坦桑尼亚太古宙绿岩带中BIF型金矿床的勘查标志——以Maheiga金矿床为例  

The BIF Gold Mine Exploration Criteria in Greenstone Belt of Archaean,Tazania:Taking Maheiga Gold Mine for Example

作　　者：杨东潮[1] 白德胜[1] 曹琼[2] 

机构地区：[1]河南省地质矿产勘查开发局第二地质矿产调查院,河南郑州450003 [2]河南理工大学资源环境学院,河南焦作454003

出　　处：《黄金科学技术》2013年第4期1-8,共8页Gold Science and Technology

基　　金：国土资源部国际科技合作项目"坦桑尼亚Mwamola地区Maheiga金矿详查"(编号:2010-188)资助

摘　　要：Maheiga金矿产于坦桑尼亚克拉通的太古宙Kahama绿岩带尼安萨(Nyanzian)群上下段接触带附近,是受层间剪切破碎带控制的隐伏条带状含铁建造型金矿床。区内褶皱发育,岩浆活动强烈。硅化、绿泥石化、黄铁矿化和褐铁矿化与金矿关系密切。矿床可分为3期5个成矿阶段,自然金―石英―多金属硫化物阶段为主要的成矿阶段。赋矿的磁铁石英岩和金矿石的磁化率(达342×10-3~1 477×10-3SI)与背景岩石变凝灰质砂岩、变质凝灰岩及绿泥石化千枚岩(仅0.16×10-3~1.26×10-3SI)差异明显;条带状含铁建造、含铁建造金矿石和变凝灰质砂岩的视极化率分别为8.66×10-2、2.18×10-2和0.48×10-2,视电阻率分别为220、280和380Ω·m,前者具明显的相对"低阻、高极化"物性特征。化探异常元素组合为Au、As、Sb、Ag、Hg、Pb和Ba。矿石中各元素的浓集克拉克值由大到小依次为Au-As-Sb-W-Pb-B-Ag-Zn-Sn-Mo-Bi-Cu-Cr-Hg,其中,Au、As和Sb在条带状磁铁石英岩中富集明显,与成矿有利层位为条带状磁铁石英岩的特征相一致,是深部寻找金盲矿体的主要指示元素。根据上述特征,确定了该类型金矿床的勘查标志。Maheiga gold mine is a concealed BIF gold deposit,which is produced in the contact zone of upper and lower sections of the Nyanzian group in Archaean Kahama greenstone belt of＂ the Tanzania Craton,and controlled by interlaminar shear zone.Folds in the region are developed,and the magmatic activities were strong.Silicification, chlorite,pyritized and limonitization have close relationship with gold ore.The deposit can be divided into three periods and five mineralization stages.The main mineralization stage is natural gold-quartz-polymetallic sulphides stage.Mineral enriched in magnetite quartzite and gold ore,the magnetic susceptibility of which （up to 342~10 3 1 477~10-3 SI） has a significant difference with the background rocks （only 0.16x10-^-1.26~10 3 SI）,the background rocks are tuffaceous sandstone,metamorphic tuff, chlorite phyllite.Apparent chargeability of banded iron formation,gold ore iron formation and tuffaceous sandstone are 8.66x10-2,2.18~lO-2and 0.48~lO-2;apparent resistivity of them are 220,280 and 380 tl-m.The former has obvious physical characteristics of relatively＂low resistance and high polarization＂.The main geochemical anomaly element combination is Au,As,Sb,Ag,Hg anti Ba.The order of concentration Clark of elements in ore is Au-As-Sb-W-Pb-B-Ag-Zn-Sn-Mo-Bi-Cu-Cr-Hg.Au, As,Sb in the banded magnetite-quartzite enriched obviously,this is consistent with the characteristics that the favorable metallogenic layers banded magnetite quartzite.They are indicator elements for seeking deep goht blind orebodies.We brought forward the exploration criteria of BIF-type gold deposits, according to above characteristics of BIF.

关 键 词：BIF型金矿床 勘查标志 太古宙绿岩带 Maheiga金矿床 坦桑尼亚 

分 类 号：P618.51[天文地球—矿床学]