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首页> 外文期刊>Earth Surface Processes and Landforms: The journal of the British Geomorphological Research Group >Constant denudation rates in a high alpine catchment for the last 6 kyrs
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Constant denudation rates in a high alpine catchment for the last 6 kyrs

机译：在过去的6个Kyrs的高山集水区中的持续剥削率

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摘要

Terrestrial cosmogenic nuclides (TCN) have widely been used as proxies in determining denudation rates in catchments. Most studies were limited to samples from modern active streams, thus little is known about the magnitude and causes of TCN variability on millennial time scales. In this work we present a 6 kyrs long, high resolution record of Be-10 concentrations (n = 18), which were measured in sediment cores from an alluvial fan delta at the outlet of the Fedoz Valley in the Swiss Alps. This record is paired with a 3-year time series (n = 4) of Be-10 measured in sediment from the active stream currently feeding this fan delta. The temporal trend in the Be-10 concentrations after correction for postdepositional production of Be-10 was found to be overall constant and in good agreement with the modern river Be-10 concentration. The calculated mean catchment-wide denudation rate amounts to 0.73 +/- 0.18 mm yr(-1). This fairly constant level of Be-10 concentrations can be caused by a constant denudation rate over time within the catchment or alternatively by a buffered signal. In this contribution we suggest that the large alluvial floodplain in the Fedoz Valley may act as an efficient buffer on Holocene time scales in which sediments with different Be-10 signatures are mixed. Therefore, presumable variations in the Be-10 signals derived from changes in denudation under a fluctuating Holocene climate are only poorly transferred to the catchment outlet and not recorded in the Be-10 record. However, despite the absence of high frequency signals, we propose that the buffered and averaged Be-10 signal could be meaningfully and faithfully interpreted in terms of long-term catchment-averaged denudation rate. Our study suggests that alluvial buffers play an important role in regulating the Be-10 signal exported by some alpine settings that needs to be taken into account and further investigated. Copyright (C) 2016 John Wiley & Sons, Ltd.
机译：陆生物学核酸核素（TCN）广泛被用作测定集水区中的剥蚀速率的代理。大多数研究仅限于现代活性物流的样本，因此关于千年时间尺度的TCN变异性的幅度和原因很少。在这项工作中，我们呈现了6 kyrs长，高分辨率的Be-10浓度（n = 18），在瑞士阿尔卑斯山的Fedoz谷的出口处，在沉积物核心中测量了沉积物核心。该记录与3年级序列（n = 4）配对，以沉积物测量的BE-10，从当前喂养此范特节的活性物流测量。发现Be-10浓度校正后的BE-10校正后的时间趋势是总体恒定的，与现代河至10份浓度良好。计算的平均集距离剥落速率为0.73 +/- 0.18mm Yr（-1）。这种相当恒定的Be-10浓度水平可以是由于集水区内的恒定剥落速率或通过缓冲信号而导致的恒定剥落速率引起。在这一贡献中，我们建议美联储谷的大型冲积泛洪叶可以充当全新世时间尺度的高效缓冲区，其中混合不同BE-10签名的沉积物。因此，在波动的全新常气氛下剥落变化的BE-10信号中的可推测变化仅被转移到集水区，并且在BE-10记录中没有记录。然而，尽管没有高频信号，但我们提出了在长期集水平均剥削率方面有意义的和忠实地解释缓冲和平均的BE-10信号。我们的研究表明，冲积缓冲区在调节由一些需要考虑并进一步调查的ALPINE设置导出的BE-10信号方面发挥着重要作用。版权所有（c）2016 John Wiley＆Sons，Ltd。

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