Scaling factors for production rates of in situ produced cosmogenic nuclides: a critical reevaluation

Dunai, Tibor J.

doi:10.1016/s0012-821x(99)00310-6

Cited by 348 publications

(247 citation statements)

References 41 publications

(139 reference statements)

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“…We exclude the 4 sample locations underlain by granite from this part of the analysis in order to avoid a bias based on lithology, as the granitic samples consistently have lower denudation rates than the samples from the gneissic lithologies. The landform with the lowest hillslope gradients are the ridges at 24º, which also have the lowest average denudation rates with 30-64 mm ky reported by Heimsath et al (1997;2000; at the saprolite-bedrock boundary for similar lithologies in the western USA and Australia.…”

Section: Resultsmentioning

confidence: 81%

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Cosmogenic nuclide‐derived rates of diffusive and episodic erosion in the glacially sculpted upper Rhone Valley, Swiss Alps

Norton

Blanckenburg

Kubik

2010

Earth Surf Processes Landf

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Denudation rates of small tributary valleys in the upper Rhone valley of the Swiss Central Alps vary by more than an order of magnitude within a very small distance (tens of kilometers). Morphometric data indicate two distinct erosion processes operate in these steep mountain valleys. We determined the rates of these processes using cosmogenic beryllium-10 ( 10 Be) in pooled soil and stream sediment samples. Denudation in deep, glacially scoured valleys is characterized by rapid, non-uniform processes, such as debris flows and rock falls. In these steep valleys denudation rates are 760-2100 mm kyr −1 . In those basins which show minimal previous glacial modification denudation rates are low with 60-560 mm kyr −1 . The denudation rate in each basin represents a binary mixture between the rapid, non-uniform processes, and soil creep. The soil production rate measured with cosmogenic 10 Be in soil samples averages at 60 mm kyr −1 . Mixing calculations suggest that the debris flows and rock falls are occurring at rates up to 3000-7000 mm kyr −1 . These very high rates occur in the absence of baselevel lowering, since the tributaries drain into the Rhone trunk stream up-stream of a knickzone. The fluxweighted spatial average of denudation rates for the upper Rhone valley is 1400 mm kyr −1 , which is similar to rock uplift rates determined in this area from leveling. The pace and location of erosion processes are determined by the oscillation between a glacial and a non-glacial state, preventing the landscape from reaching equilibrium.

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Section: Resultsmentioning

confidence: 81%

“…Scaling followed the latitude and altitude scaling laws of Dunai (2000). Corrections for geomagnetic field variations were not made.…”

Section: Methodsmentioning

confidence: 99%

Cosmogenic nuclide‐derived rates of diffusive and episodic erosion in the glacially sculpted upper Rhone Valley, Swiss Alps

Norton

Blanckenburg

Kubik

2010

Earth Surf Processes Landf

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“…This calculator returns the production rate correction factor based on the systematics of both Lal (1991) and Dunai (2000). The more recent Dunai correction factor is used to calculate the surface production rate P 0 , based on a high latitude, sea level production rate of 5.55 atoms 10 Be per gram of quartz per year (Perg et al, 2001).…”

Section: Hancock Pers Comm)mentioning

confidence: 99%

“…Production rates are dependent on local characteristics of the geomagnetic field, and so must be scaled for use at a particular altitude and geographic latitude (Lal, 1991;Dunai, 2000).…”

Section: Introductionmentioning

confidence: 99%

New constraints on the late Cenozoic incision history of the New River, Virginia

et al. 2005

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The New River crosses the core of the ancient, tectonically quiescent Appalachian orogen as it follows its course through North Carolina, Virginia, and West Virginia. It is ideally situated to record the changes in geomorphic process rates that occur in the Appalachians as a response to late Cenozoic climate variations. Active erosion features on resistant bedrock that floors the river at prominent knickpoints demonstrate that the river is currently incising toward base level. However, large packages of alluvial fill and fluvial terraces cut into this fill record an incision history for the river that includes several periods of stalled downcutting and aggradation. Cosmogenic 10 Be exposure dating, aided by mapping and sedimentological examination of terrace deposits, is used to constrain the timing of events in this history. Fill-cut and strath terraces at elevations 10, 20, and 50 m above the modern river yield cosmogenic exposure ages of approximately 130, 610, and 955 ka, respectively, but uncertainties on these ages are not well-constrained. This translates to a long-term average incision rate of 43 m/my, which is comparable to rates measured elsewhere in the Appalachians. During specific intervals over the last 1 Ma, however, the New River's incision rate reached 97 m/my. Fluctuations between aggradation and rapid incision appear to be related to late Cenozoic climate variations, though uncertainties in modeled ages preclude direct correlation of these fluctuations to specific climate change events. Erosion rates on higher alluvial deposits adjacent to the river are estimated from 10 Be concentrations; these rates are very low, about 2 m/my or less. This demonstrates a disequilibrium in the modern landscape, with river incision greatly outpacing erosion from nearby landforms.

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“…At the surface, the first variable, energy, tends to decrease with distance from the Equator due to interactions with Earth's magnetic field, and is well modelled with a series of scaling laws (Lal, 1991;Dunai, 2000;Granger and Muzikar, 2001). The second factor, angle of incidence, has a large influence on the resulting production rate (Dunne et al, 1999), but is less easily quantified owing to skyline shielding.…”

Section: Applications Of In Situ Produced Cosmogenic Nuclidesmentioning

confidence: 99%

Effects of terrain smoothing on topographic shielding correction factors for cosmogenic nuclide‐derived estimates of basin‐averaged denudation rates

Norton

Vanacker²

2008

Earth Surf Processes Landf

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Estimation of spatially averaged denudation rates from cosmogenic nuclide concentrations in sediments depends on the surface production rates, the scaling methods of cosmic ray intensities, and the correction algorithms for skyline, snow and vegetation shielding used to calculate terrestrial cosmogenic nuclide production. While the calculation of surface nuclide production and application of latitude, altitude and palaeointensity scaling algorithms are subjects of active research, the importance of additional correction for shielding by topographic obstructions, snow and vegetation is the subject of ongoing debate. The derivation of an additional correction factor for skyline shielding for large areas is still problematic. One important issue that has yet to be addressed is the effect of the accuracy and resolution of terrain representation by a digital elevation model (DEM) on topographic shielding correction factors. Topographic metrics scale with the resolution of the elevation data, and terrain smoothing has a potentially large effect on the correction of terrestrial cosmogenic nuclide production rates for skyline shielding. For rough, high-relief landscapes, the effect of terrain smoothing can easily exceed analytical errors, and should be taken into account. Here we demonstrate the effect of terrain smoothing on topographic shielding correction factors for various topographic settings, and introduce an empirical model for the estimation of topographic shielding factors based on landscape metrics.

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Scaling factors for production rates of in situ produced cosmogenic nuclides: a critical reevaluation

Cited by 348 publications

References 41 publications

Cosmogenic nuclide‐derived rates of diffusive and episodic erosion in the glacially sculpted upper Rhone Valley, Swiss Alps

Cosmogenic nuclide‐derived rates of diffusive and episodic erosion in the glacially sculpted upper Rhone Valley, Swiss Alps

New constraints on the late Cenozoic incision history of the New River, Virginia

Effects of terrain smoothing on topographic shielding correction factors for cosmogenic nuclide‐derived estimates of basin‐averaged denudation rates

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