【作者】 朱日祥； 邵济安； 潘永信； 史瑞萍； 施光海； 李大明；

【Author】 Zhu Rixiang~a,Shao Jian~b,Pan Yongxin~a,Shi Ruiping~a,Shi Guanghai~a,Li Darning~c a.Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100101 b.Geology Department,Peking University,Beijing 100871 c.Institute of Geology,China Seismological Bureau,Beijing 100029

【机构】 中国科学院地质与地球物理研究所； 北京大学地质系； 中国地震局地质研究所；

【摘要】 对辽宁义县和阜新地区55个白垩纪火山熔岩流进行的岩石磁学研究表明,主要载磁矿物为假单畴钛磁铁矿。K—Ar测年确定出火山岩喷发的时代为133-93Ma。对所有样品进行的系统热退磁揭示出,当加热温度达到250℃时,可分离出稳定的单一特征剩磁分量,由27个（28个）纪录地球磁场正（负）极性熔岩流得出的平均方向为D/I=5.9°/58.8°,α₉₅=2.9°(D/I=179.2°/-59.5°,α₉₅=5.2°),表明白垩纪以来义县和阜新地区相对于欧亚大陆没有发生明显的平移和旋转运动,但朝鲜半岛相对于欧亚大陆在白垩纪发生了33.9°的顺时针旋转。结合全球热点具有不同源区（核幔边界或上地幔）的特征,我们认为朝鲜半岛在白垩纪相对欧亚大陆的顺时针旋转主要是由于中国东部地壳在白垩纪曾发生拉张所致,与地壳拉张对应的地表过程是强烈的火山活动。更多还原

【Abstract】 Detailed rock magnetic studies of 55 lavas from Yixian and Fuxin area,West Liaoning, show the primary carriers of remanence to be pseudo-single domain titanomagnetite.K/Ar dating indicates that the volcanic sequence spans 93 to 133 Ma.Stepwise thermal demagnetization successfully isolated well-defined characteristic magnetization（ChRM） in all lavas thermal-treated above 250℃.The mean paleodirections are D/I=5.9°/58.8°(α₉₅=2.9°) and D/I=179.2°/-59.9°(α₉₅=5.2°) for twenty-seven normally magnetized flows and twenty-eight reversibly magnetized flows,respectively.It indicates that since the Early Cretaceous there is no significant horizontal movement and rotation between the Yixian-Fuxin area and Eurasia.However,Korean Peninsula may have undergone a clockwise rotation of 33.9°relative to the Yixian-Fuxin area during the Cretaceous. On the basis of characteristics of hotspot origins（core-mantle boundary or upper mantle）,the clockwise rotation of Korean relative to Eurasia is assumed to be mainly caused by an extensional force in the crust of the eastern China,which was corresponding to intensive surface volcanic activities in this area.更多还原