The zircons from Qianrentun amphibolite in eastern Liaoning show an uniform absorbing band in cathodoluminescence (CL) images, being of characteristics of zircons in the mafic-ultramafic intusives. SHRIMP U-Pb dating results of the zircons are mainly distributed between the concordia ages of 117～143 Ma with a weighted mean 206Pb/238U age of 128.6±5.1 Ma (204Pb corrected), indicating that the amphibolite was formed in Early Cretaceous. The coexistence of Early Cretaceous mafic-ultramafic igneous rocks and granitoids in eastern Liaoning, i.e. the presence of the bimodal magmatism, suggests that a strong extensional environment existed in the eastern part of the North China Craton in Early Cretaceous and that the thinning of lithospheric mantle reached its culmination in that period.