La avalancha de rocas del Moncol, Cordillera Principal (Provincia de Neuquén, República Argentina)

ESCOSTEGUY, LEONARDO; GEUNA, SILVANA; FAUQUE, LUIS

Salta

Congreso; Congreso Geológico Argentino; 1999

A well preserved rock avalanche in Moncol area, next to Reñileuvu river,is described here and its origin analyzed. The movement mechanism was studiedin the basis of morphological features of deposits, and different stages wereidentified in the movement, beginning in big landslides and ending in debrisflows. The avalanche deposits consist predominantly of pumiceous conglomeratesand lava blocks. The firsts are disaggregable and the latter are highlyjointed. The lithology, extreme climate conditions and high topography would becontrolling factors on the rock avalanche. A preliminary paleomagnetic surveyon the landslide scar revealed that the block is rotated about a vertical axisin dextral sense. We interpret the Upper Miocene sequence in the block wasaffected by neotectonic activity, which would trigger the rock avalanche.