Spatial and temporal variations in meteoric 10Be inventories and long-term deposition rates, Colorado Front Range

Ouimet, William B.; Dethier, David P.; Bierman, Paul R.; Wyshnytzky, Cianna E.; Shea, Neil M.; Rood, Dylan H.

doi:10.1016/j.quascirev.2014.11.003

Cited by 15 publications

(23 citation statements)

References 49 publications

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“…To calculate

J_{atm}^{{}^{10}{Be}}

(equation (1)), the basin‐wide meteoric 10 Be depositional flux

F_{met}^{{}^{10}{Be}}

needs to be known.

F_{met}^{{}^{10}{Be}}

can be obtained by several methods, including long‐term meteoric 10 Be inventories measured in independently dated soils (Ouimet et al, 2015), short‐term measurements of 10 Be in precipitation (Graly et al, 2011), or atmospheric general circulation models (GCMs) for global meteoric 10 Be deposition (Willenbring & von Blanckenburg, 2010). In the study area, no 10 Be flux data are reported by the first two methods, and thus, we adopted the third one, which has previously been applied to large catchments (Rahaman et al, 2017; Wittmann et al, 2015) and very small catchments (<1 km 2 ) (Dannhaus et al, 2018).…”

Section: Discussionmentioning

confidence: 99%

Denudation Rate Changes Along a Fast‐Eroding Mountainous River With Slate Headwaters in Taiwan From ¹⁰Be (Meteoric)/⁹Be Ratios

et al. 2020

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The novel 10Be (meteoric)/9Be system, where 10Be is delivered by precipitation and stable 9Be is released by weathering, provides denudation rates over weathering‐erosion timescales. The new tool is applicable to quartz‐poor lithologies, for example, mafic rock and claystone, which are not readily accessible by the commonly used in situ‐produced 10Be in quartz. We provide a first application of this proxy to a tectonically active mountainous river, the Zhuoshui River in Taiwan. Taiwan Rivers supply a disproportionately high suspended and dissolved flux to the oceans and are often underlain by fine‐grained shale/slate. 10Be (meteoric)/9Be‐derived denudation rates (Dmet) from the Zhuoshui Catchment are highest in the slate‐dominated headwaters (4–8 mm/year), and much lower (1–2 mm/year) along the midlower reaches with mixed lithologies. At the basin‐wide scale, we find a poor correlation between Dmet and basin‐averaged channel steepness despite a small climatic gradient. Because large lithological heterogeneities exist in this basin, we invoke a lithological effect to explain this poor correlation. Relying on a revised stream power incision model that incorporates rock erodibility, the resulting lithology‐ and runoff‐adjusted ksn (kLrsn) can be reconciled with denudation rates with the highest erodibility predicted to prevail in the Miocene slate of low metamorphic grade and high fracture density. This model suggests that the lithological heterogeneity can alter the coupling between surface denudation and channel morphology. On a broader perspective, the successful application of the 10Be (meteoric)/9Be proxy shows its applicability as a tracer for erosion and sediment transport processes in fast‐eroding mountain belts underlain by slate lithologies.

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“…To calculate

J_{atm}^{{}^{10}{Be}}

(equation (1)), the basin‐wide meteoric 10 Be depositional flux

F_{met}^{{}^{10}{Be}}

needs to be known.

F_{met}^{{}^{10}{Be}}

Section: Discussionmentioning

confidence: 99%

Denudation Rate Changes Along a Fast‐Eroding Mountainous River With Slate Headwaters in Taiwan From ¹⁰Be (Meteoric)/⁹Be Ratios

et al. 2020

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“…This estimate cannot be reliably obtained from short-term precipitation records (Graly et al, 2011), but rather from meteoric 10 Be soil inventories of known age or erosion (e.g. Egli et al (2010); Ouimet et al (2015); Willenbring and von Blanckenburg (2010)), or time-averaged global circulation models. Here, we use a F of 1.4610 6 ats cm -2 y -1 derived from a combination of a model for the simulation of cosmic ray particle interactions with the Earth's atmosphere (Masarik and Beer, 1999) with the "ECHAM5" fifth-generation global atmospheric circulation model (GCM) coupled to the aerosol model HAM (Heikkilä et al, 2013a;Heikkilä et al, 2013b).…”

Section: Requirements For the Successful Application Of The New Proxymentioning

confidence: 99%

Catchment-wide weathering and erosion rates of mafic, ultramafic, and granitic rock from cosmogenic meteoric 10Be/9Be ratios

