Preprints
https://doi.org/10.5194/esurf-2020-80
https://doi.org/10.5194/esurf-2020-80

  09 Nov 2020

09 Nov 2020

Review status: a revised version of this preprint is currently under review for the journal ESurf.

Top-down and bottom-up controls on mountain-hopping erosion: insights from detrital 10Be and river profile analysis in Central Guatemala

Gilles Y. Brocard1, Jane K. Willenbring2, Tristan Salles3, Michael Cosca4, Axel Guttiérez-Orrego5, Noé Cacao-Chiquín5, Sergio Morán-Ical5, and Christian Teyssier6 Gilles Y. Brocard et al.
  • 1Archéorient, University of Lyon 2, 69365 Lyon, France
  • 2Department of Geological Sciences, Stanford University, Stanford, CA 94305, USA
  • 3School of Geosciences, University of Sydney, Camperdown, Australia
  • 4U.S. Geological Survey, Denver Federal Center, Denver, CO 80225, USA
  • 5Carrera de Geología, Universitad San Carlos de Guatemala, Centro Universitario del Noreste, 16001 Cobán, Guatemala
  • 6Department of Earth Sciences, University of Minnesota, Minneapolis MN 55455, USA

Abstract. The presence of a mountain affects the circulation of water in the atmosphere and over the land surface. These effects are felt over some distance, beyond the extent of the mountain, controlling precipitation delivery and river incision over surrounding landmasses. The rise of a new mountain range therefore affects the erosion of pre-existing mountains located in close proximity. We document here this phenomenon in the mountains of Central Guatemala. The 40Ar-39Ar dating of lava flows shows that two parallel, closely spaced mountain ranges formed during two consecutive pulses of single-stepped uplift, one from 12 to 7 Ma, and the second one since 7 Ma. The distribution of erosion rates derived from the analysis of detrital cosmogenic 10Be in river sediments shows that the younger range erodes faster (~300 m/My) than the older one (20–150 m/My), and that erosion correlates with the amount of precipitation. Moisture tracking form the Caribbean Sea is intercepted by the younger range, which casts a rain shadow over the older one. The analysis of river long-profiles provides a record of longer-term interactions between the two ranges. The rivers that drain the older range were diverted by the younger range during the early stages of its rise. A few rivers were able to maintain their course across the young range, through profile steepening, but incision completely stalled along their upper reaches, upstream of the younger range. As a result, the older range has been passively uplifted, and entered a phase of a slow topographic decay: pediments have formed along its base, while ancient upstream-migrating waves of erosion, located farther up the mountain flanks, have almost stopped migrating. Aridification and cessation of river incision together explain the slowing down of erosion over the older range. They represent top-down and bottom-up processes whereby the younger range controls erosion over the older one. These controls are regarded as instrumental in the nucleation and enlargement of orogenic plateaus forming above continental accretionary wedges.

Gilles Y. Brocard et al.

 
Status: final response (author comments only)
Status: final response (author comments only)
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment

Gilles Y. Brocard et al.

Gilles Y. Brocard et al.

Viewed

Total article views: 523 (including HTML, PDF, and XML)
HTML PDF XML Total Supplement BibTeX EndNote
415 104 4 523 25 4 5
  • HTML: 415
  • PDF: 104
  • XML: 4
  • Total: 523
  • Supplement: 25
  • BibTeX: 4
  • EndNote: 5
Views and downloads (calculated since 09 Nov 2020)
Cumulative views and downloads (calculated since 09 Nov 2020)

Viewed (geographical distribution)

Total article views: 386 (including HTML, PDF, and XML) Thereof 382 with geography defined and 4 with unknown origin.
Country # Views %
  • 1
1
 
 
 
 
Latest update: 04 Mar 2021
Download
Short summary
The rise of a mountain affects the circulation of water, both in the atmosphere and over the land surface, thereby affecting the erosion of the land surface. We document how the rise of a mountain in Central Guatemala has affected the erosion of an older range nearby. The new range intercepts precipitation formerly delivered to the older range. Rivers response to the uplift of the new range has decreased incision across the older one. Both have reduced hillslope erosion over the old range.