新疆库车盆地中始新世成盐演化特征——以KL4钻孔为例
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本文为国家自然科学基金项目(编号41902064)、东华理工大学博士科研启动基金(编号DHBK2018029)和核资源与环境国家重点实验室自主基金(编号2020Z11)资助的成果。


Salt- forming evolution characteristics of Middle Eocene in the Kuqa basin, Xinjiang: a case study of borehole KL4
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    摘要:

    古盐湖成盐演化具有多期次、连续性和淡化—咸化—盐化的周期性特征,系统研究成盐剖面的沉积韵律有利于恢复古盐湖成盐演化特征。本文以库车盆地KL4钻孔含盐系剖面及其74个石盐样品为研究对象,将含盐系剖面划分为4个成盐韵律,在此基础上开展岩相学、石盐元素地球化学以及石盐流体包裹体氢氧同位素分析等工作。结果显示:剖面上部Ⅲ和Ⅳ成盐韵律发育钾石盐、含钾石盐、杂卤石、钾石膏、钾芒硝等盐类矿物;K + 含量的分布范围为0. 021%~0. 158%,平均含量0. 051%;石盐原生流体包裹体中氢氧同位素 δ D和 δ 18 O 值范围分别为-78. 2‰~-58. 7‰和-2. 4‰~1. 3‰,平均值分别为-66. 32‰和-0. 80‰。盐湖卤水从早期到晚期蒸发浓缩程度逐渐升高,早期成盐卤水在晚期高浓度卤水的形成过程扮演了预富集的角色,在Ⅲ和Ⅳ成盐阶段发现3次钾盐析出事件。本研究为探讨库车盆地中始新世古盐湖环境、沉积特征以及成盐规律提供了重要依据。

    Abstract:

    The salt- forming evolution of ancient salt lakes has periodic characteristics of multiple phases, continuity, and desalination- salinity- salinization. The systematic study of sedimentary rhythm fromthe salinization section is beneficial for thereconstruction of salt- forming evolution characteristics of ancient salt lakes. This paper investigates the salt- bearing section of borehole KL4 in the Kuqa basin and its 74 halite samples, and divides the salt- bearing section into 4 salt- forming rhythms. On this basis, work on petrographic characteristics, geochemical analysis of halite elements, and hydrogen and oxygen isotopes of halite fluid inclusions are carried out. The results show that (1) Ⅲ and Ⅳ salt- forming rhythms in the upper part of the section developed potassium, potassium- bearing halite, polyhalite, syngenite, glaserite and other salt minerals; (2) the distribution range of K+ content is 0. 021%~0. 158%, with an average value of 0. 051%; (3) the δ D and δ 18 O values of hydrogen and oxygen isotopes in halite primary fluid inclusions ranged from -78. 2‰ to -58. 7‰ and -2. 4‰ to 1. 3‰, respectively, with average values of -66. 32‰ and -0. 80‰, respectively; (4) the degree of evaporation and concentration of salt lake brine gradually increased from early to late, and the early salt- forming brine played a role in the pre- enrichment of the late high- concentration brine; (5) three potassium precipitation events were found in the third and fourth salt- forming stages. The results of this study provide an important basis for discussing the environment, sedimentary characteristics and salt- forming principles of Middle Eocene paleo- saline lake in the Kuqa basin.

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徐洋,刘成林,曹养同.2021.新疆库车盆地中始新世成盐演化特征——以KL4钻孔为例[J].地质学报,95(7):2183-2192.
Xu Yang, Liu Chenglin, Cao Yangtong.2021. Salt- forming evolution characteristics of Middle Eocene in the Kuqa basin, Xinjiang: a case study of borehole KL4[J]. Acta Geologica Sinica,95(7):2183-2192.

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  • 收稿日期:2021-01-28
  • 最后修改日期:2021-03-26
  • 录用日期:2021-06-08
  • 在线发布日期: 2021-06-12