PALEOPROTEROZOIC METAMORPHIC EVOLUTION OF TONALITIC

MARTÍNEZ J.C.(1), DRISTAS J.A., GRAFF, A., MASSONNE H-J., DRISTAS, J.A. Y THEYE T,(3) & VAN DEN KERKHOF, A.M.(4)

Heildelberg

Congreso; The 23rd Latin American Colloquium on Earth Sciences; 2014

Universidad de Heildelberg

The Tandilia belt in central-eastern Argentina represents the southernmost portion of thePaleoproterozoic Río de la Plata craton. As P-T paths were rarely estimated for metamorphicrocks of this craton, we selected the area of Cerro El Cristo for studying its P-T evolution. Inthis area, which is located ~65 km southeast of the town of Tandil, three main lithologies can berecognized: (1) amphibole(Am)-biotite(Bt) gneisses, (2) garnet(Grt)-Bt-bearing migmatites and(3) metamorphosed pegmatites and granites. In order to determine the P-T evolution of such rocks we applied the PERPLE_X software package for calculating P-T pseudosections for a gneiss and a migmatite in the 11-component system Si-Ti-Al-Fe-Mn-Mg-Ca-Na-K-O-H. Information on the experienced P-T conditions was obtained by electron microprobe analysis of the minerals and the contouring of the pseudosections by isopleths of chemical parameters of these minerals.