Petrography and structure of the igneous-metamorphic basement of the Los Cuartos region, department of Tafí del Valle, Tucumán province, Argentina

Acta geológica lilloana 22 (1-2): 2010

Abstract

The metamorphic basement of the Los Cuartos region is composed of banded schists and frequent interlayered calc-silicate rocks. These rocks have suffered two main phases of deformation and metamorphism: D1, syn-kynematic with M1, generates a main schistosity S1 , and the foliation of the calc-silicate layers; D2, generates a crenulation cleavage S2, folding of S1 veins and boudinage of the calc-silicate layers. M2, is late- to post-kynematic, and produces chlorite, biotite, garnet and staurolite porphyroblasts. The Los Cuartos granitoid has monzogranitic to tonalitic composition of two micas. The granite is inequigranular. It is calk-alkaline, peraluminous and shows post-tectonic features with regard to the regional deformation. The granitic intrusion produced contact metamorphism in the surrounding basement, with development of andalucite porphyroblasts and poiquiloblastic biotite.