Estimating Uplift Rate Histories from River Profiles using African Examples

Roberts, G. and White, N. J. (2010) Estimating Uplift Rate Histories from River Profiles using African Examples. Journal of Geophysical Research-Solid Earth, 115. B02406. ISSN 0148-0227 DOI https://doi.org/10.1029/2009JB006692

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Abstract

We describe and apply a method for estimating uplift rate his- tories from longitudinal river pro¯les. Our strategy is divided into three parts. First, we develop a forward model, which calculates river pro¯les from up- lift rate histories. Height variation along a river pro¯le is controlled by up- lift rate and moderated by the erosional process. We assume that the ero- sional process can be represented by a combination of advection and di®u- sion, which are parametrized using four erosional constants. Secondly, we have posed and solved the geologically more interesting inverse problem: which uplift rate history minimizes the mis¯t between calculated and observed river pro¯les? The inverse algorithm has been tested on synthetic river pro¯les, which demonstrates that uplift rate histories can be reliably retrieved. Our tests show that the erosional process is dominated by advection (i.e. knick- point retreat) and that changes in lithology and discharge play a secondary role in determining the transient form of a river pro¯le. Finally, we have in- verted river pro¯les from a series of African topographic swells, namely the Bi¶e, South African, Namibian, Hoggar and Tibesti domes. Fits between cal- culated and observed river pro¯les are excellent. Calculated uplift rate his- tories suggest that these domes grew rapidly during the last 30{40 million years. Uplift rate histories vary signi¯cantly from dome to dome but cumu- lative uplift histories agree closely with independent geologic estimates.

Item Type:	Article
Additional Information:	Copyright 2010 by the American Geophysical Union. This paper is Green Open Access in accordance with the conditions set out here:http://www.sherpa.ac.uk/romeo/issn/0148-0227/
Uncontrolled Keywords:	09AREP; IA58;
Subjects:	02 - Geodynamics, Geophysics and Tectonics
Divisions:	02 - Geodynamics, Geophysics and Tectonics 08 - Green Open Access
Journal or Publication Title:	Journal of Geophysical Research-Solid Earth
Volume:	115
Page Range:	B02406
Identification Number:	https://doi.org/10.1029/2009JB006692
Depositing User:	Sarah Humbert
Date Deposited:	29 Sep 2009 13:24
Last Modified:	28 Apr 2014 10:05
URI:	http://eprints.esc.cam.ac.uk/id/eprint/1176

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