内蒙古浩尧尔忽洞金矿床流体包裹体特征

Fluid Inclusions of the Haoyaoerhudong Gold Deposit,Inner Mongolia

成矿流体来源与矿床成因的关系一直是矿床学研究的重点与难点。通过流体包裹体显微测温、原位激光拉曼光谱分析和包裹体化学成分分析,对浩尧尔忽洞金矿床成矿流体进行了较系统的研究。测试结果表明:该矿床石英中流体包裹体分为气液包裹体、气体包裹体、纯气体包裹体和纯液相包裹体四类。大部分流体包裹体均一为液相,少量气体包裹体均一为气相。伟晶岩脉石英流体包裹体均一温度峰值260～340℃,炭质板岩内含矿石英细脉内石英流体包裹体均一温度峰值260～380℃。石英流体包裹体气相成分为H2O、CO2、CH4、N2和C2H6,液相成分为Cl-、SO2-4、Na+、K+、Mg2+和Ca2+。炭质板岩中石英流体包裹体的氢氧同位素(δD H2O=-96.20‰～-82.80‰,δ18O H2O=3.97‰～7.93‰)靠近原生岩浆水。认为浩尧尔忽洞金矿床成矿与海西期岩浆活动有关,属中高温低压浅成热液矿床。

The origin of ore-forming fluids and its relationship to deposit genesis are critical and difficult issues in study of mineral deposits. Taking the Haoyao erhudong gold deposit as an example, this work analyzes the microthermomtric data, in-situ laser Raman spectroscopy and chemical composi- tion of fluid inclusions and describes the ore-forming fluids systematically. The results show that the fluid inclusions in quartz can be divided into four cate- gories： two-phase inclusions of vapor and liquid, gaseous inclusions, pure gaseous inclusions, and pure liquid inclusions. Most fluid inclusions are ho- mogenized into liquids, while few inclusions are homogenized to gas phase. The homogenization temperature of the fluid inclusions in ore-bearing quartz veins is 260℃ - 380℃, and 260℃ - 340℃ for carbonaceous slates. Raman spectra of the inclusions indicate that water is the dominant component with amount of CH4 , N2 , H2 S and CO2 in the gaseous phase and C1 - , SO^- , Na ＋ , K ＋ , Mg2 ＋ and Ca2 ＋ in the liquid phase of the inclusimls. Hydrogen and oxygen isotope compositions （δDH2O = -96.20‰ - -82.80‰ δ^18 OH2O = 3.97‰- 7.93‰） suggest a mixing event between magmatic water and formation water. It is inferred that the gold mineralization may relate with the Hereynian magmatic hydrothermal activity. This gold deposit is of the meso- hypothermal type gold, which formed under low pressure in the shallow crust.