This software package calculates postburial production for samples with complex time-depth burial histories. The code was developed for Ott et al. 2022. Production rates are calculated using CRONUScalc v2.1 (Marrero et al. 2016). The current version is developed for 10Be and 36Cl but can easily be expanded to any nuclide within CRONUS. To run the code, you need to input your sample data through excel spreadsheets. The nomenclature follows the CRONUScalc input for the nuclide samples. An additional excel file with the parameters of the burial models (time-depth constraints) needs to be provided. CRONUScalc can be downloaded here https://bitbucket.org/cronusearth/cronus-calc/src/v2.1 The InputData folder contains all data from Ott et al. (2022) and can be used as an example of the input formatting. The postburial_prod.m script illustrates how to use the subroutines. Please, report bugs to richard.ott1900@gmail.com
Cosmogenic nuclide measurements are commonly biased by weathering within the cosmogenic nuclide production zone. The code package “WeCode” (Weathering Corrections for denudation rates) integrated within the CRONUScalc v2.1 (Marrero et al., 2016) software performs weathering corrections and calculations, as well as offering pixel-by-pixel catchment production rate estimates for alluvial samples. Weathering corrections can be applied for weathering within the regolith or along the regolith-bedrock interface, as is common in carbonate bedrock. The methods for the weathering corrections are described in Ott et al. (2022). Please refer to the README for information on how to use the software. A set of input examples and scripts is provided for illustration. CRONUScalc can be downloaded here https://bitbucket.org/cronusearth/cronus-calc/src/v2.1
The stochastic erosion in-situ cosmogenic nuclide model is a 1D numerical model that simulates the evolution of the concentrations of in situ-produced Be-10, C-14, and He-3 alongside the bedrock thermal field in the shallow Earth surface. It is useful for evaluating cosmogenic nuclide data derived from field samples, in order to determine the erosion rate, erosion style, as well as the time-integrated bedrock thermal history. The model simulates erosion in four styles: no erosion, uniform (steady-state) erosion, episodic erosion, and stochastic erosion. It is particularly useful for evaluating the time-temperature evolution of bedrock hillslopes in mountainous regions.
As reverse weathering has been shown to impact long-term changes in atmospheric CO2 levels, it is crucial to develop quantitative tools to reconstruct marine authigenic clay formation. We explored the potential of the beryllium (Be) isotope ratio (10Be/9Be) recorded in marine clay-sized sediment to track neoformation of authigenic clays. The power of such proxy relies on the orders-of-magnitude difference in 10Be/9Be ratios between continental Be and Be dissolved in seawater. On riverine and marine sediments collected along a Chilean margin transect we chemically extracted reactive phases and separated the clay-sized sediment fraction. We compare the riverine and marine 10Be/9Be ratio of this fraction. Moreover, we compare the elemental and mineralogical composition and the Nd and Sr-isotopic composition of these samples. 10Be/9Be ratios increase four-fold from riverine to marine sediment. We attribute this increase to the incorporation of Be high in 10Be/9Be from dissolved biogenic opal, which also serves as a Si-source for the precipitation of marine authigenic clays. 10Be/9Be ratios thus sensitively track reverse-weathering reactions forming marine authigenic clays.
Sampling large river´s sediment at outlets for cosmogenic nuclide analysis yields mean denudation rates of the sediment producing areas that average local variations in denudation commonly found in small rivers. Using this approach, we measured in situ cosmogenic 26Al and 10Be concentrations in sands of >50 large rivers over a range of climatic and tectonic regimes covering 32% of Earth’s terrestrial surface.River samples were processed in the Helmholtz Laboratory for the Geochemistry of the Earth Surface (HELGES) (von Blanckenburg et al., 2016). 10Be/9Be ratios were measured by Accelerator Mass Spectrometry (AMS) at the University of Cologne and normalized to the KN01-6-2 and KN01-5-3 standards. Denudation rates were calculated using a time-dependent scaling scheme according to Lal/Stone ”Lm” scaling (see Balco et al., 2008) together with a sea level high latitude (SLHL) production rate of 4.13 at/(gxyr) as reported by Martin et al. (2017).Measured in the mineral quartz, the cosmogenic nuclides 26Al and 10Be provide information on how fast Earth´s surface is lowering through denudation. If sediment is however stored in catchments over time spans similar to the nuclides half-lives (being 0.7 Myr and 1.4 Myr for 26Al and 10Be, respectively), the nuclide´s budget is disturbed, and meaningful denudation rates cannot be calculated. The ratio of 26Al/10Be informs us about these disturbances. In 35% of analyzed rivers, we find 26Al/10Be ratios significantly lower than these nuclides´ surface production rate ratio of 6.75 in quartz, indicating sediment storage and burial exceeding 0.5 Myr. We invoke mainly a combination of slow erosion, long transport, and low runoff for these low ratios.In the other 65% of rivers we find 26Al/10Be ratios within uncertainty of their surface production-rate ratio, indicating cosmogenic steady state, and hence meaningful denudation rates can be calculated. For these rivers, we derive a global source-area denudation rate of 140 t/km^2/yr that translates to a flux of 3.10 Gt/yr. By assuming that this sub-dataset is geomorphically representative of the global land surface, we upscale this value to the total surface area for exorheic basins, thereby obtaining a global denudation flux from cosmogenic nuclides of 15.1 Gt/yr that integrates over the past 5 kyr.In Table S1, we provide detailed 10Be nuclide production rates and their correction due to ice shielding and carbonates that are necessary to calculate denudation rates. We provide International GeoSample Numbers (ISGN) for samples used in the analysis, except values that were compiled from published sources. We then compare these denudation rates, converted to sediment fluxes, to published values of sediment fluxes from river load gauging. We find that our cosmogenic nuclide-derived sediment flux value is similar, within uncertainty, to published values from cosmogenic nuclides from small river basins (23 Gt/yr) upscaled using a global slope model, and modern sediment and dissolved loads exported to the oceans (23.6 Gt/yr). In Table S3, we compiled these modern sediment loads and give their references. We also compiled runoff values (mm/yr) from published sources (Table S2) that are used to infer what controls denudation rates.For more details on the sampling and analytical methods, please consult the data description part of this publication.
