额尔古纳成矿带西北部金矿床流体包裹体研究  

Fluid inclusion study on gold deposits in northwestern Erguna metallogenic belt,China

作　　者：武广[1] 孙丰月[2] 赵财胜[3] 丁清峰[2] 王力[2] 

机构地区：[1]中国科学院广州地球化学研究所成矿动力学重点实验室,广州510640 [2]吉林大学地球科学学院,长春130061 [3]中国地质调查局发展研究中心,北京100083

出　　处：《岩石学报》2007年第9期2227-2240,共14页Acta Petrologica Sinica

基　　金：国家自然科学基金项目(40772055);中国博士后科学基金项目(20070410850);国家973计划项目(2006CB403503和2006CB403508课题)

摘　　要：额尔古纳成矿带是中国东北重要的银、铅、锌、铜、钼多金属成矿带,它位于蒙古-鄂霍茨克造山带的东南缘。最近,额尔古纳成矿带西北部发现了砂宝斯、老沟、小伊诺盖沟等金矿床和一些金矿点。这些金矿受洛古河-二根河韧性剪切带和额尔古纳河韧性剪切带控制,矿体常赋存于韧性剪切带的次级张扭性断裂构造中。矿石中硫化物含量一般不超过3%,且硫化物以黄铁矿为主。流体包裹体有气液两相、含 CO_2三相和纯 CO_2包裹体3种类型。气相成分以 H_2O、CO_2和 N_2为主,含少量H_2S、CH_4为特征。流体包裹体的盐度低,介于2.06～8.54%NaCl eqv 之间。老沟金矿流体包裹体均一温度介于171℃～452℃之间,平均295℃,小伊诺盖沟金矿包裹体均一温度为169℃～493℃,平均亦为295℃,均属中温热液矿床。老沟金矿成矿压力为61～122MPa,平均82MPa;小伊诺盖沟金矿成矿压力为38～172MPa,平均93MPa。前者成矿深度介于6～9km,平均7km;后者成矿深度为4～11km,平均8km。上述金矿床的地质-地球化学特征与世界造山型金矿类似,形成于蒙古-中朝板块与西伯利亚板块之间的陆-陆碰撞造山作用。A lot of gold deposits and occurrences, including the Shabaosi, Laogou and Xiaoyinuogaigou deposits, have been recently found in northwestern Erguna metallogenic belt along the southeastern margin of the Mongol-Okhotsk Orogen, which is an important Ag-Pb-Zn-Mo-polymetal metallogenic belt in Northeast China. These Au deposits are strictly controlled by two ductile shear zones, i. e. the E-W-trending Luoguhe-Ergenhe and NNE-trending Ergunahe ductile shear zones. Orebodies are hosted in subsidiary fractures of these two ductile shear zones. Ores of these gold deposits contain ≤3% of sulphides dominated by pyrite. Fluid inclusions in quartz crystals can be classified into aqueous two-phase, CO2-bearing three-phase and pure CO2 types. The bubbles （vapor-phase） are mainly composed of H2O, CO2 and N2 , with minor of H2S, CH4. The salinities range from 2.06% to 8.54% NaC1 eqv. Homogenization temperatures for the Laogou and the Xiaoyinuogaigou gold deposits range from 171℃ to 452℃, 169℃ to 493℃, respectively, suggesting that both deposits are mesothermal. The ore-forming pressures of the Laogou and the Xiaoyinuogaigou deposits are 61 - 122MPa with average of 82MPa and 38 - 172MPa with average of 93MPa, corresponding to depths of 6 -9km and 4 - 1 lkm, with averages of 7km and 8km, respectively. The pressure fluctuations may be due to faulting. Hence the geological and geochemical features of the deposits are similar to those of orogenic gold deposits worldwide. The origin of these gold deposits may be related to Mesozoic collisional orogeny between the Siberia and Mongolia-Sinokorea continents.

关 键 词：流体包裹体 造山型金矿 额尔古纳成矿带 蒙古-鄂霍茨克造山带 中国东北 

分 类 号：P618.51[天文地球—矿床学]