Trace element compositions of sulfides from Pb-Zn deposits in the Northeast Yunnan and Northwest Guizhou Provinces, SW China: Insights from LA-ICP-MS analyses of sphalerite and pyrite
Trace element compositions of sulfides from Pb-Zn deposits in the Northeast Yunnan and Northwest Guizhou Provinces, SW China: Insights from LA-ICP-MS analyses of sphalerite and pyrite
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DOI：
10.1016/j.oregeorev.2021.104639
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发表时间：
2021-12
影响因子：
3.3
通讯作者：
Qing Yang;Xiaojun Zhang;T. Ulrich;Jun Zhang;Jian Wang
中科院分区：
文献类型：
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作者：
Qing Yang;Xiaojun Zhang;T. Ulrich;Jun Zhang;Jian Wang
利用LA-ICP-MS分析了川滇黔铅锌成矿集中区6个矿床中闪锌矿和黄铁矿的微量元素，探讨了微量元素的组成、分布特征和置换机制。结果表明，闪锌矿以富Fe、Ge、Cd和低Bi、Ni、Co、Tl为特征，黄铁矿以富Ni、Co、As和低Ge、Ga、Tl、Bi、In为特征。闪锌矿中的Fe、Ga、Mn、Cd、Ge和黄铁矿中的Co、Ni、Tl一般以晶格结合形式存在，而Ag、Cu、As、Sb则以微包裹体和固溶体形式存在。闪锌矿中某些元素之间存在显著的相关性，表明闪锌矿的置换机制为2 Zn 2+参与（Ag+，Cu+）+（Ga 3+，As 3+）和3 Zn 2+参与2（Cu+，Ag+）+Ge 4+，Fe和Mn之间存在负相关性，表明二者之间存在竞争。黄铁矿中微量元素之间的相关趋势体现了2 Fe 2+（Tl+、Cu+、Ag+）+Sb 3+的耦合替代机制，通常深色闪锌矿比浅色闪锌矿相对富含Fe和Ge，缺乏Ga、In和Sn。从区域上看，闪锌矿中Cu的含量由东南向西北逐渐增加，茅坪黄铁矿中Co、Ti含量和Co/Ni比值明显高于黔西北黄铁矿。黄铁矿中Co/Ni比值在矿床规模上的变化可为铅锌矿化探提供矢量，Co/Ni比值接近0.1时更有找矿存款。
Trace elements in sphalerite and pyrite from six deposits at the Sichuan-Yunnan-Guizhou lead–zinc metallogenic province were analysed to constrain the composition, distribution characteristics and substitution mechanisms of trace elements by LA-ICP-MS analyses. The results show that the sphalerites are characterized by high Fe, Ge, Cd and low Bi, Ni, Co and Tl contents, while pyrites characteristically have high contents of Ni, Co, As and low contents of Ge, Ga, Tl, Bi and In. Iron, Ga, Mn, Cd and Ge in sphalerite and Co, Ni and Tl in pyrite are generally lattice-bound, while Ag, Cu, As and Sb are usually present in both micro-inclusions and solid solution. Significant correlations between some elements in sphalerite suggest the substitution mechanisms: 2Zn2+↔ (Ag+, Cu+) + (Ga3+, As3+) and 3Zn2+↔ 2(Cu+, Ag+) + Ge4+, and the existence of negative correlation between Fe and Mn implies a competition between both elements. The correlation trends between trace elements in pyrite demonstrate the coupled substitution mechanism of 2Fe2+↔ (Tl+, Cu+, Ag+) + Sb3+.Generally, darker sphalerite is relatively rich in Fe and Ge compared to light-color sphalerite, and is deficient in Ga, In and Sn. Regionally, the Cu in sphalerite tends to gradually increase from southeast to northwest, and pyrite from Maoping has significantly higher Co and Ti concentrations and Co/Ni ratios than that from the deposits in northwestern Guizhou. The variation of the Co/Ni ratio in pyrite at the scale of these deposits may provide vectors for the geochemical exploration of Pb-Zn mineralization and the Co/Ni ratios close to 0.1 are more prospective for a larger deposit.