Figure 2. Antecedent channel responses to rapid, differential uplift. A. Map of two antecedent rivers and rock-uplift rates in the frontal anticline that grows above Main Frontal Thrust (MFT) in central Nepal. Rock-uplift rates across the map area are calculated by a three-fold process. First, rates are calculated from the deformed terraces (Figure 2). Next, these rates and the bedding geometry indicate that the slip rate on the underlying fault is the same for each valley (~20 mm/yr). Hence, the slip rate is assumed to be uniform between these valleys. Finally, as along the valleys, structural data from transects across the fold are used to define the geometry of the underlying fault which, when combined with the fault-slip rate, can be converted to local rock-uplift rates Modified after Hurtrez et al. (1999) and Wobus et al. (2006) B. Channel profile, floodplain width, incision rate, and calculated excess shear stress for the Bakeya and Bagmati Rivers as they cross MFT hangingwall. The Bagmati narrows without steepening. In the zone of the highest incision rate, the Bakeya both narrows and steepens. Patterns of excess shear stress are closely coupled to channel narrowing and the incision rate. Modified after Lavé and Avouac (2001).
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Oct28 09
