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

2009 ◽  
Vol 34 (1) ◽  
pp. 145-154 ◽  
Author(s):  
Kevin P. Norton ◽  
Veerle Vanacker
Keyword(s):  
Correction Factors ◽  
Cosmogenic Nuclide ◽  
Denudation Rates ◽  
Topographic Shielding

scholarly journals The CAIRN method: automated, reproducible calculation of catchment-averaged denudation rates from cosmogenic nuclide concentrations

2016 ◽  
Vol 4 (3) ◽  
pp. 655-674 ◽  
Author(s):  
Simon Marius Mudd ◽  
Marie-Alice Harel ◽  
Martin D. Hurst ◽  
Stuart W. D. Grieve ◽  
Shasta M. Marrero
Keyword(s):  
Uncertainty Analysis ◽  
Sampling Frequency ◽  
Cosmogenic Nuclides ◽  
Good Balance ◽  
Denudation Rate ◽  
Cosmogenic Nuclide ◽  
Computational Expense ◽  
Denudation Rates ◽  
High Sampling ◽  
Topographic Shielding

Abstract. We report a new program for calculating catchment-averaged denudation rates from cosmogenic nuclide concentrations. The method (Catchment-Averaged denudatIon Rates from cosmogenic Nuclides: CAIRN) bundles previously reported production scaling and topographic shielding algorithms. In addition, it calculates production and shielding on a pixel-by-pixel basis. We explore the effect of sampling frequency across both azimuth (Δθ) and altitude (Δϕ) angles for topographic shielding and show that in high relief terrain a relatively high sampling frequency is required, with a good balance achieved between accuracy and computational expense at Δθ = 8° and Δϕ = 5°. CAIRN includes both internal and external uncertainty analysis, and is packaged in freely available software in order to facilitate easily reproducible denudation rate estimates. CAIRN calculates denudation rates but also automates catchment averaging of shielding and production, and thus can be used to provide reproducible input parameters for the CRONUS family of online calculators.

scholarly journals <sup>10</sup>Be systematics in the Tsangpo-Brahmaputra catchment: the cosmogenic nuclide legacy of the eastern Himalayan syntaxis

2017 ◽  
Author(s):  
Maarten Lupker ◽  
Jérôme Lavé ◽  
Christian France-Lanord ◽  
Marcus Christl ◽  
Didier Bourlès ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Sediment Flux ◽  
Coarse Grained ◽  
The Tibetan Plateau ◽  
Data Set ◽  
Denudation Rate ◽  
Cosmogenic Nuclide ◽  
Denudation Rates ◽  
The Impact ◽  
Eastern Himalayan Syntaxis

Abstract. The Tsangpo-Brahmaputra River drains the eastern part of the Himalayan range, flowing from the Tibetan Plateau through the eastern Himalayan syntaxis and downstream to the Indo-Gangetic floodplain. As such it is a unique natural laboratory to study how denudation and sediment production processes are transferred to river detrital signals. In this study, we present a new 10Be data set to constrain denudation rates across the catchment and to quantify the impact of rapid erosion within the syntaxis region on cosmogenic nuclide budgets and signals. 10Be denudation rates span around two orders of magnitude across the catchments (ranging from 0.03 mm/yr to > 4 mm/yr) and sharply increase as the Tsangpo-Brahmaputra flows across the eastern Himalaya. The increase in denudation rates however occurs ~ 150 km downstream of the Namche Barwa-Gyala Peri massif (NBGPm), an area which has been previously characterized by extremely high erosion and exhumation rates. We suggest that this downstream lag is mainly due to the physical abrasion of coarse grained, low 10Be concentration, landslide material produced within the syntaxis that dilutes the upstream high concentration 10Be flux from the Tibetan Plateau only after abrasion has transferred sediment to the studied sand fraction. A simple abrasion model produces typical lag distances of 50 to 150 km compatible with our observations. Abrasion effects reduce the spatial resolution over which denudation can be constrained in the eastern Himalayan syntaxis. In addition, we also highlight that denudation rate estimates are dependent on the sediment connectivity, storage and quartz content of the upstream Tibetan Plateau part of the catchment which tends to lead to an overestimation of downstream denudations rates. Taking these effects into account we estimate a denudation rates of ca. 2 to 5 mm/yr for the entire syntaxis and ca. 4 to 28 mm/yr for the NBGPm, which is significantly higher than other to other large catchments. Overall, 10Be concentrations measured at the outlet of the Tsangpo-Brahmaputra in Bangladesh suggest a sediment flux between 780 and 1430 Mt/yr equivalent to a denudation rate between 0.7 and 1.2 mm/yr for the entire catchment.

