CONDICIONES P-T DE CRISTALIZACIÓN DE CUARZOS DEFORMADOS DE LAS PEGMATITAS DEL DISTRITO COMECHINGONES, CÓRDOBA, ESTIMADAS A PARTIR DE INCLUSIONES FLUIDAS

DEMARTIS, MANUEL; CONIGLIO, JORGE; PINOTTI, LUCIO; D'ERAMO, FERNANDO; PETRELLI, HUGO; ODDINO, HERNÁN; SILVA, D.

San Salvador de Jujuy – Jujuy

Congreso; IX Congreso de Mineralogía y Metalogenia - en el marco del XVII Congreso Geológico Argentino; 2008

Asociación Geológica Argentina

ABSTRACT In this contribution, preliminary results of a fluid inclusion study in core zone quartz samples of pegmatites from southern Comechingones Pegmatitic District, Sierras Pampeanas, are presented. These pegmatites were emplaced within the Guacha Corral Shear Zone (GCSZ), during the Famatinian orogeny. Three fluid inclusions types were recognized: type A (three-phase aqueous-carbonic, with variable degree of fill), type B (two-phase aqueous), and type C (two-phase aqueous with minor CO2 proportions). Aqueous fluids are predominant, and usually show low to moderate salinity, ranging between 1 - 8 wt % eq NaCl. Local fluid heterogeneities with CO2-rich fluids are observed. Coexistence between aqueous and variable CO2 aqueous-carbonic fluid inclusions in certain occurrence modes is explained by the selective removal of the CO2 phase in relation to aqueous from an original aqueous-carbonic fluid, developed during deformation carried out by dynamic recrystallization mechanisms. It is suggested that P-T conditions of the fluids responsible for the core zone quartz crystallization were close to those for the dynamic recrystallization. These conditions were 560ºC and between 3,3 and 4,4 kb, and they agree with the ductile deformation stabilization conditions of the GCSZ during the Famatinian orogeny.