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

Abstract

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.