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DOI	10.1016/j.chemgeo.2015.06.009
	Carbonate composition and its impact on fluvial geochemistry in the NE Tibetan Plateau region
	Yang, Yibo; Fang, Xiaomin; Galy, Albert; Zhang, Gengxin; Liu, Shaochen; Zan, Jinbo; Wu, Fuli; Meng, Qingquan; Ye, Chengcheng; Yang, Rongsheng; Liu, Xiaoming
通讯作者	Yang, YB (通讯作者)
发表日期	2015
ISSN	0009-2541
EISSN	1872-6836
起始页码	138
结束页码	148
卷号	410
英文摘要	Using co-variations of Sr/Ca and Mg/Ca, we examined the carbonate compositions of various bedrocks (silicate and carbonate rocks) and sediments (eolian and fluvial sediments, sand, and topsoil) found in the NE Tibetan Plateau (TP) region. A combined carbonate composition dataset based on our results and other reported data shows that bedrock carbonate composition on the NE TP displays amuch broader range of Sr/Ca and Mg/Ca ratios than restricted source carbonate end members reported upon in previous studies. This has clear implications for modern weathering studies in addition to paleo-reconstructions in this tectonically active and climatically variable area during the Late Cenozoic. Bedrock carbonate compositions are characterized by disseminated carbonates with higher Sr/Ca and Mg/Ca ratios, and sedimentary carbonates (mostly marine) with lower Sr/Ca, but variable Mg/Ca, ratios. The mostly authigenic carbonates found in sediments show similar trends, with a gradient similar to 0.97-1.00 in a plot of log (Sr/Ca) versus log (Mg/Ca), suggesting that 'calcite precipitation' processes - i.e. the sources of the dissolved cations in the water - control their chemistry. Based on observations and modeling, we conclude that the mixing of authigenic and bedrock carbonate end members, plus the incongruent dissolution of bedrock carbonates, accounts for the bulk carbonate composition of sediments (e.g. loess, sand and topsoil). A comparison of bedrock and sedimentary carbonate composition with reported fluvial water data in the NE TP suggests that weathering of carbonates in terrigenous sediments, rather than in bedrock, is mostly responsible for the changes in fluvial Sr, Mg and Ca compositions. Our study suggests that interactions between carbonates and water occur widely during the exposure, transport and deposition of sediments, significantly modifying regional carbonate compositions and fluvial geochemistry. (C) 2015 Elsevier B.V. All rights reserved.
关键词	LINXIA BASIN ISOTOPIC COMPOSITIONS DISSEMINATED CALCITE HIMALAYAN RIVERS CO2 CONSUMPTION TRACE-ELEMENTS QAIDAM BASIN LAKE QINGHAI SILICATE SR
英文关键词	Carbonate weathering; Fluvial geochemistry; Calcite precipitation; Incongruent calcite dissolution; NE Tibetan Plateau
语种	英语
WOS研究方向	Geochemistry & Geophysics
WOS类目	Geochemistry & Geophysics
WOS记录号	WOS:000359064300012
来源期刊	CHEMICAL GEOLOGY
来源机构	中国科学院青藏高原研究所
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/258564
推荐引用方式 GB/T 7714	Yang, Yibo,Fang, Xiaomin,Galy, Albert,et al. Carbonate composition and its impact on fluvial geochemistry in the NE Tibetan Plateau region[J]. 中国科学院青藏高原研究所,2015,410.
APA	Yang, Yibo.,Fang, Xiaomin.,Galy, Albert.,Zhang, Gengxin.,Liu, Shaochen.,...&Liu, Xiaoming.(2015).Carbonate composition and its impact on fluvial geochemistry in the NE Tibetan Plateau region.CHEMICAL GEOLOGY,410.
MLA	Yang, Yibo,et al."Carbonate composition and its impact on fluvial geochemistry in the NE Tibetan Plateau region".CHEMICAL GEOLOGY 410(2015).