High-grade metamorphism of the Sierras de la Huerta and Valle Fértil, San Juan province, NW Argentina.

MOGESSIE, A.; SCHNEIDER, I; GALLIEN, F; CASTRO DE MACHUCA, B; BJERG, E. A.; DELPINO, S; PREVILEY, L; PONTORIERO, S; MEISSL, E

San Salvador de Jujuy, Argentina

Congreso; XVII Congreso Geológico Argentino; 2008

Asociación Geológica Argentina

The Sierras de La Huerta and Valle Fértil located in the San Juan Province, NW Argentina, belong to the Western Sierras Pampeanas. They consist of a Proterozoic gneissic basement intruded by gabbroic to granodioritic rocks in Early to Middle Ordovician times (Famatinian Orogeny). The abundant gneissic rocks which are strongly deformed and metamorphosed at granulite facies conditions are composed mainly of quartz - plagioclase - biotite - garnet - sillimanite - cordierite ± potassium feldspar ± spinel ± magnetite. The tonalitic - granodioritic, gabbroic - dioritic rocks are considered to provide the heat source for a regional contact metamorphism at about 6 - 7 kbar,with temperatures in excess of 860°C.