Geochemistry, Fluid Inclusion, and Stable Isotope Studies of Luziyuan Pb-Zn Deposit in Yunnan Province, Southwestern China
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摘要: 云南省保山—镇康古生代沉积盆地的上寒武统碳酸盐岩中发育有脉状铅锌矿体, 它们均受地层和构造的双重控制. 芦子园铅锌矿是该区此类型规模最大的一个矿床, 矿体赋存于沙河厂组的大理岩及大理岩化灰岩中.其原生矿金属矿物组合为: 闪锌矿、方铅矿、黄铜矿、黄铁矿和磁铁矿.围岩蚀变有矽卡岩化、绿泥石化、硅化、黄铁矿化和大理岩化等.流体包裹体研究表明, 该地区铅锌矿化经历中低温(160~280℃) 和中高温(280~420℃) 2个主要矿化阶段.芦子园铅锌矿的硫、铅同位素组成具有变化范围窄、相对均一的特点(δ(34S)=9.23×10-3~10.17×10-3; w(206Pb)/w(204Pb)=18.224~18.338, w(207Pb)/w(204Pb) =15.715~15.849, w(208Pb)/w(204Pb)=38.381~38.874), 其矿石硫与铅同位素都反映了成矿过程曾受到岩浆活动的影响.研究表明: 镇康地区铅锌矿为与上寒武统局部层位和隐伏岩体有关的热液型铅锌多金属矿床.
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关键词:
- 碳酸盐岩中赋存的铅锌矿床 /
- 地球化学 /
- 流体包裹体 /
- 硫、铅同位素 /
- 云南镇康
Abstract: Carbonate-hosted lead-zinc sulfide veins in the Upper Cambrian are located in the southern area of the Baoshan-Zhenkang Paleozoic sedimentary basin, Yunnan Province. Geologic evidence suggests that controls on the deposit are both stratigraphic and structural. The Luziyuan Pb-Zn deposit, hosted by marble and marbleization-limestone of the Shahechang Group, is the largest in this area. Mineralization consists of galena, sphalerite, chalcopyrite, pyrite, and magnetite. Alteration consists of skarnization, chloritization, silicification, pyritization, and marbleization. Fluid inclusion studies indicate that the mineralization has two main stages: the lower-middle temperature stage (homogenization temperatures of 160 ℃ to 280 ℃) and the upper-middle temperature stage (homogenization temperatures of 280 ℃ to 420 ℃). Sulfide has a very uniform S, Pb isotope composition, with δ(34S)=(9.23-10.17)×10-3, w(206Pb)/w(204Pb)=18.224-18.338, w(207Pb)/w(204Pb) =15.715-15.849, and w(208Pb)/w(204Pb)=38.381-38.874. Both the S and Pb isotopes of ore indicate the partial role of magma hydrothermal fluid in mineralization. The carbonate-hosted Pb-Zn deposits in the Zhenkang area are considered to be strata-bound hydrothermal deposits that formed in favorable tectonic areas in the basis of ore source beds, are associated with magma activities, and have the features of multi-epochs and multi-stages as well as multi-sources in mineralization.-
Key words:
- carbonate-hosted Pb-Zn deposits /
- geochemistry /
- fluid inclusion /
- stable isotope (S /
- Pb)
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图 1 镇康地区区域地质简图及芦子园铅锌矿床Ⅱ矿带地质图(据云南地调院第四地质调查所修编)
a.研究区位置示意图; b.镇康地区区域地质简图; 1.中奥陶统; 2.上寒武统保山组第一段; 3.上寒武统沙河厂组第三段; 4.上寒武统沙河厂组第二段; 5.辉绿岩脉; 6.矿体及编号; 7.断裂; 8.勘探线及编号; 9.钻孔及编号; 10.矿床或矿点: ❶.岩脚山铅锌矿; ❷.枇杷水铅锌矿; ❸.草坝寨铅锌矿; ❹.放羊山铅锌矿; ❺.芦子园铅锌矿; ❻.水头山铅锌矿; ❼.乌木兰锡矿; ❽.小干沟金矿
Fig. 1. Geological sketch map of Zhenkang area and geological map of No.2 ore belt of Luziyuan lead-zinc deposit
图 5 芦子园铅锌矿床矿石铅的Δβ-Δγ成因分类(底图据朱炳泉, 1998)
1.幔源铅; 2.上地壳源铅; 3.上地壳与地幔混合的俯冲带铅(3a.岩浆作用; 3b.沉积作用); 4.化学沉积型铅; 5.海底热水作用铅; 6.中深变质作用铅; 7.深变质下地壳铅; 8.造山带铅; 9.古老页岩上地壳铅; 10.退变质作用铅
Fig. 5. Δβ-Δγ genetic classification map showing Pb isotope distribution of Luziyuan Pb-Zn deposit
图 6 芦子园铅锌矿矿石铅同位素组成(据Zartman and Doe, 1981铅演化模式编绘)
Fig. 6. Isotopic composition of Pb of ores in Luziyuan Pb-Zn deposit
表 1 芦子园铅锌矿Ⅱ号矿带矿体特征
Table 1. Characteristics of ore bodies in No.2 ore belt of Luziyuan Pb-Zn deposit
表 2 芦子园铅锌矿矿石微量元素
Table 2. Trace elements concentration in ores of Luziyuan Pb-Zn deposits
表 3 芦子园铅锌矿包裹体特征及测定结果
Table 3. Characteristics and analytical results for fluid inclusion of Luziyuan Pb-Zn deposit
表 4 芦子园铅锌矿矿石硫同位分析结果
Table 4. Ore S isotope results of Luziyuan Pb-Zn deposit
表 5 芦子园铅锌矿矿石铅同位素分析结果
Table 5. Ore Pb isotope results of Luziyuan Pb-Zn deposit
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