Interpreting erosion rates from cosmogenic radionuclide concentrations measured in rapidly eroding terrain
Interpreting erosion rates from cosmogenic radionuclide concentrations measured in rapidly eroding terrain
复制标题
解释快速侵蚀地形中测量的宇宙放射性核素浓度的侵蚀率
DOI：
10.1002/esp.1415
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发表时间：
2007
影响因子：
3.3
通讯作者：
L. Fifield
中科院分区：
文献类型：
--
作者：
L. Reinhardt;T. Hoey;Timothy T. Barrows;T. Dempster;P. Bishop;L. Fifield
结合数值分析和10 Be浓度测量沉积物样品从高浮雕托伦特集水区，西班牙南部，使我们能够调查的采样要求，确定侵蚀率使用宇宙成因核素在高浮雕，滑坡为主的地形。我们使用简单的建模来量化颗粒剥落和/或滑坡对使用宇宙成因原位产生的同位素确定的侵蚀速率的影响。分析结果表明，当适当数量的空间独立样本合并时，经历颗粒或块体定期分离的表面的宇宙成因核素浓度可以被认为处于稳定状态，并且可以估计“原位”侵蚀速率。我们提出的方程，使计算的基岩样本的数量，必须合并的平均侵蚀速率的估计上的露头经历定期剥离的颗粒或芯片的厚度L每T年。我们的研究结果证实，平均流域侵蚀率可以可靠地估计从10 Be浓度在河流沉积物中的高浮雕快速侵蚀地形。当侵蚀主要通过浅层（<3 m）剥落过程完成时，可以计算这些全流域综合侵蚀率;当深层（>3 m）滑坡是主要侵蚀模式时，只能确定最小侵蚀率。最后，我们介绍了托伦特流域的侵蚀速率测量结果，揭示了两个数量级（0.03 - 1.6 m ka−1）的变化，量化了快速上升流域内侵蚀速率的高度空间变化。版权所有© 2006约翰威利父子有限公司。
A combination of numerical analysis and 10Be concentrations measured in sediment samples from the high‐relief Torrente catchment, southern Spain, allows us to investigate the sampling requirements for determining erosion rates using cosmogenic nuclides in high‐relief, landslide‐dominated terrain. We use simple modelling to quantify the effect of particle spalling and/or landsliding on erosion rates determined using a cosmogenic in‐situ produced isotope. Analytical results show that the cosmogenic nuclide concentration of a surface experiencing regular detachment of a grain or block may be considered to be in steady state, and ‘in‐situ’ erosion rates estimated, when an appropriate number of spatially independent samples are amalgamated. We present equations that enable calculation of the number of bedrock samples that must be amalgamated for the estimation of mean erosion rates on an outcrop experiencing regular detachment of a grain or chip of thickness L every T years. Our findings confirm that mean catchment erosion rates may be reliably estimated from 10Be concentrations in fluvial sediment in high‐relief rapidly eroding terrain. These catchment‐wide integrated erosion rates can be calculated where erosion is primarily accomplished through shallow (<3 m) spalling processes; where deep‐seated (>3 m) landslides are the dominant mode of erosion only minimum erosion rates can be determined. Lastly, we present erosion rate measurements from the Torrente catchment that reveal variation of two orders of magnitude (0·03–1·6 m ka−1) quantifying the high degree of spatial variation in erosion rates expected within rapidly uplifting catchments. Copyright © 2006 John Wiley & Sons, Ltd.