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

MAURO GERALDES; PAULO MARCOS; LEONARDO BENEDINI; LEONARDO STRAZZERE; DANIEL A. GREGORI; MERCEDES BARROS

SAN MIGUEL DE TUCUMAN

Congreso; XX CONGRESO GEOLOGICO ARGENTINO; 2017

ASOCIACION GEOLOGICA ARGENTINA

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 ANALYZED SAMPLE IS A CRYSTALS RICH LAPILLY-TUFF OF DACITIC COMPOSITION, LOCATED 10 KM SOUTH OF GUILLERMO LAKE AND IS CONSIDERED AS A PART OF THE BASAL SECTION OF THE BOLSON DEPOCENTER OF THE ÑIRIHUAU 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.