Petrogenesis of cordierite S-type granitoids in Sierra de Chepes, Famatinian orogen, Argentina

DAHLQUIST, J.A.; RAPELA, C.W.; BALDO, E.G.

JOURNAL OF SOUTH AMERICAN EARTH SCIENCES

Elsevier

Año: 2005 vol. 20 p. 231 - 251

0895-9811

Previous research in the Sierra de Chepes suggested that the second metamorphic event (M2) to affect this sierra reached high-temperature and low-pressure conditions sufficient to induce local anatexis of the surrounding metasediments. Petrological and geochemical investigation of Early Ordovician peraluminous cordierite-bearing S-type granitoids of the Tuaní Granite unit in the Sierra de Chepes (Famatinian Orogen, Sierras Pampeanas, Argentina) reveal that this granitic unit represent a melt (crystallized) yielded from the partial melting of metasedimentary rocks. The granitic melt moved further on and formed small-scale bodies within and outside of the migmatite complex in the Sierra de Chepes. This case study enables us to improve our understanding of anatectic processes, and  constrain a model evolution through to final crystallization of Tuaní Granite unit. A complementary conclusion in this work indicate that the Tuaní Granite unit have petrological and geochemical similarities to some S-type granitoids of the Lachland Fold Belt in Australia (typical S-type granites) and that not all peraluminous granitoids can be classified as S-type granitoids (i.e. with a sedimentary source). Therefore, peraluminous granitoids are not synonymous with S-type granitoids.   Key-words: Melt, S-type granitoids, Peraluminous, Cordierite, Famatinian Orogen, Petrological, Geochemical.