Spatial controls on erosion in the Three Rivers Region, southeastern Tibet and southwestern China

Henck, Amanda C.; Huntington, Katharine W.; Stone, John O.; Montgomery, David R.; Hallet, Bernard

doi:10.1016/j.epsl.2010.12.038

Cited by 100 publications

(81 citation statements)

References 82 publications

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“…Similar, though more dramatic cross-margin denudation patterns have also been documented across the Himalayan plateau margin [Lavé and Avouac, 2001;Burbank et al, 2003;Thiede et al, 2004]. The general pattern of denudation rate decreasing plateauward is broadly similar to that found in the Three Rivers region, southeastern Tibet and west of our study area [Henck et al, 2011], except that the zone of enhanced denudation is wider than in the Longmen Shan margin.…”

Section: Pattern and Magnitude Of Modern Denudation Across The Longmesupporting

confidence: 86%

Focused modern denudation of the Longmen Shan margin, eastern Tibetan Plateau

Liu‐Zeng

Wen

Oskin

et al. 2011

Geochem. Geophys. Geosyst.

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[1] We use river sediment load data to map the pattern of modern denudation across the Longmen Shan margin of the Tibetan Plateau. Suspended sediment load, with corrections of bed load and solute load contributions, is used to calculate watershed-averaged denudation rates. Decadal erosion is spatially heterogeneous, and seasonally modulated by monsoon flows, which account for 80-90% of the sediment load. Enhanced denudation occurs in a ∼50 km wide band on the hanging wall of the Longmen Shan and Huya fault zones, reaching 0.5-0.8 mm/yr. These rates are similar to kyr-scale rates deduced from cosmogenic 10 Be and to Myr-scale rates from low-temperature thermochronology. The sediment fluxderived erosion rates decrease with increasing distance plateauward, to less than 0.05 mm/yr at a distance ∼200 km northwest of the foot of the Longmen Shan. The gradient in precipitation across this margin alone cannot explain the one order of magnitude spatial difference in erosion. Rather, the river sediment load data delineates a zone of relatively rapid denudation around active faults that carry the Longmen Shan in their hanging wall. From the similarity of denudation rates measured over Myr, kyr, and decadal time scales, we propose that erosion of the Longmen Shan margin has approached a flux steady state. The erosional efflux is balanced by advection of rock toward the Longmen margin above the ∼20°NW dipping ramp of the marginbounding fault. Our results suggest that high amounts of landslide material mobilized by earthquakes such as the Mw 7.9 2008 Wenchuan event are gradually removed by rivers, smoothing sediment flux over time. Our results also suggest that caution should be exercised when interpreting young cooling ages as evidence of the initiation of plateau uplift. Advection of an already high plateau into the belt of higher erosion rate at the Longmen Shan could also give rise to an abrupt cooling history.

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Section: Pattern and Magnitude Of Modern Denudation Across The Longmesupporting

confidence: 86%

Focused modern denudation of the Longmen Shan margin, eastern Tibetan Plateau

Liu‐Zeng

Wen

Oskin

et al. 2011

Geochem. Geophys. Geosyst.

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“…Our resamples of TRR main stem Salween sites ( n = 4 pairs) have 10 Be i concentrations 77–84% higher (mean = 81%) than those originally reported by Henck et al . (); this difference is confirmed by our laboratory replicates. In these large basins (>140 000 km 2 ), with significant proportions (>80%) of the watersheds that drain high‐elevation, low‐relief parts of the Tibetan Plateau, our data are consistent with the primary sediment source changing from a deeply sourced and/or low‐elevation location (e.g.…”

Section: Discussionmentioning

confidence: 99%

Spatial and temporal replicability of meteoric and in situ¹⁰Be concentrations in fluvial sediment

Gonzalez

Schmidt

Bierman

et al. 2017

Earth Surf Processes Landf

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Cosmogenic isotopes, short‐lived radionuclides, elemental concentrations and thermochronometric indicators are measured in river sand to quantify erosion rates and trace sediment sources, and/or infer erosional processes. Interpretations of detrital sediment analyses are often based on the rarely tested assumption of time‐invariant tracer concentration. A better understanding of when and where this assumption breaks down and what sampling strategies minimize temporal and small‐scale spatial variance will improve science done using detrital river sediment. Here, we present new and previously published spatial and temporal replicates measured for in situ and meteoric 10Be (10Bei and 10Bem, respectively). Our new data include 113 replicate pairs, taken from agricultural and/or tectonically active watersheds in China months to millennia apart and spatial replicates taken up to 2 km apart on the same day. The mean percentage difference is 10% (−122% to 150%) for both systems considered together; the mode is close to 0% for both systems; and 36% of pairs of samples replicate within our analytical accuracy at 2σ. We find that 10Bei replicates better than 10Bem (p < 0.01). 10Bei replicability is worse in steeper basins, suggesting that stochastic processes (i.e. landslides) affect reproducibility. 10Bem replicability is worse in larger basins, suggesting non‐conservative behavior of 10Bem as sediment moves downstream. Our results are consistent with the few previously published replicate studies. Considering all replicate data in a wide range of landscapes, in areas with deep erosional processes, replicability is poor; in other areas, replicability is good. This suggests that, in steep, tectonically active, and/or agricultural landscapes, individual detrital sediment measurements do not represent upstream rates as well as larger populations of samples. To ensure that measurements are representative of the upstream watershed, our data suggest that samples be amalgamated either over time or from several places close by in the same channel. Copyright © 2017 John Wiley & Sons, Ltd.

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“…While the Bhutanese drainages we sampled do not display the highest erosion rates along the Himalayan front range, an ANOVA shows that erosion rates from the Puna Tsang Chhu (n = 44) are significantly higher than average erosion rates on the Tibetan Plateau (n = 62; p = b0.01; Ouimet et al, 2009) and along the eastern margins of the Tibetan Plateau (n = 117; p = 0.01; Finnegan et al, 2008;Palumbo et al, 2009Palumbo et al, , 2010Godard et al, 2010;Harkins et al, 2007;Henck et al, 2011). In fact, the only convergent plate boundaries that demonstrate equally rapid erosion rates as those exhibited from western Bhutan are along continent-continent collisional margins - .…”

Section: Erosion In Active Orogensmentioning

confidence: 93%

Erosion rates of the Bhutanese Himalaya determined using in situ-produced 10Be

et al. 2015

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Spatial controls on erosion in the Three Rivers Region, southeastern Tibet and southwestern China

Cited by 100 publications

References 82 publications

Focused modern denudation of the Longmen Shan margin, eastern Tibetan Plateau

Focused modern denudation of the Longmen Shan margin, eastern Tibetan Plateau

Spatial and temporal replicability of meteoric and in situ¹⁰Be concentrations in fluvial sediment

Erosion rates of the Bhutanese Himalaya determined using in situ-produced 10Be

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Spatial controls on erosion in the Three Rivers Region, southeastern Tibet and southwestern China

Cited by 100 publications

References 82 publications

Focused modern denudation of the Longmen Shan margin, eastern Tibetan Plateau

Focused modern denudation of the Longmen Shan margin, eastern Tibetan Plateau

Spatial and temporal replicability of meteoric and in situ10Be concentrations in fluvial sediment

Erosion rates of the Bhutanese Himalaya determined using in situ-produced 10Be

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Spatial and temporal replicability of meteoric and in situ¹⁰Be concentrations in fluvial sediment