Arid
DOI10.5194/esurf-7-393-2019
Cosmogenic Be-10 in river sediment: where grain size matters and why
van Dongen, Renee1; Scherler, Dirk1,2; Wittmann, Hella1; von Blanckenburg, Friedhelm1,2
通讯作者van Dongen, Renee
来源期刊EARTH SURFACE DYNAMICS
ISSN2196-6311
EISSN2196-632X
出版年2019
卷号7期号:2页码:393-410
英文摘要

Concentrations of in-situ-produced cosmogenic Be-10 in river sediment are widely used to estimate catchment-average denudation rates. Typically, the Be-10 concentrations are measured in the sand fraction of river sediment. However, the grain size of bedload sediment in most bedrock rivers covers a much wider range. Where Be-10 concentrations depend on grain size, denudation rate estimates based on the sand fraction alone are potentially biased. To date, knowledge about catchment attributes that may induce grain-size-dependent Be-10 concentrations is incomplete or has only been investigated in modelling studies. Here we present an empirical study on the occurrence of grain-size-dependent Be-10 concentrations and the potential controls of hillslope angle, precipitation, lithology, and abrasion. We first conducted a study focusing on the sole effect of precipitation in four granitic catchments located on a climate gradient in the Chilean Coastal Cordillera. We found that observed grain size dependencies of Be-10 concentrations in the most-arid and most-humid catchments could be explained by the effect of precipitation on both the scouring depth of erosion processes and the depth of the mixed soil layer. Analysis of a global dataset of published Be-10 concentrations in different grain sizes (n = 73 catchments) - comprising catchments with contrasting hillslope angles, climate, lithology, and catchment size - revealed a similar pattern. Lower Be-10 concentrations in coarse grains (defined as "negative grain size dependency") emerge frequently in catchments which likely have thin soil and where deep-seated erosion processes (e.g. landslides) excavate grains over a larger depth interval. These catchments include steep (> 25 degrees) and humid catchments (> 2000 mm yr(-1)). Furthermore, we found that an additional cause of negative grain size dependencies may emerge in large catchments with weak lithologies and long sediment travel distances (> 2300-7000 m, depending on lithology) where abrasion may lead to a grain size distribution that is not representative for the entire catchment. The results of this study can be used to evaluate whether catchment-average denudation rates are likely to be biased in particular catchments.


类型Article
语种英语
国家Germany
收录类别SCI-E
WOS记录号WOS:000466793400001
WOS关键词EARTHQUAKE-INDUCED LANDSLIDES ; DENUDATION RATES ; EROSION RATES ; IN-SITU ; THRESHOLD HILLSLOPES ; COASTAL CORDILLERA ; WEATHERING RATES ; BEDROCK INCISION ; STREAM SEDIMENT ; NORTHERN CHILE
WOS类目Geography, Physical ; Geosciences, Multidisciplinary
WOS研究方向Physical Geography ; Geology
资源类型期刊论文
条目标识符http://119.78.100.177/qdio/handle/2XILL650/215082
作者单位1.GFZ German Res Ctr Geosci, Earth Surface Geochem, D-14473 Potsdam, Germany;
2.Free Univ Berlin, Inst Geol Sci, D-12249 Berlin, Germany
推荐引用方式
GB/T 7714
van Dongen, Renee,Scherler, Dirk,Wittmann, Hella,et al. Cosmogenic Be-10 in river sediment: where grain size matters and why[J],2019,7(2):393-410.
APA van Dongen, Renee,Scherler, Dirk,Wittmann, Hella,&von Blanckenburg, Friedhelm.(2019).Cosmogenic Be-10 in river sediment: where grain size matters and why.EARTH SURFACE DYNAMICS,7(2),393-410.
MLA van Dongen, Renee,et al."Cosmogenic Be-10 in river sediment: where grain size matters and why".EARTH SURFACE DYNAMICS 7.2(2019):393-410.
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