中文摘要：

位于燕山构造带东端的医巫闾山变质核杂岩经历了两次地壳伸展活动，早期在NNE-SSW拉伸背景下形成了现今围绕医巫间山岩体周缘分布的拆离韧性剪切带与相应的变质核杂岩，晚期隆升过程中由于拉伸方向转变又叠加发育了瓦子峪伸展韧性剪切带。早期伸展变形中，围绕在拆离韧性剪切带及变形下盘中侵入了大量不同变形样式的同构造花岗岩脉。通过对不同阶段侵入的岩脉进行LA—ICP—MS锆石u—Ph定年，显示该核杂岩的活动时间为157～149Ma。医巫间山地区晚侏罗世伸展活动的确定，暗示华北克拉通北部可能从晚侏罗世已经开始发生破坏，到早白垩世达峰期并遍及整个华北克拉通东部。

英文摘要：

Yiwultishan metamorphic core complex （MCC）, situated in the eastern Yanshan structural belt, has experienced two phases of crustal extensional activities： An early development of detachment ductile shear zone around the Yiwultishan pluton under a NNE-SSW extensional regime, and a subsequent truncation of its southwestern segment by later Waziyu ductile shear zone because of a change in extensional direction during doming. In the early extensional period, there were a great deal of syn- kinematic granitic dikes with different deformation styles intruded in the detachment shear zone and its deformed lower plate. LA- ICP-MS zircon U-Pb dating results of these dikes suggest that Yiwultishan metamorphic core complex was formed between 157 Ma and 149 Ma. The Late Jurassic extensional activities in the Yiwultishan area imply that destruction might have been happened in the northern part of North China Craton since Late Jurassic and reached peak period throughout the whole eastern North China Craton in the Early Cretaceous.