投稿时间：2022-07-27
修订日期：2023-03-03
网络发布日期：2023-05-06
中文摘要:羌塘盆地是一个资源丰富的含蒸发岩盆地。为进一步探讨盆地内蒸发岩原始物源、沉积环境以及钾盐资源的成矿潜力，文章分析了北羌塘坳陷QY-1井37件中侏罗统夏里组硬石膏岩样品的硫同位素特征。结果表明：① QY-1井硬石膏岩的硫同位素值介于11.76‰~15.96‰，主峰值区间为15.0‰~16.0‰，平均值为15.16‰，与中侏罗世海水相比偏小，相对较低的硫同位素值指示存在陆源淡水补给蒸发盆地；②硫同位素值分布范围非常集中，98%的样品硫同位素值介于14.0‰~16.0‰。稳定的硫同位素值指示硬石膏沉积期及成岩后未遭受微生物的改造，沉积和成岩环境的氧化还原电位较高；③北羌塘坳陷地表盐泉水具有与夏里组硬石膏岩相一致的硫同位素特征，这表明盐泉水在地下运移时可能溶解了地层中的石膏沉积。再结合沉积学、矿物学、古地磁学等研究成果，笔者综合判断北羌塘坳陷具有良好的钾盐成矿条件和远景。
Abstract:The Qiangtang Basin is an evaporite basin with abundant resources. In order to further explore the original provenance, sedimentary environment and metallogenic potential of the evaporite in the basin, the sulfur isotope characteristics of 37 anhydrite samples of the Middle Jurassic Xiali Formation from drill hole QY-1 in the North Qiangtang Depression were analyzed. The results show that:① The sulfur isotope values of the anhydrite rock in drill hole QY-1 are between 11.76‰ and 15.96‰, the main peak values are between 15.0‰ and 16.0‰, and the average value is 15.16‰, which is smaller than that of the seawater in the Middle Jurassic. The relatively low sulfur isotope value indicates the existence of an evaporative basin supplied by terrestrial freshwater. ② The distribution range of sulfur isotope values is very concentrated, and the sulfur isotope values of 98% samples are between 14.0‰ and 16.0‰. Stable sulfur isotope values indicate that anhydrite was not modified by microorganisms during and after diagenesis, and the redox potential of sedimentary and diagenetic environments is relatively high. ③ The surface salt spring water in the North Qiangtang Depression has the characteristics of sulfur isotope consistent with the anhydrite rock of Xiali Formation, there may be gypsum deposition in the dissolved formation of salt spring water, and the salt spring water has the hydrochemical conditions for deposition of potassium salt. Combined with the research results of sedimentology, mineralogy and paleomagnetism, it is concluded that the North Qiangtang Depression has good conditions and prospects for potash mineralization.
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基金项目:本文得到中国地质调查局地质调查二级项目“重点含盐盆地锂钾资源调查评价（编号：DD20221913）”资助
引用文本：
徐其辉,苗忠英,娄鹏程,郑绵平,陈文西.2023.北羌塘坳陷中侏罗统夏里组蒸发岩硫同位素特征及其钾盐成矿意义[J].矿床地质,42(2):366~380XU QiHui,MIAO ZhongYing,LOU PengCheng,ZHENG MianPing,CHEN WenXi.2023.Sulfur isotope characteristics of evaporite and its metallogenic significance of potassium salts from Middle Jurassic Xiali Formation in North Qiangtang depression[J].Mineral Deposits42(2):366~380
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