Structural interpretation of the mountain front in the Diamante river zone, Mendoza

Abstract

At the junction of Las Aucas stream with the Diamante river (69° 30' W; 34° 40' S) kilometre-scale structures affecting both Cordillera Principal and Cordillera Frontal rocks were surveyed. A rigid basement block is uplifted, without folding, by a reverse fault at its eastern edge. Sedimentary cover above this block forms an anticline whose steeply dipping limb is highly deformed. Several models for basement-involved structures can explain the observed features. Multiple interpretations can be a useful tool to understand the geological process involved and a guide for predicting both macro- and mesoscale structures in outcrops or at the subsurface. A backthrust which detached from the uplifted basement block, produced a west-verging anticline. This structure is interpreted using a geometric and kinematic model, which can be combined with any of those used for major structures. Our studies highlight the deformation style affecting both basement and cover rocks. Its typical features can be used to understand the deformation in more internal parts of an orogenic belt, including those areas where basement rocks are not exposed. Shortening values were calculated from two retrodeformable cross-sections interpreted with the triple junction and Trishear models for basement-involved structures.