NUEVA EDAD U-PB EOCENA TARDIA PARA LA FORMACION VENTANA. ANDES NORDPATAGONICOS PROVINCIA DE RIO NEGRO

BENEDINI, LEONARDO; GERALDES, MAURO C.; DANIEL GREGORI; STRAZZERE, LEONARDO

Congreso; XX CONGRESO GEOLÓGICO ARGENTINO; 2017

New late Eocene U-Pb age for the Ventana Formation, Northpatagonian Andes, Rio Negro Province. In the present contribution we present a new U-Pb age obtained from igneous zircons for the Ventana Formation. The analized sample is a crystals rich lapilli-tuff of dacitic composition, located 10 km south of Guillermo Lake and is consi-dered as a part of the basal section of the Bolsón depocenter, Ñiirihuau Basin. This pyroclastic lithofacies have subhedrales to euhedral zircon grains that have served to perform the dating. The results indicate a Late Eocene age for the magmatic crystallization (35.8 ± 1.7 Ma) that corresponds with a Priabonian stage.