Análisis sedimentológico del miembro Pilmatué, formación Agrio, en el área del anticlinal El Churqui.

Abstract

The study of the Agrio Formation is essential for understanding petroleum systems in the Neuquén Basin; this unit, along with the Tordillo, Vaca Muerta, Quintuco, and Mulichinco formations, comprises the Mendoza Group. The Agrio Formation is characterized by its lithological variability and is divided into three members: Pilmatué, Avilé, and Agua de la Mula. Some authors include the Chorreado Member within this group. The objective of this thesis was to carry out a detailed sedimentological analysis of the Pilmatué Member in the El Churqui anticlinal area, complemented by petrographic, X-ray diffraction (XRD), and scanning electron microscopy (SEM) analyses. This sedimentological analysis identified seven sedimentary facies, grouped into two facies associations corresponding to a proximal outer ramp and a distal outer ramp. Additionally, this study has allowed the recognition of the sedimentary processes and paleoenvironmental conditions in which this unit was deposited. In the proximal outer ramp, sedimentation was influenced by processes such as flocculation, fine material settling, and gravitational flows, while in the distal outer ramp, settling and sediment transport by bottom currents predominated. Sedimentation in this member alternated between periods of high carbonate productivity and periods of high terrigenous sediment input, resulting in significant rhythmicity, especially in the middle interval. Despite the thickness difference of this unit compared to the nearby El Portón locality, well data indicate values similar to those obtained in the El Churqui anticline area. Additionally, the lithology, sedimentary processes, and depositional environment of this unit are consistent with other sections in different sectors of the Neuquén Basin. These findings provide a more comprehensive understanding of geological processes in this region.