Structural Style in the Subandean Fold and Thrust Belt of Argentina and its Main Associated Hydrocarbon Fields

Abstract

The Subandean System covers an area of 11,000 km[sup 2] in northern Argentina and it is represented by a set of structural trends orientated north-northeast-south southwest. The major oil and gas accumulations occur in its eastern trends, that is, Ramos, Aguarague, Campo Duran and Madrejones Ranges. Based on data provided by wells, seismic lines and outcrops, a series of balanced cross sections which show the structural style in each trend and the different hydrocarbon traps, was carried out. The deformation model that rules this set is represented by a Tectonic wedge which generates a triangle zone, with a lower detachment in the Kirusillas Formation (Silurian) and an upper detachment at the base of Los Monos Formation (Upper Devonian). This latter formation in the Ramos and Aguarague Ranges generates a clear disharmony between the lower and upper units. The shortening is resolved by a strong thickening of its original thickness, on the other hand, in the Madrejones and Campo Duran Ranges, part of the shortening is transferred to the foreland. The Carbonic and Tertiary units, are passively folded above the Los Monos Fm. These units show, in some cases, imbricated thrusts which displate the superficial anticlinal axis. Important hydrocarbon accumulations were more » discovered in each one of these structural units. Understanding their deformation mechanism would reduce risk in future exploratory prospects. « less