Volcanism of the Triassic Cuyo Basin in the Calingasta-Barreal Valley, western Argentina

ROCHER, SEBASTIAN; LOPEZ, MARIA GIMENA; ABARZUA, FERNANDO; TAPIA BALDIS, CARLA

Acta Geológica Lilloana

Fundación Miguel Lillo-Dirección de Geología

Lugar: Tucumán; Año: 2016 vol. 28 p. 163 - 169

0567-7513

The Middle-Upper Triassic deposits of the Calingasta-Barreal valley, northern expression of the Cuyo Basin of western Argentina, contain the register of rift- related basic and silicic volcanism. Basic rocks are basalts and consist in two lava flow units characterized by flow foliations, columnar jointing and vesicles at the top. Silicic rocks are represented by two ignimbrite flow units which show small volume, massive structure, low grade of welding and high aspect ratio. Geochemically, basic rocks are alkaline basalts associated to partial melting of a mantle OIB like enriched source. Ignimbrites are high silica rhyolites, with alumina, alkalis and trace element compositions similar to A-type granites. Triassic bimodal volcanism of Cuyo Basin shows a distinctive extensional withinplate magmatic setting, different from the previous Choiyoi arc related to within-plate transitional rhyolite magmatism.