Análisis sedimentológico e icnológico de la sección basal de la formación Picún Leufú (Tithoniano-Berriasiano) en su localidad tipo, Cuenca neuquina, Argentina

Abstract

The sedimentological, ichnological and geobiological analyses of the deposits that integrate the basal section of the Picún Leufú Formation, allowed to recognize eighteen sedimentary facies, grouped in three facies associations related to offshore, shoreface and bay deposits. The stacking pattern shown by the three facies associations indicates a prograding arrangement in its basal and middle section, and a retrograding arrangement in the cuspidal section. In addition, several levels with microbial mats show evidence of subaerial exposure (e.g. mud cracks, edaphization and rhizolites) and they are interpreted as formed in muddy and mixed plains bay deposits. The presence of a substrate-controlled ichnofacies at the top of the analyzed section suggests the combined action of erosive processes and early diagenesis of carbonates that occurred during transgression. These studies allowed refining the depositational model for this unit, which was formed in a ramp system with offshore, shoreface and bay deposits. In addition, these results help to understand and refine the sedimentary facies distribution, stacking pattern and depositational model of one of the most important unconventional oil systems of the Neuquén basin.