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D. Karátson, T. Telbisz, B. Székely, G. Wörner:
"Style, rate and pattern of erosion on stratovolcanoes and ignimbrite surfaces in the Central Andes";
Poster: EGU 2009, Vienna; 2009-04-19 - 2009-04-24; in: "Geophysical Research Abstracts", 11 (2009), Paper ID EGU2009-10547-1, 1 pages.

In our work, erosion of active and extinct (Holocene to Miocene)stratovolcanoes (18-24° and 70-67° W) and
various-aged (22-2 Ma old) ignimbrite surfaces (16-20° deg S, 72-69° W) of the Central Andes in Peru-Chile-
Bolivia-Argentina have been studied by DEM analysis. Starting from the SRTM data base, we created various
maps including slope, ridge and aspect maps, in order to see how erosion operates with time and what kinds of
erosion pattern result. Style and pattern of erosion of Central Andean stratovolcanoes strongly depend on climate,
elevation and latitudinal position. Valley development, enhanced by episodic glaciations, play a key role in the
typical evolutionary scheme of stratocones. We can distinguish crater-topped active volcano, cone-shaped volcano
with initial planezes without crater or enlarged erosion crater (depending on the presence or absence of glaciation),
remnant cone with well-developed planezes at the periphery, and a final "valley-stage" where headward erosion
of large valleys result in a flat-topped, lowered cone. These stages can be quantified by morphometric variables
such as ridge pattern analysis, surface roughness, cone shape ratios, etc. Original landforms can be reliably
reconstructed by using planeze remnants that can survive in the long term especially under arid climates. Missing
volumes of valleys and eroded summit help to calculate erosion rates of stratovolcanoes.
Valley incision and landscape evolution can also be studied quantitatively on large ignimbrite sheets, that are
especially well-preserved along the arid to hyperarid Western Andean Escarpment. At these areas, long-term
landscape evolution include gully incision (parasol ribbing), quebrada retreatment by sapping and headward
erosion, as well as large-volume landslides, all these types controlled by episodic, long-term uplift and various
climates in the
Central Andes during the past 20 Ma. Valley volumes can be calculated by using ridge pattern and restored valley
infill. By using these valley volumes, as well as age constraints (i.e. ignimbrite eruptions) and paleoclimate data,
rates of valley erosion and related landscape
denudation change are assessed.

http://publik.tuwien.ac.at/files/PubDat_175598.pdf