Zircons with core-rim structure are common in granitoids worldwide. Mostly, the cores have strikingly older ages than the rims. Whether the zircon cores are inherited from the source of the granitoids or just occasionally captured from the wallrocks during magma ascent is highly controversial. In this paper, three Mesozoic granites with diverse ages and geochemical compositions but uniformly ~1.8 Ga zircon cores are reported from the Fengning area of North China Craton. The zircon cores in the Bingshanliang I-type granites have much higher δ18O values (8.3‰ to 10.1‰) than the magmatic zircons, strongly arguing against that these zircon cores are from the source of the granites. Instead, they could come from the wallrock during magma ascent. This conclusion is consistent with the occurrence of ~1.8 Ga S-type granites and meta-sedimentary rocks in the region which are characterized by high δ18O values. Similarly, zircon cores in the Wudaoying and Niuquanziba granites share many similarities in trace elements with the widely outcropped ~1.8 Ga granitoids, suggesting their probably xenocrystic origin from the Paleoproterozoic granitoids. The xenocrystic speculation is further supported by the lack of obviously modified internal textures and trace element imprints in the ~1.8 Ga zircon cores due to the effect of the Mesozoic anatexis if they had been derived from the source region of the granites. Combined with the bulk rock Nd isotopic and magmatic zircon Hf isotopic compositions, the three Mesozoic granites are suggested to be derived from the late Archean lower crust. It is inferred that ~2.5 zircon cores in some Mesozoic granitoids from other parts of the North China Craton are also likely captured grains from the wallrock during magma intrusion into the ~2.5 Ga basement rocks, rather than from the source. The magmatic zircon trace elements from the Wudaoying and Niuquanziba granites fingerprint the adakitic and A-type characters of their respective magma, implying their utility in tracing granites' derivation.