西藏邦铺钼(铜)多金属矿床隐爆角砾岩型矿体的发现及找矿意义  

Discovery of cryptoexplosive breccia-type ore bodies and its prospecting signifi⁃cance in Bangpu porphyry Mo(Cu)polymetallic deposit,Xizang

作　　者：王晓青 刘敏[3] WANG XiaoQing;LIU Min(School of Earth Science and Resources,Chang’an University,Xi’an 710054,Shaanxi,China;The 214 Geological Team of Shanxi Provincial Geological Prospecting Bureau Co.,Ltd.,Yuncheng 044000,Shanxi,China;MNR Key Laboratory of Metallogeny and Mineral Assessment,Institute of Mineral Resource,Chinese Academy of Geological Sciences,Beijing 100037,China)

机构地区：[1]长安大学地球科学与资源学院,陕西西安710054 [2]山西省地质勘查局214地质队有限公司,山西运城044000 [3]中国地质科学院矿产资源研究所自然资源部成矿作用与资源评价重点实验室,北京100037

出　　处：《矿床地质》2024年第5期1081-1094,共14页Mineral Deposits

基　　金：中国地质调查局地质调查项目(编号:DD20230336和DD20160124)联合资助。

摘　　要：邦铺矿床为冈底斯成矿带东段一个大型斑岩-矽卡岩Mo(Cu)多金属矿床,笔者首次在矿区东部发现了隐爆角砾岩型Pb-Zn-Cu矿体,从而进一步深化完善了邦铺斑岩成矿系统。通过详细的钻孔地质编录和岩相学研究发现,角砾岩筒在垂向上和横向上具有明显的分带性:从浅部到深部,从角砾岩筒中心到边部,依次为爆破相-震碎相-震裂相-裂隙相。角砾岩型Pb-Zn-Cu矿体主要赋存于角砾岩筒的裂隙相和震裂相中,少数赋存于震碎相和爆破相中。方铅矿和闪锌矿呈脉状、网脉状、条带状产于裂隙相的裂隙中和震裂相胶结物中。根据隐爆角砾岩中石英二长斑岩角砾LA-ICP-MS锆石U-Pb年龄((14.51±0.12)Ma)将隐爆角砾岩的形成年龄限定在~14 Ma,该年龄与斑岩矿体成矿年龄((14.67±0.54)Ma~(14.11±0.31)Ma)及矽卡岩矿体成矿年龄((13.93±0.87)Ma)相一致,统一的形成年龄说明隐爆角砾岩应为斑岩成矿系统的一部分。根据斑岩成矿系统中各类型矿体的分布规律,结合冈底期成矿带碰撞造山背景下后碰撞阶段斑岩成矿系统多中心复合成矿的特征,推测邦铺矿区东部很可能还存在另一个同期的斑岩型矿化中心。The Bangpu deposit is a large porphyry-skarn Mo(Cu)polymetallic deposit in the East of the Gangdese metallogenic Belt.Authors of this paper discovered the cryptoexplosive breccia and diatreme for the first time in the east of the Bangpu ore deposit.Detailed drill core logging and studies on petrography and mineragraphy show that,the cryptoexplosive breccia can be divided into four facies zones:From shallow to deep and from center to the edge of diatreme,explosive facies,shattering facies,cracking facies and fissure facies.Breccia-type Pb-Zn-Cu ore bodies mainly occur in the fissure facies and cracking facies of breccia,and a small amount is in the shattering facies and explosive facies.Galena and sphalerite occur as veins,stockworks and bands in the fissure and cement of breccias.The rock-forming age of cryptoexplosive breccia is about~14 Ma,constrained by LA-ICP-MS U-Pb age of zircon in quartz monzonite porphyry breccia(14.51±0.12)Ma.This consists with the metallogenic ages of porphyry ore bodies(14.67±0.54)Ma~(14.11±0.31)Ma and skarn ore bodies(13.93±0.87)Ma.Their spatiotemporal distribution relationship suggests that the three types of orebodies belong to one common porphyry mineralized system.According to the distribution of different types of ore bodies in the porphyry metallogenic system,combined with the polycentric complex mineralization of the Gangdese metallogenic belt in the Tibetan Plateau,the discovery of cryptoexplosive breccia-type ore body indicates that there is probably another porphyry mineralization center in the eastern part of the Bangpu ore district.

关 键 词：隐爆角砾岩 石英二长斑岩 斑岩-矽卡岩矿床 邦铺Mo(Cu)多金属矿床 

分 类 号：P618.65[天文地球—矿床学] P618.41[天文地球—地质学]