Caracterización petrográfica y geoquímica y condiciones de deformación del plutón San Cristóbal, Sierra de Velasco (La Rioja, Argentina)

Abstract

RESUMEN

Petrographical and geochemical features of the granite-pegmatite transition in the Velasco Pegmatitic District, NW Argentina

“…The host rocks of the Be-pegmatites in this district are the Huaco and Sanagasta granites (Fig. 1B) (TOSELLI et al 2000;BÁEZ et al 2005;. Intrusive relationships and clear contacts between both granites have not been observed; thus a gradational contact is suggested.…”

“…The Velasco range is formed essentially by granitoids with different tectono-magmatic evolution and age (e.g. TOSELLI et al 2000TOSELLI et al , 2005GROSSE et al 2003;BÁEZ et al 2005). Three main types of granitoids can be recognized: (1) Ordovician peraluminous meta-granitoids; (2) Ordovician (?)…”

“…The metaluminous to weakly peraluminous metagranodiorites and meta-tonalites outcrop in the southern part of the range. They contain biotite, hornblende, titanite, allanite and magnetite (BELLOS et al 2002;BELLOS 2005). Although their age has not been dated yet, they can be considered Ordovician based on their similarity with Ordovician metaluminous granitoids of the neighboring Famatina region (e.g.…”

Across-arc variation of the Famatinian magmatic arc (NW Argentina) exemplified by I-, S- and transitional I/S-type Early Ordovician granitoids of the Sierra de Velasco

“…The biotitemuscovite SG and the TG emplaced at w14e18 km depths (Rossi and Toselli, 2004;Rossi et al, 2005;de los Hoyos et al, in press), whereas the IG emplaced at shallower levels (Bellos et al, 2010, estimate a maximum depth of w12 km), along with the biotiteecordierite SG (w10 km; de los Hoyos et al, in press). The shallower emplacement level of the IG compared to the biotiteemuscovite SG and the TG may be related to more favorable tectonic conditions towards the continental margin and/or the lower viscosity and higher temperatures of the I-type magmas.…”

Lower Carboniferous post-orogenic granites in central-eastern Sierra de Velasco, Sierras Pampeanas, Argentina: U–Pb monazite geochronology, geochemistry and Sr–Nd isotopes

“…The Sierra de Velasco granitoids have generally been regarded as part of the Famatinian inner peraluminous S-type belt (e.g. Rapela et al 1990;Toselli et al 1996Toselli et al , 2000Pankhurst et al 2000), with the exception of the southern portion of the sierra which seems to correspond to the main calc-alkaline I-type belt (Bellos et al 2002;Bellos 2005) (Fig. 1a, b).…”