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
作者:
作者单位:

1.中国地质科学院矿产资源研究;2.中国科学院地质与地球物理研究所;3.中国地质科学院矿产资源研究所 国土资源部成矿作用与资源评价重点实验室

基金项目:

本文为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。


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

1.Institute of Mineral Resources, Chines Academy of Geological Sciences;2.Institute of geology and geophysics, Chinese academy of sciences;3.MLR Key Laboratory of Metallogeny and Mineral Assessment, Institute of Mineral Resources, Chinese Academy of Geological Sciences

  • 摘要
  • | |
  • 访问统计
  • |
  • 参考文献
  • |
  • 相似文献
  • |
  • 引证文献
  • | |
  • 文章评论
    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 2 O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 2 O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 2 O,气相成分为H 2 O、CO 2 、CH 4 以及N 2 。碳、氧同位素组成(δ13 C PDB 值介于-8. 54‰~3. 76‰,δ18 O SMOW 值介于8. 57‰~24. 22‰)在 δ18 O- δ13 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( δ D值介于-97. 4‰~-71. 4‰,δ18 O 水 值介于-4. 6‰~8. 0‰)在 δD- δ18 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,数据分布呈线性趋势,几乎所有点均落在地壳铅平均演化线以上,且位于峨眉山组玄武岩、碳酸盐岩地层和基底岩石的Pb同位素组成范围之内,说明成矿物质具有多源性,铅同位素在成矿之前存在均一化过程。结合成矿物质和成矿流体来源,以及区域成矿地球动力学背景,认为荒田铅锌矿属于密西西比河谷型(MVT)叠加岩浆热液改造型矿床。

    Abstract:

    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, CO 2 - H 2 O type and H 2 O 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 H 2 O 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 H 2 O, and gaseous H 2 O, CO 2 , CH 4 and N 2 . Carbon isotopic compositions ( δ 13 C PDB from -8.54‰ to 3.76‰) and oxygen isotopic compositions ( δ 18 O SMOW from 8.57‰ to 24.22‰) are plotted in the transition zone of primary carbonatite and marine carbonatite in the δ 18 O- δ 13 C diagram, suggesting that CO 2 was probably derived from mantle, dissolution of marine sedimentary carbonate, and dehydroxylation of organic matter in the sediments. Hydrogen isotopic compositions ( δ D from -97.4‰ to -71.4‰) and oxygen isotopic compositions ( δ 18 O H2O from -4.6‰ to 8.0‰) indicate that the ore- forming fluids were generated from the magmatic fluid, mixed with the meteoric water in later process and perhaps some seawater added. Sulfur isotopic compositions ( δ 34 S from -5.5‰ to 10.3‰) indicate that reduced sulfur was derived from basalts, ancient seawater sulfate and the carbonate strata by thermal- chemical sulfate reduction (TSR). 208 Pb/ 204 Pb, 207 Pb/ 204 Pb and 206 Pb/ 204 Pb ratios of ore sulfides are 38.320 to 39.365, 15.603 to 15.860, and 18.136 to 18.786, respectively, and all the data are plotted above the average line of crustal lead evolution and within the lead isotopic range of Emeishan Formation basalt, carbonatic rock and Proterozoic basement rocks. All these features suggest that ore- forming material was multiple in origin and homogenization of Pb isotopes occurred in hydrothermal fluids before the lead- zinc mineralization. Based on the origin of ore- forming material and fluids, as well as regional metallogenic geodynamic setting, it can be concluded that the Huangtian lead- zinc deposit belongs to an typical MVT deposit superimposed by magmatic hydrothermal reconstruction.

    参考文献
    相似文献
    引证文献
引用本文

刘瑞麟,张宝林,武广,沈晓丽,刘军港.2019.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[J].地质学报,93(3):674-700.
LIU Ruilin, ZHANG Baolin, WU Guang, SHEN Xiaoli, LIU Jungang.2019. Genesis of the Huangtian large lead- zinc deposit in Yunnan Province:constrains from fluid inclusions and C- H- O- S- Pb isotope geochemisty[J]. Acta Geologica Sinica,93(3):674-700.

复制
分享
文章指标
  • 点击次数:1150
  • 下载次数: 1611
  • HTML阅读次数: 10
  • 引用次数: 0
历史
  • 收稿日期:2017-12-10
  • 最后修改日期:2018-06-15
  • 录用日期:2018-06-16
  • 在线发布日期: 2019-02-25