Geochemical and isotopic constraints on the sources of the Permian-Early Triassic granitoids of the northeastern sector of the North Patagonian Massif

LÓPEZ DE LUCHI, M. G.; MARTÍNEZ DOPICO, C.; RAPALINI, A.E.; TOHVER, E.

General Roca

Simposio; Tercer Simposio Petrología Ígnea y Metalogénesis Asociada; 2015

Universidad de Rio Negro.Sede Roca/ AGA

The extensive belt of Late Paleozoic?Early Triassic granitoids cropping out between Yaminué and Nahuel Niyeu villages, northeastern North Patagonian Massif (NPM) were used as evidence either for intraplate, arc, collisional or post-collisional magmatism resulting from slab break-off (Pankhurst et al. 2006, 2014, López de Luchi et al. 2010, Rapalini et al. 2010, 2013, Chernicoff et al. 2013, and references therein). This magmatism can be separated into two main groups of granitoids: the oldest at 280 Ma, the Early Permian Granitoids (Navarrete Plutonic Complex) and the youngest that is made up by several igneous complexes, i.e. the intensively deformed Yaminué Metaigneous Complex (YMIC), the Cabeza de Vaca Granite (CVG), the Ramos Mejia Igneous Complex (RMIC) (López de Luchiet al. 2015) and the Madsen Tonalite (MT) that cover the time span from 255 to 245 Ma. Structural and emplacement studies indicate that the Early Permian Granitoids (EPG) are mostly undeformed and intrude a low grade basement whereas the Late Permian- Early Triassic granites (LPETG) are either mostly undeformed (MT) and intrude Cambrian granites or in the western sector they are synkinematic sheeted intrusion (YMIC) concordantly emplaced in medium grade metaclastic rocks of probably Devonian age, dykes intruding YMIC, and variably deformed granites (CVG) and RMIC which is the youngest granitoid and intrudes a very low grade metaclastic unit).