Quantifying geomorphological evolution from 10Be denudation rates: Insights from high‐resolution depth profiles, topsoils, and stream sediments (Strengbach CZO, France)

A rare dataset of in‐situ 10Be from high‐resolution depth profiles, soils, rock outcrops, and stream sediments is combined with geochemical analysis and modelling of regolith evolution to understand the variability of denudation rates in a mountain watershed (Strengbach critical zone observatory). High‐resolution depth profiles are key to detect the presence of mobile regolith and to highlight how it affects the critical zone evolution. The modelling of regolith evolution and 10Be concentrations along depth profiles allow us to estimate both the cosmic ray exposure age (19 kyr) and the mean denudation rate (22 mm kyr−1) of the regolith without any steady‐state assumption on 10Be concentrations. Comparison with maximum denudation rates inferred from topsoil samples collected from the surface of the depth profiles and calculated using the temporal steady‐state assumption of 10Be concentrations highlights an overestimation of denudation by a factor of two. Maximum spatially averaged denudation rates determined from stream sediment samples also likely overestimate denudation rates by a factor of two. These biases are significant for investigating the geomorphological evolution and we propose a method to correct denudation rates using the inherited 10Be concentrations and the cosmic ray exposure age deduced from the high‐resolution depth profiles. A key result is also that a steady state of 10Be concentrations and a steady state of regolith thickness are two different equilibrium states that do not necessarily coincide. The comparison between locally corrected and spatially averaged denudation rates indicates that the watershed geomorphology is not in a topographic steady state but is modulated by regressive fluvial erosion. Nonetheless, our study demonstrates that even in a watershed where the steady‐state assumption of 10Be concentrations is not verified, the spatial variations of in‐situ 10Be concentrations in sediments still carry qualitatively relevant information on the geomorphological evolution of landscapes.

[1]  Lucas Yann,et al.  Characterization of groundwater circulations in a headwater catchment from an analysis of chemical concentrations, Sr-Nd-U isotope ratios, and CFC, SF6 gas tracers (Strengbach CZO, France) , 2021, Applied Geochemistry.

[2]  F. Delay,et al.  Crossing hydrological and geochemical modeling to understand the spatiotemporal variability of water chemistry in a headwater catchment (Strengbach, France) , 2020 .

[3]  F. Delay,et al.  Variability of Water Transit Time Distributions at the Strengbach Catchment (Vosges Mountains, France) Inferred Through Integrated Hydrological Modeling and Particle Tracking Algorithms , 2019 .

[4]  S. Gangloff,et al.  Plant-soil-water interactions: Implications from U-Th-Ra isotope analysis in soils, soil solutions and vegetation (Strengbach CZO, France) , 2019, Geochimica et Cosmochimica Acta.

[5]  C. Petit,et al.  Denudation systematics inferred from in situ cosmogenic 10Be concentrations in fine (50–100 µm) and medium (100–250 µm) sediments of the Var River basin, southern French Alps , 2019, Earth Surface Dynamics.

[6]  P. Blard,et al.  Basinga: A cell‐by‐cell GIS toolbox for computing basin average scaling factors, cosmogenic production rates and denudation rates , 2019, Earth Surface Processes and Landforms.

[7]  D. Scherler,et al.  Cosmogenic 10Be in river sediment: where grain size matters and why , 2018, Earth Surface Dynamics.

[8]  M. Pierret,et al.  In-situ dissolution rates of silicate minerals and associated bacterial communities in the critical zone (Strengbach catchment, France) , 2019, Geochimica et Cosmochimica Acta.

[9]  R. Schmidt.  response to reviews on van Dongen et al .-Cosmogenic 10 Be in river sediment : where grain size matters and why , 2019 .

[10]  D. Froese,et al.  Age-erosion constraints on an Early Pleistocene paleosol in Yukon, Canada, with profiles of 10Be and 26Al: Evidence for a significant loess cover effect on cosmogenic nuclide production rates , 2018, CATENA.

