This paper takes the Guzhen intrusive complex which is located in Hebei Province in the central part of the North China Craton (NCC) as a research object. The author conducted detailed field geological survey, combined with indoor research, including petrography, mineralogy, geochemistry, Sr-Nd isotope, Lu-Hf isotope and U-Pb zircon chronology analysis, so as to explore the formation age, source area, petrogenesis of Guzhen intrusive complex, in order to draw new inspiration for the Mesozoic lithospheric thinning in the central NCC. In this paper, it is believed that the formation age of the Guzhen complex is related to the structure of the rock. The formation age of the rock with equal grain structure is earlier than that of the rock with porphyritic structure. Magmatic activity can be divided into two phases:the first stage (130 similar to 135Ma) magmatic activity forms plutonic bodies with equal grain structure, including medium-fine diorite, monzonite, quartz monzonite and syenite; the second stage (127Ma) magmatism forms hypabyssal bodies, including porphyritic diorite and porphyritic quartz monzonite. Combined with field observation, petrography, mineralogy and geochemical characteristics, the petrogenesis of the Guzhen complex is analyzed. The Guzheng diorite has HMA properties. Guzhen diorite is a product of partial melting of the mantle peridotite metasomatized by the subduction slab melt and fluid, and the magma has weak assimilation and contamination with the crustal material on the ascending route. The Guzhen syenite is a product of partial melting of the thickened continental crust with the depth of 40 similar to 67km. The Guzhen monzonite is formed by the mixing of syenite and diorite in the study area. The Guzhen quartz monzonite is formed by mixing of Guzhen diorite and another silicon-rich magma. The subduction material (fluid+melt) has an important contribution to the formation of Guzheng high-Mg diorite, which shows that the influence of the subduction of the Paleo-Pacific plate also involves the central NCC, but the degree of the impact is less than that of the eastern NCC. The Guzhen syenite is formed by partial melting of the thickening continental crust, which shows that the delamination plays an important role in the thinning process of the NCC lithosphere in the Middle Mesozoic. Combined with the calculation results of the amphibole thermobarometer and the previous research results, it can be inferred that the time node of the large-scale delaminatiom of the central NCC is 127Ma.
