Multistage evolution of mantle plume and the ore-forming and ore-controlling role of mantle branch structure: A study on mineralization of the Guojiadian mantle branch structure in northwestern Jiaodong

This paper briefly introduces the establishment of metallogenic theory of mantle branch structure, the characteristics, unit division and fault structure system of mantle branch structure, as well as its mineralization. During the late Yanshanian movement, the eastern part of North China entered the evolutionary stage of mantle plume dominated by extensional structures. The Laiyang mantle sub plume and its surrounding mantle branch structures, such as Guojiadian, Qipeng and Mouru, were formed in northwestern Jiaodong. The Guojiadian mantle branch structure was strongly active in the late Yanshanian, which generally formed the Jiaojia fault as a main detachment zone in the hanging wall and the Sanshandao fault as a reverse shovel fault intersecting with the Jiaojia fault, and controlled the formation of a series of large and super large deposits such as the Linglong, Jiaojia and Sanshandao gold deposits. Among many ore-forming and controlling factors, regional fault structure should be an important dominant factor, which not only provides channels for the migration of ore-forming fluids, but also provides favorable spaces for the precipitation of ore-forming materials. The deep source ore-bearing fluids are concentrated and mineralized through mantle plume, sub-mantle plume, mantle branch structure, favorable structural expansion zones successively, i.e.brittle ductile-brittle shear zone, internal and external contact zone of intrusive rock mass, dense structural fracture zone, contact zone between vein rock and surrounding rock. In recent years, deep geological exploration in northwestern Jiaodong has found that several large and medium-sized gold deposits in the shallow distributed along the regional fault might be integrated in a certain depth and often became a super large gold deposit.