Petrología de las asociaciones máficas-ultramáficas de la sierra de La Huerta, San Juan, Argentina

CASTRO DE MACHUCA, BRÍGIDA; CONTE-GRAND, ALICIA; MEISSL, ESTELA; PONTORIERO, SANDRA; SUMAY, CELINA

Buenos Aires

Congreso; XIII Congreso Geológico Argentino y III Congreso de Exploración de Hidrocarburos; 1996

Asociación Geológica Argentina - Instituto Argentino del Petróleo y del Gas

Several outcrops of mafic-ultramafic igneous rocks were recognized in the Precambrian-Paleozoic crystalline basement of the La Huerta range, San Juan province. The bodies are small and irregular, made up mainly of gabbronorites with minor pyroxenites, peridotites and hornblendites. They are considered to be related to the main tectonic-metamorphic event of upper amphibolite to granulite facies. The mafic-ultramafic rocks show little evidences of metamorphism and igneous fabrics as layering, cumulate textures, reactional rims and others are well preserved. Mafic mylonites are the result of shear zones developed along the contacts between these igneous rocks and their host-rocks, mainly mafic granulites and amphibolites. Chemical abundances of major and trace-elements indicate tholeiitic affinity. The petrologic and geochemical evidences, together with the geological setting, suggest a genesis derived from an altered oceanic crust related to an island-arc tectonic environment.