摘要
塔里木盆地是我国一重要成盐盆地,地史时期曾有过长期海侵,被列为我国最有远景的钾盐找矿远景区之一。为判断塔里木盆地主要含盐构造海陆相沉积特征,选择了蒸发岩沉积序列普遍存在的石膏、硬石膏矿物,做了其硫同位素34S/32S比值分析。结果表明,塔里木盆地西部盐岩沉积区石膏矿物硫同位素相对分布于低值段,但均为正值,且比较集中普遍分布于+10‰～+20‰之间。这种石膏硫同位素的较低值分布范围(没有高于+30‰的样品)说明细菌的还原作用较弱,对石膏硫同位素的分馏作用贡献不大。从石膏硫同位素分布特征分析,塔里木盆地成盐环境为开阔氧化条件为主,物质来源不同构造单元各不相同,喀什凹陷以海水为主,库车拗陷及阳霞凹陷则以海水与陆缘水混合为主。
From the late Cretaceous to the early Tertiary period, the Tethys seawater repeatedly invaded the Shacha subbasin and entered into the Kuche subbasin through the Awati strait. At the same time, as a result of tectonic and paleoenvironmental conditions, many sequences of thick strata of evaporites, especially in its two largest subbasins of Kuche in the north and Shaqa in the southwest have been deposited. Therefore, the western Tarim Basin has been considered to be a favorable location to prospect for ancient potash deposits. In order to clearly distinguish between a marine or a continental origin, the paper analyzed the late stages of evaporites of gypsum and measured sulfur isotopes in gypsum. The results showed that the sulfur isotope composition of gypsum can be used to distinguish between a marine and continental origin. The late Cretaceous halite deposited in the Kashi Depression of the southwestern Tarim Basin have a marine origin, the Tertiary salt rocks in the Shaqa or the Kuche sub-basin were closer to continental or mixed sea water / fresh water facies in terms of their depositional environment.
出处
《甘肃地质》
2010年第1期32-37,共6页
Gansu Geology
