多宝山铜钼金成矿带永新金矿床 黄铁矿微量元素地球化学特征研究. (Chinese)

Geochemical characteristics of micro-elements in pyrite from Yongxin Gold Deposit in Duobaoshan Cu-Mo-Au metallogenic belt. (English)

Yongxin Gold Deposit is located in the southern part of Duobaoshan Cu-Mo-Au metallogenic belt. To understand the genesis of the deposit and provide exploration insights, a study was conducted on the rare earth elements, micro-elements, and isotopic composition of gold-bearing pyrite. The results indicate that the chemical composition of pyrite shows enrichment in light REEs and depletion in heavy REEs, with a right-sloping REE distribution pattern. The pyrite is enriched in high-field-strength elements such as U, Th, Zr, and Hf, and depleted in large-ion lithophile elements like Ba and Sr. Ratios such as w(Hf)/w(Sm), w(Nb)/w(La), and w(Th)/w(La) suggest that the ore-forming fluid contained more Cl than F. A negative Eu anomaly and the absence of a Ce anomaly indicate that the ore-forming fluid formed under reducing conditions. Ratios like w(Y)/w(Ho), w(Zr)/w(Hf), and w(Nb)/w(Ta) suggest that the mineralization process did not involve external hydrothermal fluids, nor did metasomatism occur, with the ore-forming fluid closely related to both mantle and crustal sources. The sulfur isotopic characteristics indicate that the ore-forming materials originated from deeper sources. Genetic indicators such as w(Co)/w(Ni) and w(Fe)/w(S＋As) suggest that the deposit is of a meso-epithermal volcanic hydrothermal origin. Based on the magmatic origin, tectonic setting, diagenesis-mineralization age, metallogenic process, geochemical characteristics, and the main features of representative gold deposits in the region, it is concluded that Yongxin Gold Deposit belongs to a porphyry metallogenic system, forming during the Early Cretaceous as a meso-epithermal, relatively Cl-rich, weakly reducing gold deposit. [ABSTRACT FROM AUTHOR]

永新金矿床位于多宝山铜钼金成矿带南部, 为了揭示矿床的成因和找矿信息, 对载金矿物黄铁矿进行了稀土元素、微量元素和同位素等研究。研究结果表明, 其化学成分特征为: 稀土元素整体呈轻稀土元素富集、重稀土元素亏损, 右倾型稀土元素配分模式, 富集U、Th、Zr 和 Hf 高场强元素, 亏损 Ba 和 Sr 大离子亲石元素。w(Hf)/w(Sm) 值、w(Nb)/w(La) 值和 w(Th)/w(La) 值等反映成矿流体含 Cl 多于 F; 负Eu异常, 无 Ce 异常, 表明成矿流体形成于还原环境; w(Y)/w(Ho) 值、w(Zr)/w(Hf) 值和 w(Nb)/w(Ta)值反映成矿过程没有混入外来热液物质, 未发生交代作用, 成矿流体与地幔和地壳关系密切; 硫同位素特征表明成矿物质来源较深; w(Co)/w(Ni) 值和 w(Fe)/w(S＋As) 值等成因标型特征反映该矿床为中浅成火山热液成因。结合岩浆成因、构造背景、成岩-成矿时代、成矿作用、地球化学特征和本区域代表性金矿床主要特征认为, 该矿床属斑岩成矿系统, 为早白垩世形成的中浅成相对含 Cl 弱还原性金矿床。 [ABSTRACT FROM AUTHOR]

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