蒋浩^1,2,3,,
徐志方^1,2,,,
赵童^1,2,3,
刘文景^1,2
1. 中国科学院地质与地球物理研究所, 中国科学院新生代地质与环境重点实验室, 北京 100029
2. 中国科学院地球科学研究院, 北京 100029
3. 中国科学院大学, 北京 100049

基金项目: 国家重大科学研究计划项目（批准号：2013CB956400）和国家自然科学基金项目（批准号：41173114和41402323）共同资助


详细信息

作者简介: 蒋浩, 男, 28岁, 博士研究生, 地质工程专业, E-mail:jianghao@mail.iggcas.ac.cn或531199419@qq.com

通讯作者: 徐志方, E-mail:zfxu@mail.iggcas.ac.cn

中图分类号: P578.94;P596;P941.74

收稿日期:2017-09-26
修回日期:2017-11-21
刊出日期:2018-01-30

The weathering rates and controlling factors of the Tibetan Plateau: A case study of small catchments of typical lithology in Gongga Mountainous area

Jiang Hao^1,2,3,,
Xu Zhifang^1,2,,,
Zhao Tong^1,2,3,
Liu Wenjing^1,2
1. Key Laboratory of Cenozoic Geology and Environment, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029
2. Institutions of Earth Science, Chinese Academy of Sciences, Beijing 100029
3. University of Chinese Academy of Sciences, Beijing 100049


More Information

Corresponding author: Xu Zhifang,E-mail:zfxu@mail.iggcas.ac.cn

MSC: P578.94;P596;P941.74

--> Received Date: 26 September 2017
Revised Date: 21 November 2017
Publish Date: 30 January 2018


摘要
摘要:以青藏高原东缘贡嘎山地区30余个典型地质背景小流域为研究对象，在河流水体物质来源定量辨识的基础上，估算了流域岩石风化速率，并系统分析了高原流域风化速率与物理剥蚀速率、径流量和温度之间的关系。雅家河西岸、加则拉、雅家河东岸以及大渡河东岸流域的硅酸盐岩风化速率（SWR_cat）平均值（范围）分别为2.49（0.40~6.93）t/km²/a、3.20（2.20~3.90）t/km²/a、0.74（0.50~0.90）t/km²/a以及2.63（0.70~9.40）t/km²/a；TDR的平均值（范围）分别为332.85（31.03~2231.23）t/km²/a、66.92（38.5~167.7）t/km²/a、10.82（8.49~13.79）t/km²/a以及36.27（8.49~176.50）t/km²/a。研究区SWR_cat流域面积加权平均值为2.1 t/km²/a。研究表明，硅酸盐岩风化速率受物理剥蚀和气候等多种因素的共同影响，这些小流域岩石风化控制机制可分为"运移限制（transport-limited）"和"风化限制（weathering-limited）"。在"运移限制"下的小流域，其化学风化速率取决于物理剥蚀速率，化学风化主要受流域的物理剥蚀所控制；而在"风化限制"下，其化学风化速率主要受风化反应动力学所控制，与温度、径流量等气候因子有关。
关键词: 青藏高原/
风化速率/
控制因素

Abstract:Here we present hydro-geochemical investigation results of 32 small catchments on the Eastern Tibetan Plateau. The small catchments are sub-catchments of 3 rivers draining areas with granitoid lithologies, which are the Jiazela River (JR), the Yajiahe River (YR)and the Daduhe River (DR). The altitude and catchment areas are variable from one to another, ranging from 1000 m to 3400 m and 0.56 km² to 46 km², respectively. 32 stream water samples, 4 precipitation samples, 8 spring samples, 3 glacier meltwater samples and 8 fresh rock samples were collected from the small catchments. Chemistry characteristics, δ¹⁸O and δD of stream, precipitation, glacier melt water and spring water were examined for these catchments. Water mixing processes as well as concomitant solutes fluxes were explored with end-members mixing model using δ¹⁸O and Cl as tracers. The results show that three major reservoirs (precipitation, glacier and spring)contribute to the stream discharge, and five major reservoirs (carbonates, silicates, precipitation, glacier and spring)contribute to the dissolved solutes. The contribution of rock weathering accounts for more than 90% of the total dissolved cations. The silicate cation weathering rate (SCWR), the total cation weathering rate (TCWR), the SiO₂ weathering rate (SiO₂ WR), the total chemical weathering rate (CWR), and the total denudation rate were calculated. The TDR of the studied catchments ranges between 8.49 t/km²/a and 2231.23 t/km²/a. The SCWR ranges between 0.4 t/km²/a and 9.4 t/km²/a. The area-weighted mean SCWR is 2.1 t/km²/a. In addition, the correlations between the weathering rates and total denudation rate, runoff and temperature were explored. We show that silicate weathering rates are not governed by any single parameter. The weathering regimes can be divided into two sorts, which are "transport-limited" and "weathering-limited". For the "transport-limited" catchments, physical erosion rates (fresh mineral supply)limits weathering. In this case, the silicate weathering rates are controlled by physical erosion. For the "weathering-limited" catchments, silicate chemical weathering is dependent on the kinetics of the reactions, which are regulated by climatic factors (temperature and runoff). The results have implications for the mechanism of the "tectonics-weathering-climate" hypothesis.
Key words:Tibetan Plateau/
weathering rate/
controlling factor



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