Geochemistry International

, Volume 57, Issue 12, pp 1327–1338 | Cite as

Origin of Underground Brine in Potassium-Bearing Strata in Khammouane, Central Laos

  • Zhanjie QinEmail author
  • Qingkuan Li
  • Qishun Fan
  • Xiangru Zhang
  • Yongsheng Du
  • Haicheng Wei
  • Qin Yuan
  • Jianping WangEmail author
  • Fashou Shan


The Khorat Plateau is one of the largest potash deposits in the world. In recent years, exploitation of potash resources accompanied by leakage of underground brines (UB) in potassium-bearing strata has threatened mining safety. However, there is little research on origin of UB in Laos. In this study, twelve samples of UB, salt springs (SS) and river waters were collected in Khammouane mining area, central Laos and analyzed for ionic and boron isotopic compositions. The results show that both of UB, dominated by K+, Mg2+, Na+ and Cl ions, and SS, enriched in Na+ and Cl, are chloride-type brines, while river waters abundant in Ca2+ and HC\({\text{O}}_{3}^{ - }\) ions are carbonate-type waters. K+ (35.1–53.7 g/L) and Rb+ (12.9–16.6 mg/L) concentrations of UB are higher than the peak (25.9 g/L, 9.4 mg/L) of seawater evaporation trajectories (SET). UB is also characterized by high Mg2+ (32.7–68.0 g/L) and Br (1795.2–2801.3 mg/L) concentrations and its lg(Cl/Br) ratios (1.9–2.1) deviate from the halite dissolution line. These comparisons indicate that the water chemistries of UB are mainly influenced by dissolution of carnallite and sylvite. High Sr2+ concentrations (31.8–58.6 mg/L) in UB might be simultaneously associated with dissolution of potash salt and Ca-bearing minerals (carbonate and anhydrite). The negative saturation indices (SI) of different salt minerals in UB suggest that salt minerals are unsaturated in UB. Meanwhile, boron (B) concentrations (396.0–426.0 mg/L) and δ11B values (+19.8–+21.0‰) of UB fall in between low B–δ11B end member (0.02 mg/L, +2.31‰) of river water and high B-δ11B end member (126.7–890.8 μg/g, +25.94–+32.94‰) of evaporitic minerals. The comparison implies that UB was influenced and mixed by two end members. Therefore, combining with major and trace ionic concentrations, isotopic compositions and lithologies of salt-bearing strata revealed by drillings in mining area, we conclude that the major solute source in UB is derived from dissolution of carnallite and sylvite. These geochemical evidences provide insights into dealing with leakage of underground brines occurred in the underground mining of potash deposits in Laos.


underground brine water chemistry boron isotope potash deposit Laos 



We thank Bo Wang, Yuan Xue, Guangfen Ran, Haijun Li, Xiaoli Chai, Yuan Li, Guangqin Zhu for their help in the laboratory. We also thank Lao Kai Yuan Mining Co., Ltd for the chance to sample.


This research was supported by the National Natural Science Foundation of China (Grant no. 41 502 096), “The Belt and Road” Key Project of theBureau of International Co-operation Chinese Academy of Sciences (Grant no. 122363KYSB20170002) and One-Thousand Innovative Talent Project of Qinghai Province (Grant to QS Fan).


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© Pleiades Publishing, Ltd. 2019

Authors and Affiliations

  • Zhanjie Qin
    • 1
    • 2
    • 3
    Email author
  • Qingkuan Li
    • 1
    • 2
    • 3
  • Qishun Fan
    • 1
    • 2
  • Xiangru Zhang
    • 1
    • 2
    • 3
  • Yongsheng Du
    • 1
    • 2
    • 3
  • Haicheng Wei
    • 1
    • 2
  • Qin Yuan
    • 1
    • 2
    • 3
  • Jianping Wang
    • 1
    • 2
    Email author
  • Fashou Shan
    • 1
    • 2
  1. 1.Key Laboratory of Comprehensive and Highly Efficient Utilization of Salt Lake Resources, Qinghai Institute of Salt Lakes, Chinese Academy of SciencesXiningChina
  2. 2.Qinghai Provincial Key Laboratory of Geology and Environment of Salt LakesXiningChina
  3. 3.University of Chinese Academy of SciencesBeijingChina

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