Melt- and fluid-inclusions studies in the Wunugetushan porphyry Cu–Mo deposit, NE China: Constraints on the separation of Cu and Mo
Melt- and fluid-inclusions studies in the Wunugetushan porphyry Cu–Mo deposit, NE China: Constraints on the separation of Cu and Mo
复制标题
DOI：
10.3389/feart.2023.1121856
复制
发表时间：
2023-02
期刊：
影响因子：
12.8
通讯作者：
Wei Lu;Yuecheng Zhang;Jing-guo Du;Z. Song
中科院分区：
文献类型：
--
作者：
Wei Lu;Yuecheng Zhang;Jing-guo Du;Z. Song
乌奴格吐山大型斑岩型铜钼存款矿床产于中生代石英二长斑岩中，在空间上具有富钼核、富铜边的特征。本文通过对斑岩岩体中的熔融包裹体和不同阶段石英脉中的流体包裹体的研究，探讨了导致铜钼退耦的潜在参数。斑岩侵入体中的熔体包裹体具有71.7- 85.3wt.%的流纹质成分SiO2，1.9- 31.3ppm Cu和1.7- 2.6ppm Mo。热液活动经历了三个阶段：1）早期钼成矿作用发生在高温（543°C-560°C）和中等盐度（11.0- 17.3wt.%）的富CO2流体中NaCl当量），伴有黑云母化和少量的钾长石化; 2）晚期钼矿化，涉及高盐度（高达77.0 wt.% NaCl当量）中温（400°C-454°C）氧化流体，含钾长石化和少量绢云母化; 3）高盐度（高达45.6wt.%）的铜矿化阶段NaCl当量）贫CO2流体的特征是温度峰值在250°C-300°C和400°C-450°C，并伴有绢云母化和伊利石化。考虑到岩浆活动和氧化还原条件，pH值，流体成分和温度在热液流体阶段导致铜和钼分离的熔体铜/钼比可能的变化，我们发现，综合参数，包括增加的铜/钼比在残留熔体，氧化还原状态的变化和更酸性的热液流体环境确定两种金属的空间分离。
The Wunugetushan large porphyry Cu–Mo deposit in NE China is hosted by Mesozoic quartz monzonite porphyry and has a Mo-rich core and Cu-rich rim in space. In this paper, melt inclusions in porphyry intrusions and fluid inclusions in different-stage quartz veins were studied to explore potential parameters leading to Cu–Mo decoupling. Melt inclusions in porphyry intrusions have rhyolitic compositions of 71.7–85.3 wt.% SiO2, 1.9–31.3 ppm Cu and 1.7–2.6 ppm Mo. Hydrothermal activity occurred over three stages: 1) Early Mo mineralization at high temperatures (543°C–560°C) and CO2-rich fluids of intermediate salinity (11.0–17.3 wt.% NaCl equivalent), accompanied by biotitization and minor K-feldspathization; 2) Late Mo mineralization involving high-salinity (up to 77.0 wt.% NaCl equiv.) oxidized fluids at intermediate temperatures (400°C–454°C), with K-feldspathization and minor sericitization; 3) A Cu-mineralization stage with high-salinity (up to 45.6 wt.% NaCl equiv.) and CO2-barren fluids characterized by temperature peaks at 250°C–300°C and 400°C–450°C, accompanied by sericitization and illitization. Given possible variations in melt Cu/Mo ratios during magmatic activity and redox conditions, pH, fluid composition, and temperature during the hydrothermal-fluid stage led to the separation of Cu and Mo, we found that integrated parameters including increased Cu/Mo ratios in residual melt, variations in the redox state and more acidic environment of hydrothermal fluids determine spatial separation of two metals.