吉林大黑山斑岩型钼矿床流体包裹体研究

STUDY OF FLUID INCLUSION FROM DAHEISHAN Mo DEPOSIT IN JILIN PROVINCE

吉林大黑山钼矿床位于兴蒙造山带东缘,为一典型的超大型斑岩型钼矿床,矿体主要产于花岗闪长斑岩岩体内。矿床的成矿阶段包括石英-黄铁矿、石英-磁黄铁矿-黄铁矿、石英-辉钼矿、石英-多金属硫化物和石英-碳酸盐化5个阶段。流体包裹体研究结果表明:流体包裹体的类型主要为气液两相包裹体,其次为纯气相和纯液相包裹体,还有少量含子矿物的三相包裹体。流体包裹体的均一温度为160℃~417.6℃,盐度为4.48%~41.05%。从早阶段到晚阶段成矿流体的温度具有规律的演化,均一温度分别为400℃~417.6℃,340℃~378℃,230℃~340℃,218℃,160℃~185℃。其中含子矿物三相包裹体均一温度为320℃~405℃,盐度为34.43%~41.05%,密度为0.94g/cm3~1.03g/cm3;气液两相包裹体均一温度为160℃~417.6℃,盐度为4.48%~13.55%,密度为0.62g/cm3~0.97g/cm3。激光拉曼光谱分析表明,气液两相包裹体成分主要为CO2。氢氧同位素研究结果显示,该矿床的成矿流体主要以岩浆水为主,后期有大气水的加入。流体沸腾是大黑山钼矿床成矿的重要机制。

The Daheishan molybdenite deposit,occurred along the eastern edge of the Xing-Meng orogenic belt of norhteast China,is a porphyry-type Mo deposit and the ore bodies are mainly hos- ted in granodiorite-porphyry. The hydrothermal ore-forming processes can be divided into five sta- ges： quartz-pyrite stage, quartz-pyrrhotite-pyrite stage, quartz- molybdenite stage, quartz-poly- metallic sulfides stage, and quartz-carbonate, respectively. Petrographic observation shows that there are mainly gas liquid biphase （Lq-V） inclusions,some pure volatile （V） and pure liquid in- clusions （L） ,and minor daughter minerals bearing polyphase inclusions （L-FV＋S）. The homoge- nization temperatures of ore-forming fluid regularly evolve from the early stage to the late stage. The homogenization temperature ranges from 160 ~C to 417.6 ~C, salinities from 4. 48% to 41.05% ,respectively. The peak value of homogenization temperatures of different stages are 400 ~C^417.6 ~C,340 ~C--378 ~C,230 ~C^340 ~C,218 ~C,160 ~C^185 ~C,respectively,the tempera- ture of daughter mineral bearing inclusions are mainly in ranges of 320 ~C ~405 ~C ,34.43% 41.05 %, and 0.94 g/cm3 ~ 1.03 g/cm3 , respectively, and gas liquid biphase inclusions are mainly in ranges of 160 ~C^417.6 ~C,4.48%~13.55% ,and 0.62 g/cm3 ~0.97 g/cma ,respectively. La- ser Raman spectroscopy study of inclusions indicate that the gas components are COs. The analy- ses of oxygen and hydrogen isotopes indicate that the hydrothermal fluid is dominated by magmat- ic water with input of meteoric water in the later stage,and the mechanism for ore-metals precipi- tation is fluid-boiling.