Influence of the Triassic-Jurassic rift structures on the deformation style of the Aconcagua and Malargüe fold and thrust belts, Mendoza

Abstract

The Aconcagua and Malargüe fold and thrust belts developed in the Cordillera Principal, which between 32º- 34º and 34º-36º S latitude respectively, show a complex interaction between the sedimentary cover and the basement as a result of the existence of Triassic-Jurassic rift-related normal faults of the northern part of the Neuquén basin. Structural studies, together with chronological analysis of the deformation in the thin-skinned and thick-skinned zones, indicate that the evolution of both belts was controlled by the presence of NNW-trending border faults of the Atuel, Nieves Negras - Alvarado and Yeguas Muertas depocentres of the Neuquén basin. In this study we analyze three possible mechanisms of interaction between the thin-skinned and thick-skinned deformation. For the Aconcagua FTB, we propose that the pre-existing normal faults controlled the location of ramps within the basement. For the southernmost part of the Aconcagua FTB and the northern part of the Malargüe FTB we propose a mechanism of tectonic inversion of rift-related faults, together with short-cut faults, which propagated into the sedimentary cover generation the thin-skinned deformational area.