Structural evolution of the transition zone between the Aconcagua and Malargûe fold and thrust belts, province of Mendoza

Abstract

In this work we describe briefly the stratigraphy and the structure of the Andes in the transition zone between the Aconcagua and Malargüe fold and thrust belts. The outcrops are a permotriasic volcanic acid basement, Mesozoic sediments of the Neuquén basin and Neogene volcanic rocks and continental deposits. Structuraly we distinguish from west to east four segments: a tectonic inversion zone, a tight folds zone, a central or imbrication zone, and the Carrizalito anticlinal. Two structural sections were built using field data collected from the thight folds and imbrication zones and the from western flank of the Carrizalito anticlinal, that describe the structures in the area. Regional lineaments with northwest trends, could be acting as transfer zones. It can be recognize two or three deformational pulses according to the relative ages between the structures and the uplift of the Cordillera Frontal. If the cordon del Carrizalito was a basement high we propose two deformational pulses, the first one of thin skinned type and the second one responsible of the uplift of the Frontal Cordillera, tilting the previously deformed sequence. If the uplift of the Carrizalito anticlinal worked as a sticking point of the fold and thrust belt, a third deformational episode with out-ofsequence faults could be recognized.