DOI: http://dx.doi.org/10.5027/andgeoV40n1-a04

Role of climate and tectonics in the geomorphologic evolution of the Semiarid Chilean Andes between 27-32°S.

Germán Aguilar, Rodrigo Riquelme, Joseph Martinod, José Darrozes

Abstract


A morphometric analysis that considers hypsometry and topographic slope reveals longitudinal and latitudinal differences in the degree of maturity of the relief of the Andes between 27-32°S. Whereas landscape rejuvenation of the Coastal Cordillera takes place to the south of 29.5°S, in the Main Cordillera it happens south of 28.5°S. The combination of a wetter climate towards the south and the presence of segments with different tectonic features would explain these variations. Longitudinally, the geomorphological features indicate the presence of a mountain front that separates the Coastal Cordillera and the Main Cordillera. Between 28.5 and 30.5°S this front can be attributed to the activity of the Vicuña-San Félix Fault System, wich during the Oligocene-Early Miocene would have accommodated the relative uplift of the Main Cordillera. In response to this tectonic activity, successive levels of cut-and-fill pediments may have been formed. During the Middle Miocene, there was a new episode of uplift affecting the fore-arc and it is in response to this uplift that the valleys that cross this region were excavated. Between 28.5 and 30.5°S, the valleys head reached a sufficient altitude to generate fluvio-glacial erosion that allowed the incision of deep canyons in this segment of the Main Cordillera.

How to cite this article Aguilar, G.; Riquelme, R.; Martinod, J.; Darrozes, J. 2013, Role of climate and tectonics in the geomorphologic evolution of the Semiarid Chilean Andes between 27-32°S.. Andean Geology 40 (1): 79-101. [doi:http://dx.doi.org/10.5027/andgeoV40n1-a04]

 

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