The relationship between Cenozoic shallow igneous bodies and thrust systems of the mountain front of the Cordillera Principal, Mendoza province, Argentina

Abstract

Within the Malargüe fold and thrust belt, located in the southern Central Andes, south of Mendoza province, Argentina, several shallow intrusive bodies which are part of extensive Neogene magmatism are exposed and linked to the subduction of the Nazca plate beneath the western edge of South America. This study attempts to establish the relationship between these igneous bodies and thrusts that are part of fault systems that built the Andean orogen. It is interpreted that these thrusts have acted as feeding channels for the ascent of magma and therefore there is a direct link between the distribution of magmatism and fault systems. The igneous bodies are emplaced through low-angle faults and it results in longitudinal strips of intrusive bodies of younger ages towards the Andean foreland. The petrographic and geochemical analysis shows that the sills, dikes and laccoliths, outcropping in the Malargüe fold and thrust belt, have a calc-alkaline affinity indicating an origin related to the Andean magmatic arc. The evolutionary model of the emplacement of the intrusive bodies and their relationship with the Andean thrust systems has significant implications for geotectonic models that consider the shifting of the magmatic sources of the Andean Arc currently proposed for these regions of the Andes.