内蒙古阿拉善庆格勒图黑云斜长片麻岩的单颗粒锆石U-Pb法年龄

The U-Pb Isotopic Dating Age of Single Zircon from Biotite Plagioclase Gneiss in the Qinggele Area,Alashan,Western Inner Mongolia

内蒙古阿拉善庆格勒图地区出露地层以片麻岩为主,夹斜长角闪岩。但其归属尚无确切的同位素年龄资料。本文最近获得的黑云斜长片麻岩的单颗粒锆石U-Pb法年龄为1826±13 Ma,这是迄今获得的较为可靠的直接测年数据。结合前人研究成果,提出该区出露的主要变质岩石——黑云斜长片麻岩的形成时代应为古元古代。

Tectonically,the Qinggele area,Alashan,westarn Inner Mongolia is located in the margin of North China Platform.The outcropped stratum,which is named as the Alashan group by predecessors,in the Qinggele area is mainly composed of gneiss,with minor plagioclase amphibolite.Due to the lack of isotopic dating ages,this series of rocks was not clearly understood.The individual zircon U-Pb isotopic dating method has been applied to date the age of biotite plagioclase gneiss in this study with the age of 1826 ± 13 Ma.Till now,this age is the most reliable and direct isotopic dating age obtained for the metamorphic rocks in the region.With the combination of previous results,it is proposed that the main outcropped metamorphic rock-biotite plagioclase gneiss in the region research was formed in early Proterozoic.