CHEMICAL AND BORON ISOTOPE COMPOSITIONS OF NONMARINE BRINES FROM THE QAIDAM BASIN, QINGHAI, CHINA

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	CHEMICAL AND BORON ISOTOPE COMPOSITIONS OF NONMARINE BRINES FROM THE QAIDAM BASIN, QINGHAI, CHINA
	VENGOSH, A ; CHIVAS, AR ; STARINSKY, A ; KOLODNY, Y ; BAOZHEN, Z ; PENGXI, Z
	1995-02-01
发表期刊	CHEMICAL GEOLOGY
卷号	120 期号:1-2 页码:135-154
摘要	The general chemistry and boron isotope composition were investigated in fresh waters and hypersaline brines from the Qaidam Basin, northern Qinghai-Xizang (Tibet) Plateau, China. This basin is a large, tectonically active system, isolated from the ocean and composed of thick elastic and evaporite sediments. The modern playas are subject to intense evaporation and are characterized by hypersaline brines as well as potash and borate evaporites. The chemical composition of the dissolved solutes in the modern brines and waters reveals three main sources: (1) inflow of hot springs enriched in sodium, sulphate and boron. Evaporation of these waters leads to a high Na/Cl ratio (>1), a Na-Cl-SO4 brine and an evaporite mineral assemblage of halite-mirabilite-borate (Lakes Daqaidam and Xiaoqaidam); (2) inflow surface river waters which are modified by preferential dissolution of halite and potassium and magnesium salts characterized by a Na-(Mg)-Cl solute type with low Na/Cl (<1), Br/Cl, Li/Cl and B/Cl ratios; and (3) Ca-chloridic subsurface brines which are controlled by both salt dissolution and dolomitization processes. Evaporation and salt crystallization of mixtures of the latter two types leads to a ''marine-like'' brine (e.g., a Na-Mg-Cl type, Na/Cl ratio <<1) and mineral assemblages similar to that predicted for progressive evaporation of seawater (e.g., Qarhan playa: halite-sylvite-carnallite-bischofite). The delta(11)B-values of the input waters to the Qaidam Basin (range of -0.7 to +10.9 parts per thousand vs. NBS-951) and brines from salt lakes (+0.5 to +15.0 parts per thousand) are similar to those of associated granitic rocks (delta(11)B = -2.3 to +3.7 parts per thousand; n = 3) and hence indicate the non-marine origin of these fluids. The highest delta(11)B-values are associated with fluids with low B/Li ratios, indicating selective removal of elemental boron and B-10 by adsorption onto clay minerals. The magnitude of B-11 enrichment due to adsorption is similar to 15-20 parts per thousand, and thus non-marine brines are well distinguished from marine-derived brines (delta(11)B of +39 to +59 parts per thousand) preserving the large isotopic difference (similar to 40 parts per thousand) of their source waters. It is proposed to use this distinctive isotopic signature for tracing the origin of ancient evaporite environments.
语种	英语
引用统计
文献类型	期刊论文
条目标识符	http://ir.isl.ac.cn/handle/363002/6002
专题	青海盐湖研究所知识仓储中国科学院青海盐湖研究所
作者单位	1.AUSTRALIAN NATL UNIV, RES SCH EARTH SCI, CANBERRA, ACT 0200, AUSTRALIA 2.HEBREW UNIV JERUSALEM, DEPT GEOL, IL-91904 JERUSALEM, ISRAEL 3.ACAD SINICA, QINGHAI INST SALT LAKES, XINING 810008, PEOPLES R CHINA
推荐引用方式 GB/T 7714	VENGOSH, A,CHIVAS, AR,STARINSKY, A,et al. CHEMICAL AND BORON ISOTOPE COMPOSITIONS OF NONMARINE BRINES FROM THE QAIDAM BASIN, QINGHAI, CHINA[J]. CHEMICAL GEOLOGY,1995,120(1-2):135-154.
APA	VENGOSH, A,CHIVAS, AR,STARINSKY, A,KOLODNY, Y,BAOZHEN, Z,&PENGXI, Z.(1995).CHEMICAL AND BORON ISOTOPE COMPOSITIONS OF NONMARINE BRINES FROM THE QAIDAM BASIN, QINGHAI, CHINA.CHEMICAL GEOLOGY,120(1-2),135-154.
MLA	VENGOSH, A,et al."CHEMICAL AND BORON ISOTOPE COMPOSITIONS OF NONMARINE BRINES FROM THE QAIDAM BASIN, QINGHAI, CHINA".CHEMICAL GEOLOGY 120.1-2(1995):135-154.