| Content: On the basis of summarizing the result of the predecessors'work, field observation, measurement, analysis of Huanghuadian-Dayingzi region in in Liaodong Penisula, thin section analysis and the experimental analysis of chronology and geochemistry, its composition and regional tectonic implications of the Huanghuadian-Dayingzi extensional structure were introduced in details.(1) The Huanghuadian-Dayingzi extensional structure was divided into three major units, ie., extensional fault basins (including Huanghuadian and Dayingzi basin) in the hanging wall, the detachment fault and the Cretaceous plutons in the lower plate.(2) The evolution process of those tectonites indicate that rocks in the lower plate experienced the deformed process: from high greenschist facies to low greenschist facies, ie. from the mid-upper crust to the upper crust, even to the ground surface. The same dip direction of foliation and the streching lineaion indicated the uniform to SW shearing along the detachment fault zone.(3) U-Pb ages of pre-tectonic pluton in lower plate (ca.155Ma) and a volcanic rock (ca.135Ma) in the extensional fault basin attest that the extensional movement started before 135±1.2Ma, and ended in 127±1Ma.(4) Considering the rock geochemistry analysis of the volcanic rocks, and combining with the regional tectonic setting, we speculate that on the one hand, the basalt underplateing induced the basaltic magma eruption. On the other hand, it caused the middle-lower crust baking and made the temperature higher. The decompression caused by the extension and detachment brought about the old middle-lower crust remelting, and formed the new lower crust magma, and edmmited with the developing of the detachment fault.The occurrence of the Huanghuadian-Dayingzi extensional structure provides evidences for understanding the mechanical and rheological behavior and thinning processes of the lithosphere in North China Craton in the late Mesozoic.
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