Trace and minor elements in sulfides from the Lengshuikeng Ag–Pb–Zn deposit, South China: a LA–ICP–MS study
Trace and minor elements in sulfides from the Lengshuikeng Ag–Pb–Zn deposit, South China: a LA–ICP–MS study
复制标题
DOI：
10.1016/j.oregeorev.2021.104663
复制
发表时间：
2021-12
影响因子：
3.3
通讯作者：
Youqiang Qi;R. Hu;Jianfeng Gao;Chengbiao Leng;Wei Gao;Haotian Gong
中科院分区：
文献类型：
--
作者：
Youqiang Qi;R. Hu;Jianfeng Gao;Chengbiao Leng;Wei Gao;Haotian Gong
闪锌矿、黄铁矿和方铅矿是锌铅（银）矿床中常见的硫化物矿物，含有微量元素，对成矿过程有重要的制约作用。冷水坑银铅锌存款矿床是我国最大的银矿床之一。除个别银矿物外，硫化物中银的赋存状态尚不清楚。采用激光原位烧蚀-电感耦合等离子体质谱（LA-ICP-MS）技术，对块状、脉状和细脉浸染状硫化物矿物中微量元素含量进行了分析。硫化物矿物的元素组成是可变的。结合岩相学观察和前人的研究，认为斑岩型和层控型两种矿化类型的硫化物矿物形成于同一热液体系，其微量元素含量主要受温度、围岩蚀变和热液成分变化的影响。方铅矿中Ag的含量为n × 103 ppm × 104 ppm，而闪锌矿和黄铁矿中Ag的含量均为n × 103 ppm × 103 ppm。除方铅矿外，闪锌矿中金（平均= 0.76 ppm）和银（平均= 151 ppm）的含量均高于黄铁矿中金（平均= 0.26 ppm）和银（平均= 69.9 ppm）的含量。一般来说，蚀变样品在黄铁矿和闪锌矿中显示出较高的Ag和Au含量。银以固溶体的形式存在于块状结构样品的硫化物中，并以显微包裹体的形式存在于蚀变样品的硫化物中。微量元素（如Cd、In）含量及其比值（Ga/In、Zn/Cd、Cd/Fe）对温度和存款形成过程并不总是敏感的。认为块状结构、蚀变有限的样品中的硫化物可作为确定存款成因类型的依据。结果表明，该热液是与花岗斑岩有关的岩浆流体。
Sphalerite, pyrite and galena are common sulfide minerals in Zn–Pb–(Ag) deposits, containing minor and trace elements that can be used to constrain the ore-forming processes. The Lengshuikeng Ag–Pb–Zn deposit (LSKD) is one of the largest silver deposits in China. The mode of silver occurrence in sulfides remains unclear except for individual silver minerals. In this study, we analyzed the minor and trace element contents of sulfide minerals from massive, vein, and veinlet-disseminated ores by in-situ laser ablation–inductively coupled plasma–mass spectrometry (LA–ICP–MS). The elemental compositions of sulfide minerals are variable. Combining petrographic observations and previous studies, we suggest that the sulfide minerals from two types of mineralization (porphyry and strata-bound types) were formed in a same hydrothermal system, and their content of minor and trace elements mainly is influenced by temperature, alteration of wall rocks and composition change of hydrothermal fluid. The Ag content in galena ranges n*103∼ n*104ppm, whereas that in both sphalerite and pyrite ranges from n*10 ∼ n*103ppm. Except for galena, a higher content of gold (mean = 0.76 ppm) and silver (mean = 151 ppm) occurs in sphalerite compared with the content of gold (mean = 0.26 ppm) and silver (mean = 69.9 ppm) in pyrite. Generally, altered samples display higher Ag and Au contents in pyrite and sphalerite. Silver occurs in the form of a solid solution in sulfides from samples with massive textures, and as micro-inclusions in sulfides from altered samples. The contents of minor and trace elements (e.g. Cd and In) and their ratios (Ga/In, Zn/Cd and Cd/Fe) are not always sensitive to the temperature and processes of deposit formation. We suggest that sulfides from samples with massive texture and limited alteration are suitable for determining the genetic type of the deposit. Our results show that the hydrothermal fluid is a magmatic fluid related to porphyry granite in the LSKD.