scholarly journals Millennial-scale denudation rates in the Himalaya of Far Western Nepal

2019 ◽  
Author(s):  
Lujendra Ojha ◽  
Ken L. Ferrier ◽  
Tank Ojha
Keyword(s):  
Stream Power ◽  
Denudation Rate ◽  
The Past ◽  
Cosmogenic Nuclide ◽  
Northern India ◽  
Denudation Rates ◽  
Cosmogenic 10Be ◽  
Channel Steepness ◽  
The Himalaya ◽  
Millennial Scale

Abstract. Over the past two decades, rates and patterns of Himalayan denudation have been documented through numerous cosmogenic nuclide measurements in central and eastern Nepal, Bhutan, and northern India. To date, however, few denudation rates have been measured in Far Western Nepal – a ~ 300-km-wide region near the center of the Himalayan arc – which presents a significant gap in our understanding of Himalayan denudation. Here we report new catchment-averaged millennial-scale denudation rates inferred from cosmogenic 10Be in fluvial quartz at seven sites in Far Western Nepal. The inferred denudation rates range from 385 ± 31 t km−2 yr−1 (0.15 ± 0.01 mm yr −1) to 8737 ± 2908 t km−2 yr−1 (3.3 ± 1.1 mm yr−1), and, in combination with our analyses of channel topography, are broadly consistent with previously published relationships between catchment-averaged denudation rates and normalized channel steepness across the Himalaya. These data show a weak correlation with catchment-averaged specific stream power, consistent with a Himalaya-wide compilation of previously published stream power values. Together, these observations are consistent with a dependence of denudation rate on both tectonic and climatic forcings, and represent a first step toward filling an important gap in denudation rate measurements in Far Western Nepal.

scholarly journals Denudation rates derived from spatially-averaged cosmogenic nuclide analysis in Nelson/Tasman catchments, South Island, New Zealand

2021 ◽  
Author(s):  
◽  
Abby Jade Burdis
Keyword(s):  
New Zealand ◽  
Dynamic Environment ◽  
Low Frequency ◽  
Short Term ◽  
Erosion Rates ◽  
Cosmogenic Nuclide ◽  
Denudation Rates ◽  
Conventional Methods

<p>New Zealand’s tectonically and climatically dynamic environment generates erosion rates that outstrip global averages by up to ten times in some locations. In order to assess recent changes in erosion rate, and also to predict future erosion dynamics, it is important to quantify long-term, background erosion. Current research on erosion in New Zealand predominantly covers short-term (100 yrs) erosion dynamics and Myr dynamics from thermochronological proxy data. Without competent medium-term denudation data for New Zealand, it is uncertain which variables (climate, anthropogenic disturbance of the landscape, tectonic uplift, lithological, or geomorphic characteristics) exert the dominant control on denudation in New Zealand. Spatially-averaged cosmogenic nuclide analysis can effectively offer this information by providing averaged rates of denudation on millennial timescales without the biases and limitations of short-term erosion methods.  Basin-averaged denudation rates were obtained in the Nelson/Tasman region, New Zealand, from analysis of concentrations of meteoric ¹⁰Be in silt and in-situ produced ¹⁰Be in quartz. The measured denudation rates integrate over ~2750 yrs (in-situ) and ~1200 yrs (meteoric). Not only do the ¹⁰Be records produce erosion rates that are remarkably consistent with each other, but they are also independent of topographic metrics. Denudation rates range from ~112 – 298 t km⁻² yr⁻¹, with the exception of one basin which is eroding at 600 - 800 t km⁻² yr⁻¹. The homogeneity of rates and absence of a significant correlation with geomorphic or lithological characteristics could indicate that the Nelson/Tasman landscape is in (or approaching) a topographic steady state.  Millennial term (¹⁰Be-derived) denudation rates are more rapid than those inferred from other conventional methods in the same region (~50 – 200 t km⁻² yr⁻¹). This is likely the result of the significant contribution of low frequency, high magnitude erosive events to overall erosion of the region. Both in-situ and meteoric ¹⁰Be analyses have the potential to provide competent millennial term estimates of natural background rates of erosion. This will allow for the assessment of geomorphic-scale impacts such as topography, tectonics, climate, and lithology on rates of denudation for the country where many conventional methods do not. Cosmogenic nuclides offer the ability to understand the response of the landscape to these factors in order to make confident erosion predictions for the future.</p>

