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Basinga: A cell-by-cell GIS toolbox for computing basin average scaling factors,cosmogenic production rates and denudation rates |
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| Authors: | Julien Charreau Pierre-Henri Blard Jéna Zumaque Léo CP Martin Tony Delobel Lucas Szafran |
| Institution: | 1. CRPG, UMR 7358, CNRS, Université de Lorraine, 54501 Vandoeuvre-lès-Nancy, France;2. CRPG, UMR 7358, CNRS, Université de Lorraine, 54501 Vandoeuvre-lès-Nancy, France
Geotop, Université de Québec à Montréal, CP, 8888 Succ. Centre Ville Montréal, Québec, Canada;3. CRPG, UMR 7358, CNRS, Université de Lorraine, 54501 Vandoeuvre-lès-Nancy, France Department of Geosciences, University of Oslo, P.O. Box 1047, Blindern, 0316 Oslo, Norway |
| Abstract: | The calculation of denudation rates from the measured cosmogenic nuclide concentrations in river sediments requires assumptions and approximations. Several different approaches and numerical tools are available in the literature. A widely used analytical approach represents the muogenic production with one or two exponentials, assumes the attenuation length of muons to be constant and also neglects temporal variations in the Earth's magnetic field. The denudation rates are then calculated directly and analytically from the measured concentrations. A second numerical and iterative approach was more recently proposed and considers a more rigorous muogenic production law based on pre-calculated variable attenuation length of muons and accounts for temporal changes of the magnetic field. It also assumes a specific distribution of denudation rates throughout the basin and uses an iterative approach to calculate the basin average denudation rates. We tested the two approaches across several natural basins and found that both approaches provide similar denudation results. Hence, assuming exponential muogenic production and constant attenuation length of muons in the rock has little impact on the derived denudation rates. Therefore, unless a priori known distributions of denudation rates are to be tested, there does not appear to be any particular gain from using the second iterative method which is computationally less effective. Based on these findings, we developed and describe here Basinga , a new ArcGIS® and QGIS toolbox which computes the basin average scaling factors, cosmogenic production rates and denudation rates for several tens of drainage basins together. Basinga follows either the Lal/Stone or the Lifton/Sato/Dunai scaling schemes and includes several optional tools for correcting for topographic shielding, ice cover and lithology. We have also developed an original method for correcting the cosmogenic production rates for past variations in the Earth's magnetic field. © 2019 John Wiley & Sons, Ltd. |
| Keywords: | scaling factors cosmogenic production rates denudation rates ArcGIS® and QGIS |