Geometric and kinematic model for basement-involved backthrusting at Diamante River, southern Andes, Mendoza province, Argentina

MARTÍN TURIENZO,; LUIS DIMIERI

JOURNAL OF SOUTH AMERICAN EARTH SCIENCES

Elsevier

Lugar: Oxford; Año: 2005 vol. 19 p. 111 - 125

0895-9811

At the confluence of the Las Aucas stream with the Diamante River (698300W Long.; 348400S Lat.), kilometer-scale structures affectingbasement rocks were surveyed. Andean deformation involved both Cordillera Principal and Cordillera Frontal rocks, whose structuresprobably were locally contemporaneous and intimately related. The Cordon del Carrizalito, a huge structure interpreted as a rigid basementblock raised by a reverse fault on the eastern edge, which produced intense deformation in the sedimentary cover, can be explained by a geometric and kinematic model for basement-involved structures in the upper crustal levels. The Lomas Bayas structure is considered a westvergent anticline associated with a backthrust, which branches out from the basement block?s eastern edge. A new kinematic quantitativemodel, based on the Lomas Bayas structure, explains basement-involved backthrusts. Shearing of the basement rocks produced progressiverotation of the backthrust?s hangingwall block, whose upper toe is bent but sedimentary cover is delaminated and detached. Theseretrodeformable models are applied to two cross-sections to test their viability and calculate the structural shortening.