Abstract:

The Benxi area, situated within the northeastern segment of the eastern block of the North China craton, represents a critical region for investigating Archean evolution and holds significant importance for understanding the formation and evolution of the Precambrian continental crust of the North China craton. To elucidate the petrogenesis and tectonic setting of the newly identified Liujiapuzi pluton in Benxi (within the Jiao-Liao-Ji orogenic belt), an integrated study of petrology, whole-rock geochemistry, and zircon U-Pb geochronology was conducted. The Liujiapuzi pluton is compositionally defined as porphyritic fine- to medium-grained biotite monzogranite, displaying metaluminous to weakly peraluminous characteristics and high-K calc-alkaline affinities typical of I-type granite. Geochemically, it exhibits enrichment in large-ion lithophile elements (e.g., Sr, La, Th) and depletion in high-field-strength elements (e.g., Nb, P), with a right-sloping REE pattern and negative Eu anomaly. Zircon U-Pb dating yields an emplacement age of ((2 518±21) Ma), indicating formation during the Late Neoarchean. Petrogenetic modeling suggests a hybrid magma source involving crustal assimilation with mantle-derived components, generated in an active continental margin environment characterized by oceanic subduction. This implies the Longgang and Langlin blocks of the eastern North China craton were not amalgamated at ((2 518±21) Ma). The Liujiapuzi pluton represents an early accretionary product distinct from the post-collisional Majiagou pluton ((2 490±21) Ma) in the same area. This event likely represents the last major magmatic episode before stabilization of the Archean basement in the North China craton.

Key words: Late Neoarchean, geochemistry, zircon U-Pb chronology, North China craton, Liujiapuzi pluton, Benxi area