ABSTRACT
A total of 55 rock-avalanche deposits in the intra-Andean Puna Plateau and its eastern arid foreland have been analysed systematically by remote-sensing techniques and field studies in order to evaluate boundary conditions of rock avalanching in an arid setting. Most of them were dated either directly by 21Ne exposure ages or indirectly by 14C ages of organic material, 39Ar/40Ar ages of volcanic tephra, and by tephrochronology. Rock avalanches occurred at tectonically active mountain fronts and in three types of lithology: granites, low grade metamorphic rocks, and coarse clastic sedimentary rocks. While avalanching is relatively young in narrow valleys and took place during phases of enhanced river discharge these landslides are older in piedmont environments and have recurrence intervals of several tens of thousand years. Although the trigger mechanism of landsliding is in general difficult to define, stratigraphic relations in one setting indicate that strong seismicity generated multiple landslides.
