Ostracods and paleoambiental inferences in the Plottier Formation (Coniancian - Upper Cretaceous) of the Barreales Lake, Neuquén

Abstract

Upper Cretaceous outcrops, at the northeast of Barreales lake, Neuquén, Argentina, has given in the last 20 years a rich vertebrate fauna including dinosaur, reptiles, fish and plants on different sites. In this contribution, rocks of the Plottier Formation at Babilonia Site at Proyecto Dino Geopaleontological Park have given, for the first time, an interesting microfauna composed by ostracods. The ostracofauna recovered is represented by the family Ilyocyprididae with four taxa, Neuquenocypris calfucurensis Musacchio, 1973, Neocyprideis zampalensis (Angelozzi, 1980), Neuquenocypris tenuipunctata Musacchio & Simeoni, 1991 and Neuquenocypris nahuelniyuensis Musacchio, 1989 and the family limnocytheridae, with one taxa Vecticypris sp. The ssociation of theses ostracod indicates a paleoenvironment characterized by a shallow meandering river with low energy, probably an abandoned oxbow lake. Palaeoecological analyses indicate a fresh water with fluctuating oligohaline salinities throughout deposition.