Cosmogenic dating of rock avalanches constraining Quaternary stratigraphy and regional neotectonics in the Argentine Central Andes (32º S)

MOREIRAS, S.M.; HERMANNS, R.; FAUQUÉ, L.

QUATERNARY SCIENCE REVIEWS

PERGAMON-ELSEVIER SCIENCE LTD

Lugar: Amsterdam; Año: 2015 vol. 112 p. 45 - 58

0277-3791

This paper provides a comprehensive review of the chrono-stratigraphy of six rock avalanches clustered in the northern extreme of the Cordon del Plata range, which are stratigraphically related to Pleistocene glacial drifts and valley fill deposits documenting regional neotectonic activity. We used cosmogenic dating (TCN) to directly date block surfaces of rock avalanche deposits, as well as optically stimulated luminescence dating (OSL) of paleo-lakes dammed by these rock avalanches. Our new direct dates (17 TCN and 4 OSL) determine a Middle- Late Pleistocene age for these collapses. These are in contrast to the previously established chronostratigraphy that bases on relative dating techniques, paleontological context, and tephrochronology. These new data help to redefine the geomorphological evolution of the Mendoza river valley. Especially indicate that the glacial stratigraphy earlier proposed must be reconsidered. We redefine this stratigraphy as far as possible with our data and discuss them in relation with other lately published results. However it becomes clear that the glacial history of the Mendoza valley has to be studied newly using modern dating techniques. In addition our data suggest that the Carrera Fault system bounding the valleys of the Cordillera del Plata has been more recently active than earlier proposed.