PALEOGEOGRAPHIC CHARACTERIZATION OF THE LOWER CRETACEOUS CENTENARIO FORMATION, NEUQUEN BASIN, ARGENTINA

SHCHEPETKINA, A.; RIBAS, S.; CARMONA, N.B.; PONCE, J.J.; VILLAR BENVENUTO, M.C.

General Roca

Conferencia; RAS 2018; 2018

Universidad de Rio Negro

The upper Valanginian-lower Aptian Centenario Formation is an important producer of oil and gas in the Neuqeun Basin, western Argentina. The formation is located exclusively in the subsurface of the Neuquen Basin, and averages 450-1000 m in thickness. The Centenario Formation is a lateral continuation of the Agrio Formation. The previous studies dealing with the paleogeographic characterization of the Centenario Formation are scarce, and a comprehensive geological model has few previous contributions.Current study scrutinizes the lower Centenario Formation within the Volcan Auca Mahuida area operated by YPF, using sedimentological and ichnological core data, geophysical well logs, and petrographic thin sections. Eleven sedimentary facies and three facies associations have been recognized within the core dataset, providing insight into the paleodepositional environmental setting. The north-eastern part of the deposit, located by the Neuquen Basin limit, was characterized by deposition in the continental environments comprising ephemeral fluvial channels, crevasse splays, abandoned channels, floodplain and paleosoils. The middle part of the study area, located towards the south-west, experienced deposition in the shallow-water ephemeral lakes and their littoral zone, fluvio-dominated lake deltas, and coastal lagoons and sabkhas. Storm-dominated delta deposits typified the marginal-marine environment, which gradually transitioned into the basinal facies of the Agrio Formation. Semi-arid to arid climate conditions have been evoked for the Centenario Formation. Possible sedimentary record of ancient earthquakes during the lower Cretaceous has been provided based on the observations of the deformation features interpreted as seismites.