Nanpu Sag underwent two magmatic cycles and four episodic eruptions.Zircons of volcanic rocks from Nanpu Sag are dated by U-Pb SHRIMP

LA-ICPMS and Lu-Hf isotope method.The results indicate that more than 95% of zircons in the early magmatic cycle are formed by metamorphic recrystallization

with a big range of U-Pb age.It is explained that they are formed by collision granite crust in 1 800 Ma

which is caused by remelt and recycling process induced by collision between new crust of Middle and Neo-Archean(2 900～2 600 Ma)with palaeo-oceanic crust.In the middle to late magmatic cycle

zircons are formed by crystallization of mantle-derived magma overflow

and they contain magmatic zircon and rich captive crystal

which are helpful for chronology and isotope studies.Through those zircon ages

a vertical sequence of correspondent tectono-thermal events of the North China craton and Nanpu Sag is established.Moreover

the absolute ages of mantle-derived magma overflow and the related strata are calibrated accurately.The result shows that Guantao Formation belongs to Miocene

Dongying Formation belongs to the Oligocene and Shahejie Formation crosses Paleocene and Eocene.