New Age Constraints for the Cenozoic Marine Ingressions of Northwest Patagonia, San Carlos de Bariloche Area, Argentina

FLORENCIA BECHIS; ALFONSO ENCINAS; ANDREA CONCHEYRO; VICTOR A. RAMOS

Antofagasta

Congreso; 13º Congreso Geológico Chileno; 2012

Universidad Católica del Norte, Sociedad Geológica de Chile

In this contribution we present new age constraints for the Cenozoic marine successions that crop out along the Argentinean slope of the North Patagonian Andes in the San Carlos de Bariloche area (41°-42° SL). New geochronologic data from U-Pb LA-ICPMS analysis, and new bioestratigraphic data from calcareous nannofossils studies have led us to identify at least three marine successions constrained between the uppermost Oligocene and the lowermost Middle Miocene. These marine levels are registered both in the El Foyel and Nahuel Huapi Groups, which constitute the infill of distinct depocenters of the Ñirihuau basin. The new data indicate that deposition of the El Foyel Group was coeval with the Nahuel Huapi Group, and it does not represent a previous tectono-sedimentary cycle, as previously considered.