Geochronology, geochemistry and tectonic setting of the Mesozoic granites in Wenchun Town, southern Jilin Province

Southern Jilin Province, located in the eastern margin of the Eurasian Plate, has undergone the tectonic evolution of the North China Craton and the Central Asian Orogenic Belt. During the Mesozoic, the region was affected by the westward subduction of the Paleo-Pacific Ocean, resulting in intense tectonomagmatic activity and associated mineralization. The Cretaceous monzogranites and syenogranites exposed in the Wenchun area of southern Jilin Province are therefore of great significance for understanding the evolution of the East Asian continental margin. This study integrates petrogeochemical and geochronological analyses to investigate the tectonic setting of the area. Petrogeochemical results indicate that the granites have SiO₂ contents of 68.46%-74.52%, Al₂O₃ of 13.55%-16.24%, total alkali (Na₂O+K₂O) of 7.69%-10.45%, and K₂O/Na₂O ratios of 0.92-1.30. The rocks are characterized by high Si, K, and Al, with aluminum saturation index(A/CNK) ranging from 0.98 to 1.17(averagely 1.04, <1.1), defining a metaluminous to weakly peraluminous composition, and exhibiting overall I-type granite affinities. Zircon U-Pb dating yields ages of 122.2±1.2 Ma, 123.1±1.8 Ma, and 126.02±0.95 Ma, indicating a late Early Cretaceous formation. Tectonic discrimination diagrams suggest a continental arc setting. Integrated analysis suggests that these granites were formed in an extensional environment related to the westward subduction of Paleo-Pacific slab.