Mineralogía y microtermometría de la veta Buena Vista, Distrito Minero Andacollo. Neuquén, Argentina

PONS, AGUSTINA; D´ANNUNZIO, M.C.; STRAZZERE L.; CÓCOLA M.A.

Córdoba

Congreso; XIII Congreso de Mineralogía, Petrología Ígnea y Metamórfica, y Metalogenia. Córdoba. Argentina.; 2019

Asociación Mineralógica Argentina

Geological characterization of the Buena Vista vein, Andacollo mining district, Neuquén,Argentina. The Andacollo Mining District is located on the western margin of the Cordilleradel Viento, in the Neuquén province. The Buena Vista vein (Fig. 1a) is a mineralizedstructure emplaced in the Arroyo del Torreón Formation and located on Las Minas hill. Ithas NE-SO (N30 °E- N45 °E) direction and an average width of 3.5 meters. Five pulses wererecognized. The first one (Fig. 1b, d) is composed by quartz (quartz I) in mosaic; the second(Fig. 1b) is formed by quartz veins with primary growth textures (quartz II) and the third one(Fig. 1c, d) is constituted by veins of anhedral quartz (quartz III). The fourth pulse (Fig. 1d)represents the formation of hydrothermal breccias from the previous pulses. The cement ofthe breccias is formed by microcrystalline quartz (quartz IV), pyrite, galena, sphalerite,chalcopyrite, marcasite, argentite and electrum (Fig. 1e, f, g). The fifth pulse is formed bycalcite veins which cut the previous pulses. The mineralogical and microthermometricstudies were made systematically in different positions within the Buena Vista vein with theobjective of comparing the abundance of minerals and the characteristics of the hydrothermalfluids at different depths. From the surface to the deeper vein levels, silver content decrease,while sulfides and electrum increase. The fluids of the third pulse (Fig. 1c, d), prior to themineralization episode, had minimum temperatures between 210 and 278ºC and an averagesalinity of 1.37% wt. NaCl eq and show dilution and cooling processes.