Abstract: Exploration in the Sub Andean Thrust/Fold Belt of North West Argentina

A. Schulz, M. Alarcon, F. Aramayo, M. Santiago, W. J. Ashby

A significant portion of the 15,000 square kilometer Aguarague exploration permit is located with the Sub Andean zone of northwest Argentina bordering Bolivia.

The Sub Andean sedimentary section is dominated by a succession of tectonostratigraphic cycles of Silurian to recent age. These cycles display a complex geological history prior to the onset of the Andean deformation of Upper Miocene age.

As the structures are complex, several different exploration techniques were combined, including satellite imagery, aeromagnetics, geological mapping, geochemistry, microtectonic studies, magneto stratigraphy, seismic modeling and seismic with pre- and post-stack depth migration.

The interpretation of these techniques produced three dimensional structural models, at regional and prospect scales, that demonstrated the deformation mechanism, sequence and timing of the structures; these were then linked to the timing of generation/expulsion of hydrocarbons.

The physical properties of the sedimentary sequence produces three structural environs, each with distinct fold and fault mechanisms.

1. (Upper): A product of the cumulative deformation of the underlying environs;

2. (Middle): The presence of an incompetent shale, the principal source rock, within this unit produces "fold disharmony" (horizontally and vertically) between the overlying and underlying environs.

3. (Lower): Characterized by folds developed by Fault Bend Fold processes (Suppe, 1983).

Hydrocarbon fields and exploration prospects are present within all three environs.

The work performed has permitted the successful evaluation of several structures within the Sub Andean of the UTE Aguarague.

AAPG Search and Discovery Article #90951©1996 AAPG International Conference and Exhibition, Caracas, Venezuela