云南勐野井钾盐矿床石盐包裹体特征及古环境意义  

The characteristics of halite inclusions in the Mengyejing potash deposit, Yunnan Province, and their palaeoenvironmental significance

作　　者：董娟[1] 高翔[1] 方勤方[1] 彭强[1] 马宏伟[2] 刘广耀[1] 

机构地区：[1]中国地质大学科学研究院,北京100083 [2]北京理工大学化学学院,北京100081

出　　处：《岩石矿物学杂志》2015年第2期227-236,共10页Acta Petrologica et Mineralogica

基　　金：国家重点基础研究发展计划项目(2011CB403004)

摘　　要：云南江城勐野井钾盐矿床是我国唯一的一个古代氯化物型固体钾盐矿床,主要盐类矿物是石盐,其次是钾石盐和光卤石,其中钾石盐是该矿床主要的钾盐矿物。本文采用流体包裹体冷冻加热法,对该矿床含矿层中的原生单一液相石盐包裹体进行了均一温度测定,以期获得该矿床钾盐成矿和盐湖古水温方面的信息。实验结果表明,从白色石盐层→青灰色钾石盐层→含光卤石的青灰色钾石盐层,均一温度的均值呈现逐渐升高的趋势,即由23.8℃→27.7℃→38.6℃,这与盐类矿物晶出的顺序一致,即由石盐→钾石盐→光卤石。可见,上部含光卤石的钾石盐层的蒸发强度明显高于其下部的钾石盐层和底部的石盐层,说明钾盐矿层的形成是湖盆卤水不断浓缩咸化的结果,这种咸化是缘于湖盆卤水温度的不断升高。湖盆卤水温度的变化是环境气候变化的结果。因此,原生包裹体均一温度可直接反映矿床形成时湖盆的古水温,同时可推测当时的气温。The Mengyejing potash deposit in Jiangcheng area of Yunnan Province is the unique ancient chloride type solid potash deposit in China. The main salt minerals include halite, sylvite and carnallite, with sylvite being the most important potassium-bearing mineral. In this paper, the authors used cooling-heating methods to study the homogenization temperatures of primary halite fluid inclusions in order to obtain the information concerning the deposit formation and ancient temperature of the salt lake. The result shows that, in order of white halite layer→grayish sylvite layer → carnallite-bearing grayish sylvite layer, the homogenization temperatures increase gradually in order of 23. 8 ℃ →27. 7 ℃ →38. 6 ℃. This trend is consistent with the crystallization sequence of salt minerals, i. e., halite→sylvite→carnallite. Therefore, the evaporative intensity for the carnallite-bearing upper sylvite layer is obviously higher than that of the lower sylvite layer and the halite layer, implying that the formation of potash deposit might have resulted from the continuous concentration and salinization of the lake brine, and this salinization trend was probably caused by the rise of the brine temperature in the lake. Moreover, the change of brine temperature was influenced by atmospheric temperature. Therefore, the homogenization temperature of primary fluid inclusions in different layers of the deposit can not only reflect the ancient water temperature directly during the formation of the deposit but also indicate environmental atmospheric temperature of that time.

关 键 词：原生纯液相流体包裹体 均一温度 石盐 古水温 勐野井 钾盐矿床 

分 类 号：P578.32[天文地球—矿物学]