scholarly journals Yangtse River sediments and erosion rates from source to sink traced with cosmogenic 10Be: Sediments from major rivers

2006 ◽  
Vol 241 (1) ◽  
pp. 79-94 ◽  
Author(s):  
John Chappell ◽  
Hongbo Zheng ◽  
Keith Fifield
Keyword(s):  
River Sediments ◽  
Erosion Rates ◽  
Source To Sink ◽  
Cosmogenic 10Be

scholarly journals Top-down and bottom-up controls on mountain-hopping erosion: insights from detrital <sup>10</sup>Be and river profile analysis in Central Guatemala

2020 ◽  
Author(s):  
Gilles Y. Brocard ◽  
Jane K. Willenbring ◽  
Tristan Salles ◽  
Michael Cosca ◽  
Axel Guttiérez-Orrego ◽  
...  
Keyword(s):  
Land Surface ◽  
Profile Analysis ◽  
River Sediments ◽  
Mountain Range ◽  
Top Down ◽  
Bottom Up ◽  
Erosion Rates ◽  
River Incision ◽  
Orogenic Plateaus ◽  
Cosmogenic 10Be

Abstract. The presence of a mountain affects the circulation of water in the atmosphere and over the land surface. These effects are felt over some distance, beyond the extent of the mountain, controlling precipitation delivery and river incision over surrounding landmasses. The rise of a new mountain range therefore affects the erosion of pre-existing mountains located in close proximity. We document here this phenomenon in the mountains of Central Guatemala. The 40Ar-39Ar dating of lava flows shows that two parallel, closely spaced mountain ranges formed during two consecutive pulses of single-stepped uplift, one from 12 to 7 Ma, and the second one since 7 Ma. The distribution of erosion rates derived from the analysis of detrital cosmogenic 10Be in river sediments shows that the younger range erodes faster (~300 m/My) than the older one (20–150 m/My), and that erosion correlates with the amount of precipitation. Moisture tracking form the Caribbean Sea is intercepted by the younger range, which casts a rain shadow over the older one. The analysis of river long-profiles provides a record of longer-term interactions between the two ranges. The rivers that drain the older range were diverted by the younger range during the early stages of its rise. A few rivers were able to maintain their course across the young range, through profile steepening, but incision completely stalled along their upper reaches, upstream of the younger range. As a result, the older range has been passively uplifted, and entered a phase of a slow topographic decay: pediments have formed along its base, while ancient upstream-migrating waves of erosion, located farther up the mountain flanks, have almost stopped migrating. Aridification and cessation of river incision together explain the slowing down of erosion over the older range. They represent top-down and bottom-up processes whereby the younger range controls erosion over the older one. These controls are regarded as instrumental in the nucleation and enlargement of orogenic plateaus forming above continental accretionary wedges.

scholarly journals Short Communication: Increasing vertical attenuation length of cosmogenic nuclide production on steep slopes negates topographic shielding corrections for catchment erosion rates

2018 ◽  
Author(s):  
Roman A. DiBiase
Keyword(s):  
Effective Mass ◽  
Erosion Rate ◽  
Attenuation Length ◽  
Erosion Rates ◽  
10Be Concentration ◽  
Shielding Factor ◽  
Cosmogenic 10Be ◽  
Topographic Shielding ◽  
Surface Production ◽  
Mass Attenuation

