Evidencias de neotectónica en el sector interno de la Faja Plegada y Corrida de Malargüe, valle del río Grande, Mendoza, Argentina

Neotectonic evidence in the inner section of the Malargüe Fold-and-Thrust Belt, Grande river valley, Mendoza, Argenti-na

Diego A. Winocur^1,*, Ana-hí Benítez¹, Iván Barbero²

¹ Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Ciencias Geológicas. IDEAN (Instituto de Estudios Andinos UBA-CONICET). Intendente Güiraldes 2160, Ciudad Universitaria,1428, Ciudad Autónoma de Buenos Aires, Argentina.

² Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Ciencias Geológicas. Intendente Güiraldes 2160. Ciudad Universitaria, 1428, Ciudad Autónoma de Buenos Aires, Argentina.

* Autor para correspondencia: (D. A. Winocur) This email address is being protected from spambots. You need JavaScript enabled to view it.

Cómo citar este artículo:

Winocur, D.A., Benítez, A., Barbero, I., 2021, Evidencias de neotectónica en el sector interno de la Faja Plegada y Corrida de Malargüe, valle del río Grande, Mendoza, Argentina: Boletín de la Sociedad Geológica Mexicana, 73 (2), A201220. http://dx.doi.org/10.18268/BSGM2021v73n2a201220

ABSTRACT

This work exposes some features of the landscape that enable us to determine neotectonic activity in the internal sector of the cordillera (35º30’S - 70º15’W). Through field observations, there were recognized lacustrine depos-its characterized by laminated sands, silts, and clays, which records the sedimentation in a paleolake during a stage of the Last Glacial Maximum. The age of the deposits is in-ferred from their position in relation to a frontal moraine attributed to the last glaciation. Based on a sedimentary profile in the lacustrine deposits, there are described soft-sediment deformation structures and tectonic faults, one of them named El Seguro fault, presents 4 m of displacement measured along the fault plane, and an inverse movement. Morphological features indicate a seismic trigger, proposing the activity of the fault as a possible source. The frequency and distribution of >0.1 km² mass movement deposits and their location close to the active structures allow us to identify an accumulation of landslides around them. Alt-hough many factors have favored these movements as lithology, steep slopes and pos-glacial relief, their position in the landscape suggest that seismic activity accelerated the development of large mass movements. Finally, it is proposed that tectonic activity has taken place during the Pleistocene-Holocene inclusive, with earthquakes of magnitude Ms ≥6, so that El Seguro fault could be an active fault at present.

Keywords: liquefaction, earthquakes, neotectonics, megalandslides, last glacial maximum, Malargüe.