Geoquímica de las rocas hospedantes del Distrito Minero Castaño Nuevo, Cordillera Frontal de San Juan

LEONARDO STRAZZERE; CÓCOLA, MARÍA AGUSTINA; D'ANNUNZIO, MARÍA CELESTE

Córdoba

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

Asociación Geológica Argentina

Castaño Nuevo mining district is located at Calingasta Department, San Juan Province. The studied area is sited in the eastern rim of Cordillera Frontal and had been mined between the XIX and XX centuries. Gold mineralization is controlled by quartz/adularia veins. Previous studies indicate that veins? host rocks are subvolcanic andesites named as Pórfido Andesítico (Cegarra et al., 1998, Delendatti, 2005). This contribution summarizes detailed mapping results and geochemistry analysis of major and trace elements.Outcropping rocks form a volcanic-pyroclastic sequence, oriented NNE dipping at low angles to the SE. Regarding Cegarra et al. (1998) and Rocher et al. (2015), this sequence corresponds to Vega de los Machos Formation (Caballé, 1986). Three units were defined from detailed mapping. Geochemistry data show a calc-alkaline tendency, varying from andesite (Units I and II) to rhyodacite (Unit III), according to major elements and SiO2 vs Zr/TiO2 graph (Winchester and Floyd, 1977). Chondrite-normalized spider diagram (Thompson, 1982) shows LILE enrichment. In addition, it is important to emphasize a high Nb-Ta anomaly and moderate negative anomaly of Sr, P, and Ti, corresponding to a strong arc component. Concerning to Rb vs Y/Nb diagram from Pearce et al. (1984), allsamples plot in the volcanic arc field (Figure 1).