[11]  M. Schmid,et al.  Addressing the contribution of climate and vegetation cover on hillslope denudation, Chilean Coastal Cordillera (26◦–38◦S) , 2018 .

[12]  P. Ackerer,et al.  The Strengbach Catchment: A Multidisciplinary Environmental Sentry for 30 Years , 2018 .

[13]  L. Aquilina,et al.  Geochemical tracing and modeling of surface and deep water–rock interactions in elementary granitic watersheds (Strengbach and Ringelbach CZOs, France) , 2017, Acta Geochimica.

[14]  J. Lavé,et al.  The CREp program and the ICE-D production rate calibration database: A fully parameterizable and updated online tool to compute cosmic-ray exposure ages , 2017 .

[15]  Susan L. Brantley,et al.  Controls on deep critical zone architecture: a historical review and four testable hypotheses , 2017 .

[16]  V. Vanacker,et al.  Coupling uranium series and 10Be cosmogenic radionuclides to evaluate steady-state soil thickness in the Betic Cordillera , 2016 .

[17]  P. Ackerer,et al.  Regolith evolution on the millennial timescale from combined U–Th–Ra isotopes and in situ cosmogenic 10Be analysis in a weathering profile (Strengbach catchment, France) , 2016 .

[18]  M. Pierret,et al.  Evaluation of fluxes of suspended matters and bedload in the small granitic Strengbach catchment (Vosges massif, France) , 2016 .

[19]  R. Anderson,et al.  Hillslope lowering rates and mobile-regolith residence times from in situ and meteoric 10Be analysis, Boulder Creek Critical Zone Observatory, Colorado , 2014 .

[20]  C. Riebe,et al.  Tracing and Pacing Soil Across Slopes , 2014 .

[21]  S. Gangloff,et al.  Characterization and evolution of dissolved organic matter in acidic forest soil and its impact on the mobility of major and trace elements (case of the Strengbach watershed) , 2014 .

[22]  D. Montgomery,et al.  Rapid Soil Production and Weathering in the Southern Alps, New Zealand , 2014, Science.

[23]  K. Norton,et al.  Soil formation rates on silicate parent material in alpine environments: Different approaches-different results? , 2014 .

[24]  E. Kirby,et al.  Regolith production and transport at the Susquehanna Shale Hills Critical Zone Observatory, Part 2: Insights from meteoric 10Be , 2013 .

[25]  E. Dambrine,et al.  Searching for ancient forests: A 2000 year history of land use in northeastern French forests deduced from the pollen compositions of closed depressions , 2013 .

[26]  J. Harbor,et al.  Paleo-climate of the central European uplands during the last glacial maximum based on glacier mass-balance modeling , 2013, Quaternary Research.

[27]  A. West,et al.  Thickness of the chemical weathering zone and implications for erosional and climatic drivers of weathering and for carbon-cycle feedbacks , 2012 .

[28]  F. Blanckenburg,et al.  Soils as pacemakers and limiters of global silicate weathering , 2012 .

[29]  S. Gangloff,et al.  Erosion and weathering fluxes in granitic basins: The example of the Strengbach catchment (Vosges massif, eastern France) , 2012 .

[30]  Sunil Kumar Singh,et al.  Predominant floodplain over mountain weathering of Himalayan sediments (Ganga basin) , 2012 .

[31]  P. Bierman,et al.  Understanding Earth’s eroding surface with 10Be , 2011 .

[32]  Lin Ma,et al.  Regolith production rates calculated with uranium-series isotopes at Susquehanna/Shale Hills Critical Zone Observatory , 2010 .

[33]  K. Norton,et al.  Cosmogenic nuclide‐derived rates of diffusive and episodic erosion in the glacially sculpted upper Rhone Valley, Swiss Alps , 2010 .

[34]  T. Dunai.  Cosmogenic Nuclides: Principles, Concepts and Applications in the Earth Surface Sciences , 2010 .

