柴达木盆地氯同位素组成特征  

CHLORINE ISOTOPIC COMPOSITION IN QAIDAM BASIN

作　　者：刘卫国[1] 肖应凯[1] 孙大鹏[1] 祁海平[1] 王蕴慧[1] 

机构地区：[1]中国科学院青海盐湖研究所

出　　处：《地球化学》1996年第3期296-303,共8页Geochimica

基　　金：国家自然科学基金

摘　　要：采用正热电离高精度测定Ｃｌ同位素的方法对我国柴达木盆地水体及盐类沉积的Ｃｌ同位素组成进行了精确测定，结果表明，柴达木盆地Ｃｌ同位素组成存在着明显的变化。各种水体的平均δ３７Ｃｌ值顺序为：河水（０．９４‰）＞咸水湖水（－０．２‰）＞油田水（－０．６２‰）＞盐湖卤水（－０．９７‰）。卤水具有最低的δ３７Ｃｌ值，这是盐湖卤水蒸发析盐的结果。盐湖卤水与共存盐类矿物间的分馏系数为１．０００１－１．００２１。来自马海盐湖地区钻孔盐类沉积垂直剖面的δ３７Ｃｌ值为０．００‰－１．０５‰。盐湖卤水的δ３７Ｃｌ值与卤水的水化学类型、ｐＨ值、密度、Ｃｌ的浓度以及Ｃｌ的物质来源有关，因此，盐湖卤水的Ｃｌ同位素组成研究将成为盐湖形成演化环境和盐湖物质来源研究方面新的重要手段。The chlorine isotopic composition of brine, saline water,fresh water,oil-field water and salt deposite in the Qaidam Basin have been examined with high precision by the Cs2Cl+ positive ionization mass spectrometry. The results indicate that chlorine isotope of the Qaidam Basin have evident fractionation. The averageδ37Cl value from different water system are as follows: fresh water(0.94‰) > saline water(0.2‰)> oil-field water-0.82‰)> brine(-0.97‰). Brine has the lowestδ37Cl value as a result of brine evaporation and saline miner.al precipitation in salt lakes. Fractionation factor between halite and brine is from 1.0001 to 1.0021. The δ37Cl value for vertical profile of salt deposits from the Mahai drill hole is from 0.00‰to 1.05‰. Theδ37Cl value of the brine from salt lake is a function of the type of water chemistry,the pH value, the density,the chlorine content and the chlorine isotopic fractionation of brine, Therefore, the chlorine isotopic composition of brine will become an importent means to trace the material origin and evolution condition of salt lakes.

关 键 词：柴达木盆地 氯同位素 同位素分馏 

分 类 号：P578.32[天文地球—矿物学]