REINTERPRETACIÓN DE LAS GRANULITAS ÁCIDAS AFLORANTES EN VIRORCO, PROVINCIA DE SAN LUIS

ZAFFARANA CLAUDIA B., POMA STELLA M. N, LEAL PABLO R. Y BRODTKORB MILKA K. DE

Facultad de Ciencias Exactas y Naturales, UBA

Congreso; VII Congreso de Mineralogía y Metalogenia 2006; 2006

VII Congreso de Mineralogía y Metalogenia

ABSTRACT: The aim of this study is to provide a modern interpretation of the origin of the rocks formerly named acid granulites which outcrop along the eastern border of Virorco mafic-ultramafic body. The analysis of their macroscopical properties suggests a similarity between these outcrops and the Sin-kinematic Granitoids that occur in the study area, therefore they could be considered part of this unit. However, their petrographic features demonstrate that the studied rocks can be classified as granodiorites, while the surrounding Sin-kinematic Granitoids belong to the granite field. Geochemical analyses confirm these differences. Moreover they also evidence their peraluminous character and a heavy REE pattern similar to the mafic-ultramafic rocks of Virorco. With regards to the origin of the acid granulites, they could be the product of the metamorphism of either a granodiorite or a plagi-granite. If the protolith were a granodiorite, they could be interpreted as the result of the partial melting of the country rocks (Pringles Metamorphic Complex) with contribution of the Virorco mafic-ultramafic rocks. If we consider the second option (plagi-granite), they could represent the acid residue of the crystallisation of the stratified mafic-ultramafic rocks.