Published 1995 as part of Memoir 62
Copyright © 1995 The American Association of Petroleum Geologists.   All Rights Reserved.

The sub-Andean fold and thrust belt of northern Argentina is characterized by a set of north-northeast and south-southwest oriented structural trends. Major oil and gas accumulations occur in the eastern sub-Andean ranges, including the Ramos, Aguaragüe, Campo Duran, and Madrejones fields. Thin-skinned deformation involves a tectonic wedge that generated triangle zones bounded by a lower detachment in the Silurian Kirusillas Formation and by an upper detachment at the base of the Upper Devonian Los Monos Formation. In the Ramos and Aguaragüe structures, this configuration creates a distinct disharmony between the tectonic wedge and its passive roof. The shortening is accommodated by major tectonic thickening of the Los Monos Formation, while the overlying Carboniferous and Tertiary units are deformed into box folds. In the Aguaragüe structure, these overlying units are cut by imbricate thrusts that offset the box fold crest eastward with respect to the anticlinal axis of the underlying tectonic wedge. The Campo Duran structure represents an early stage of this process without active folding of its passive roof. In contrast, the Madrejones structure transferred shortening to the foreland, forming the Ipaguazu structure. Balanced cross sections were used in the interpretation of structural styles and hydrocarbon traps to resolve the structures and reduce the exploration risk.