Geoquímica y Geocronología de secuencias volcánicas Neógenas de trasarco, en el extremo oriental de la Cadena Volcánica Transversal del Quevar, noroeste de Argentina.

PETRINOVIC, I.A.; MITJAVILA, J.; VIRAMONTE, J.G.; MARTI, J; BECCHIO, R.; ARNOSIO, M.; F. COLOMBO

ACTA GEOLOGICA HISPANICA

Año: 1999 vol. 34 p. 255 - 273

0567-7505

34 new geochronological data and 39 new geochemical analyses have been made in the Neogene backarc volcanic sequences in the “El Quevar Transversal Volcanic Chain” defined by Viramonte et al (1984a). This chain starts at the present N-S arc with WNW-ESE trend. New volcanic centres have been recognised and analysed at the oriental end of this chain. The different pulses in each emission centres (Aguas Calientes, Acay, El Morro-Organullo and Tocomar) are petrographically and geochemically homogeneous. The magmatic chambers related in each one, were geochemically homogeneous and did not have crystal rich sectors. The Acay eruptive centre is an exception of this assumption; a compositionally differentiated magmatic chamber could be infered. The isotopic composition of the Aguas Calientes emission centre has a crust signature in its origin, related with melts generated by crustal fussion. The geochronological determinations show volcanic pulses at 17-19 Ma, 13-12 Ma, 10 Ma, 7-6 Ma, 1-0.5 Ma in this region of the Central Andes.