Is TaiwanCentralRange in steady-state?
Yang, Wan-Huei
Abstract
The dynamic system of tectonics and erosion contains important feedback mechanisms such that orogenic systems tend toward a steady state.This concept is often invoked, but the nature of the steady state is commonly not specified.Willett et al. (2002) identified four types of steady state that characterize the orogenic system and illustrate these cases by using numerical-model results and nature examples.These types are (1) flux steady-state, (2) topographic steady-state, (3) thermal steady-state, and (4) exhumation steady-state: they refer to the erosional flux, the topography, the subsurface temperature field, and the spatial pattern of cooling ages, respectively.Suppe (1981) used time-space equivalence method, mountain width and cross-sectional area data and found 120 to 290 km north of the southern tip of Taiwan is in topographic steady-state; Willett et al. (2002) used zircon fission-track data and found 120 to 250 km north of the southern tip of Taiwan is in exhumation steady-state.Whether or not steady-state topography and denudation are probable states depends on the timescale of system response to tectonic and climatic perturbations relative to the frequency of those perturbations.Whipple et al. (2001) calculated the landscape response times to know when steady-state would be reached.Estimated response times generally range from 0.25 to 2.5 M.y., depending on the non-linearity of the incision rule and the magnitude and type of perturbation.Thus it may be reasonably argued that steady-state topography and denudation are likely to prevail during periods of climatic stability (response time is sufficiently short compared with plate tectonic timescales).However, rapid climatic fluctuation in the Quaternary appears to preclude the attainment of steady-state conditions in modern orogens.
Reference
Suppe, J., 1981, Mechanics of mountain building and metamorphism in Taiwan, Memoir Geol. Soc. China, 4, 67-89.
(Abstract) (Full text)
Whipple, K. X., 2001, Fluvial landscape response time: how plausible is steady-state denudation?, American Journal of Science, 301, 313-325.
Willett, S. D., and M. T. Brandon, 2002, On steady states in mountain belts, Geology, 30, 175-178.