Erosional control on the geometry and kinematics of thrust belt development in the central Andes

Building the central Andes through axial lower crustal flow

“…The highest values occur on the steep topographic escarpment abutting the northeastern edge of the plateau in Peru and Bolivia (centered on 15°S-17°S), and low values occur in all other areas of the plateau and associated high topography [Peterson and Vose, 1997] ( Figure 3f). Some studies have suggested that increased erosion in areas of high precipitation in the Andes has affected the geomorphic, metamorphic, and structural characteristics of the orogen [Masek et al, 1994;Horton, 1999;Montgomery et al, 2001], but variations in precipitation do not appear to significantly affect the large-scale morphology of the central Andes, particularly at elevations above 3000 m.…”

“…In particular, the width and slope of the Andean flanks below 3 km appear sensitive to lithology and precipitation and erosion rate (Figure 3). A number of studies [Masek et al, 1994;Horton, 1999;Montgomery et al, 2001;Allmendinger et al, 1997] have related variations in precipitation, erosion rate, and lithology to variations in morphology along strike in the Andes. Our modeling, and the large-scale symmetry described above, suggests that these processes primarily influence the flanks of the orogen and the regions below ∼3 km elevation, while the higher elevation regions and orogen-scale morphology remain largely unaffected.…”

Tectonics, Climate, and Landscape Evolution of the Southern Central Andes: the Argentine Puna Plateau and Adjacent Regions between 22 and 30°S

“…For example, the northern portion of this fold-and-thrust belt is narrow, out-of-sequence deformation is common, and precipitation and erosional processes are efficient (e.g., Horton 1999). Conversely, the southern sector of this tectonic province corresponds with reduced precipitation a wider fold-and-thrust belt, regional erosion surfaces are preserved, and deformation has successively migrated eastward (e.g., Horton 1999). Therefore, as erosion becomes less efficient in the Subandean belt, systematic changes in geometry and deformation are observed.…”

“…Consequently, discharge within channels, and hence incision and landscape lowering rates will ultimately be reduced over geologic time in the arid interior of the orogen (e.g., . Second, as a consequence of the topographic configuration erosion will likely be strongest in those parts of the Andes where precipitation impinges on the eastern slopes or where topographic lows or gaps associated with structural discontinuities allow moisture to migrate farther into the orogen (Horton 1999;Coutand et al 2006). In light of the long-term aridity of the Central Andes Lamb and Davis (2003) suggested an intimate link between aridity and tectonic uplift.…”

“…Given the large gradients in climate, and coupling between deformation and erosional efficiency that have been postulated for other orogens (e.g., Koons 1989;Isacks 1992;Willett 1999;Zeitler et al 2001;Burbank 2002;Reiners et al 2003;Whipple and Meade 2004;Thiede et al 2004), it is likely that the feedbacks between erosion and deformation could be important in the development of the Andes as well (Masek et al 1994;Horton 1999;Montgomery et al 2001;Lamb and Davis 2003). First, the topographic configuration and climatic conditions imply that ongoing tectonic uplift and migration of deformation in the Andes may have had a significant impact on the distribution of precipitation, and hence erosion, in space and time.…”