Abstract. Interpreting catchment-mean erosion rate from in situ produced cosmogenic 10Be concentration in stream sands requires calculating the catchment-mean 10Be surface production rate and effective mass attenuation length, both of which can vary locally due to topographic shielding and slope effects. The most common method for calculating topographic shielding accounts only for the effect of shielding at the surface, leading to catchment-mean corrections of up to 20 % in steep landscapes, and makes the simplifying assumption that the effective mass attenuation length for a given nuclide production mechanism is spatially uniform. Here I evaluate the validity of this assumption using a simplified catchment geometry to calculate the spatial variation in surface skyline shielding, effective mass attenuation length, and the total effective shielding factor for catchments with mean slopes ranging from 0° to 80°. For flat catchments (i.e., uniform elevation of bounding ridgelines), the increase in effective attenuation length as a function of hillslope angle and skyline shielding leads to a catchment-mean total effective shielding factor of one, implying that no topographic shielding factor is needed when calculating catchment-mean vertical erosion rates. For dipping catchments (as characterized by a plane fit to the bounding ridgelines), the catchment-mean total effective shielding factor is also one, except for cases of extremely steep range-front catchments, where the shielding correction is counterintuitively greater than one. These results indicate that in most cases, topographic shielding corrections are inappropriate for calculating catchment-mean erosion rates, and only needed for steep catchments with non-uniform distribution of quartz and/or erosion rate. By accounting only for shielding of surface production, existing shielding approaches introduce a slope-dependent systematic error that could lead to spurious interpretations of relationships between topography and erosion rate.

scholarly journals Glaciation's topographic control on Holocene erosion at the eastern edge of the Alps

2016 ◽  
Vol 4 (4) ◽  
pp. 895-909 ◽  
Author(s):  
Jean L. Dixon ◽  
Friedhelm von Blanckenburg ◽  
Kurt Stüwe ◽  
Marcus Christl
Keyword(s):  
Eastern Alps ◽  
European Alps ◽  
Glacial Erosion ◽  
Erosion Rates ◽  
The Alps ◽  
Glacial Processes ◽  
Cosmogenic 10Be ◽  
Topographic Forcing ◽  
Eastern Edge

Abstract. What is the influence of glacial processes in driving erosion and uplift across the European Alps? It has largely been argued that repeated erosion and glaciation sustain isostatic uplift and topography in a decaying orogen. But some parts of the Alps may still be actively uplifting via deep lithospheric processes. We add insight to this debate by isolating the role of post-glacial topographic forcing on erosion rates. To do this, we quantify the topographic signature of past glaciation on millennial-scale erosion rates in previously glaciated and unglaciated catchments at the easternmost edge of the Austrian Alps. Newly measured catchment-wide erosion rates, determined from cosmogenic 10Be in river-borne quartz, correlate with basin relief and mean slope. GIS-derived slope–elevation and slope–area distributions across catchments provide clear topographic indicators of the degree of glacial preconditioning, which further correlates with erosion rates. Erosion rates in the easternmost, non-glaciated basins range from 40 to 150 mm ky−1 and likely reflect underlying tectonic forcings in this region, which have previously been attributed to recent (post 5 Ma) uplift. By contrast, erosion rates in previously glaciated catchments range from 170 to 240 mm ky−1 and reflect the erosional response to local topographic preconditioning by repeated glaciations. Together, these data suggest that Holocene erosion across the Eastern Alps is strongly shaped by the local topography relict from previous glaciations. Broader, landscape-wide forcings, such as the widely debated deep mantle-driven or isostatically driven uplift, result in lesser controls on both topography and erosion rates in this region. Comparing our data to previously published erosion rates across the Alps, we show that post-glacial erosion rates vary across more than 2 orders of magnitude. This high variation in post-glacial erosion may reflect combined effects of direct tectonic and modern climatic forcings but is strongly overprinted by past glacial climate and its topographic legacy.

Quantifying the dynamic topography through a combination of basin-averaged erosion rates and geomorphic analysis from the Anti Atlas and Western Meseta (Morocco) transient landscape

2020 ◽  
Author(s):  
Romano Clementucci ◽  
Lionel Siame ◽  
Paolo Ballato ◽  
Ahmed Yaaqoub ◽  
Abderrahim Essaifi ◽  
...  
Keyword(s):  
Large Scale ◽  
River Sediments ◽  
Transient State ◽  
Dynamic Topography ◽  
Erosion Rates ◽  
Marine Deposits ◽  
Surface Uplift ◽  
Atlas Mountains ◽  
Middle Atlas

