Geochronological characteristics and tectonic significance of granite plutons in Shenggeshungun area, Ejina Banner, Inner Mongolia

The study area is located in the middle section of the southern margin of the Central Asian Orogenic Belt, which is the junction zone between the North China Plate and the Tarim Plate. In this study, geochemical and geochronological analyses were conducted on the granite plutons in the study area, and then the tectonic setting of their formation was discussed, which is of great significance for studying the regional tectonic evolution of the Central Asian Orogenic Belt. The research results show that the diagenetic age of the Middle Devonian monzogranite is 385.1 ± 3.4 Ma. Geochemical analysis indicates that the Middle Devonian monzogranite is a syn-collisional (S-type) granite, and its tectonic setting belongs to the syn-collisional period. The zircon U-Pb dating of the Late Triassic monzogranite yields an age of 227.0 ± 4.9 Ma. Geochemical analysis shows that the Late Triassic monzogranite is an intra-plate granite, and its tectonic setting belongs to the intra-plate continent-building environment. The study area experienced a plate collision process during the Middle Devonian. From the Permian to the Triassic, the study area gradually transitioned from a syn-collisional tectonic environment to an intra-plate continent-building environment. By the Late Triassic, it entered the intra-plate continent-building stage. This study provides strong reference for the research on the regional tectonic evolution of the Central Asian Orogenic Belt.