Denudation rates determined from the accumulation of in situ-produced 10Be in the luquillo experimental forest, Puerto Rico

Brown, E. T.; Stallard, Robert F.; Larsen, Matthew C.; Raisbeck, G. M.; Yiou, F.

doi:10.1016/0012-821x(94)00249-x

Cited by 495 publications

(560 citation statements)

References 16 publications

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“…At the catchment area scale (A), gain due to production is (P x A), while losses can be estimated by the mean concentration in grains in the river sediments at the outlet (C) multiplied by the sediment flux (F). The concentration of a cosmogenic nuclide (10Be) measured in sediments sampled at river outlets makes it possible to estimate the sediment flux (and hence the denudation rate) at catchment scale, assuming steady-state concentrations within the catchment (Brown et al, 1995;Bierman and Steig, 1996;Granger et al, 1996). When the sediments are buried deeply enough rapidly after their deposition, the concentration is only affected by radioactive decay.…”

Section: 5estimate Of Subsequent Erosion Using Cosmogenic Nuclide mentioning

confidence: 99%

The Roussillon Basin (S. France): A case-study to distinguish local and regional events between 6 and 3 Ma

Clauzon

Strat²,

Duvail³

et al. 2015

Marine and Petroleum Geology

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The Roussillon Basin is a non-silled Miocene sedimentary basin filling a late Oligocene-early Miocene graben. The basin was intensively impacted by the 2 Messinian fluvial erosion, as evidenced in exposed sections, in seismic profiles and in deep boreholes drilled for hydrocarbon exploration. As the basin was open to the Mediterranean Sea, the huge drop in sea level at the peak of the Messinian Salinity Crisis is clearly recorded, along with the subsequent sudden marine reflooding and the resulting prograding sedimentary filling, particularly in Gilbert-type fan deltas. Here, the Messinian Erosional Surface (MES) is accurately mapped in a high-resolution document, which corrects the confusion resulting from the set of 1:50,000 scale regional maps. Aim of the 3D reconstruction of the MES is to modernize geological mapping, a crucial challenge for Mediterranean and peripheral areas. Thanks to a reliable chronostratigraphy provided by planktonic foraminifers, calcareous nannofossils, micro-and macro-mammal remains, paleomagnetism and a 10 Be cosmogenic nuclide-derived study, our reconstruction is one of the most comprehensive models of changes in sea level from 6 to 3 Ma. After the marine reflooding of the Mediterranean Basin at 5.46 Ma, the fluctuations in sea level recorded in the Roussillon Basin were forced by global changes. Following reflooding, the Prades large olistostrome collapsed prepared by the previous exhumation along the Canigou fault. The olistostrome is a good example of a local accident resulting from Messinian events. The exceptional changes in sea level at the peak of the Messinian Salinity Crisis deeply marked the Roussillon Basin, momentarily overprinting the Pyrenean orogenesis.

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Section: 5estimate Of Subsequent Erosion Using Cosmogenic Nuclide mentioning

confidence: 99%

The Roussillon Basin (S. France): A case-study to distinguish local and regional events between 6 and 3 Ma

Clauzon

Strat²,

Duvail³

et al. 2015

Marine and Petroleum Geology

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“…The weathering Tertiary-age Rio Blanco quartz diorite is capped with 2-8 m of saprolite overlain by another 0.5-1 m of soil [16][17][18][19][20][21][22]. The rate of advance of the weathering front has been estimated at approximately 1 cm per 100 years based upon cosmogenic evidence [23]. The transition between the coarse-grained Rio Blanco quartz diorite and the saprolite is not a sharp interface, but consists rather of a 20-60 cm-thick zone characterized by fracture-bound concentric shells, termed here rindlets [7] (Fig.…”

Section: Geologic Setting and Observationsmentioning

confidence: 99%

“…We may also approximate the model profiles of reaction extent as a function of space and time, ξ(x, t), by means of the simple relation (23). However, relation (23) was obtained specifically for ξ 1 from an integration over T = 0 to T, in recognition that the outermost rindlet reacts over the entire time interval T. In contrast, significant reaction at any point x inboard of that first rindlet occurs only over the time duration during which that point has been situated outboard (nearer the saprolite) of a fracture.…”