Dannhaus

Wittmann

Krám

et al. 2018

Geochimica et Cosmochimica Acta

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Quantifying rates of weathering and erosion of mafic rocks is essential for estimating changes to the oceans alkalinity budget that plays a significant role in regulating atmospheric CO 2 levels. In this study, we present catchment-wide rates of weathering, erosion, and denudation measured with cosmogenic nuclides in mafic and ultramafic rock. We use the ratio of the meteoric cosmogenic nuclide 10 Be, deposited from the atmosphere onto the weathering zone, to stable 9 Be, a trace metal released by silicate weathering. We tested this approach in stream sediment and water from three upland forested catchments in the northwest Czech Republic. The catchments are underlain by felsic (granite), mafic (amphibolite) and ultramafic (serpentinite) lithologies. Due to acid rain deposition in the 20 th century, the waters in the granite catchment exhibit acidic pH, whereas waters in the mafic catchments exhibit neutral to alkaline pH values due to their acid buffering capability. The atmospheric depositional 10 Be flux is estimated to be balanced with the streams' dissolved and particulate meteoric 10 Be export flux to within a factor of two. We suggest a correlation method to derive bedrock Be concentrations, required as an input parameter, which are highly heterogeneous in these small catchments. Derived Earth surface metrics comprise 1) Denudation rates calculated from the 10 Be/ 9 Be ratio of the "reactive" Be (meaning sorbed to mineral surfaces) range between 110 to 185 t km-2 y-1 (40 to 70 mm ky-1). These rates are similar to denudation rates we obtained from in situ-cosmogenic 10 Be in quartz minerals present in the bedrock or in quartz veins in the felsic and the mafic catchment. 2) The degree of weathering, calculated from the fraction of 9 Be released from primary minerals as a new proxy, is about 40 to 50% in the mafic catchments, and 10% in the granitic catchments. Lastly, 3) erosion rates were calculated from 10 Be concentrations in river sediment and corrected for sorting and dissolved loss. These amount to 50% of denudation rates from 10 Be/ 9 Be in the mafic and ultramafic catchments, the remainder being mass loss in the dissolved form by weathering. In contrast, erosion comprises most of the mass loss in the granitic catchment. These first results are encouraging, given that we find overall good agreement between in situ and meteoric cosmogenic methods, that our denudation rates are in the range of those published for middle European river catchments, and that degrees of weathering are as expected for these diverse lithologies. This method allows quantifying rates of erosion and weathering in mafic rock over the time scale of weathering that are, unlike in situ cosmogenic 10 Be, independent from the presence of quartz. 10 Be/ 9 Be therefore offers to quantify Earth surface processes in a wide range of landscapes underlain by mafic rock-rates that are of high importance for exploring climate-weathering feedbacks but that have been inaccessible to date.

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“…Heikkilä et al (2013)) that also incorporates a 889 physical model simulating processes of cosmic particle production and transport 890 (Masarik and Beer, 1999) and variations in solar modulation and magnetic field 891 strength. For smaller scales, measured inventories 10 Be in soil for given latitudes and 892 precipitation rates can be used to determine local 893 Willenbring and von Blanckenburg, 2010;Graly et al, 2011;Ouimet et al, 2015). As 894 >95% of meteoric 10 Be production in the atmosphere takes place at elevations above 895 3 km altitude, scaling for altitude is not required for most locations (Willenbring and 896 von Blanckenburg, 2010).…”

Section: General Principles 857mentioning

confidence: 99%

The geological significance of cosmogenic nuclides in large lowland river basins

Wittmann

Blanckenburg

2016

Earth-Science Reviews

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12Measured from a bag of sand taken in large rivers, the concentration of cosmogenic 13 nuclides such as in situ-produced 10 Be, 26 Al, and 14 C can be used to constrain the 14 mean sediment flux of the headwaters and assess the duration of sediment storage 15 from source to sink. We revisit these principles, with examples from the Amazon and 16 Ganga basins. 17We identify two end member cases controlling the concentration of cosmogenic 18 nuclides in lowland river sediment: 1) if the time scale of floodplain sediment storage 19 is short compared to the half-life of the nuclide, in situ cosmogenic nuclide 20 concentrations are not significantly altered in lowland basins. In this case the 21 concentration of e.g. in situ-produced 10 Be in the sediment taken in the lowland 22 2 basin equals in most cases that exported from the sediment source area, but the 23 variability in nuclide concentrations between headwater streams is significantly 24 averaged-out. Thus to convert the measured river sediments' in situ cosmogenic 25 nuclide concentration into a catchment-wide denudation rate, production rates are 26 scaled to include those of the sediment-producing mountainous areas only, rather 27 than the entire catchment area. Nuclide production in the lowlands, where no 28 sediment is being produced, is hence excluded. This correction is termed "floodplain 29 Be ratio on Be adsorbed to particles provides the denudation 51 rate. Both are similar to denudation rates from in situ 10 Be. We show that this 52 system responds more sensitively to sediment storage than the in situ system, and 53 both accumulation and decay of meteoric concentrations may thus be used to 54 determine sediment residence time. 55 56

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Spatial and temporal variations in meteoric 10Be inventories and long-term deposition rates, Colorado Front Range

Cited by 15 publications

References 49 publications

Denudation Rate Changes Along a Fast‐Eroding Mountainous River With Slate Headwaters in Taiwan From ¹⁰Be (Meteoric)/⁹Be Ratios

Denudation Rate Changes Along a Fast‐Eroding Mountainous River With Slate Headwaters in Taiwan From ¹⁰Be (Meteoric)/⁹Be Ratios

Catchment-wide weathering and erosion rates of mafic, ultramafic, and granitic rock from cosmogenic meteoric 10Be/9Be ratios

The geological significance of cosmogenic nuclides in large lowland river basins

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Spatial and temporal variations in meteoric 10Be inventories and long-term deposition rates, Colorado Front Range

Cited by 15 publications

References 49 publications

Denudation Rate Changes Along a Fast‐Eroding Mountainous River With Slate Headwaters in Taiwan From 10Be (Meteoric)/9Be Ratios

Denudation Rate Changes Along a Fast‐Eroding Mountainous River With Slate Headwaters in Taiwan From 10Be (Meteoric)/9Be Ratios

Catchment-wide weathering and erosion rates of mafic, ultramafic, and granitic rock from cosmogenic meteoric 10Be/9Be ratios

The geological significance of cosmogenic nuclides in large lowland river basins

Contact Info

Product

Resources

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Denudation Rate Changes Along a Fast‐Eroding Mountainous River With Slate Headwaters in Taiwan From ¹⁰Be (Meteoric)/⁹Be Ratios

Denudation Rate Changes Along a Fast‐Eroding Mountainous River With Slate Headwaters in Taiwan From ¹⁰Be (Meteoric)/⁹Be Ratios