Geometrical analysis and timing of structures on mafic-ultramafic bodies and high grade metamorphic rocks, Sierras Grandes of San Luis, Argentina.

SERGIO DELPINO,; LUIS DIMIERI; ERNESTO BJERG,; JOSÉ KOSTADINOFF,; ABERRA MOGESSIE,; GERARD HOINKES,; CHRISTOF HAUZENBERGER,; ANYA FELFERNIG,

JOURNAL OF SOUTH AMERICAN EARTH SCIENCES

Elsevier

Lugar: Oxford; Año: 2001 vol. 14 p. 101 - 112

0895-9811

The study area comprise a portion of the Sierras Grandes of San Luis, located in central western Argentina. These sector is composed of high-grade granulite facies metamorphic rocks, mainly gneisses and migmatites, with intercalated igneous mafic-ultramafic bodies. These bodies occur as discontinuous lenses along a narrow central belt concordant with the general Northeast-Southwest structural trend. The granulite facies metamorphism (Mg) reached by this central area, has been adscribed to the intrusion of the mafic-ultramafic bodies into an amphibolite facies metamorphic sequence (Gonzalez Bonorino 1961, Hauzenberger 1997, Sims et al. 1998; Hauzenberger et al. 1998). On both sides of the mafic-ultramafic bodies, a decrease of metamorphic grade to amphibolite facies is apparent. Numerous pegmatitic bodies intruding the metamorphic complex can be found elsewhere, and towards the west limit of the study area La Escalerilla metagranite constitutes one of the bigger granitic exposures of the Sierras.The results of the structural analysis, done along cross-sections transversal to the mafic-ultramafic belt, allowed to establish a structural evolution for this large geological feature.