Section: Model Implicationsmentioning

confidence: 99%

A spheroidal weathering model coupling porewater chemistry to soil thicknesses during steady-state denudation

Fletcher

Buss

Brantley

2006

Earth and Planetary Science Letters

206

229

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Spheroidal weathering, a common mechanism that initiates the transformation of bedrock to saprolite, creates concentric fractures demarcating relatively unaltered corestones and progressively more altered rindlets. In the spheroidally weathering Rio Blanco quartz diorite (Puerto Rico), diffusion of oxygen into corestones initiates oxidation of ferrous minerals and precipitation of ferric oxides. A positive ∆V of reaction results in the buildup of elastic strain energy in the rock. Formation of each fracture is postulated to occur when the strain energy in a layer equals the fracture surface energy. The rate of spheroidal weathering is thus a function of the concentration of reactants, the reaction rate, the rate of transport, and the mechanical properties of the rock. Substitution of reasonable values for the parameters involved in the model produces results consistent with the observed thickness of rindlets in the Rio Icacos bedrock (≈ 2-3 cm) and a time interval between fractures (≈ 200-300 a) based on an assumption of steady-state denudation at the measured rate of 0.01 cm/a. Averaged over times longer than this interval, the rate of advance of the bedrock-saprolite interface during spheroidal weathering (the weathering advance rate) is constant with time. Assuming that the oxygen concentration at the bedrock-saprolite interface varies with the thickness of soil/saprolite yields predictive equations for how weathering advance rate and steadystate saprolite/soil thickness depend upon atmospheric oxygen levels and upon denudation rate. The denudation and weathering advance rates at steady state are therefore related through a condition on the concentration of porewater oxygen at the base of the saprolite. In our model for spheroidal weathering of the Rio Blanco quartz diorite, fractures occur every ~ 250 years, ferric oxide is fully depleted over a four rindlet set in ~ 1000 years, and saprolitization is completed in ~ 5000 years in the zone 2 containing ~ 20 rindlets. Spheroidal weathering thus allows weathering to keep up with the high rate of denudation by enhancing access of bedrock to reactants by fracturing.Coupling of denudation and weathering advance rates can also occur for the case that weathering occurs without spheroidal fractures, but for the same kinetics and transport parameters, the maximum rate of saprolitization achieved would be far smaller than the rate of denudation for the Rio Blanco system. The spheroidal weathering model provides a quantitative picture of how physical and chemical processes can be coupled explicitly during bedrock alteration to soil to explain weathering advance rates that are constant in time.

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“…This method has been applied to diverse landscapes (Brown et al, 1995;Matmon et al, 2003b;Vanacker et al, 2007;Norton et al, 2008) and processes, such as the long-held relationship between hillslope gradient and erosion rate (Ahnert, 1970;Granger et al, 1996;Matmon et al, 2003a;von Blanckenburg, 2005). Cosmogenic methods have been combined with topographic and chemical analyses in order to relate the production of sediment on hillslopes to the controlling sediment production and transport processes (Heimsath et al, 2001), and to better understand the relationship between physical erosion and chemical weathering (Riebe et al, 2003), and climate and denudation (Riebe et al, 2001;von Blanckenburg, 2005).…”

Section: Applications Of In Situ Produced Cosmogenic Nuclidesmentioning

confidence: 99%

“…This sediment is assumed to be an amalgam of grains that are released from all parts of the landscape in proportion to their long-term denudation rate (Brown et al, 1995;Granger et al, 1996). The nuclide concentration measured is then a mass balance weighed mean of the contributed concentrations from all points in the watershed.…”

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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Denudation rates determined from the accumulation of in situ-produced 10Be in the luquillo experimental forest, Puerto Rico

Cited by 495 publications

References 16 publications

The Roussillon Basin (S. France): A case-study to distinguish local and regional events between 6 and 3 Ma

The Roussillon Basin (S. France): A case-study to distinguish local and regional events between 6 and 3 Ma

A spheroidal weathering model coupling porewater chemistry to soil thicknesses during steady-state denudation

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

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