In-situ Trace Element Analysis Characteristics of Pyrite in Sanshandao Gold Deposit in Jiaodong Peninsula: Implications for Ore Genesis |
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| Authors: | Zuwei Lin Xinfu Zhao Le Xiong Zhaoxian Zhu |
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| Institution: | Faculty of Earth Resources, China University of Geosciences, Wuhan 430074, China |
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| Abstract: | There are controversies about the genesis of the lode gold deposits in Jiaodong area. The Sanshandao gold deposit is the largest one in Jiaodong area. To better understand the genesis of the gold deposit, it is necessary to know the evolution of ore-forming fluid and the source of ore-forming material for the Sanshandao gold deposit. In this paper, the trace element composition of pyrite at different metallogenic stages in the Sanshandao gold deposit was analyzed by using LA-ICP-MS. Based on geological characteristics and petrography observation and SEM analysis, pyrite can be divided into three stages and six classes, including porous Py1-a and smooth Py1-b in pyrite-sericite-quartz alteration (Py1), many mineral inclusions in the Py2-a and smooth Py2-b associated with carbonate in the quartz-pyrite ± siderite veins (Py2), a lot of polymetallic sulfide inclusions hosted Py3-a and Py3-b with smooth and oscillation band in the quartz-polymetallic sulfide vein (Py3). The experimental results show that the gold content is very low in the lattice of pyrite, most of which is less than 1×10-6, and gold mainly occurs in the form of visible gold. The contents of Au, Ag, Cu, Pb and Sb of pyrite gradually increase from early stage to late stage. The high content of Co+Ni in the earliest stage (up to 9268×10-6) reflects that pyrite in the early stage is likely derived from magma, and the Co/Ni ratio gradually decreases, suggesting the decrease of ore forming fluid temperature. Combined with the geological observations and trace elements component of pyrite, the study shows that the genesis of the Sanshandao gold deposit is related to the evolution of magmatic hydrothermal reservoir. The ore-forming fluid is transported several times along the fault by seismic pumping. |
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| Keywords: | Sanshandao Gold Deposit LA-ICP-MS Pyrite Trace element Ore genesis |
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