&lt;p&gt;The topography of the Atlas-Meseta system (Morocco) is the result of Late Cenozoic rejuvenation related to mantle-driven uplift. This recent, large-scale dynamic uplift is testified by the occurrence of uplifted shallow-water marine deposits in the Middle Atlas Mountains and in the Western Meseta, indicating that surface uplift must have started after the Late Miocene (Messinian) at rates of 0.1 to 0.2 mm yr&lt;sup&gt;-1&lt;/sup&gt;. This recent pulse is still recorded by transient river networks and by the presence of uplifted relict landscape. In particular, in the Anti Atlas and Western Maroccan Meseta, the lack of significant Cenozoic crustal shortening and the occurrence of several hundred of meters of mantle-driven uplift, offers the possibility to investigate magnitude, timing and rates of deep-seated uplift. In this study we have combined geomorphic analysis of stream profiles with in situ-produced cosmogenic concentrations (&lt;sup&gt;10&lt;/sup&gt;Be, &lt;sup&gt;26&lt;/sup&gt;Al) in river sediments and bedrock surfaces (corresponding to relict landscape upstream of knickpoints), in order to decipher the uplift history. Our catchment-mean erosion rates allow us to quantitatively constrain the transient state of landscape and hence to unravel the contribution of regional surface uplift on mountain building processes in Morocco during the Plio-Quaternary.&lt;/p&gt;

scholarly journals Escarpment retreat rates derived from detrital cosmogenic nuclide concentrations

2021 ◽  
Author(s):  
Yanyan Wang ◽  
Sean Willett
Keyword(s):  
Western Ghats ◽  
Current Position ◽  
Passive Margins ◽  
Erosion Rates ◽  
Cosmogenic Nuclide ◽  
Constant Rate ◽  
Western Ghats Of India ◽  
Dependent Mass ◽  
Cosmogenic 10Be ◽  
The Western Ghats

Abstract. High-relief great escarpments at passive margins present a paradoxical combination of high relief topography, but low erosion rates suggesting low rates of landscape change. However, vertical erosion rates do not offer a straightforward metric of horizontal escarpment retreat rates, so we attempt to address this problem in this paper. We show that detrital cosmogenic nuclide concentrations can be interpreted as a directionally-dependent mass flux to characterize patterns of non-vertical landscape evolution, e.g. an escarpment characterized by horizontal retreat. We present two methods for converting cosmogenic nuclide concentrations into escarpment retreat rates and calculate the retreat rates of escarpments with published cosmogenic 10Be concentrations from the western Ghats of India. Escarpment retreat rates of the Western Ghats inferred from this study vary within a range of 100s m/Ma to 1000s m/Ma. We show that the current position and morphology of the Western Ghats are consistent with an escarpment retreating at a near constant rate from the coastline since rifting.

scholarly journals Glaciation's topographic control on Holocene erosion at the eastern edge of the Alps

2016 ◽  
Author(s):  
Jean L. Dixon ◽  
Friedhelm von Blanckenburg ◽  
Kurt Stüwe ◽  
Marcus Cristl
Keyword(s):  
Eastern Alps ◽  
European Alps ◽  
Glacial Erosion ◽  
Erosion Rates ◽  
The Alps ◽  
Glacial Processes ◽  
Cosmogenic 10Be ◽  
Topographic Forcing ◽  
Eastern Edge

