云南荒田大型铅锌矿床的成因:流体包裹体和C-H-O-S-Pb同位素地球化学约束  

Genesis of the Huangtian large lead-zinc deposit in Yunnan Province:constrains from fluid inclusions and C-H-O-S-Pb isotope geochemisty

作　　者：刘瑞麟[1,2] 张宝林 武广[1] 沈晓丽 刘军港[7] LIU Ruilin;ZHANG Baolin;WU Guang;SHEN Xiaoli;LIU Jungang(MNL Key Laboratory of Metallogeny and Mineral Assessment, Institute of Mineral Resources , Chines Academy of Geological Sciences ,Beijing, 100037;Key Laboratory of Orogen and Crust Evolulioti, Ministry of Education ,Peking University, Beijing, 100871;Key Laboratory o f Mineral Resources , Institute of Geology and Geophysics ,Chinese Academy of Sciences , Beijing, 100029;Institute of Earth Science , Chinese Academy of Sciences ,Beijing, 100029;University of Cheese Academy of Sciences , Beijing, 100049;Key Laboratory of Depositional Mineralization & Sedimentary Mineral of Shandong Province , College of Earth Science and Engineering , Shandong University of Science and Technology、Qingdao, Shandong, 266590;Beijing Research Institute of Uranium Geology, Key Laboratory of Uranium Resource Exploration and Evaluation Techniques , CNNC, Beijing, 100029)

机构地区：[1]中国地质科学院矿产资源研究所自然资源部成矿作用与资源评价重点实验室,北京100037 [2]北京大学造山带与地壳演化重点实验室,北京100871 [3]中国科学院地质与地球物理研究所中国科学院矿产资源研究重点实验室,北京100029 [4]中国科学院地球科学研究院,北京100029 [5]中国科学院大学,北京100049 [6]山东科技大学地球科学与工程学院山东省沉积成矿作用与沉积矿产重点实验室,山东青岛266590 [7]核工业北京地质研究院中核集团铀资源勘查与评价技术重点实验室,北京100029

出　　处：《地质学报》2019年第3期674-700,共27页Acta Geologica Sinica

基　　金：中国科学院知识创新工程重要方向项目"云南红河州主要矿床类型的找矿勘查技术集成示范"(编号KZCX2-YW-Q04-03)的资助成果

摘　　要：荒田铅锌矿位于扬子板块西南缘,与华夏地块和三江地块相接,属峨眉山大火成岩省的南延部分,川-滇-黔铅锌银多金属成矿域的南部。矿体赋存于上二叠统峨眉山玄武岩底部与下二叠统茅口组接触面上及其附近的玄武质-灰质角砾岩层中。本文应用流体包裹体和C-H-O-S-Pb同位素地球化学研究手段,来探讨荒田铅锌矿的成因。流体包裹体分析表明,成矿流体性质具有阶段性演化特征,早期硫化物阶段(阶段Ⅰ)出现含子矿物包裹体、CO_2包裹体和H_2O包裹体的组合发育特征,均一温度介于245～320℃,平均为270℃;到中期硫化物阶段(阶段Ⅱ)和晚期硫化物阶段(阶段Ⅲ)则逐渐变为以H_2O包裹体为主要类型,均一温度分别介于180～250℃和100～210℃,平均为224℃和174℃。随着成矿作用的进行,成矿流体的均一温度和盐度均表现出从早阶段到晚阶段逐渐降低的趋势。显微激光拉曼光谱分析显示流体包裹体的液相成分主要为H_2O,气相成分为H_2O、CO_2、CH_4以及N_2。碳、氧同位素组成(δ^(13)C_(PDB)值介于-8.54‰～3.76‰,δ^(18)O_(SMOW)值介于8.57‰～24.22‰)在δ^(18)O-δ^(13)C图上分布于原生碳酸岩和海相碳酸盐岩之间,指示CO_2可能来自地幔、海相沉积碳酸盐岩溶解和沉积物中有机质的脱羟基作用。氢氧同位素组成(δD值介于-97.4‰～-71.4‰,δ^(18)O_水值介于-4.6‰～8.0‰)在δD-δ^(18)O图上落在岩浆水和大气降水的过渡带上,推测热液流体运移过程中与顺层下渗的大气降水流体混合,期间可能有海水的加入。矿石硫化物的δ^(34)S值介于-5.5‰～10.3‰,指示矿化剂硫具有多种来源,除了直接来自玄武岩外,还来自古海水硫酸盐和碳酸盐岩地层,硫酸盐通过热化学还原(TSR)过程发生还原作用。矿石硫化物铅的^(208)Pb/^(204)Pb、^(207)Pb/^(204)Pb和^(206)Pb/^(204)Pb比值分别为38.320～39.365、15.603～15.860和18.136～18.786,数据分�Tectonically located in the conjunction of southwestern Yangtze Block, Cathaysian Block and Sanjiang Block, the Huangtian lead-zinc deposit is in the south of Sichuan-Yunnan-Guizhou(SYG) Pb-Zn metallogenic domain, which belongs to the southern extension of Emeishan Large Igneous Province. Orebodies occur in the contact zone between lower Upper Permain Emeishan basalt and lower Permian Maokou Formation limestone, as well as nearby basaltic-carbonated breccia layers. This study presents new data on fluid inclusions and C-H-O-S-Pb isotopic compositions to discuss the genesis of the Huangtian lead-zinc deposit. Fluid inclusions analyses reveal that ore-forming fluid was characterized by stage evolution. The early sulfide-forming stage(Stage I) contains various types of fluid inclusions, including daughter mineral containing type, CO2-H2O type and H2O type, with homogenization temperatures of 245~320℃(an average of 270℃). Fluid inclusions in the middle sulfide-forming stage(Stage II) and the late sulfide-forming stage(Stage Ⅲ) are dominated by H2O type, with homogenization temperatures of 180~250℃(an average of 224℃) and 100~210℃(an average of 174℃), respectively. Homogenization temperatures and salinity of the ore-forming fluids gradually decreased from the early stage to late stage. Laser Raman analysis shows that the fluid inclusions are dominated by liquid H2O, and gaseous H2O, CO2, CH4 and N2. Carbon isotopic compositions(δ13CPDB from-8.54‰ to 3.76‰) and oxygen isotopic compositions(δ18OSMOW from 8.57‰ to 24.22‰) are plotted in the transition zone of primary carbonatite and marine carbonatite in the δ18O-δ13C diagram, suggesting that CO2 was probably derived from mantle, dissolution of marine sedimentary carbonate, and dehydroxylation of organic matter in the sediments. Hydrogen isotopic compositions(δD from-97.4‰ to-71.4‰) and oxygen isotopic compositions(δ18OH2O from-4.6‰ to 8.0‰) indicate that the ore-forming fluids were generated from the magmatic fluid, mixed with the mete

关 键 词：流体包裹体 C-H-O-S-Pb同位素 成矿流体 荒田 MVT型铅锌矿 官厅铅锌成矿带 

分 类 号：P618.42[天文地球—矿床学] P618.43[天文地球—地质学] P597