse et al, 2009). Others have argued for a distinctive and extended Achalian orogenic event in the Devonian Early Carboniferous (e.g., Sims et al, 1998;Stuart-Smith et al, 1999;Lopez de Luchi et al, 2004;Siegesmund et al, 2004;Dahlquist et al, 2006;Rapela et al. 2008).…”

Evolução estrutural da Sierra de Umango, Sierras Pampeanas Ocidentais, Noroeste da Argentina

“…Foi associado ao período Pré-Granítico descrito por Hausen A Sierra de Maz seria parte de crosta continental durante todo esse período, iniciada como margem continental no Paleoproterozóico, passando para margem continental ativa no Mesoproterozóico vinculada à subducção do tipo Andina, a pelo menos 1330 Ma, seguido de evento colisional (entre 1230 e 1170 Ma) responsável pelo desenvolvimento de metamorfismo de alto grau (Rapela et al, 2010). O final da história mesoproterozóica da Sierra de Maz foi caracterizado por um evento extensional vinculado à intrusão de um complexo intraplaca AMCG (plutonismo com a associação anortosito-mangerito-charnockito-granito) entre 1050 e 1090 Ma (Rapela et al, 2010).…”