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

SEBASTIAN ROCHER; FERNANDO ABARZÚA; CARLA C. TAPIA BALDIS; MARÍA GIMENA LÓPEZ

Acta Geológica Lilloana

Fundación Miguel Lillo-Dirección de Geología

Lugar: Tucumán; Año: 2016 vol. 28 p. 153 - 160

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. The petrology of these rocks, particularly the silicic members, has been poorly documented as well as their relationships with previous magmatic events. Basalts consist in two lava flow units characterized by flow foliations, columnar jointing and vesicles at the top. Ignimbrites form two 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 within-plate magmatic setting, different from the previous Choiyoi arc related to within-plate transitional rhyolite magmatism.