Structural style of the Chos Malal fold and thrust belt, Neuquén basin, Argentina: Relationship between thick- and thin-skinned tectonics

SÁNCHEZ, NATALIA; TURIENZO, MARTÍN; LEBINSON, F; ARAUJO, VANESA; COUTAND, ISABELLE; DIMIERI, L

JOURNAL OF SOUTH AMERICAN EARTH SCIENCES

PERGAMON-ELSEVIER SCIENCE LTD

Lugar: Amsterdam; Año: 2015 vol. 64 p. 399 - 417

0895-9811

The Chos Malal fold and thrust belt (FTB) is a thick-skinned mountain belt formed by Mesozoic depositsof the Neuquen Basin during the Andean orogeny. Four structural cross-sections in the entire deformedarea, supported by field and subsurface data, suggest a strong link between thick and thin-skinnedstructures. Major Andean thrusts branching from a detachment placed 12 km into the crust createdlarge basement wedges, which were inserted in the cover producing minor order structures. Thewesternmost of these wedges is exposed forming the Cordillera del Viento, while others basement slicesat depth were interpreted from seismic lines. These thick-skinned structures transferred deformation tothe cover along the Auquilco Formation and contributed to create all thin-skinned structures surveyed inthe Chos Malal FTB. We recognized half-graben geometries in the seismic lines, preserving theirextensional configuration, which suggests that the main normal faults were not inverted. Shorteningscalculated from the restoration of the four cross-sections are 16.9 km (29.7%), 16.9 km (29.7%), 14.7 km(26.9%) and 14.15 km (26.3%), which evidence a slight diminution of the contraction toward the southprobably associated with the plunge of the Cordillera del Viento structure in this segment of the ChosMalal FTB.