Características Geoquímicas de las rocas ígneas Pre-Carbonífero Superior, Distrito Minero Andacollo, Neuquén, Argentina.

LEONARDO STRAZZERE; D'ANNUNZIO, MARÍA CELESTE

Córdoba

Congreso; XIII CONGRESO DE MINERALOGÍA, PETROLOGÍA ÍGNEA Y METAMÓRFICA, Y METALOGÉNESIS (XIII MINMET ? IV PIMMA); 2019

Asociación Geológica Argentina

The Andacollo Mining District is located in the northwestern sector of the province of Neuquén, 2 km west of the homonymous town.The oldest unit in the area corresponds to the Fm. Arroyo del Torreón, which is composed of crystalline tuffs, lithic tuffs, and tuffs with eutaxitic texture. Based on the stratigraphic relationships established by Zöllner and Amos (1973), it is considered to be of Early Carboniferous age, although Rovere et al. (2004) does not reject the possibility of Devonian age.Intruding the Fm. Arroyo del Torreón, small outcrops of subvolcanic bodies corresponding to the Dacite Sofia are recognized (327.9 ± 2.0 Ma, U-Pb SHRIMP in zircons, Suárez et al., 2008). It has a porphyritic texture composed of oriented phenocrysts, immersed in a felsitic paste. The paste is formed by volcanic glass with spherulitic devitrification textures.The composition of both units corresponds to rio-dacites/dacites- riolites according to the diagram of Winchester and Floyd (1977). The sample analyzed from the Dacite Sofia is characterized by an arc signature with pronounced anomalies of Nb-Ta, P and Ti (Pearce 1983), while the Fm. Arroyo del Torreón shows a smaller arc component. A similar tendency can be observed in the Nb vs Y diagram (Pearce et al., 1984). According to the obtained results, the rocks analyzed correspond to different events.