Formation of Contractional Wedge Structures in the Andean Forearc, Northern Chile: A Comparative Model From Physical Experiments Applied on the Eastern Domeyko Cordillera

Contractional wedge structures represent one of the most efficient mechanisms for developing orogenic growth. Their displacement is often transferred from deeper thrust faults to overlying oppositely verging thrust faults, accommodating a great amount of tectonic shortening. In this context, ductile upper stratigraphic levels play an important role in generating potential detachment-thrust faults. In the inner Andean forearc of northern Chile, specifically in the transitional border between the Domeyko Cordillera and the Salar de Atacama Basin, structures that affect both the basement and its stratigraphic cover are recognized. However, the geometry and kinematics of those structural styles defined as a hybrid system (thick- and thin-skinned tectonics) are yet to be characterized. One interesting question is to understand what the most efficient mechanisms are in generating orogenic growth and synorogenic sedimentations along the inner Andean forearc. In this study, we present a new structural model explaining the development and orogenic growth of the eastern Domeyko Cordillera. We analyze and interpret fieldwork data combined with a 2-D reflection seismic profile. We compare and validate our interpretations by performing a new series of analog models addressing positive tectonic inversion. On this basis, we propose an integrated kinematic model for the eastern Domeyko Cordillera and the Salar de Atacama Basin. Our structural interpretation describes the relationships between inherited extensional, inversion, and shortening-related structures. This model considers the effects of post-rift sequences on the formation of contractional wedge structures, particularly the role of evaporitic levels as controlling factors for the formation of detachment-thrust faults and wedge structures.