Concentrations of in-situ-produced cosmogenic 10Be in river sediment are widely used to estimate catchment-average denudation rates. Typically, the 10Be concentrations are measured in the sand fraction of river sediment. However, the grain size of bedload sediment in most bedrock rivers covers a much wider range. Where 10Be concentrations depend on grain size, denudation rate estimates based on the sand fraction alone are potentially biased. To date, knowledge about catchment attributes that may induce grain-size-dependent 10Be concentrations is incomplete or has only been investigated in modelling studies. Here we present an empirical study on the occurrence of grain-size-dependent 10Be concentrations and the potential controls of hillslope angle, precipitation, lithology, and abrasion. We first conducted a study focusing on the sole effect of precipitation in four granitic catchments located on a climate gradient in the Chilean Coastal Cordillera. We found that observed grain size dependencies of 10Be concentrations in the most-arid and most-humid catchments could be explained by the effect of precipitation on both the scouring depth of erosion processes and the depth of the mixed soil layer. Analysis of a global dataset of published 10Be concentrations in different grain sizes (n=73 catchments) – comprising catchments with contrasting hillslope angles, climate, lithology, and catchment size – revealed a similar pattern. Lower 10Be concentrations in coarse grains (defined as “negative grain size dependency”) emerge frequently in catchments which likely have thin soil and where deep-seated erosion processes (e.g. landslides) excavate grains over a larger depth interval. These catchments include steep (> 25°) and humid catchments (> 2000mm yr-1). Furthermore, we found that an additional cause of negative grain size dependencies may emerge in large catchments with weak lithologies and long sediment travel distances (> 2300–7000 m, depending on lithology) where abrasion may lead to a grain size distribution that is not representative for the entire catchment. The results of this study can be used to evaluate whether catchment-average denudation rates are likely to be biased in particular catchments.Samples from the Chilean Coastal Cordillera were processed in the Helmholtz Laboratory for the Geochemistry of the Earth Surface (HELGES). 10Be/9Be ratios were measured at the University of Cologne and normalized to the KN01-6-2 and KN01-5-3 standards. Denudation rates were calculated using a time-independent scaling scheme according to Lal (1991) and Stone (2002) (St scaling scheme) and the SLHL production rate of 4.01 at g-1 yr-1 as reported by Phillips et al. (2016)The global compilation exists of studies that measured 10Be concentrations in different grain sizes from the same sample location. We only included river basins of <5000 km2 which measured 10Be concentrations in at least one sand-sized fraction <2 mm and at least one coarser fraction >2 mm. Catchment parameters have been recalculated using a 90-m SRTM DEM.The data are presented in Excel and csv tables. Table S1 describes the characteristics of the samples catchments, Table S2 includes the grain size dependent 10Be-concentrations measured during this study and Table 3 the global compilation of grain size dependent 10Be-concentrations. All samples of this study (the Chilean Coastal Cordillera) are assigned with International Geo Sample Numbers (IGSN). The IGSN links are included in Table S2 and in the Related References Section on the DOI Landing Page. The data are described in detail in the data description file and in van Dongen et al. (2018) to which they are supplementary material to.
The determination of exposure ages, erosion rates, or terrigenous fluxes into the oceans with meteoric cosmogenic 10Be or 10Be/9Be ratios requires knowledge of the depositional fluxes of this nuclide (Willenbring and von Blanckenburg, 2010). The spatial distribution of these fluxes depends on stratospheric production, solar and paleomagnetic modulation, and atmospheric restribution. To allow for the estimation of such fluxes at a given site, and to enable the GIS-based calculation of such fluxes that integrate over large spatial areas (river basins, ocean basins) we provide global maps and excel sheets interpreted to present the average Holocene 10Be fluxes and an estimate of their uncertainty as modeled by atmospheric distribution models (Heikkilä et al., 2013, Heikkilä et al., 2013, Heikkilä and Smith, 2013).
| Origin | Count |
|---|---|
| Wissenschaft | 7 |
| Type | Count |
|---|---|
| unbekannt | 7 |
| License | Count |
|---|---|
| offen | 7 |
| Language | Count |
|---|---|
| Englisch | 7 |
| Resource type | Count |
|---|---|
| Keine | 7 |
| Topic | Count |
|---|---|
| Boden | 6 |
| Lebewesen & Lebensräume | 6 |
| Luft | 6 |
| Mensch & Umwelt | 7 |
| Wasser | 6 |
| Weitere | 7 |