Fluvial landscape response time: How plausible is steady-state denudation?

Authors
Citation
Kx. Whipple, Fluvial landscape response time: How plausible is steady-state denudation?, AM J SCI, 301(4-5), 2001, pp. 313-325
Citations number
52
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Earth Sciences
Journal title
AMERICAN JOURNAL OF SCIENCE
ISSN journal
0002-9599 → ACNP
Volume
301
Issue
4-5
Year of publication
2001
Pages
313 - 325
Database
ISI
SICI code
0002-9599(200104/05)301:4-5<313:FLRTHP>2.0.ZU;2-2
Abstract
Whether or not steady-state topography and denudation are probable states d epends on the timescale of system response to tectonic and climatic perturb ations relative to the frequency of those perturbations. This paper present s analytical derivations of algebraic relations for the response time of de tachment-limited fluvial bedrock channel systems both to tectonic and clima tic perturbations. Detachment-limited fluvial erosion is described by the s tream-power incision model, and the derivations are limited to the applicab ility of that model. All factors likely to influence system response time t hat are not adequately captured by the stream-power incision model will ten d to increase the response time. The calculations presented thus provide mi nimum estimates of landscape response time and therefore over-predict the p robability of attaining and sustaining steady-state topography and denudati on. The Central Range of Taiwan is used as a case study to estimate respons e times in a landscape often argued to be in steady state. Model parameters are fit to modem stream profiles by assuming that the topography represent s a quasi-steady state form. Estimated response times generally range from 0.25 to 2.5 Ma, 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 p late tectonic timescales). However, rapid climatic fluctuation in the Quate rnary appears to preclude the attainment of steady-state conditions in mode rn orogens.