APPLIED GEOMORPHOLOGY TO TECTONICS ACTIVE IN THE NANGARITZA RIVER BASIN

Abstract

The Nangaritza River is located in the subandine zone of the southeastern Ecuador. Along the river draining from south to north, the valley appears segmented into open sub-basins (Guaysimi and Centro Shaime) and river bottlenecks in deep canyons. A transpressive fault system configured by dominant N-S reverse faults and NW-SE left-hand strike-slip faults controls the development of valley morphology.

The morphological indexes of the Integral Hypsometric and Factor of Asymmetry confirm the young tectonic activity of the zone. An asymmetry greater than 56% considered high, seems closely related to the tilting of the basin towards the east, where the drains are blocked against the main reverse fault that causes the uplift of cordillera del Cóndor. The hypsometric integral indicates differences in the maturity of sub-basins analyzed that shows values ​​greater than 0.5, reflected in the model curve, but also from the analysis it was obtained that 256 basins have a tendency to convexity, interpreted as unstable.

Significant evidence in the Centro Shaime sector with negative hypsometries and with high asymmetries indicate strong instability with structural control in the water basin, modifying the river system as it seems that the rivers Numpatakaime and Nangaritza (upper course) drained into the Achuime River to Peru, but that the rise of some 70 m of unevenness of the mountain range by effect of the fault, redirected the course of the river towards the north.