Whether a series of Precambrian terranes in the Bainaiiomio-Jizhong orogenic belt belong to the same microplate has always been controversial,which restricts not only the understanding of Precambrian tectonic evolution of this orogenic belt but also the determination of the microplate'basement tectonic affinity.Field observation and zircon U-Pb chronology of the Tongdaogou Formation in the eastern part of the orogenic belt indicate that this formation is formed in 631～460Ma,and it is an important part of the Changchun-Yanji ophiolitic mélange belt.Age spectrum and εHf(t)values of Precambrian detrital zircons in the eastern and western sections of the Bainaimiao-Jizhong orogenic belt are very similar,i.e.,the zircon Hf isotope model ages and the whole rock Nd isotope ages of magmatic rocks in different areas of the orogenic belt have a good correlation,indicating that the Precambrian terranes involved in the orogenic belt belong to a same microplate.Furthermore,there are a large number of Pan African detrital zircons(～600Ma)in the Lower Paleozoic of the Bainaimiao-Jizhong orogenic belt,which have good coincidence with those of the Gondwana Continent.Combined with the Precambrian detrital zircon age spectrum and εHf(t)values,we believe that the microcontinent in the orogenic belt may come from Gondwana Continent,although its location is far away from other blocks(Erguna,Xing'an and Bureya-Jiamusi-Khanka blocks)in the eastern section of the Central Asian Orogenic belt.
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