新疆黄山东铜镍硫化物矿床Re-Os同位素测定及其地球动力学意义  

Re-Os Dating of Cu-Ni Sulfide Ores from Huangshandong Deposit in Xinjiang and Its Geodynamic Significance

作　　者：毛景文[1] 杨建民[1] 屈文俊[2] 杜安道[2] 王志良[1] 韩春明[1] 

机构地区：[1]中国地质科学院矿产资源研究所 [2]国家地质实验测试中心,北京100037

出　　处：《矿床地质》2002年第4期323-330,共8页Mineral Deposits

基　　金：自然科学基金项目 (编号 :40 172 0 2 1);地质大调查项目 (DKD990 2 0 0 1);国家重点基础研究发展规划项目 (G19990 43 2 0 16)的部分研究成果

摘　　要：通过对黄山东铜镍硫化物矿石的Re_Os同位素测年 ,获得等时线年龄数据为 (2 82± 2 0 )Ma。该数据表明产于东天山的这套铜镍硫化物矿床及其相关的镁铁质_超镁铁质岩并非泥盆纪_早石炭世洋底的蛇绿岩建造和相关成矿系统 ,它晚于岛弧演化阶段 ,出现于碰撞后的伸展环境 ,与区内广泛发育的造山型金矿和浅成低温热液型金矿为同一时期形成。其等时线187Os/188Os初始比值为 0 .2 4± 0 .0 4 ,γOs值平均为 99。A group of mafic_ultramafic plutons in East Tianshan Mountain intruded into the Lower Carboniferous turbudite of Gandun Formation and Middle Carboniferous basic volcanic rocks of Wutongwozi Formation (or Qi'e_shan Formation). Some of them are spatially and temporally associated with Cu_Ni sulfide deposits. Heated argument exists on the genesis of the suite of the mafic_altramafic rocks: some consider them to be post orogenic intrusions, while others hold that they should be ophiolites; therefore, the origin of the mineralization is still a problem of much controversy. The authors chose seven different types of Cu_Ni sulfide ore samples from the representative Huangshandong deposit to conduct Re_Os dating. The seven measured points defined an isochronal age of 282±20 Ma(2 σ ) with an initial 187 Os/ 188 Os of 0.24±0.04(MSWD) and a correction coefficient of 0.9987 . The data suggest that the ore_forming age is younger than that of Early Carboniferous turbudite and Middle Carboniferous volcanic rocks which host the mafic_ultramafic rock intrusions, corresponding to the extension stage. They share the same mineralization time with the extensively developed orogenic gold and epithermal gold deposits and are younger than the porphyry copper system in the same area. Their initial 187 Os/ 188 Os value of 0.25±0.04 and mean γ Os value of 99 indicate that abundant crustal substances were mixed with the Cu_Ni sulfide ore system during their formation process.

关 键 词：地球动力学 地球化学 同位素测年 二叠纪 铜镍硫化物矿床 铼 新疆 锇 

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