内蒙古中部大青山北西乌兰不浪紫苏斜长麻粒岩锆石U-Pb年龄  

U-Pb Ages of zircons from the Xi Ulanbulang hypersthene-plagioclase granulite in the North Daqing Mountains, Central Inner Mongolia

作　　者：张玉清[1] 王弢[1] 贾和义[1] 张志祥[1] 

机构地区：[1]内蒙古自治区地质调查院,内蒙古呼和浩特010020

出　　处：《中国地质》2003年第4期394-399,共6页Geology in China

基　　金：国土资源部区域地质大调查项目(20001300008051)资助。

摘　　要：内蒙古西乌兰不浪北紫苏斜长麻粒岩是1∶5万石兰哈达幅和1∶25万白云鄂博幅从加里东期斜长花岗岩和华力西期花岗闪长岩中解体出来的古老花岗质侵入体。通过对紫苏斜长麻粒岩进行单颗粒锆石U-Pb法年龄测定,获得不一致线与谐和线上、下交点年龄分别为(2511.4±4.9)Ma和(818±159)Ma。结合区调成果认为(2511.4±4.9)Ma年龄代表古老花岗岩侵入体上侵就位时代,(818±159)Ma代表后期叠加变形变质热事件时代。这两组年龄为大青山中段地壳演化提供了直接证据。The Xi Ulanbulang hypersthene-plagioclase granulite in central Inner Mongolia is regarded as an old granitic intrusion separated from the Caledonian plagiogranite and Variscan granodiorte, as has been determined by regional surveys of the 1∶50 000 and 1∶250 000 Shilanhada Sheet and Bayan Obo sheet. Single-zircon U-Pb dating of the hypersthene-plagioclase granulite gave discordia and concordia upper and lower intercept ages of (2 511.4±4.9) Ma and (818±159) Ma respectively. These ages, combined with the results of regional survey, suggest that the former age represents the age of emplacement of the older granitic intrusion; while the latter represents the age of the superimposed deformational-metamorphic thermal event in the late stage .The two ages give direct evidence for crustal evolution in the Central Daqing Mountains.

关 键 词：紫苏斜长麻粒岩 锆石 U-PB年龄 新太古代 

分 类 号：P597[天文地球—地球化学]