CONICET | Buscador de Institutos y Recursos Humanos

The deformation front of the Neuquén fold and thrust belt (∼37°30′S) comprises kilometer-scale basement-involved anticlines, related to development of the Las Yeseras and Pampa Tril thrust systems, connected with a wide frontal syncline. The interpretation of more than 70 seismic lines led to the construction of a time-structure map at top of the Cuyo Group (Middle Jurassic), which shows a structural high east of the Tromen volcano produced by the superposition of thick-skinned structures. Moreover, data from 35 oil wells constrain the along-strike variations in structural reliefs. The structural relief of the Las Yeseras anticline increase from north to south, between ∼1000 m and 2000 m, while the structural relief of the Pampa Tril anticline reaches its maximum height of 3700 m in the north and decreases southwards to only 1600 m height and then disappears. Three structural cross-sections based on surface and subsurface information show the overall structural style dominated by north-trending basement-involved anticlines, with subhorizontal backlimbs and maximum structural reliefs around 3?4 km, associated with thick-skinned thrust systems and without significant participation of inverted normal faults. Calculated thick-skinned shortenings are ∼8.3 km (14.8%) in the north and ∼4 km (7.8%) in the south, which principally reflects the decreasing displacement of the Pampa Tril thrust system. Along-strike structural changes were locally controlled by WNW transfer zones that can be interpreted as SSW-dipping preexisting normal faults with minor positive inversion. Thin-skinned structures that form oil fields at depth are genetically associated with the thick-skinned thrust systems, thus the understanding of basement-cover interaction in the mountain fronts will aid to future hydrocarbon explorations and to comprehend the mechanisms of Andean mountain building.

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