白云鄂博巨型REE-Nb-Fe矿区矽卡岩化时代：单颗粒金云母Rb-Sr法定年  

Skarnization age in the giant Bayan Obo REE-Nb-Fe ore district,Inner Mongolia,China:Rb-Sr isochrone dating on single-grain phiogopite.

作　　者：杨奎锋[1] 范宏瑞[1] 胡芳芳[1] 李向辉[1] 柳建勇[2] 赵永岗[2] 刘爽[1] 王凯怡[1] 

机构地区：[1]中国科学院地质与地球物理研究所矿产资源研究重点实验室,北京100029 [2]包头钢铁(集团)公司白云鄂博铁矿,包头014080

出　　处：《岩石学报》2007年第5期1018-1022,共5页Acta Petrologica Sinica

基　　金：国家自然科学基金项目(40472057);国家重点基础研究发展规划项目(2006CB403503)资助

摘　　要：内蒙古白云鄂博REE-Nb-Fe矿是目前世界上最大的稀土矿床。在白云鄂博东矿体的东南侧,分布有大面积的晚古生代花岗岩。花岗岩与赋矿白云岩(H_8)呈直接的侵入接触关系,接触带发育强烈的矽卡岩化和小型铁矿化。我们在东矿采坑南侧22线1598m平台北倾探矿钻孔650～660m岩芯段,首次发现两段矽卡岩化蚀变带。对矽卡岩中的金云母进行超低本底Rb-Sr法定年,获得309±12Ma年龄。结合矽卡岩与矿体的侵入接触关系,可以认为,晚古生代花岗岩虽已深入到矿体下部,但其侵位时间应晚于矿区最后一期强烈的稀土矿化事件,它对白云鄂博矿床来说只是一次后期破矿的构造—岩浆活动。The giant Bayan Obo REE-Nb-Fe mine is currently the largest REE deposit in the world. A large area late Paleozoic granitoids are distributed in the southeast of east open pit of the mine. The granitoids intruded directly into the ore-bearing dolomite （Hs ）, and produced intense skarnization. Moreover, at 650 -660m of the drill core on 22 line and 1598m level flat in the south of east open pit, we firstly found skarnization rocks. Single grain and low background Rb-Sr isochrone dating on phlogopite in skarn gives 309 - 12Ma. Considering the intruded contacting relationship, the late Paleozoic granitoids, already extended to the under part of REE ore bodies, must be posterior to the latest intense REE mineralization, and is only a destructive tectonic and magmatic activity.

关 键 词：矽卡岩 Rb-Sr法定年 晚古生代花岗岩 REE-Nb-Fe矿床 白云鄂博 

分 类 号：P597.3[天文地球—地球化学]