中国东北及邻区白垩纪古地磁分析与块体旋转运动动力学背景

Cretaceous Paleomagnetism of the Northeast China and Adjacent Regions and the Geodynamic Setting of Block Rotations

为了更好地理解中国东北及邻区白垩纪各块体的旋转运动模式及其运动量,本文根据最新的地层学进展分早白垩世中期、早白垩世晚期与晚白垩世三个阶段对该区古地磁数据进行了精细分析。通过与华北—华南地块(不包括朝鲜半岛、辽东及胶东半岛)相应时期的古地磁极对比,说明朝鲜半岛及辽东早白垩世中、晚期相对于华北—华南地块分别顺时针旋转约11°,晚白垩世以来没有明显的旋转运动。辽西地区则出现了小幅度的逆时针旋转运动。以上旋转运动与太平洋板块俯冲引起的中国东北及邻区强烈岩石圈减薄和伸展作用具有密切联系。

In order to better understand the block rotations in the Northeast China and adjacent regions, we analyses mid-early Cretaceous, late-early Cretaceous and late Cretaceous paleomagnetic data respectively. The eastern Liaoning and Korean peninsula is rotated about 11 clockwise relative to the North and South China blocks （except Korean peninsula, eastern Liaoning and Jiaodong peninsula ） during mid-early Cretaceous and late-early Cretaceous. No significant rotations occurred since late Cretaceous between Korean peninsula and the North and South China blocks. About 13 counterclockwise rotations of the western Liaoning with respect to the North and South China blocks took place since mid-early Cretaceous. These rotations are accommodated by lithosphere thinning and extension beneath the Northeast China and adjacent regions, which resulted from the strong upwelling of asthenosphere caused by the subduction of the Pacific plate.