川滇黔二叠系铅锌成矿物质来源：C-H-O-S-Pb同位素制约——以云南太平子铅锌矿为例

丁伟品; 谢财富; 黄诚; 张斌; 辛卓; 詹华思; 郑立龙; 孔凡全; 王红兵; 黄福林

doi:10.12029/gc20220611

川滇黔二叠系铅锌成矿物质来源：C-H-O-S-Pb同位素制约——以云南太平子铅锌矿为例

Sources of Permian lead-zine ore-forming materials in Sichuan-Yunnan-Guizhou area: C-H-O-S-Pb isotope constraints——An example from Taipingzi lead-zinc deposit in Yunnan Provinces

摘要

摘要:
研究目的 川滇黔地区铅锌矿成因具有多样性，特别是与峨眉山玄武岩的关系存在较大的争议，本文从前人关注较少的二叠系碳酸盐岩中的铅锌矿入手，研究成矿物质来源。
研究方法 以云南寻甸县太平子铅锌矿为研究对象，运用S、Pb、C、H、O同位素实验数据及流体包裹体测温等方法，对成矿物质来源及成矿流体特征进行探讨。
研究结果 矿石铅同位素组成比较均一，分布集中，²⁰⁶Pb/²⁰⁴Pb、²⁰⁷Pb/²⁰⁴Pb、²⁰⁸Pb/²⁰⁴Pb的变化范围分别为18.543~18.584、15.646~15.694、38.799~38.958，属于正常普通铅，具壳源特征，主要来源于基底岩石，水岩反应可能使赋矿围岩贡献少量的成矿物质。矿石硫化物δ³⁴S变化范围为-13.6‰~-7.3‰，方铅矿的δ³⁴S高于闪锌矿，硫同位素分馏并未达到平衡，生物成因硫酸盐还原作用（BSR）是还原硫的主要来源。热液方解石δ¹³C_V-PDB范围为3.8‰~4.7‰，δ¹⁸O_V-SMOW范围为12.0‰~16.7‰，相较于滇东北其他重要的铅锌矿床，具有明显的低δD、高δ¹⁸O_fluid特点，成矿流体中的水主要来源于岩浆水和有机水的混合，具有中—高温、低盐度特征。
结论太平子铅锌矿在成矿物质、流体、成矿温度等均与区域上其他典型铅锌矿有较明显差别，具有典型的岩浆-热液成因特点。

Abstract: This paper is the result of the geological survey engineering.
Objective The genesis of Pb-Zn deposit in Sichuan, Yunnan and Qianhai is diverse, especially the relationship with the Emei Mountain basalt is more controversial. In this paper, we study the source of ore-forming material, starting from Pb-Zn deposit in Permian carbonate rocks, which has received less attention from previous authors.
Methods Using experimental data of S, Pb, C, H, and O isotopes and fluid inclusion temperature measurements, the source of mineralized materials and the characteristics of mineralized fluids were investigated in the Taipingzi Pb-Zn deposit in Xundian County, Yunnan Province.
Results The Pb isotopic compositions of the ore are relatively homogeneous and concentrated, with the variations of ²⁰⁶Pb/²⁰⁴Pb, ²⁰⁷Pb/²⁰⁴Pb and ²⁰⁸Pb/²⁰⁴Pb ranging from 18.543 to 18.584, 15.646 to 15.694 and 38.799 to 38.958, respectively. These suggest that the Pb in Taipingzi Pb-Zn deposit belongs to normal common Pb with crustal origin. The metal-forming materials are mainly from the basement rocks, and the water-rock reaction may make the mineralized enclosing rocks contribute a small number of mineralized materials. The δ³⁴S in ore sulfide varies from -13.6 ‰ to -7.3 ‰ and δ³⁴S of the galena is higher than that in sphalerite. Sulfur isotope fractionation has not reached equilibrium, sulfur is mainly from crustal source. Biogenic sulfate reduction (BSR) is the main mechanism of sulfur reduction. A large amount of biogenic sulfur reduction has accumulated in the mineralized area before mineralization. The hydrothermal calcite δ¹³C_V-PDB ranges from 3.8 ‰ to 4.7‰ and δ¹⁸O_V-SMOW ranges from 12.0 ‰ to 16.7 ‰ with obvious low δD and high δ¹⁸O_fluid characteristics compared to other important Pb-Zn deposits in northeast Yunnan. The water in the mineralizing fluid mainly originates from a mixture of magmatic and organic water, with medium-high temperature and low salinity characteristics.
Conclusions Taipingzi Pb-Zn deposit is significantly different from other typical Pb-Zn ores in the region in terms of metallogenic material, fluids and metallogenic temperature, and has typical magmatic-hydrothermal genesis characteristics.

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