POSSIBLE FACTORS AFFECTING THE TOPOGRAPHY OF THE BACKBONE RANGE OF TAIWAN

Topography of an active mountain range is a reflection of perplexed interactions between bedrock uplift and denudation and consequently can provide valuable information on the responsible processes. The topographic architecture of the Backbone Range of Taiwan is asymmetric in the E-W profile. The highest elevation of the range developed where low-grade metamorphic rocks outcrop and is skewed to the west. Analyses of the available fission-track and structural data suggest that synorogenic extensional structures contributed significantly to the development of the asymmetric topographic profile, although differential erosion across the mountain range may also have played a role. On the other hand, decreasing extrusion velocity or decreasing strike-slip extrusion component westward across the mountain range during the upward extrusion of the Backbone Range caused by oblique convergence, and the "space " problem induced by the presence of the Hsuehshan Range in the west hampering the westward rock movement of the uprising Backbone Range in the east, might also be important factors. Key words: uplift, denudation, topography, Taiwa