Jennifer West (nee McIntosh)

There is currently insufficient information regarding topographic changes in the southern Andes from 32^o to 39^o S. Mean elevation north of 35^o S is 430.7 m, from 35^o to 36^o elevation is decreasing with a mean 207.8 m and south of 39^o the mean 189.2 m. The object of this thesis is to shed some light on other geomorphic indices and determine whether there are other means of quantifying these three zones. A digital elevation map (DEM) was acquired for the study area, and was analyzed using RiverTools software for river network and topography analysis, and ArcMap. In a geomorphometric analysis of any kind, it is important to measure a variety of parameters to establish trends in uplift, erosion and mountain front stability. Analysis of basin relief, stream concavity, hypsometry, tributary asymmetry and mountain front sinuosity found various trends. From north to south, basin relief decreased and hypsometric integral and slope both decreased. Mountain front sinuosity increased moving south, indicating more rounded and mature mountains. Tributary asymmetry suggested differential uplift patterns in the study area, with uplift occurring in the north and in the south east. Stream concavity showed no conclusive pattern. Using these metrics, it was possible to distinguish the zones of high tectonic activity in the area the Liquine Ofqui fault and the Aconcagua fold and thrust zone. Tests of mountain front sinuosity of the range and hypsometry of the basins showed that the southern mountains are more glaciated than other regions. Uplift determined by tributary asymmetry and mountain front sinuosity in the area surrounding the longitudinal valley between 32^o and 34^o S helped confirm that present day uplift of the valley has taken place since the Late Miocene. Based on these measurements of the topography, I concluded that zones of quantifiably different topography do not exist however the geomorphometrics successfully identified many structural and surficial features of the study area.

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Pages: 93
Supervisor: John Gosse