| 思茅盆地下白垩统蒸发岩硫同位素地球化学特征及其钾盐成矿意义 |
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| 关键词:Simao basin evaporite potash sulfur isotope mineralization geochemistry |
| 基金项目:国家重点研发计划子课题“特提斯东段深部海相钾盐勘查增储示范”(编号: 2017YFC0602801);中国地质调查局地质调查二级项目“西部地区钾盐矿产远景调查评价”(编号: DD20160054) |
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| Sulfur Isotope Geochemistry of the Lower Cretaceous Evaporite and Its Significance for Potash Mineralization in the Simao Basin,Southwest China |
| Scientists believe that primary material sources of the Mengyejing potash deposit are seawater but there are still disputes about the metallogenic epoch and metallogenic model. In addition, the influence of terrestrial freshwater on the composition of evaporite is still lacking of discussion. In order to explore the material source of evaporite, the effect of freshwater on the evaporite composition, the age of material source, the metallogenic epoch, and the probable potassium metallogenic model, the authors analyzed composition and sulfur isotope of 27 evaporite samples from well L2 in the Simao basin, and also considered the published sulfur isotope data of evaporite from adjacent basins. Some conclusions have been reached: (1) Material sources of the evaporite in the Simao basin were recharged by freshwater and volcanic hydrothermal fluids except seawater. The data of sulfur isotope of the evaporite were significantly lower than that of other marine samples in the same geological epoch, it was caused by freshwater flowing into basin. (2) Seawater flowed northwestward into the Simao basin. There existed two times of seawater recharge in the first-order period and at least seven times in the second-order period. (3) The epoch of material source seawater is the Middle Jurassic, and the salting out age is the late Early Cretaceous. The probable potassium mineralization model was as follows: "Middle Jurassic seawater of lateral migration evaporated and crystallized in the late Early Cretaceous". These results are of great significance in explaining the abnormally low sulfur isotope values and high sulfur isotope values of marine evaporites in the Simao basin and its adjacent areas, which are comparable to those of Middle Jurassic seawater, and the absence of " carbonate facies and sulphate facies" in potassium mineralization. |
| MIAO Zhong-ying,ZHENG Mian-ping,ZHANG Xue-fei,ZHANG Zhen,LIU Jian-hua,GAO Yun-zhi,ZHAI Xue-feng.2019.Sulfur Isotope Geochemistry of the Lower Cretaceous Evaporite and Its Significance for Potash Mineralization in the Simao Basin,Southwest China[J].Acta Geoscientica Sinica,40(2):279-290. |
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