3-D Structural Modeling of the Tordillo Formation: Structural Styles and Strain Partitioning in the Southern Agrio Fold Belt, Neuquen Basin, Argentina

David G. Repol and Deborah A. Spratt
University of Calgary, Calgary, AB

The Agrio fold and thrust belt is a world-class example of a tectonically inverted belt comprising both thin- and thick-skinned structures. It resulted from tectonic inversion of a Jurassic extensional system in the western part of the Neuquen Basin during the Andean orogeny (Late Cretaceous - Middle Neogene). Surface mapping indicates that the inherited geometries of this extensional system affected the thick-skinned domain, where broad synclines and anticlines are obliquely oriented relative to the main NNW-SSE trend of tight folds in the eastern, thin-skinned domain. The subsurface interpretation is constrained by an approximately 23,500 square kilometer seismic dataset through which we have reconstructed the 3D distribution of the Tordillo Formation. Analysis of this key horizon shows that the Jurassic half-graben system controlled the orientation, structural style and vergence direction of folds in this part of the Andean belt. Furthermore, changes in plate convergence direction over time affected the magnitude of the strike-slip component of strain partitioning at different structural positions and times across the region. Our 3D structural analysis is used to reassess the hydrocarbon potential of this complex area, providing different perspectives for the development of new ventures in this part of the Neuquen basin and in other inverted belts.

AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005