甘肃敦煌太古宙英云闪长岩：单颗粒锆石U—Pb年龄和Nd同位素

ARCHEAN TONALITE IN THE DUNHUANG,GANSU PROVINCE:AGE FROM THE U-Pb SINGLE ZIRCON AND Nd ISOTOPE

甘肃敦煌地块是塔里木地台早前寒武纪岩石广泛出露区之一，但是否出露太古宙岩石长期存在着争议。本文对该区广泛出露的英云冈长岩单锆石U－Pb年龄和Sm－Nd同位素研究，获得了2．67Ga的锆石U－Pb年龄和268Ga的Nd模式年龄。证实了敦煌地块存在太古宙基底。同时反映新太古代是该区重要的造壳事件，英云闪长岩派生于亏损地幔。

Dunhuang block is one of the largest exprecambrian rocks in the TarimPlatform It has been disputing if the Archean rocks occur. U - Pb single zircon from theShibaocheng tonalite in the Dunhuang block yields Nanrchean age of 267O ± 12 Ma, suggestingthat an Archean basement occur. A whole rock sarnple from the tonalite yields Nd value of 4. 28and Nd medel age Of 2680 Ma, simlar to the age from the U - Pb, which implies that the tonalite derived from a depleted mantle.