College of Earth Sciences��Jilin University��Changchun 130061��China

The authors studied the detrital zircon aging from the Upper Paleozoic Zhesi Formation in southern Songliao block�� The U--Pb dating of detrital zircon from the Zhesi Formation by LA--ICP MS technique showed 4 major age groups: 263 �� 378 Ma ( peak age as 274 Ma) ; 405 �� 547 Ma ( peak age 515 Ma) ; 660 �� 974 Ma ( peak age 923 Ma) ; and the fourth group including 1 165 Ma��1 369 Ma��1 476 Ma and 1 517 Ma�� The youngest zircon age of 263 ± 2 Ma represents the lower limit of the deposition age of the Zhesi Formation��in which the peak age 274 Ma is consistented with the ages of the surrounding volcanic rocks and island arc magmatic rocks in Dashizhai Formation�� The peak age 515 Ma showed the age of the Pan-African metamorphic complex in NE China�� The rest old ages reflect the information of basement in Songliao block�� Considered the ages of the detrital zircon aging of the Upper Paleozoic strata such as the Tumenling Formation in northern Songliao block��Benbatu Formation in western Songliao block and Heilongong Formation in eastern Songliao block��it is suggested that the Songliao block had Archean and Proterozoic metamorphic basement��providing rich source of material for the Paleozoic sediments�� The fact indicats that the Songliao block was more likely a stable micro continental block rather than long-term activities of orogenic belt��