Quantitative and qualitative insights into bedrock landform erosion on the South Indian craton using cosmogenic nuclides and apatite fission tracks

Gunnell, Yanni; Braucher, Régis; Bourlès, Didier; André, Grégoire

doi:10.1130/b25945.1

Cited by 31 publications

(17 citation statements)

References 18 publications

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“…The total eroded volume (98,100 m 3 ), relates to the total area of the watershed (4.1 km²) and along a period of 5 kyr denotes a physical erosion rate of about 4.8 10 − 3 m/kyr. This value is in agreement with the recent results presented by Gunnell et al (2007), who estimated the denudation rate (physical erosion + chemical weathering), which is controlled by fluvial incision rates, at about 13.6 ± 2.9 10 − 3 m/kyr into the plateau surface of the South Indian Western Ghats ( Table 2 in Gunnell et al, 2007).…”

Section: Application To the Assessment Of Physical Erosion Rate At Thsupporting

confidence: 91%

“…This estimate is roughly 4.8 10 − 3 m/kyr for the last 5 kyr. In further studies, this result should be compared to the present-day exportation of sediments at the outlet and also compared to the assessment of the denudation rate (physical erosion + chemical weathering) obtained using cosmogenic nuclides (Gunnell et al, 2007). Because the streambed incision is a regional process and ferrolysis is likely occurring at other spots, this type of study should be applied for the assessment of the physical erosion rate at a wider scale in the Kabini upper basin.…”

Section: Discussionmentioning

confidence: 98%

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Ferrolysis induced soil transformation by natural drainage in Vertisols of sub-humid South India

Barbiéro¹,

Kumar²,

Violette³

et al. 2010

Geoderma

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In sub-humid South India, recent studies have shown that black soil areas (Vertisols and vertic Intergrades), located on flat valley bottoms, have been rejuvenated through the incision of streambeds, inducing changes in the pedoclimate and soil transformation. Joint pedological, geochemical and geophysical investigations were performed in order to better understand the ongoing processes and their contribution to the chemistry of local rivers. The seasonal rainfall causes cycles of oxidation and reduction in a perched watertable at the base of the black soil, while the reduced solutions are exported through a loamy sand network. This framework favours a ferrolysis process, which causes low base saturation and protonation of clay, leading to the weathering of 2:1 then 1:1 clay minerals. Maximum weathering conditions occur at the very end of the wet season, just before disappearance of the perched watertable. Therefore, the by-products of soil transformation are partially drained off and calcareous nodules, then further downslope, amorphous silica precipitate upon soil dehydration. The ferrolysed area is fringing the drainage system indicating that its development has been induced by the streambed incision. The distribution of 14 C ages of CaCO 3 nodules suggests that the ferrolysis process started during the late Holocene, only about 2 kyr B.P. at the studied site and about 5 kyr B.P. at the watershed outlet. The results of this study are applied to an assessment of the physical erosion rate (4.8 × 10 − 3 m/kyr) since the recent reactivation of the erosion process.

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Section: Application To the Assessment Of Physical Erosion Rate At Thsupporting

confidence: 91%

Section: Discussionmentioning

confidence: 98%

Ferrolysis induced soil transformation by natural drainage in Vertisols of sub-humid South India

Barbiéro¹,

Kumar²,

Violette³

et al. 2010

Geoderma

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“…40 Ma; Gunnell et al, 2003). However, the timing and magnitude of erosion inferred from modelling of AFT data depends largely on assumptions.…”

Section: Implications For Landscape Evolution In Southern Peninsular mentioning

confidence: 98%

Spatial variability of 10 Be-derived erosion rates across the southern Peninsular Indian escarpment: A key to landscape evolution across passive margins

Mandal

Lupker

Burg

et al. 2015

Earth and Planetary Science Letters

103

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“…There is, however, no clear pattern between regolith thickness and elevation 10.1002 or distance to the outlet [see Braun et al, 2009, Figure 10]. The present-day catchment-averaged erosion rate determined by cosmogenic isotope analysis iṡ≈ 14 × 10 −6 m/yr [Gunnell et al, 2007] From these estimates, we can derive values for the model parameters, K and F, making basic assumptions about the better constrained parameters, S and P 0 . The mean slope of the catchment is S ≈ 0.02, and, being covered by a dry deciduous forest and affected by summer monsoons, infiltration rate should be a fraction only of mean annual rainfall, which we take to be P 0 ≈ 0.3 m/yr.…”

Section: How To Use This Model: Case Example Of the Mule Hole Gneiss mentioning

confidence: 99%

A simple model for regolith formation by chemical weathering

et al. 2016

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We present here a new model for the formation of regolith on geological timescales by chemical weathering based on the assumption that the rate of chemical weathering is primarily controlled by the ability of groundwater to transport solute away from the reacting solid‐fluid interface and keep the system from reaching equilibrium (saturation). This allows us to specify the rate of propagation of the weathering front as linearly proportional to the pore fluid velocity which we obtain by computing the water table geometry in the regolith layer. The surface of the regolith layer is affected by mass transport and erosion. The main prediction of the model is that the geometry of the regolith, i.e., whether it is thickest beneath topographic highs or topographic lows, is controlled by the value of a dimensionless number, which depends on the square of the surface slope, the hydraulic conductivity, and local precipitation rate, but is independent of the chemical weathering rate. In orogenic environments, where regolith formation by chemical weathering competes with surface erosion, the model predicts that the existence and thickness of the regolith layer are controlled by the value of another dimensionless number which is the ratio between the timescale for erosion and the timescale for weathering. The model also predicts that in anorogenic areas, regolith thickness increases as the square root of time, whereas in orogenic environments, a steady state regolith thickness can be achieved, when the propagation of the weathering front is equal to erosion rate.

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Quantitative and qualitative insights into bedrock landform erosion on the South Indian craton using cosmogenic nuclides and apatite fission tracks

Abstract: International audienceno abstrac

Cited by 31 publications

References 18 publications

Ferrolysis induced soil transformation by natural drainage in Vertisols of sub-humid South India

Ferrolysis induced soil transformation by natural drainage in Vertisols of sub-humid South India

Spatial variability of 10 Be-derived erosion rates across the southern Peninsular Indian escarpment: A key to landscape evolution across passive margins

A simple model for regolith formation by chemical weathering

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