西藏班公湖—怒江缝合带东段多金属矿床地质特征与时空分布

Geological characteristics and temporal and spatial distribution of polymetallic deposits in the eastern section of Bangonghu Nujiang River suture zone,Tibet

班公湖—怒江缝合带东段矿产资源丰富,成矿地质条件优越,成矿潜力巨大,由于交通条件较差,地质找矿工作程度较低,理论研究薄弱。基于前人研究及出波松多、白库、热昌、扎罗卡矿区等典型矿床勘查成果,通过对矿床成因类型、控矿因素、成岩成矿时代及岩浆岩等研究,确认成矿时代为早—中侏罗世燕山早期和早白垩世燕山晚期两个期次。矿床地质特征受地层、构造及燕山期岩浆岩的约束,铅锌多金属矿床以中低温热液充填-交代型为主,矿体赋存于层间破碎带或断层带内,少数为MVT型铅锌矿床,矿体呈囊状—似层状产出于碳酸盐岩地层中;金多金属矿床主要为中低温热液-构造破碎带蚀变岩型,矿体或金异常分布于侵入岩体外接触带附近发育的断裂构造上;Cr-Ni-Co-Pt-Fe矿床矿体赋存于燕山早期超基性岩脉及附近断裂带中。通过对区域成矿规律的总结,划分出唐古拉前陆复合盆地Cu-Au-Pb-Zn、丁青Cr-Ni-Co-Pt-Fe和冈底斯—念青唐古拉弧盆系Au-Cu-Ag-Pb-Zn三个成矿带,可以为该地区的进一步找矿工作提供参考。

There are rich mineral resources in the eastern section of Bangong Lake-Nujiang River suture zone,and the metallogenic geological condition is superior with a great metallogenic potential.Due to the poor traffic condition,the degree of geological prospecting is lower and the theoretical research is relatively weak.On the basis of the previous studies and exploration result of typical deposits such as Bosongduo,Baiku,Rechang and Zaroka mining areas,through the study of the genetic type,ore controlling factor,diagenetic and metallogenic age and magmatic rock of the deposit,it is confirmed that there are two stages of metallogenic period,Early Yanshan of early Middle Jurassic and Late Yanshan of Early Cretaceous.The geological characteristics of the deposit are constrained by the strata,structures and Yanshanian magmatic rocks.The lead-zinc polymetallic deposits are mainly of medium and low temperature hydrothermal filling metasomatic type.The orebody is hosted at the interlayer fracture zone or fault zone,and a few orebodies belong to MVT type lead-zinc deposit.The orebody is in saccate-stratoid shape and hosted at the carbonate rock stratum.The gold polymetallic deposits are mainly of medium low temperature hydrothermal structural alteration type,and the orebody and gold anomaly are distributed on the fault structure near the outer contact zone of the intrusive rock mass.The orebody of Cr-Ni-Co-Pt-Fe deposit is hosted in the Early Yanshanian ultrabasic dikes and near the fault zones.According to the summary of metallogenic regularity in the region,there are divided into three metallogenic belts,Cu-Au-Pb belt of Tanggula foreland composite basin,Dingqing Cr-Ni-Co-Pt-Fe belt and Au-Cu-Ag-Pb-Zn belt of Gangdise Nianqing Tanggula arc basin system.It can provide a guiding reference for the further exploration work in this area.