矿物流体包裹体中稀有气体的保存能力初探  

A preliminary study of the retention of noble gases in fluid inclusions of different minerals

作　　者：张东亮[1] 郑德顺[2] 彭建堂[1,3] 袁顺达[4] 

机构地区：[1]中南大学有色金属成矿预测教育部重点实验室地球科学与信息物理学院,湖南长沙410083 [2]河南理工大学资源环境学院,河南焦作454000 [3]中国科学院地球化学研究所矿床地球化学国家重点实验室,贵州贵阳550002 [4]中国地质科学院矿产资源研究所,北京100037

出　　处：《矿床地质》2011年第5期933-940,共8页Mineral Deposits

基　　金：国家自然科学基金项目(编号:40902033;41073036);中南大学青年教师助推基金(编号:201012200125)资助

摘　　要：查明流体包裹体中稀有气体的保存能力,对于判断其初始组分特征是否因后生作用而发生改变具有重要意义。文章以Ar为例,从扩散动力学角度对稀有气体地球化学研究中常用的矿物中流体包裹体稀有气体的保存能力进行了定量分析和系统比较,计算了Ar在这些矿物中的封闭温度以及不同温度条件下的保存时间,得出相同条件下各矿物对Ar、He等保存能力的大小顺序为:重晶石(天青石)>黄铜矿>黄铁矿>方铅矿>钾盐>闪锌矿>萤石>黑钨矿>白钨矿>绿柱石>方解石>石英,其中石英中Ar的封闭温度对矿物颗粒大小变化十分敏感,它会随着晶体颗粒半径的增大而迅速提高,但其扩散速率受温度变化的影响相对较小。这为准确评估不同矿物的流体包裹体中稀有气体信息受后生地质作用的影响程度提供了理论依据,有望促进稀有气体同位素地球化学的发展。Studies of the retention of noble gases in fluid inclusions from various hydrothermal minerals are necessary for tracing the source of ore-forming fluid by using noble gas isotopic geochemistry.Mainly with Ar as an example,the retention of noble gases in several minerals commonly used to study fluid inclusion geochemistry was quantitatively evaluated and systematically compared with each other in this paper in terms of diffusion dynamics.In addition,closure temperature and preservation time of noble gases in these minerals were also calculated.The result reveals that,under the same conditions,the component characteristics of Ar,He and other noble gases can be preserved in these minerals in order of barite（=celestite） chalcopyrite pyrite galena sylvite sphalerite fluorite wolframite scheelite beryl calcite quartz.It is also indicated that the closure temperature of Ar in quartz is more sensitive to the change of grain size than that of other minerals and will increase rapidly with the radius of the crystal,but the diffusivity is insensitive to the change of temperature.On such a basis,the authors present a theoretical scale for accurate assessment of variations of noble gas components resulting from post-entrapment processes.

关 键 词：地球化学 流体包裹体 矿物 稀有气体 保存能力 

分 类 号：P599[天文地球—地球化学]