Sequential stratigraphic analysis of the Anacleto and Allen formations (Late Cretaceous) in the northeastern margin of the Neuquina Basin, Argentina

Sequential stratigraphic analysis of the Anacleto and Allen formations (Late Cretaceous) in the northeastern margin of the Neuquina Basin, Argentina. Based on a detailed sedimentological study we carried out a sequential stratigraphic analysis of the Upper Cretaceous deposits of the Anacleto Formation and lower member of the Allen Formation in the north-eastern border of the Neuquina Basin. The lithofacies association allowed interpreting architectural elements of fluvial origin and tide influenced elements. Three fluvial systems (a braided system, an anastomosed one, and a high sinuosity one), a proximal and a middle estuarine system were recognized for the Anacleto Formation. A distal estuarine system or estuary outlet was defined for the basal member of the Allen Formation. In the sequential stratigraphy analysis the following systems were identified: a low accommodation system tract in a continental environment limited by a flooding fluvial surface (discontinuity I) and discontinuity II; and a high accommodation system tract and its equivalent transgressive system tract in a marine environment, with discontinuities III, IV y V.