摘要
Various extensional structures,e.g.,half grabens,detachment faults,and metamorphic core complexes,were formed in the Liaodong Peninsula.There are two metamorphic core complexes (mcc's) in the western part of the Peninsula,i.e.the Liaonan mcc and the Wanfu mcc.They share the same lower plate and constitute a conjugate mcc pair.The Dayingzi detachment fault system and the three half grabens are exposed in the central and eastern parts,respectively.U-Pb dating of zircons from syntectonic plutons in the lower plates of the detachment faults and volcanic rocks from half graben basins indicates that their formation spans from 135 to 106 Ma,although the individual structure may be formed at a particular stage.Despite the differences in age of formation,in the regional attitudes,and in rooting depths,the extensional structures have great similarities in their kinematics,geometrical asymmetry,and coeval tectono-magmatic activities etc.Macroscopically,the extensional structures constitute conjugate associations,but a particular one generally has asymmetric patterns.Early Cretaceous extensional structures extend from the Liaodong Peninsula to North China,Northeast China,South China,and eastern Mongolia and Transbaikal area in Russia.The extensional structures from different areas share many common features.The Liaodong Peninsula is the miniature of the East Asia with respect to the formation of extensional structures in Early Cretaceous.It is suggested that the interaction of the Izanagi Plate with Eurasia Plate is responsible for the extension of crust.The structural mobility of the lithosphere,partly attributed to the fluid flow at the depth,and detachment faulting in both the crustal and mantle lithosphere provide important constraints on the development of Early Cretaceous extensional structures in the East Asia.
Various extensional structures,e.g.,half grabens,detachment faults,and metamorphic core complexes,were formed in the Liaodong Peninsula.There are two metamorphic core complexes （mcc＇s） in the western part of the Peninsula,i.e.the Liaonan mcc and the Wanfu mcc.They share the same lower plate and constitute a conjugate mcc pair.The Dayingzi detachment fault system and the three half grabens are exposed in the central and eastern parts,respectively.U-Pb dating of zircons from syntectonic plutons in the lower plates of the detachment faults and volcanic rocks from half graben basins indicates that their formation spans from 135 to 106 Ma,although the individual structure may be formed at a particular stage.Despite the differences in age of formation,in the regional attitudes,and in rooting depths,the extensional structures have great similarities in their kinematics,geometrical asymmetry,and coeval tectono-magmatic activities etc.Macroscopically,the extensional structures constitute conjugate associations,but a particular one generally has asymmetric patterns.Early Cretaceous extensional structures extend from the Liaodong Peninsula to North China,Northeast China,South China,and eastern Mongolia and Transbaikal area in Russia.The extensional structures from different areas share many common features.The Liaodong Peninsula is the miniature of the East Asia with respect to the formation of extensional structures in Early Cretaceous.It is suggested that the interaction of the Izanagi Plate with Eurasia Plate is responsible for the extension of crust.The structural mobility of the lithosphere,partly attributed to the fluid flow at the depth,and detachment faulting in both the crustal and mantle lithosphere provide important constraints on the development of Early Cretaceous extensional structures in the East Asia.
基金
supported by the National Natural Science Foundation of China (Grant No. 90814006)
111 Project (Grant No. B07011)
