PLUTÓN CARBONÍFERO ANDALUCA (SIERRA DE VINQUIS, CATAMARCA): PETROGRAFÍA, GEOQUÍMICA Y GEOCRONOLOGÍA U-Pb SHRIMP

DAHLQUIST, JUÁN A.; CARMEN GALINDO; MORALES CÁMERA, MATÍAS M.; BASEI, MIGUEL A. S.

Córdoba

Congreso; XIII CONGRESO DE MINERALOGÍA, PETROLOGÍA ÍGNEA Y METAMÓRFICA, Y METALOGÉNESIS; 2019

Asociación Geológica Argentina y Asociación Mineralógica Argentina

Andaluca Carboniferous pluton (Sierra de Vinquis, Catamarca): Petrography, whole-rock chemistry and SHRIMP U-Pb geocronology. The Andaluca pluton is a semi-elliptical intrusive body of approximately 60 km2 located in the southwestern part of Sierra de Vinquis, eastern Sierras Pampeanas. The host rocks are Carboniferous (355 ± 7 Ma) strongly peraluminous A-type granites of the Vinquis batholith (Morales Cámera et al., 2017). A new SHRIMP U-Pb zircon crystallization age of 344 ± 3 Ma indicates emplacement in earliest carboniferous time.Three main facies have been recognized: (Fa) porphyritic sienogranite with largemicrocline crystals in a medium to coarse-grained matrix, (Fb) porphyritic quartz monzonite with large microcline crystals in a coarse-grained matrix and (Fc) porphyritic monzogranite with large microcline crystals in a coarse-grained matrix with garnet.The granites display SiO2 contents between 67.8 and 75.4 wt.% and they are slightly peraluminous (aluminum saturation index, ASI = 1.04 - 1.10). On FeO/(FeO+MgO) plot the samples plot in the ferroan field (FeO/(FeO+MgO) = 0.87-0.95%). They have a fractionated composition (Rb/Sr = 2.0 - 14.8). The high concentrations for the High Field Strength Elements (HSFE) and flat REE patterns showing significant negative Eu anomalies are typical features of A-type granites.The isotopic data (Rb-Sr and Sm-Nd) indicate that these A-type granites represent variable mixtures of Carboniferous mafic magmas and continental crust. So, a petrogenetic model that involves AFC processes could be tested.