scholarly journals Effects of long soil surface residence times on apparent cosmogenic nuclide denudation rates and burial ages in the Cradle of Humankind, South Africa

2019 ◽  
Vol 44 (15) ◽  
pp. 2968-2981 ◽  
Author(s):  
T.V. Makhubela ◽  
J.D. Kramers ◽  
D. Scherler ◽  
H. Wittmann ◽  
P.H.G.M. Dirks ◽  
...  
Keyword(s):  
South Africa ◽  
Soil Surface ◽  
Residence Times ◽  
Cosmogenic Nuclide ◽  
Denudation Rates ◽  
Cradle Of Humankind

scholarly journals Geomorphological applications of cosmogenic isotope analysis

2004 ◽  
Vol 28 (1) ◽  
pp. 1-42 ◽  
Author(s):  
Hermione A.P. Cockburn ◽  
Michael A. Summerfield
Keyword(s):  
Mass Movement ◽  
Isotope Analysis ◽  
Cosmogenic Nuclides ◽  
Cosmogenic Isotope ◽  
Meteorite Impacts ◽  
Incremental Change ◽  
Cosmogenic Nuclide ◽  
Denudation Rates ◽  
Wide Range ◽  
Fault Displacement

Cosmogenic isotope analysis involves the measurement of cosmogenic nuclides that have accumulated in the upper few metres of the Earth’s surface as a result of interactions between cosmic rays and target elements. The concentrations of these cosmogenic nuclides can provide quantitative estimates of the timing and rate of geomorphic processes. In dating applications the concentration of cosmogenic nuclides is interpreted as reflecting the time elapsed since a surface exposure event. However, over most of the Earth’s surface for most of the time the landsurface experiences incremental denudation and in these circumstances cosmogenic nuclide concentrations are related to the rate of denudation. Applications of event dating using cosmogenic isotopes include constructional landforms such as volcanic and depositional features, fault displacement, meteorite impacts, rapid mass movement, bedrock surfaces rapidly eroded by fluvial or wave action or exposed by glacial retreat, and the burial of sediment or ice. Strategies for quantifying rates of incremental change include estimates of denudation rates from site-specific samples and from fluvial sediment samples reflecting catchment-wide rates, and measurements of cosmogenic nuclide concentrations in soils and regolith to quantify rates of rock weathering. The past decade has seen a rapid growth in applications of cosmogenic isotope analysis to a wide range of geomorphological problems, and the technique is now playing a major role in dating and quantifying rates of landscape change over timescales of several thousands to several millions of years.

Subtropical denudation rates of granitic regolith along a hill ridge in Longnan, SE China derived from cosmogenic nuclide depth-profiles

2016 ◽  
Vol 117 ◽  
pp. 146-152 ◽  
Author(s):  
Li-Feng Cui ◽  
Cong-Qiang Liu ◽  
Sheng Xu ◽  
Zhi-Qi Zhao ◽  
Tao-Ze Liu ◽  
...  
Keyword(s):  
Depth Profiles ◽  
Cosmogenic Nuclide ◽  
Denudation Rates ◽  
Se China
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