Abstract. What is the influence of glacial processes in driving erosion and uplift across the European Alps? It has largely been argued that repeated erosion through glaciation sustains isostatic uplift and topography in a decaying orogen. But, some insist that the Alps are an orogen still actively uplifting (e.g., Hergarten et al., 2010). We add insight to this debate by isolating the role of post-glacial topographic forcing on erosion rates. To do this, we quantify the topographic signature of past glaciation on millennial scale erosion rates in previously glaciated and unglaciated catchments at the easternmost edge of the Austrian Alps. Newly measured catchment-wide erosion rates, determined from cosmogenic 10Be in river-borne quartz, correlate with basin relief and mean slope. GIS-derived slope-elevation and slope-area distributions across catchments provide clear topographic indicators of the degree of glacial preconditioning, which further correlates with erosion rates. Erosion rates in the eastern-most, non-glaciated basins range from 40 to 150 mm/ky and likely reflect underlying tectonic forcings in this region, which have previously been attributed to recent (post 5 Ma) uplift (Legrain et al., 2015). By contrast, erosion rates in previously glaciated catchments range from 170 to 240 mm/ky and reflect the erosional response to local topographic preconditioning by repeated glaciations. Together, these data suggest that Holocene erosion across the Eastern Alps is strongly shaped by the local topography relict from previous glaciations. Broader, landscape-wide forcings, such as the widely debated deep mantle-driven or isostatically-driven uplift, result in lesser controls on both topography and erosion rates in this region. Comparing our data to previously published erosion rates across the Alps, we show that post-glacial erosion rates vary across more than two orders of magnitude with poor topographic indicators of controls. This high variation in post-glacial erosion may reflect combined effects of direct tectonic and modern climatic forcings, but is strongly overprinted by past glacial climate and its topographic legacy.

scholarly journals Temporal variability in detrital <sup>10</sup>Be concentrations in a large Himalayan catchment

2018 ◽  
Vol 6 (3) ◽  
pp. 611-635 ◽  
Author(s):  
Elizabeth H. Dingle ◽  
Hugh D. Sinclair ◽  
Mikaël Attal ◽  
Ángel Rodés ◽  
Vimal Singh
Keyword(s):  
River Sediments ◽  
Sediment Flux ◽  
Ganga River ◽  
Sediment Delivery ◽  
Sediment Fluxes ◽  
Sediment Deposits ◽  
Tectonically Active ◽  
Mountain Front ◽  
Floodplain Deposits ◽  
Cosmogenic 10Be

Abstract. Accurately quantifying sediment fluxes in large rivers draining tectonically active landscapes is complicated by the stochastic nature of sediment inputs. Cosmogenic 10Be concentrations measured in modern river sands have been used to estimate 102- to 104-year sediment fluxes in these types of catchments, where upstream drainage areas are often in excess of 10 000 km2. It is commonly assumed that within large catchments, the effects of stochastic sediment inputs are buffered such that 10Be concentrations at the catchment outlet are relatively stable in time. We present 18 new 10Be concentrations of modern river and dated Holocene terrace and floodplain deposits from the Ganga River near to the Himalayan mountain front (or outlet). We demonstrate that 10Be concentrations measured in modern Ganga River sediments display a notable degree of variability, with concentrations ranging between ∼9000 and 19 000 atoms g−1. We propose that this observed variability is driven by two factors. Firstly, by the nature of stochastic inputs of sediment (e.g. the dominant erosional process, surface production rates, depth of landsliding, degree of mixing) and, secondly, by the evacuation timescale of individual sediment deposits which buffer their impact on catchment-averaged concentrations. Despite intensification of the Indian Summer Monsoon and subsequent doubling of sediment delivery to the Bay of Bengal between ∼11 and 7 ka, we also find that Holocene sediment 10Be concentrations documented at the Ganga outlet have remained within the variability of modern river concentrations. We demonstrate that, in certain systems, sediment flux cannot be simply approximated by converting detrital concentration into mean erosion rates and multiplying by catchment area as it is possible to generate larger volumetric sediment fluxes whilst maintaining comparable average 10Be concentrations.

Erosion rates in and around Shenandoah National Park, Virginia, determined using analysis of cosmogenic 10Be

2015 ◽  
Vol 315 (1) ◽  
pp. 46-76 ◽  
Author(s):  
J. Duxbury ◽  
P. R. Bierman ◽  
E. W. Portenga ◽  
M. J. Pavich ◽  
S. Southworth ◽  
...  
Keyword(s):  
National Park ◽  
Shenandoah National Park ◽  
Erosion Rates ◽  
Cosmogenic 10Be
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