Características Geoquímicas de las rocas Ígneas Pérmicas Del Distrito Minero Andacollo, Neuquén (Argentina)

D'ANNUNZIO, MARÍA CELESTE; LEONARDO STRAZZERE; COCOLA, MA. AGUSTINA

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 at the northwest side of the Neuquén province, 2 km west of the Andacollo city. Igneous rocks with Devonian to Lower Permian ages, crop out in this área.The Huinganco Volcanic-Plutonic Complex is composed of basic to intermediate volcanites (281,8±2,1 magmtic biotites K-Ar age; Suárez y De la Cruz 1997) which are cut by afanitic dikes and intruded by bodies with granular textures with acidic-intermediate compositions (287±9 Ma; magmtic biotites K-Ar age; Suárez et al. 2008). In addition, these granite bodies are cut by aplite dikes.The extrusive volcanites and the aphanitic dikes correspond to riodacites / dacites, rhyolites, according to the Winchester and Floyd diagram (1977) while the intrusives and the aplitic dike show compositions that vary from diorite to granite (Middlemost 1994). All analyzed rocks show marked negatives anomalies of Nb-Ta, P and Ti, confirming their arc signature (Pearce 1983). According to the REE diagram of Nakamura (1974) the diorites are linked to the same event as the andesites, while the granite corresponds to another more evolved episode. The aplitic dikes are not coincident with any of the mentioned events and the presence of a significant negative Eu anomaly would indicate fractionation of feldspar or the retention of feldspar in the magmatic chamber after partial melting. The afanitic dike does not correspond to the aforementioned events either.