Estructura interna y petrología del ortogneis tonalítico Chicamtoltina en Alta Gracia y alrededores, margen oriental de la Sierra Chica de Córdoba

MARTINO, R. D.; AUGSBURGER, J.; GUERESCHI, A. B.

Córdoba

Congreso; XIII Congreso de Mineralogía, Petrología Ígnea y Metamórfica, y Metalogénesis (XIII MINMET-IV PIMMA); 2019

Asociación Mineralógica Argentina y Comisión de Petrología (COMPETRO) de la Asociación Geológica Argentina

In the Sierra Chica, near Alta Gracia city and surroundings, a gray-colored rock, tonalitic appearance, here called Chicamtoltina tonalitic orthogneiss crops out. It is composed of plagioclase and quartz, with scarce biotite and muscovite, defining the S2 metamorphic foliation during the M2-D2 regional event in amphibolite facies. Minor accessories are allanite, epidote, apatite, zircon, magnetite and ilmenite. Field rocks are formed by sillimanitic and garnetiferous gneisses. A D3 deformation event reworked S2, generating folding and boudinage in a simple shear regime under temperatures close to M2. The lenticular shape of the foliated body, concordant with S2, indicates a syntectonic emplacement of the tonalitic orthogneiss Chicamtoltina during M2-D2 (Pampean orogeny, Early Neoproterozoic-Cambrian).