Rl. Hermanns et al., Neotectonics and catastrophic failure of mountain fronts in the southern intra-Andean Puna Plateau, Argentina, GEOLOGY, 29(7), 2001, pp. 619-622
New cosmogenic nuclide exposure ages of rock-avalanche deposits in front of
Sierra Laguna Blanca in the arid Argentine Puna Plateau demonstrate the ef
fects of westward propagation of reverse faulting and the influence of acti
ve faulting on slope oversteepening and subsequent gravitational collapse.
The Ne-21 exposure ages of 8 superposed landslides with volumes >0.3 km(3)
are between ca, 150 and 430 ka, and indicate an average recurrence interval
of large gravitational mountain-front failures of similar to 27.5 k.y. for
the ultimate 7 landslides. Landsliding did not occur after 150 ka along th
is sector of the Sierra Laguna Blanca. The termination of landsliding activ
ity correlates with reverse-fault propagation into the piedmont area of the
Sierra Laguna Blanca, The exposure age of ca, 130 ka of a tectonically upl
ifted terrace postdates initiation of fault activity in the piedmont region
, and the fault scarp height of 120 m indicates important continued uplift
in the piedmont; no further offsets occurred at the mountain front. Due to
this lack of tectonic activity at the mountain front, no further collapse h
as occurred, indicating that in this environment catastrophic mountain-fron
t failure is mainly controlled by tectonically driven slope oversteepening.