Transient hillslope erosion in slow evolution landscapes. Issue 12 (13th August 2021)

• Record Type: Journal Article
• Authors: V., Godard; A., Salgado; L., Siame; J., Fleury; Team, ASTER
• Is Part Of: Earth surface processes and landforms. Volume 46:Issue 12(2021)
• Page Start: 2485
• Page End: 2500
• Publication Date: 2021-08-13
• Subjects: cosmogenic nuclides -- erosion -- high‐resolution topography -- hillslopes -- landscape evolution; Geomorphology -- Periodicals; 551.4
• DOI: 10.1002/esp.5190
• Languages: English
• ISSNs: 0197-9337

Abstract

Summary: Transient evolution and adjustment to changing tectonic and climatic boundary conditions is an essential attribute of landscapes, and characterizing transient behavior is a key to understanding their dynamics and history. Developing new approaches to detect such transience has been explored by various methods, in particular to identify landscape response to Late Cenozoic and Quaternary climatic changes. Such studies have often focused on regions of high relief and/or active tectonic activity where interferences between tectonic and climatic signals might complicate the interpretation of the observations. We investigated the case of the hillslopes of the Serra do Cipó quartzitic range in SE Brazil in order to detect and quantify transience in a tectonically quiescent landscape over 100‐ka timescales. We determined hilltop curvature from a high‐resolution digital surface model derived from Pléiades imagery and measured cosmogenic nuclide ( 10 Be and 26 Al) concentrations at these hilltop sites. We compare both observations with predictions of hillslope diffusion theory, observing a distinctive signature of an acceleration of denudation. We performed a joint inversion of topographic and isotopic data to retrieve an evolution of the hillslope sediment transport coefficient through time. The timing of the increase in denudation cannot be unequivocally associated with a single climatic event but is consistent with important, climatically modulated fluctuations in precipitation and erosion in this area during the Middle and Late Pleistocene. Abstract : We explored transient hillslopes erosion in the slowly evolving landscape of the Serra do Cipo range in SE Brazil. We used measurements of cosmogenic nuclides concentrations ( 10 Be and 26 Al) and hilltop curvature from a High Resolution Digital Elevation Model to constrain the denudation history at hilltop sites. Our observations suggest a significant acceleration of hillslope erosion over the last few 100s of ka.