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首页> 外文期刊>Earth Surface Processes and Landforms: The journal of the British Geomorphological Research Group >Effects of deep-seated versus shallow hillslope processes on cosmogenic Be-10 concentrations in fluvial sand and gravel
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Effects of deep-seated versus shallow hillslope processes on cosmogenic Be-10 concentrations in fluvial sand and gravel

机译：深井与浅层山坡工艺对氟砂和砾石中的宇宙素浓度的影响

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Terrestrial cosmogenic nuclide (TCN) concentrations in fluvial sediment, from which denudation rates are commonly inferred, can be affected by hillslope processes. TCN concentrations in gravel and sand may differ if localized, deep-excavation processes (e.g. landslides, debris flows) affect the contributing catchment, whereas the TCN concentrations of sand and gravel tend to be more similar when diffusional processes like soil creep and sheetwash are dominant. To date, however, no study has systematically compared TCN concentrations in different detrital grain-size fractions with a detailed inventory of hillslope processes from the entire catchment. Here we compare concentrations of the TCN Be-10 in 20 detrital sand samples from the Quebrada del Toro (southern Central Andes, Argentina) to a hillslope-process inventory from each contributing catchment. Our comparison reveals a shift from low-slope gullying and scree production in slowly denuding, low-slope areas to steep-slope gullying and landsliding in fast-denuding, steep areas. To investigate whether the nature of hillslope processes (locally excavating or more uniformly denuding) may be reflected in a comparison of the Be-10 concentrations of sand and gravel, we define the normalized sand-gravel index (NSGI) as the Be-10-concentration difference between sand and gravel divided by their summed concentrations. We find a positive, linear relationship between the NSGI and median slope, such that our NSGI values broadly reflect the shift in hillslope processes from low-slope gullying and scree production to steep-slope gullying and landsliding. Higher NSGI values characterize regions affected by steep-slope gullying or landsliding. We relate the large scatter in the relationship, which is exhibited particularly in low-slope areas, to reduced hillslope-channel connectivity and associated transient sediment storage within those catchments. While high NSGI values in well-connected catchments are a reliable signal of dee
机译：河流沉积物中的陆生物核酸核素（TCN）浓度，通常推断出剥削率，可受到山坡过程的影响。如果局部，深挖工艺（例如山体滑坡，碎片流动）影响碎片和砂岩中的TCN浓度可能不同，而当土壤蠕变和片材如散发过程如下散射过程时，砂和砾石的TCN浓度往往更加相似。然而，迄今为止，在不同滴乳粒度分数中没有系统地将TCN浓度与整个集水区的详细清单进行了系统地比较了不同的滴乳晶粒尺寸分数。在这里，我们将TCN BE-10的浓度与来自Qubrada Del Toro（南部的中央安培，阿根廷）到每个贡献集水区的山坡流程库存中的浓度。我们的比较揭示了在慢慢裸露，低斜坡沟壑的低斜坡沟壑生产中的速度，陡峭，陡峭地区的沉睡地区的陡峭区域的转变。为了调查山坡过程的性质（局部挖掘或更均匀剥落）是否可以反映在BE-10浓度的砂和砾石浓度的比较中，我们将标准化的砂砾指数（NSGI）定义为BE-10-沙子和砾石之间的浓度差异除以其总结浓度。我们在NSGI和中位数坡之间找到了积极的线性关系，使我们的NSGI值广泛地反映了从低斜坡沟壑和轧制生产的山坡工艺的转变，以陡坡沟壑和滑坡。较高的NSGI值表征受陡坡沟壑或滑坡影响的区域。我们在这种情况下涉及特别是在低斜面区域的关系中的大散射，以减少这些集水区内的山坡通道连接和相关的瞬态沉积物储存。虽然连接良好的集水区中的高NSGI值是DEE可靠的信号

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