DOI: 10.5880/gfz.3.3.2021.001
title: Geochemical data on rock weathering along an erodosequence

description: We provide geochemical background data on the partitioning and cycling of elements between rock, saprolite, soil, plants, and river dissolved and solid loads from at three sites along a global transect of mountain landscapes that differ in erosion rates – an “erodosequence”. These sites are the Swiss Central Alps, a rapidly-eroding post-glacial mountain belt; the Southern Sierra Nevada, USA, eroding at moderate rates; and the slowly-eroding tropical Highlands of Sri Lanka. The backbone of this analysis is an extensive data set of rock, saprolite, soil, water, and plant geochemical data. This set of elemental concentrations is converted into process rates by using regolith production and weathering rates from cosmogenic nuclides, and estimates of biomass growth. Combined, they allow us to derive elemental fluxes through regolith and vegetation. The main findings are: 1) the rates of weathering are set locally in regolith, and not by the rate at which entire landscapes erode; 2) the degree of weathering is mainly controlled by regolith thickness. This results in supply-limited weathering in Sri Lanka where weathering runs to completion, and kinetically-limited weathering in the Alps and Sierra Nevada where soluble primary minerals persist; 3) these weathering characteristics are reflected in the sites’ ecosystem processes, namely in that nutritive elements are intensely recycled in the supply-limited setting, and directly taken up from soil and rock in the kinetically settings; 4) contrary to common paradigms, the weathering rates are not controlled by biomass growth; 5) at all sites we find a deficit in river solute export when compared to solute production in regolith, the extent of which differs between elements but not between erosion rates. Plant uptake followed by litter erosion might explain this deficit for biologically utilized elements of high solubility, and rare, high-discharge flushing events for colloidal-bound elements of low solubility. Our data and the new metrics have begun to serve for calibrating metal isotope systems in the weathering zone, the isotope ratios of which depend on the flux partitioning between the compartments of the Critical Zone. We demonstrate this application in several isotope geochemical companion papers with associated datasets from the same samples. All samples are assigned with International Geo Sample Numbers (IGSN), a globally unique and persistent Identifier for physical samples. The IGSNs are provided in the data tables and link to a comprehensive sample description in the internet.
description: Part 1: Tables included in this data publication (All tables are included in 2021-001_vonBlanckenburg-et-al_ASS_Data_part-1.xlsx and additionally provided in tab delimited text version): Table A1. Swiss Alps analyses of soil, saprolite, rock Table A2. Swiss Alps analyses of water samples Table A3. Swiss Alps analyses of plant samples from the Swiss Alps Table SN1. Sierra Nevada analyses of soil, saprolite, rock Table SN2. Sierra Nevada analyses of water samples Table SN3. Sierra Nevada analyses of plant samples Table SL1. Sri Lanka analyses of soil, saprolite, rock Table SL2. Sri Lanka analyses of water samples. Element concentration analyses and pH Table SL3. Sri Lanka analyses of plant samples Table C1. Summary of principle ASS site characteristics Table C2. Compilation of Denudation rates from river cosmogenic nuclides in river sediment and soil associated production rates Table C3. Compilation of soil production rates, CDF, and chemical weathering rates of ASS sites Table C4. Fractional contributions of endmembers from a inversion of dissolved elements in streams Table C5. Flux Summary: Plant uptake rates, recycling ratios, and dissolved export efficiency Table C6. Data quality control for plant concentration analyses Part 2: Supplementary Data included in this data publication (file: 2021-001_vonBlanckenburg-et-al_ASS_Data_part-2.pdf): 1. Sources of River Solutes from End Member Mixing Analysis (EMMA) 2. Reassessment of Dust Input in the Sierra Nevada 3. Rock and Regolith Mineralogical Composition from X_Ray Diffraction ((XRD)