Geology and Geochemistry of K-feldspar Veins in Lamprophyre at the Zhenyuan Gold Deposit, Yunnan, Southwest China: Implications for Gold Mineralization
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引用次数: 0
Abstract
Lamprophyres typically appear in hydrothermal gold deposits. The relationship between lamprophyres and gold deposits is investigated widely. Some researchers suggest that the emplacement of lamprophyres triggers gold mineralization, whereas others hypothesize that the formation of lamprophyres increases the fertility of mantle sources and ore-forming fluids. K-feldspar veins, with ages between those of lamprophyres and gold deposits, appear in lamprophyres in Zhenyuan. Therefore, K-feldspar veins are ideal for investigating the relationship between lamprophyres and gold deposits. Phlogopite in K-feldspar veins has lower Mg#, Ni, and Cr contents and higher TiO2, Li, Ba, Sr, Sc, Zr, Nb, and Cs contents than phlogopite in lamprophyres. The in-situ Sr isotopic values of apatites (0.7063–0.7066) in K-feldspar veins are within the range for apatites (0.7064–0.7078) from lamprophyres. High large-ion lithophile element concentrations and low Nb and Ta concentrations in phlogopite from lamprophyres, in addition to high (87Sr/86Sr)i values of apatite (0.7064–0.7078), indicate that the magma parental to these phlogopite and apatite crystals is derived from an enriched mantle. K-feldspar veins are genetically correlated with lamprophyres, whereas sulfide mineral assemblage and trace element compositions of pyrite in K-feldspar veins suggest that K-feldspar veins in lamprophyres are not directly related to gold mineralization of the Zhenyuan deposit.
灯泡岩通常出现在热液金矿床中。人们对灯泡岩与金矿床之间的关系进行了广泛的研究。一些研究人员认为,灯泡岩的形成引发了金矿化,而另一些研究人员则假设,灯泡岩的形成增加了地幔源和成矿流体的肥度。镇沅地区的灯斑岩中出现了年龄介于灯斑岩和金矿床之间的钾长石脉。因此,K长石脉是研究灯泡岩与金矿床关系的理想材料。与灯斑岩中的辉石相比,K长石矿脉中的辉石Mg#、Ni和Cr含量较低,TiO2、Li、Ba、Sr、Sc、Zr、Nb和Cs含量较高。K长石矿脉中磷灰石的原位Sr同位素值(0.7063-0.7066)在灯辉石中磷灰石的范围内(0.7064-0.7078)。除了磷灰石的高(87Sr/86Sr)i 值(0.7064-0.7078)之外,来自灯泡岩的辉绿岩中大离子亲岩元素浓度高,Nb 和 Ta 浓度低,这表明这些辉绿岩和磷灰石晶体的母岩来自富集地幔。钾长石矿脉在遗传学上与灯斑岩相关,而钾长石矿脉中硫化物矿物组合和黄铁矿的微量元素组成表明,灯斑岩中的钾长石矿脉与镇沅矿床的金矿化没有直接关系。
期刊介绍:
Acta Geologica Sinica mainly reports the latest and most important achievements in the theoretical and basic research in geological sciences, together with new technologies, in China. Papers published involve various aspects of research concerning geosciences and related disciplines, such as stratigraphy, palaeontology, origin and history of the Earth, structural geology, tectonics, mineralogy, petrology, geochemistry, geophysics, geology of mineral deposits, hydrogeology, engineering geology, environmental geology, regional geology and new theories and technologies of geological exploration.