Cratons are old, stable parts of the continental crust thathave survived at least since Proterozoic time and have not undergonestrong magmatism or tectonism since their stabilization. Traditionally,the growth of continental crust in the North China craton isconsidered to have been complete by Paleoproterozoic time, Phanerozoicevents being largely restricted to surrounding orogenic belts.However, the eastern part of the North China craton containslarge volumes of Mesozoic igneous rocks, with widespread metamorphiccore complexes and pull-apart basins. Hf isotope compositionsof magmatic zircon grains from igneous rocks in the LiaodongPeninsula indicate that widespread late Mesozoic granitoidsformed by partial melting of ancient crust, but with significantinput of a mantle component via magma mixing and crustal assimilation.This magmatism has resulted from removal and modification oflithospheric mantle, accompanied by asthenospheric upwelling.The Hf isotopic signatures thus record the addition of juvenilecrust beneath the eastern part of the North China craton, whichappears related to major extension and possibly slab rollbackof the Pacific plate. Whatever the mechanism, it is apparentthat since ca. 200 Ma, ancient lithosphere beneath the easternNorth China craton has been progressively reactivated and replaced,resulting in "decratonization." Tertiary to Holocene volcanismin the area and major subsidence around the Gulf of Bohai suggestthat the effects of the process are continuing. Similar processesprobably operated in the geological past, leading to significantmodification of continental crust and requiring reconsiderationof mechanisms for continental breakup and dispersal and of continentalgrowth rates.