Tectonic uplift, threshold hillslopes, and denudation rates in a developing mountain range

Binnie, Steven A.; Phillips, William R.; Summerfield, Michael A.; Fifield, L.K.

doi:10.1130/g23641a.1

Cited by 202 publications

(216 citation statements)

References 21 publications

(24 reference statements)

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“…6b). This limit has been observed in many other landscapes around the world (Montgomery and Brandon, 2002;Binnie et al, 2007;Ouimet et al, 2009;DiBiase et al, 2010). Basin-averaged hillslope angle values tend to reach a maximum around 34 • , as also shown by Montgomery (2001) using 100 km 2 grids across the Olympic range.…”

Section: Interpreting Relationships Between Erosion and Basin Metricsmentioning

confidence: 61%

Tectonic controls of Holocene erosion in a glaciated orogen

Adams

Ehlers

2018

Earth Surf. Dynam.

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Abstract. Recent work has highlighted a strong, worldwide, alpine glacial impact on orogen erosion rates over the last 2 Ma. While it may be assumed that glaciers increased erosion rates when active, the degree to which past glaciations influence Holocene erosion rates through the adjustment of topography is not known. In this study, we investigate the influence of long-term tectonic and post-glacial topographic controls on erosion in a glaciated orogen: the Olympic Mountains, USA. We present 14 new 10 Be and 26 Al analyses which constrain Holocene erosion rates across the Olympic Mountains. Basin-averaged erosion rates scale with basin-averaged values of 5 km local relief, channel steepness, and hillslope angle throughout the range, similar to observations from non-glaciated orogens. These erosion rates are not related to mean annual precipitation or the marked change in Pleistocene alpine glacier size across the range, implying that glacier modification of topography and modern precipitation parameters do not exert strong controls on these rates. Rather, we find that despite spatial variations in glacial modification of topography, patterns of recent erosion are similar to those from estimates of long-term tectonic rock uplift. This is consistent with a tectonic model where erosion and rock uplift patterns are controlled by the deformation of the Cascadia subduction zone.

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Section: Interpreting Relationships Between Erosion and Basin Metricsmentioning

confidence: 61%

Tectonic controls of Holocene erosion in a glaciated orogen

Adams

Ehlers

2018

Earth Surf. Dynam.

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“…Roering et al, 1999Roering et al, , 2007Montgomery andBrandon, 2000, Binnie et al, 2007) while the pooled-soil rates remain low even at high slope angles (Figure 6). Landscape denudation rates are commonly interpreted with reference to threshold hillslopes Burbank et al, 1996;Montgomery and Brandon 2002;Binnie et al, 2007). Two types of gradients are commonly discussed; critical slopes and threshold slopes.…”

Section: Discussionmentioning

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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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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“…6B). This limit has been observed in many other landscapes around the world (DiBiase et al, 2010;Ouimet et al, 2009;Montgomery and Brandon, 2002;Binnie et al, 2007). Basin-averaged hillslope angle values tend to reach a maximum around 34°, as also shown by Montgomery (2001) using 100 km 2 grids across the Olympic range.…”

Section: Interpreting Relationships Between Erosion and Basin Metricsmentioning

confidence: 61%

Tectonic controls of Holocene erosion in a glaciated orogen

Adams¹,

Ehlers²

2018

Preprint

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Abstract. Recent work has highlighted a strong, worldwide, glacial impact of orogen erosion rates over the last 2 Ma. While it may be assumed that glaciers increased erosion rates when active, the degree to which past glaciations influence Holocene erosion rates through the adjustment of topography is not known. In this study, we investigate the influence of long-term tectonic and post-glacial topographic controls on erosion in a glaciated orogen, the Olympic Mountains, USA. We present 14 10 new 10 Be and 26 Al analyses which constrain Holocene erosion rates across the Olympic Mountains. Basin-averaged erosion rates scale with basin-averaged values of 5-km local relief, channel steepness, and hillslope angle throughout the range, similar to observations from non-glaciated orogens. These erosion rates are not related to mean annual precipitation or the marked change in Pleistocene alpine glacier size across the range, implying that glacier modification of topography and modern precipitation parameters do not exert strong controls on these rates. Rather, we find that despite intense spatial variations in 15 glacial modification of topography, patterns of recent erosion are similar to those from estimates of long-term tectonic rock uplift. This is consistent with a tectonic model where erosion and rock uplift patterns are controlled by the deformation of the Cascadia subduction zone.

show abstract

Tectonic uplift, threshold hillslopes, and denudation rates in a developing mountain range

Cited by 202 publications

References 21 publications

Tectonic controls of Holocene erosion in a glaciated orogen

Tectonic controls of Holocene erosion in a glaciated orogen

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

Tectonic controls of Holocene erosion in a glaciated orogen

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