Erosion in Tectonically Active Areas

In many active moimtain belts, both rapid longterm uplift and erosion are sustained by tectonic recycling of sediments. For example, the island 

Earth (Li, 1976). The high denudation rate is a reflection of the poorly lithifled, highly tecton-ized nature of the sedimentary rocks that compose the island. Sediment-yield data compiled by Milliman and Meade (1983) and Milliman and Syvitski (1992) indicate that island arcs and mountain belts in the tropical and subtropical west Pacific may contribute as more than 22% of all solid material discharged by rivers into the ocean. Furthermore, the tropical mountainous areas in southeast Asia and India may contribute another 33%. 

Mountain building usually involves compres-sional deformation of the crust. Studies of the physics of orogeny suggest that there is a feedback between the nature of the building process and denudation rates. Suppe (1981), Davis et al. (1983), and Dahlen et al. (1984) have modeled the effects of brittle deformation in accretionary fold-thrust mountain belts such as Taiwan and the Andes. The basis of their model is the hypothesis that rock deformation is governed 

The presence of unstable and cation-rich minerals in the suspended load and bed material of rivers that drain the Andes indicates that 

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