The role of debris flow on total denudation in small basins of the Ashio Mountains, Japan
The role of debris flow on total denudation in small basins of the Ashio Mountains, Japan
复制标题
泥石流对日本足尾山脉小盆地全剥蚀的作用
DOI：
10.1016/j.geomorph.2018.12.022
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发表时间：
2019
期刊：
影响因子：
3.9
通讯作者：
Wasklewicz T.A.
中科院分区：
文献类型：
--
作者：
Hattanji;T.;Matsushi;Y.;Matsuzaki;H.;Wasklewicz T.A.
总的和持续的剥蚀率估计使用宇宙成因核素和密集的实地观测的沉积物输运在两个小盆地（C3和S3），从日本的Ashio山。C3盆地下伏于三叠系层状硅质岩中，而S3盆地则发育于侏罗系蚀变砂泥岩中。根据6年（2004-2009年）粗泥沙输移和流量记录、土壤粒度分布和溪流溶解负荷，估计了持续剥蚀率。在C3（燧石）中观察到泥石流并测量了其体积。宇宙成因的10 Be和26 Al在河流砂的浓度进行了测量，以确定这些盆地的空间平均总剥蚀率的基础上，稳态假设。C3（硅质岩）盆地的持续剥蚀率（不包括碎屑流质量）约占宇宙成因核素测量的总剥蚀率的75%。假设总剥蚀率和持续剥蚀率之间的差异表明重复泥石流的影响，观察到的规模（质量为24吨）的泥石流发生的复发间隔为100-550年（平均167年）的C3（硅质岩）盆地。对于S3（砂岩）盆地，连续剥蚀率明显小于总剥蚀率，其中至少有17年没有发生泥石流。不同时间尺度下的剥蚀率差异较大，说明了具有较长重现期的高强度泥石流事件的贡献。
Total and continuing denudation rates were estimated using cosmogenic nuclides and intensive field observations of sediment transport in two small basins (C3 and S3) from the Ashio Mountains, Japan. The C3 basin underlain by Triassic bedded chert, while the S3 basin has evolved in altered Jurassic sandstone-shale. Continuing denudation rates were estimated from the records of coarse sediment transport and stream discharge for 6 years (2004–2009), soil grain-size distribution, and dissolved load in stream water. A debris flow was observed and the volume was measured in C3 (chert). Concentrations of cosmogenic10Be and26Al in fluvial sand were measured to determine spatially-averaged total denudation rates for these basins on the basis of steady-state assumption. Continuing denudation rate for C3 (chert) basin excluding the debris-flow mass accounted for ~75% of the total denudation rate as measured from the cosmogenic nuclides. Assuming a difference between the total and continuing denudation rates indicates the impact of repeat debris flows, the debris flows with the observed magnitude (the mass of 24 t) occur with the recurrence intervals of 100–550 years (mean 167 years) for C3 (chert) basin. For S3 (sandstone) basin, the continuous denudation rates were significantly smaller than the total rates, where debris flow had not occurred for at least 17 years. The large gap in the denudation rates with different time scales shows contribution of higher magnitude debris-flow events with longer recurrence intervals.