This work reports an important episode of extensional,mafic magmatism that impacted the North China Craton (NCC) during the Permo-Triassic and influenced the evolution of this Craton.We sampled 30 representative mafic dykes cropping out in eastern NCC,within the Hebei Province,China.New zircon LA-ICP-MS U-Pb ages,geochemical,and Sr-Nd-Pb isotopic data for these mafic dykes identified them as typical dolerites formed between 211.9 ±1.3 and 263.9 ±2.6 Ma.The mafic rocks fall into the alkaline and calc-alkaline series.They are enriched in light rare earth elements,some large ion lithophile elements (e.g.,Rb,Ba,and Sr),K,and Pb,and depleted in Nb,Ta,and Ti.The dykes have high initial 87Sr/86Sr ratios (0.7034-0.7178),negative εNd (t) values (-2.2 to-5.9),and relatively constant initial Pb isotopic ratios,that are EM1-like: (206Pb/204Pb)i =16.39-16.74,(207Pb/204Pb)i =15.22-15.24,and (208Pb/204Pb)i-=36.66-36.86,respectively.Our results indicate that the Hebei Province dolerites were likely derived from magma generated through low-medium degree partial melting (3.0-20％) of an EM1-like garnet-lherzolite mantle source.The parental magmas fractionated olivine,clinopyroxene,and Ti-bearing phases with obvious crustal contamination during rapid ascent and dyke emplacement.Since the possible influence of subduction of the Yangtze Plate has been excluded,we propose a model for the origin of the investigated mafic rocks,involving the Permian collision between the Siberian Block and the NCC.The mafic dykes of eastern NCC within Hebei Province formed during a period of crustal thinning in response to extension after the early Permian collision.