马海盐湖区卤水和盐类矿物的氯同位素特征及意义

Characteristics and Significance of Chlorine Isotope of Brine and Deposits in The Mahai Salt lakes

采用以Ｃｓ２Ｃｌ＋为发射离子的高精度正热电离质谱方法，对柴达木盆地马海盐湖区卤水和共存的盐类沉积、河水、钻孔盐类沉积中的氯同位素组成进行了精确的测定．该地区盐湖卤水氯同位素组成表明，在相同的蒸发沉积环境地质条件下，地表卤水δ３７Ｃｌ变化范围为－１．５５‰到０．５３‰。盐类沉积垂直剖面的δ３７Ｃｌ值变化范围在０．００‰。到１．０５‰。在此基础上，初步研究了利用卤水及盐类矿物氯同位素组成变化追踪盐湖补给水来源及盐湖古气候变化．

The chlorine isotopic compositions of brine and salt deposits from the Mahai salt lakes in the Qaidam basin have been examined by the Cs2CI+ positive ionization mass spectrometry.The result indicated that chlorine isotope have evident fractionation. Under the same condition of evaporated convenience, δ37CI value of surface brine changed from-1.55‰to0.53‰. Vertical profile showed that δ37CI value trend to reduce with increasing depthupward from 50 to 2 meter, δ37CI value is from 0. 00‰to 1.05‰. Tracing the source water of salt lakes and paleoclimate change in the area by the chlorine geochemistry of brine and salt deposits was preliminarily studied.