新疆阿尔泰托莫尔特铁(锰)矿床成矿流体研究

A study of ore-forming fluids of Tuomoerte Fe-(Mn) deposit in Altay,Xinjiang

托莫尔特铁（锰）矿床赋存于上志留统—下泥盆统康布铁堡组上亚组变质火山-沉积岩系中。矿床的形成经历了火山沉积期、岩浆热液叠加改造期和区域变质期,火山沉积期为铁和锰主要成矿期。火山沉积期石英中流体包裹体类型以气液两相包裹体为主,均一温度集中于170~300℃,峰值为190℃,流体的w（NaCleq）为3.23%~22.71%,密度为0.62~1.09 g/cm3,气相和液相成分表明成矿流体富含Na＋、Cl-和H2O,为中-低温、中-低盐度、中-低密度的H2O-NaCl体系。区域变质期石英中以发育含液体CO2包裹体为特征,完全均一温度介于210~523℃,w（NaCleq）为4.80%~11.33%,密度为0.85~1.05 g/cm3,气相和液相成分表明流体富含Na＋、Cl-、SO24-、CO2、CH4、C2H6和N2,显示成矿流体为中-高温、中-低盐度、中-低密度的H2O-CO2-CH4-N2-NaCl体系。氢和氧同位素特征表明,火山沉积期成矿流体为海水和岩浆水的混合,区域变质期成矿流体主要为变质水混合深循环的大气降水。

The Tuomoerte Fe-（Mn） deposit occurs in metavolcanic-sedimentary sequence within the upper subforma- tion of Upper Silurian-Lower Devonian Kangbutiebao Formation. Field evidence and petrographic observation indicate three periods of metallogenesis, i.e., volcano-sedimentation, magmatic-hydrothermal activity and re- gional metamorphism. The majority of the Fe-Mn metallogenic activity occurred during the volcano-sedimenta- tion period. The homogenization temperatures of the liquid inclusions in quartz of the volcano-sedimentation pe- riod are concentrated between 17012 and 30012, with a peak temperature of 19012, the salinities range from 3.23% to 22.71%, and the densities range from 0.62 to 1.09 g/cm3 Th ,inclusions in this period show that the ore-forming fluid was rich in Na＋ , Cl- and H2O, indicating that the ore- forming fluid was of moderate-low temperature, moderate-low salinity and moderate-low density, belonging to the HzO-NaCl system. In regional metamorphism period, it was characterized by CO2-bearing three-phase fluid inclusions in quartz. Homogenization temperatures of this type of fluid inclusions vary from 210℃ to 523℃, salinities range from 4.80 % to 11.33 %, and densities range from 0.85 to 1.05 g/cm3. The vapor and liquid compositions of fluid inclusions in the regional metamorphism period show that the ore-forming fluid was rich in Na＋, Cl-, SO4^2-, CO2, CH4, C2H6 and N2 and characterized by moderate-high temperature, moderate-low salinity and moderate-low density, belonging to the H2O-CO2-CH4-Na-NaCl system. The oxygen and hydrogen isotopic characteristics of quartz imply that the ore-forming fluid in the volcano-sedimentation period was derived from mixed magmatic water and seawater, whereas the ore-forming fluid in the regional metamorphism period was derived from mixed metamorphic water and meteoric water.