Intraplate mantle-sourced dikes as constraints on plate margin processes: An anisotropy of magnetic susceptibility study from the Jiaodong Peninsula, eastern China

How the intraplate deformation of the East Asian continent was coupled with ocean-continent subduction during the Early Cretaceous has been hotly debated over the past few decades. In this study, magnetic fabric analysis of 26 Early Cretaceous mantle-sourced intermediate−mafic dikes (376 samples) in the Jiaodong Peninsula of eastern China was conducted to constrain the paleostress fields during dike emplacement. The results indicate that the asymmetric arrangement of magnetic foliations about the dike symmetry plane resulted from syn-emplacement tectonic stresses. Based primarily on the magnetic fabric results of the dikes, we demonstrate that the Jiaodong Peninsula experienced five stages of Early Cretaceous tectonic deformation, i.e., WNW-ESE extension (135−124 Ma), NW-SE compression (123−122 Ma), NW-SE (121−117 Ma) and NNW-SSE (116−112 Ma) extensions, and NNW-SSE compression (111−107 Ma). It is inferred that the cyclic intraplate extension and compression were controlled predominantly by plate margin dynamics. The Early Cretaceous subduction direction of the Paleo-Pacific Plate beneath the Eurasian Plate changed from west-northwest (135−124 Ma), through northwest (123−117 Ma), to north-northwest (116−107 Ma). Therefore, acting as a tectonic bridge, these dikes provide critical evidence linking intraplate deformation to subduction processes along the plate margin.