Quaternary tectonics along oblique deformation zones in the Central Andean retro-wedge between 31°30′S and 35°S

Abstract

Quaternary tectonics along oblique deformation zones in the Central Andean retro-wedge between 318 8 8 8 830 ′ S and 358 8 8 8 8SAbstract: The distribution of the Quaternary deformation in the outer retro-wedge of the Andes (31830 ′ -358S) is controlled by the subduction geometry, the position of the structural front, and the location of oblique pre-Cenozoic mechanical anisotropies. In the Southern Precordillera, Quaternary structures tend to group along the Barreal-Las Peñas deformation zone with a NW to NNW trend. This Cenozoic belt (31830 ′ -32840 ′ S) developed on the northern segment of the Triassic Cuyo Basin and broadened laterally during the Quaternary. New radiocarbon ages on dam deposits confirm Holocene tectonic activity on the northwestern edge. The oldest ages of dam deposits are 5810 + 90 a BP (Cabeceras Creek) and 810 + 50 a BP (Dolores Creek). Palaeoseismological and seismic data suggest active tectonic growth on the NW and SE extremes. Quaternary tectonics has contributed to modifying the relief along this oblique belt. This contribution is evident from the tectonic uplift of blocks (minimum 90-120 m in the Barreal block), the initial development of intermontane basins (Pampa de los Burros Basin), the Quaternary rejuvenation of tectonic depressions (at least 32-37 m of tectonic subsidence in the Vizcacheras half-graben) and the incipient development of low-relief morphotectonic units by soft-linkage of Quaternary structures.

Geodynamic processes in the Andes of Central Chile and Argentina: an introduction

“…The contribution by Cortés et al (2014) presents a synoptic overview of Quaternary structures across the Precordillera and the low foothills south of the Precordillera. They document the growing lateral expansion of deformation and the subsequent creation of topographic highs and depressions, with a particular emphasis on the Uspallata -Calingasta Valley.…”

Quaternary tectonics and seismic potential of the Andean retrowedge at 33–34°S

“…At least two earthquakes recorded in this zone during the last 21 years are located above these NW faults oblique to the mountain front and have been interpreted as the reactivation of pre-Cenozoic mechanical anisotropies (( Fig. 1; Cortés et al 2006;Cortés et al 2014) Several field studies provide additional evidence of Quaternary reverse activity of the La Carrera fault system (Borgnia 2004;Casa 2005;Casa et al 2010). All of these tectonic geomorphology studies describe fault scarps that affect piedmont deposits and several geomorphic indices that reflect the continuity of tectonic activity during the Quaternary.…”

“…Rapid uplift of the Frontal Cordillera began in late Late Miocene -Pliocene time through eastverging basement-cored thrust sheets (Caminos 1965;Kozlowski et al 1993;Baldauf 1997;Giambiagi & Ramos 2002;Irigoyen et al 2002;Giambiagi et al 2003Giambiagi et al , 2014Hoke et al 2014). The inversion of the Cuyo basin began in Middle Pliocene time at a slow rate as evidenced by the angular unconformity between the Río de los Pozos and Mogotes formations (Yrigoyen 1993).…”

“…Approximately 3 km south of this creek, the mountain front is separated 2 km west from this fault, which continues parallel to the same strike. Cortés & Sruoga (1998) linked the development of the Loma Grande de Yaucha syncline, located south of the Del Rosario creek, with activity of the Chalet fault and the termination of this structure against the NW-striking Casa de Piedra fault, which is part of the Papagayos fault zone (Cortés & Sruoga 1998;Cortés et al 2014). The folded sediments correlate with the Los Mesones Formation.…”

New data on neotectonic contractional structures in Precordillera, south of Río de La Flecha: Structural setting from gravity and magnetic data. San Juan, Argentina

“…The association of thrust and strike-slip faults, the stepped arrangement and their oblique orientation to expected regional efforts in plate convergence direction, helped these authors to interpret a transpressive character for the region. Fazzito et al (2009) mentioned that the Southern Precordillera has evolved under the influence of structural anisotropies as oblique mega-shear zones with NW trending and paleogeographic features of Paleozoic and Triassic age (Cortés et al, 2005(Cortés et al, , 2006. Giambiagi et al (2011) made a detailed investigation of the structure and evolution of the Precordillera southern sector (South of 32 S) and described a west verging style characterized by partitioned transpression with a high shortening component, and an oblique strike-slip dominated subdomain.…”