Abstract

CISTERNA, Clara Eugenia; MON, Ricardo  and  MENA, Rodolfo. Internal structure of the migmatitic belt in the crystalline core of the northern Sierras Pampenas Northwestern Argentina. Rev. Asoc. Geol. Argent. [online]. 2010, vol.66, n.1-2, pp.66-79. ISSN 0004-4822.

The Las Cañas Complex located in Aconquija Range (Sierras Pampeanas Septentrionales) is formed by rocks of the crystalline basement, mainly migmatites and, in smaller proportion, schists which are as resisters included in the migmatites. The migmatites range from metatexites to diatexites. They show a migmatitic foliation accompanied by intrafoliated folds generated under high metamorphic conditions, with partial melt and anatexis. A later superposed folding episode under high ductile conditions generated interference patterns. Finally a brittle-ductile shear episode involving the migmatites is recognized. It affects some portions more intensively than others; its distribution is not uniform. The structural and petrographic observations in the field and in microscope allow the recognition of pre, syn and post migmatization deformation episodes. This tectonic evolution occurred along a significant stretch of the crystalline basement of NW Argentina in a mobile belt along the west border of supercontinent Gondwana, where the recognized deformation episodes correspond to the Pampean Orogeny (550 - 500 Ma) and to the superposed Famatinian Orogeny (500 - 440 Ma).

Keywords : Migmatites; Deformation; Aconquija Range; Sierras Pampeanas; Argentina.

        · abstract in Spanish     · text in Spanish     · Spanish ( pdf )