Difference of the syn-tectonic magma flow and granite emplacement in relatively stable tectonic environment and its tectonic implication

Granitoid intrusions constitute most of continental crust, and provide vital evidences for researching continental formation and evolution. Different from granite emplacement in relatively stable tectonic environment, syn-tectonic magma flow usually occurs in active tectonic zones such as continental margin and orogenic belt. The structure of syn-tectonic granite, magmatic process and flow direction are usually complicated affected by strong tectonic stress field. A large number of granitic plutons intruded in the north margin of the North China Plate during the Late Paleozoic, and their tectonic properties and genetic analysis provide key evidence for the study of the subduction of the Paleo-Asian Ocean and the destruction of the North China Craton. The structural deformation and petrographic characteristics of the Daguangding granodiorite and Panshan granite on the northern margin of North China Plate are analyzed from macro to micro, and semi-quantitative mineralogy research is carried out by electron probe microanalysis. Forming pressure of the pluton are calculated by hornblende pressure gauge, so as to invert the emplacing depth. The results show that the late Paleozoic (320-290Ma) granodiorite is characterized by a large number of root-less folds with north dipping axial plane. Under the microscope, dark minerals such as amphiboles and biotite are oriented alignment, and the long axes of xenolith are parallel to the flow foliation, showing typical syn-tectonic deformation characteristics. Its hornblende all-aluminum manometer indicates a crystallization pressure of 3.62~5.64 kbar, roughly corresponding to the depth of the middle crust (12.86~22.99km). This indicates that the remelting of the middle and lower crust on the northern margin of the North China Plate in the late Paleozoic was formed by syn-tectonic magmatic flow from north to south, which formed the Daguangding pluton and also provided a medium for the stress transfer in the middle and deep layers. The xenolith in Mesozoic Panshan granite are not deformed, and there is no directional arrangement of dark minerals, but marble is formed by thermal contact metamorphism in the contact zone between pluton and surrounding rock, which belongs to granite emplacement under stable tectonic environment.