李乐,
李来峰,
李高军
南京大学地球科学与工程学院, 表生地球化学教育部重点实验室, 江苏 南京 210023

基金项目: 国家自然科学基金项目（批准号：41422205和41730101）资助


详细信息

作者简介: 李乐, 男, 24岁, 博士研究生, 地球化学专业, E-mail:lilenju@126.com

中图分类号: P596;P597⁺.3;P941.74

收稿日期:2017-08-22
修回日期:2017-10-18
刊出日期:2018-01-30

Soil production function at basin scale tested by uranium comminution age in the Tibetan Plateau catchments

Li Le,
Li Laifeng,
Li Gaojun
Key Laboratory of Surficial Geochemistry, Ministry of Education, School of Earth Sciences and Engineering, Nanjing University, Nanjing 210023, Jiangsu



MSC: P596;P597⁺.3;P941.74

--> Received Date: 22 August 2017
Revised Date: 18 October 2017
Publish Date: 30 January 2018


摘要
摘要:剥蚀速度与风化带深度的关系是理解构造和气候影响化学风化的关键。在土壤剖面尺度，经典土壤产生方程表明剥蚀速度随着土壤深度的增加呈指数级下降。但是，剥蚀速度与土壤厚度的关系在流域尺度还不明晰。细粒物质的（²³⁴U/²³⁸U）比值记录了颗粒自破碎以来经历的时间，受控于土壤厚度与物理剥蚀速度的比值，可能为研究流域尺度的土壤产生过程提供新的手段。本研究调查了青藏高原及其周边多个地貌单元河流沉积物的铀同位素破碎年龄。结果表明，流域尺度上土壤颗粒破碎年龄与剥蚀速度的关系符合经典土壤产生方程的预测。
关键词: 物理剥蚀/
化学风化/
碳循环/
铀同位素/
破碎年龄学

Abstract:The relationship between the erosion rate and weathering depth is of critical importance to an understanding of the influence of tectonic and climate on chemical weathering. At soil profile scale, the classical equation of soil production showed that the erosion rate decreased exponentially with increasing soil depth. However, the relationship between erosion rate and soil depth is not clear at basin scale. The (²³⁴U/²³⁸U) ratio of fine particles can record the time since the particle breaking, which depend on the soil depth and erosion rates, may provide a new technique to study the soil production function at basin scale.
This study investigated the (²³⁴U/²³⁸U) ratio of the catchment sediments across several geomorphic units on the Tibetan Plateau and its surrounding areas, including Gobi Alluvial Fan (0.939±0.013), the central Tibetan Plateau (0.932±0.022), the upper Yellow River (0.925±0.001), the catchments of Northern Qilian Mountains (0.961±0.004), Golmud River basin (0.973±0.007), Minjiang River (1.001±0.003)and Gongga Mountain (0.992±0.006).
The results show the (²³⁴U/²³⁸U) ratio of catchments on each geomorphic unit has a good positive correlation with the denudation rate. The comminution age of the fine particles decreases with the increasing denudation rate. The relationship between uranium comminution age of soil particles and erosion rates is consistent with the theoretical prediction, proving that the classical soil production function can be applied to the basin scale.
Key words:erosion rate/
chemical weathering/
carbon cycle/
uranium isotope/
comminution age



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