[35]  H. Strauss,et al.  Determining the growth rate of topographic relief using in situ-produced 10Be: A case study in the Black Forest, Germany , 2010 .

[36]  A. Heimsath,et al.  Eroding Australia: rates and processes from Bega Valley to Arnhem Land , 2010 .

[37]  G. Humphreys,et al.  Breaking ground: Pedological, geological, and ecological implications of soil bioturbation , 2009 .

[38]  Hoshin Vijai Gupta,et al.  Decomposition of the mean squared error and NSE performance criteria: Implications for improving hydrological modelling , 2009 .

[39]  D. Bourlès,et al.  Determination of both exposure time and denudation rate from an in situ-produced 10Be depth profile: A mathematical proof of uniqueness. Model sensitivity and applications to natural cases , 2009 .

[40]  J. Kirchner,et al.  Effects of physical erosion on chemical denudation rates: A numerical modeling study of soil-mantled hillslopes , 2008 .

[41]  S. P. Anderson,et al.  Physical and Chemical Controls on the Critical Zone , 2007 .

[42]  Veerle Vanacker,et al.  Restoring dense vegetation can slow mountain erosion to near natural benchmark levels , 2007 .

[43]  A. Kääb,et al.  Surface displacements and surface age estimates for creeping slope landforms in Northern and Eastern Iceland using digital photogrammetry , 2006 .

[44]  A. Codilean.  Calculation of the cosmogenic nuclide production topographic shielding scaling factor for large areas using DEMs , 2006 .

[45]  W. Dietrich,et al.  The illusion of diffusion: Field evidence for depth-dependent sediment transport , 2005 .

[46]  F. Blanckenburg.  The control mechanisms of erosion and weathering at basin scale from cosmogenic nuclides in river sediment , 2005 .

[47]  B. Hamelin,et al.  Local erosion rates versus active tectonics: cosmic ray exposure modelling in Provence (south-east France) , 2004 .

[48]  N. Hovius,et al.  Paleoerosion Rates from Cosmogenic 10Be in a 1.3 Ma Terrace Sequence: Response of the River Meuse to Changes in Climate and Rock Uplift , 2004, The Journal of Geology.

[49]  C. Riebe,et al.  Long-term rates of chemical weathering and physical erosion from cosmogenic nuclides and geochemical mass balance , 2003 .

[50]  David R. Montgomery,et al.  Topographic controls on erosion rates in tectonically active mountain ranges , 2002 .

[51]  A. Heimsath,et al.  Creeping soil , 2002 .

[52]  J. G. King,et al.  Mountain erosion over 10 yr, 10 k.y., and 10 m.y. time scales , 2001 .

[53]  A. Kb,et al.  Surface Geometry, Thickness Changes and Flow Fields on Creeping Mountain Permafrost: Automatic Extraction by Digital Image Analysis , 2000 .

[54]  J. Stone.  Air pressure and cosmogenic isotope production , 2000 .

[55]  B. Zolitschka,et al.  Palynological analyses in the laminated sediment of Lake Holzmaar (Eifel, Germany): duration of Lateglacial and Preboreal biozones , 2000 .

[56]  E. Dambrine,et al.  Mineral evolution of acid forest soils in the Strengbach catchment (Vosges mountains, N-E France) , 1998 .

[57]  W. Dietrich,et al.  The soil production function and landscape equilibrium , 1997, Nature.

[58]  James W. Kirchner,et al.  Spatially Averaged Long-Term Erosion Rates Measured from in Situ-Produced Cosmogenic Nuclides in Alluvial Sediment , 1996, The Journal of Geology.

[59]  R. Stallard,et al.  Denudation rates determined from the accumulation of in situ-produced 10Be in the luquillo experimental forest, Puerto Rico , 1995 .

[60]  K. Nishiizumi,et al.  Chemical isolation of quartz for measurement of in-situ-produced cosmogenic nuclides , 1992 .

[61]  D. Lal,et al.  Cosmic ray labeling of erosion surfaces: in situ nuclide production rates and erosion models , 1991 .