吉林夹皮沟金成矿带南东段金矿找矿远景评价

吉林夹皮沟成矿带金成矿作用与太古宇变质岩系、幔源岩浆活动、韧性剪切带密切相关.成矿流体以地幔流体为主,成矿物质主要来源于地幔,地幔活动形成的韧性剪切带及其伴生的次一级断裂构造不仅是成矿流体的运移通道,而且是矿体就位的有利空间.论述了新立屯-马家店、大朝阳沟地区具有金矿成矿的基本地质条件——太古宇变质岩系广泛分布,幔源岩浆、韧性-脆性构造活动强烈;金矿化体(石英脉)受韧性剪切带两侧的次一级断裂控制,伴随金矿化有黄铁矿化、黄铜矿化、方铅矿化及闪锌矿化等,金品位与金属硫化物含量呈正相关;与矿化关系密切的围岩蚀变是硅化(-钾长石化).金矿化、围岩蚀变特征与矿带内已知金矿床相似.找矿研究表明,新立屯矿化点深部具有较强烈的主成矿期热液活动,且围岩条件、构造条件适宜金矿成矿作用;马家店矿点、大朝阳沟地区的矿化点同样具有较大的成矿潜力.因此,夹皮沟成矿带南东部外围具有良好的成矿远景.

PROSPECTIVE VALUE OF THE SOUTHEAST JIAPIGOU GOLD MINERALIZATION BELT

Jiapigou Au mineralization belt is a large scale one.The wall rocks of gold deposits in the belt are metamorphic rocks of Archean and mantle derived granites,and the structures that control Au mineralization are large scale shear zone and faults accompanying ductile shear zone. The main Au mineralization occurred in 2455~2469 Ma and 180~90 Ma, corresponding to the peaks of mantle derived magmatic activities. The compositions of inclusions in the quartz form ore are rich in Na +,Mg 2+ ,SO 2- 4,CO 2,CH 4 and C 2H 4 .The f O 2 is low while f CO 2 is high.The values of isotopic compositions for ore are respectively δ 32 S=-0 73, δ 13 C= -4 83 , 87 Sr/ 86 Sr=0.703, ε Nd (t) =8.4,illustrating that the ore forming materials come from the mantle. The fluids of Au mineralization have three characteristics:(1)The fluids for two main mineralization epochs come from the same source .(2)The isotopic compositions of fluid have well homogeneity,showing that the volume of fluid source is large.(3)The fluids are C H O system and rich in CO 2,CH 4 and C 2H 4,the value of water/rock is high.The characteristics of fluid are the same as those of the fluids from mantle. Xinlitun Majiadian and Dachaoyanggou areas have the basic ore forming conditions which are Archaen metamorphic rocks, mantle derived magmas and ductile brittle faults. In the areas,many Au mineralization places are discovered, such as Xinlitun, Majiadian, Nanshan etc. The Au quartz veins are controlled by faults near Jiapigou large scale ductile shear zone, and the wall rock alteration associated with Au mineralization are silicification and potash feldspathization. There are metal sulphides such as pyrite, chalcopyrite, galena and sphalerite in the Au quartz veins, and the gold grade changed with the quantity of metal sulphides. To summarize,the Au mineralization characteristics in the area are the same as those in Jiapigou Au belt.There are similar characteristics in Majiadian and Dachaoyanggou areas.So,the area of southeast Jiapigou Au mineralization belt is potential for prospecting.