摘要
新疆库车前陆坳陷新生代地层发育巨厚的蒸发岩沉积.本文通过对库车坳陷内11口钻井的盐岩样品进行锶同位素地球化学特征的分析,进一步研究坳陷内盐岩地层的成盐物质来源.测试结果表明,库车坳陷盐岩的锶同位素在0.708718~0.710868之间,不同时代的盐岩沉积的锶同位素组成明显不同.古近纪盐岩的锶同位素较低,大多在0.7093左右,与海水的锶同位素值接近,表明物质来源主要是海水.中新世盐岩的锶同位素多在0.7100以上,锶同位素组成介于海水和陆源盐湖之间,表明是海水和陆源水的混合的结果.推断库车坳陷古近纪早期受到海侵,渐新世海侵结束后,残余海水在中新世形成泻湖,与陆源卤水相混合并沉积成盐.
Great thickness of evaporite strata were formed in Xinjiang Kuqa foreland depression during Cenozoic period.In this paper,we analyzed the strontium isotope geochemistry of salt which were collected from eleven drillings in Kuqa depression to provide insight into the origin of the deposit＇s brine.Results show that the 87Sr/86 Sr ratios of the samples from Kuqa depression varied from 0.708718 to 0.710868.There are different strontium isotope between two evaporite strata.The strontium isotopic ratios of Paleogene salt which are in the lower level,are mostly around 0.7093,consistent with the 87Sr/86 Sr ratios of seawater,indicating that the brine of the salt deposits were mostly from seawater in Kuqa depression.Miocene salt samples show the 87Sr/86 Sr ratios higher than seawater and lower than the continental water.This indicates that the brine of the Miocene salt deposits are from both seawater and continental water.We concluded that the Kuqa depression were suffered transgression in early Paleogene.The transgression ended in Oligocene.Residual seawater which formed lagoon in Miocene mixed with continental water to deposit into salt.
出处
《南京大学学报（自然科学版）》
CAS
CSCD
北大核心
2015年第5期1068-1074,共7页
Journal of Nanjing University（Natural Science）
基金
国家自然科学基金(40872134
41272227)
国家油气重大专项(2011ZX05029-001)
地质调查计划(1212011085517)
关键词
锶同位素
库车坳陷
海源
盐岩沉积
strontium isotope
Kuqa depression
marine origin
salt deposits
