川滇密西西比河谷型铅锌矿床成矿流体来源研究:流体Na-Cl-Br体系的证据  

Na-Cl-Br SYSTEMATICS OF MINERALIZING FLUID IN MISSISSIPPI VALLEY-TYPE DEPOSITS FROM SOUTHWEST CHINA

作　　者：李泽琴[1] 王奖臻[1] 倪师军[1] 李朝阳[2] 胡晓强[1] 李桃叶[3] 

机构地区：[1]成都理工大学,四川成都610059 [2]中国科学院地球化学研究所,贵州贵阳550002 [3]国土资源部宜昌地质矿产研究所,湖北宜昌443003

出　　处：《矿物岩石》2002年第4期38-41,共4页Mineralogy and Petrology

基　　金：国家自然科学基金项目 (4 0 172 0 3 9);中国科学院重点项目 (ZK95 1-B1-4 11)资助

摘　　要：应用流体包裹体滤液分析方法 ,测定了川滇 7个 MVT铅锌矿床成矿流体的Na,Cl,Br含量 ,结果表明成矿流体的 x(Na/ Br)和 x(Cl/ Br)的平均值分别为 185和 73,并与高度蒸发浓缩的残留海水的 x(Na/ Br)和 x(Cl/ Br)相近。成矿流体的 Na,Cl含量呈正相关 ,在 lg Na- lg Cl图解中呈线性分布。根据这些事实以及矿床地质特征 ,认为原始成矿卤水起源于蒸发浓缩的残留海水 ,原始含矿卤水与富含有机质的大气降水混合导致矿质沉淀而成矿。The region along the border of southeast Sichuan and east Yunnan comprises of numerous Mississippi Valley type deposits. The contents of Cl, Na and Br of fluid inclusion leachates of sphalerite and quartz from seven deposits have been analyzed. The ranges of the values of Cl -, Na + and Br - are 0.106 7～1.995 5, 0.069 9～2.606 2 and 0.000 5～0.010 4 respectively. And the molar ratios of Na/Br and Cl/Br ranges from 75 to 358 and from 67 to 394, respectively. All of these rates project along with the trend of evaporation seawater in Na/Br vs Cl/Br diagram. These results suggest that the primitive mineralizing brine originated from the evaporation of seawater during sedimentation of Dengying formation (Late Proterozoic). But the salinity in the inclusions of minerals from the deposits is 5%～15%,which is much lower than that of the seawater. Moreover, the plots of the leachates parallel with the line of the seawater evaporation in logNa logCl diagram. So it is suggested that the primitive mineralization brine must be diluted by meteoric water. In addition, there is much bitumen in the deposits.Thus we infer that there are hydrocarbon in the meteoric water. And it was the mixing of the two fluids that produced H 2S and led to the precipitation of Pb 2+ , Zn 2+ from the fluids.

关 键 词：成矿流体 铅锌矿床 流体Na-Cl-Br体系 流体混合作用 四川 云南 

分 类 号：P618.42[天文地球—矿床学] P618[天文地球—地质学]