--> Abstract: Lower Cretaceous Avile Sandstone, Neuquen Basin, Argentina--Exploration Model for a Lowstand Clastic Wedge in a Back-Arc Basin, by T. A. Ryer; #91004 (1991)

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Lower Cretaceous Avile Sandstone, Neuquen Basin, Argentina--Exploration Model for a Lowstand Clastic Wedge in a Back-Arc Basin

RYER, THOMAS A., Apache International, Denver, CO

The Neuquen basin of western Argentina is a back-arc basin that was occupied by epeiric seas during much of Jurassic and Cretaceous time. The Avile Sandstone Member of the Agrio Formation records a pronounced but short-lived regression of the Agrio sea during middle Hauterivian (Early Cretaceous) time. Abrupt lowering of relative sea level resulted in emergence and erosion of the Agrio sea floor; shoreline and fluvial facies characteristic of the Centenario Formation shifted basinward. The Avile rests erosionally upon lower Agrio shale over a large area; well-sorted, porous sandstones within the member pinch out laterally against the base-Avile erosional surface. Avile deposition closed with an abrupt transgression of the shoreline to the approximate position it had occupied prior to he Avile regression. The transgressive deposits are carbonate rich, reflecting starvation of the basin as a consequence of sea-level rise.

The Avile lowstand clastic wedge consists predominantly of sandstones deposited in fluvial to shallow-marine paleoenvironments; eolian sandstones probably constitute an important component in the eastern part of the area. The sandstones locally have excellent reservoir characteristics; they constitute the reservoirs in the Puesto Hernandez, Chihuido de la Sierra Negra, and Filo Morado fields.

The pinch-out of the Avile lowstand clastic wedge has the potential to form stratigraphic traps in favorable structural positions. The depositional model indicates that there may be a viable stratigraphic play to be made along the Avile pinch-out in the deep, relatively undrilled, northwestern part of the Neuquen basin.

 

AAPG Search and Discovery Article #91004 © 1991 AAPG Annual Convention Dallas, Texas, April 7-10, 1991 (2009)