大兴安岭北部金矿床地质特征、成因及构造背景  

CHARACTERISTICS OF GEOLOGICAL,GENESIS AND STRUCTURAL BACKGROUND OF GOLD DEPOSITS IN THE NORTH DAXING′ANLING,NORTHEAST CHINA

作　　者：宋丙剑 王晓勇[2] 马靖[2] 

机构地区：[1]武警警种学院,北京昌平102202 [2]武警黄金第三支队,黑龙江哈尔滨150069

出　　处：《矿物岩石》2015年第2期15-24,共10页Mineralogy and Petrology

基　　金：中国地质调查局地质调查项目(1212O10786005)

摘　　要：大兴安岭北部毗邻蒙古-鄂霍茨克造山带,是中国东北重要的金、银、铅、锌、铜、钼多金属成矿区之一。近年来发现了砂宝斯、宝兴沟、老沟、砂宝斯林场、小伊诺盖沟等金矿床和一些金矿点,它们严格受NEE向漠河推覆构造带和NNE向额尔古纳河韧性剪切带控制,矿体常赋存于其次级张扭性断裂构造中。矿石中硫化物以黄铁矿为主,含量≤3%,为少金属硫化物矿石。矿石中黄铁矿等的δ34S值为-8.5‰^+7.8‰;成矿流体的δ18 O值为-4.5‰^+13.9‰,δD值为-105‰^-89‰;铅同位素表现出造山带铅同位素的特征。流体包裹体类型有气液两相、含CO2三相和纯CO2包裹体等3种。包裹体气相成分主要为CO2,H2O,CH4和N2,总体上属CO2-H2O-N2±CH4±H2S±H2±CO体系。流体包裹体的盐度平均为5.0%~7.0%,密度平均为0.69g/cm3~0.86g/cm3,属低盐度、低密度流体;均一温度为225.9℃~295.2℃,属中低温热液矿床;成矿压力平均为65MPa^93MPa,成矿深度平均为6.5km^8.0km。上述金矿床的地质-地球化学特征与世界造山型金矿类似,应属造山型,形成于蒙古-鄂霍茨克陆-陆碰撞造山环境,深部成矿流体和浅层的大气降水混合,在适宜的地球化学环境下形成了以中成、低温为主的金矿。Gold deposits of the Shabaosi, Baoxinggou, Laogou, Shabaosilinchang and Xiaoyinuogaigou have been recently found in northern Daxinganling along the Mongolia-Okhotsk Orogen,which is an important Au-Ag-Pb-Zn-Mo-polymetal metallogenic province in northeast China. These gold deposits are controlled by NEE-trending Mohe nappe strueture zones and NNE-trending Ergunahe ductile shear zones with the ore bodies hosted in the subsidiary fractures. Ores in the gold deposits contain poorly developed sulfides （≤3%, mainly pyrite）. The isotopic components of S,Pb, H and O from typical ores range from --8.5%0 to 7.8%o ,~180 values of ore-forming fluids from -4. 5%0 to 13.9‰,while δD form -105‰ to -89‰. Lead isotopes of ores have characteristics of the orogenic belt. Fluid inclusions in quartz can be classified into aqueous two-phase, CO2-bearing three-phase and pure CO2 types. The compositions of liquid in the inclusions were CO2, H2 O, CH4 and N2 and the ore-forming fluids belong to CO2-H2O-N2±CH4±H2 S±H2±CO system with low salinity （average 5.0-7.0%） and low density （average 0. 69 g/cm^3-0.86 g/ cm^3）. The homogenization temperature of fluid inclusions ranges from 225.9℃-295.2℃,belonging to mesothermal type. The ore：forming pressures of the deposits are 65 MPa-93 MPa, corresponding to depth of 6.5 km-8. 0 km. Their geological and geochemical features were similar to those Of orogenic gold deposits worldwide, and could be assigned to the orogenic type. It is considered that the formation of deposit is related to Mongolia-Okhotsk orogeny.

关 键 词：金矿床 地质特征 地球化学 成因类型 构造背景 大兴安岭北部 

分 类 号：P618.51[天文地球—矿床学]