Kinematics of a backthrust system in the Agrio fold and thrust belt, Argentina: Insights from structural analysis and analogue models

LEBINSON, FERNANDO; TURIENZO, MARTÍN; SÁNCHEZ, NATALIA; CRISTALLINI, ERNESTO; ARAUJO, VANESA; DIMIERI, LUIS

JOURNAL OF SOUTH AMERICAN EARTH SCIENCES

PERGAMON-ELSEVIER SCIENCE LTD

Año: 2020 vol. 100

0895-9811

The Agrio fold and thrust belt is an orogenic belt located in the Southern Central Andes25 (37°-38°S latitude). A set of thin-skinned thrust-related folds with opposite vergence to the26 tectonic push, occur in front of major thick-skinned structures. Seven west-vergent27 anticlines that involve the Late Jurassic - Early Cretaceous sequences of the Mendoza28 Group were mapped. These folds were formed by imbricate faults detached on underlying29 Jurassic evaporites (Auquilco Formation). A regional balanced-cross section shows that this30 backthrust system accommodates part of the shortening transferred by major east-directed31 basement-involved thrusts developed in the inner zone of the Agrio fold and thrust belt.32 Analogue model was constructed to reproduce the structures and to understand their33 kinematic evolution. The model illustrates that the individual backthrusts develop in a34 normal sequence of faulting; it means that successively younger backthrusts are formed in35 the footwall to the west of previous faults. The comparison between field structures and36 those obtained in laboratory allows to analyze the close relationship between the thick and37 thin-skinned structures during the development of the Agrio fold and thrust belt and to38 discuss possible causes that favored the generation of the studied backthrust system.