内蒙古朱拉扎嘎金矿矿床地质特征  

Geological Characteristics of the Zhulazhaga Gold Deposit in Inner Mongolia,China

作　　者：江思宏[1] 杨岳清[1] 聂凤军[1] 张建华[1] 刘妍[1] 李福喜[2] 贾林柱[2] 

机构地区：[1]中国地质科学院矿产资源研究所,北京100037 [2]内蒙古自治区国土资源勘查开发院,呼和浩特010020

出　　处：《矿床地质》2001年第3期234-242,共9页Mineral Deposits

基　　金：国土资源部定向基金科研项目"内蒙古朱拉扎嘎金矿床地质特征和找矿勘查标志研究"的资助

摘　　要：朱拉扎嘎金矿是华北地台北缘中新元古界地层中首次找到的大型金矿床 ,其独特的产出地质背景和矿床规模引起了国内外地质学界的关注。文章对该金矿床形成的地质背景进行了综述 ,对矿床的地质地球化学特征进行了较为系统的研究与总结 ,对矿床的形成过程及其成因进行了较为深入的探讨 ,并与国内外典型浅变质碎屑岩型金矿进行了对比。研究结果表明 ,尽管朱拉扎嘎金矿的容矿围岩为中元古界朱拉扎嘎毛道组浅变质碎屑岩 ,但是矿区内外大量产出的海西期侵入岩和金矿的主成矿年龄 [(2 75± 6 )Ma]等证据表明 ,朱拉扎嘎金矿的形成与海西晚期的构造_岩浆活动有着密切的联系。金矿的形成可能经历了两个阶段 ,即早期金在中元古代海盆地中预富集 ,之后 ,晚期地层中的金在岩浆热液作用下再次富集成矿。因此 。The orebodies in Zhulazhaga occur in the first lithologic unit of Middle Proterozoic Zhulazhagamaodao Formation (MPZF), which is mainly composed of a series of epimetamorphic sandstone and siltstone. With high concentration of gold, the first lithologic unit of MPZF became the ore source for the late ore_forming process. Controlled by the interstratified fracture zone, the orebodies mostly appear along the bedding, with the attitude similar to that of the strata. The primary ores are predominantly of altered rock type, and subordinately of quartz vein type. There are also some oxidized ores near the surface. The metallic minerals are mainly composed of pyrite, pyrrhotite and arsenopyrite. Most gold minerals appear as native gold and electrum. The fineness of the native gold changes from 900 to 922, averagely 911. The hydrothermal alterations associated with the ore_forming process are actinolitization, silicatization and carbonation. The ore_forming process might have experienced two metallogenetic epochs. In the early epoch, gold was initially concentrated in the strata, forming ore sources. During the late epoch, the ores were formed after the reconcentration of gold under the condition of hydrothermal activity. There are five metallogenetic periods in the late epoch, viz., ① silicification period, ② actinolitization period, ③ early period of sulfide formation, ④ late period of sulfide formation,and ⑤ carbonation period. Gold ores were mainly formed during the fourth period. Rb_Sr isochron dating reveals that the main ore_forming age is (275±6) Ma. This age is identical with the time of late Hercynian tecotonic_magmatic activities (LHTMC), which indicates that the ore_forming process was closely related to the LHTMC. The orebodies were mainly formed during the late hydrothermal transformation. A comparison with the typical gold deposits related to the epimetamorphic clastic rocks shows that the Zhulazhaga deposit is similar to them in orebody occurrence, ore_controlling structure, wall_rock alteratio

关 键 词：金矿床 矿源层 岩浆活动 矿床成因 内蒙古 矿床地质特征 

分 类 号：P618.51[天文地球—矿床学]