内蒙浩尧尔忽洞金矿流体包裹体和矿床成因研究

STUDY ON FLUID INCLUSIONS AND GENETIC TYPE OF HAOYAOERHUDONG GOLD DEPOSIT,INNER MONGOLIA

内蒙浩尧尔忽洞金矿中比鲁特岩组一、二岩性段是主要的赋矿层位,岩石类型有炭质变粉砂岩、粉砂质板岩、炭质板岩和千枚岩等.该组中Au含量是地壳丰度值的7.14倍,且碳含量较高,介于1％ ～7％之间.矿化过程分为4个阶段：早期石英脉阶段包裹体均一温度245.2～323.3℃,石英-黄铁矿阶段均一温度为236.9 ～317.5℃,石英-多金属硫化物阶段均一温度231.7 ～324.5℃,石英-碳酸盐阶段均一温度187.6 ～312.9℃.激光拉曼显微探针分析结果显示,气液两相包裹体中液相成分主要为H2O,含少量CO2;气相成分主要为CO2,含少量的CH4和N2.氢、氧同位素特征表明成矿流体与岩浆热液关系密切.气相成分中大量有机成分可能是岩浆上侵促使地层中有机质发生热降解而生成的.矿床类型属于黑色岩系型金矿,与中亚成矿带的黑色岩系型金矿具有很高的可比性.

The first and second members of Bilute formation are the major ore-bearing horizons in Haoyaoerhudong gold deposit. The rock types contain carbonaceous meta-siltstone, silty slate, carbonaceous slate and phyllite, etc. Au content is 7.14 times of the crustal abundance in the formation and the carbon content is higher, with values of 1% to 7%. The metallogenic process can be divided into four stages： The homogenization temperature of fluid inclusions in the early quartz vein stage and the quartz-pyrite stage are from 245.2 to 323.3 and from 236.9 to 317.5℃ respectively; And the homogenization temperature are between 231.7 and 324.5℃ in the quartzpolymetallic sulfide stage andbetween 187.6 and 312. 9℃ in the quartz-carbonate stage. According to the results of laser raman microprobe, The main liquid phase composition are H20 with minor amounts of CO2 and the main gas phase composition are CO2 with minor amounts of CH4 and N2 in fluid inclusions. Hydrogen and oxygen isotopic features indicate that the ore-forming fluid is closely related to magmatic hydrothermal. A large number of organic compounds in the gas phase composition may be generated in the thermal degradation of organic matter prompted by the magma invasion. The deposit type belongs to the black rock-hosted gold, with a high comparability of that in central Asian metallogenic belt.