The Crystallization Age and Tectonic Significance of Multi-Stage Magmatic Intrusions in the Jiangligou Area, Western Qinling, China

This study takes the Jiangligou Plutonic Complex (JPC) in the Western Qinling tectonic belt as the research object and systematically investigates the crystallization age, magmatic genesis, and tectonic setting of the plutons. Results indicate that the Jiangligou Plutonic Complex was formed during the Triassic period (252–216 Ma, corresponding to the “Indosinian” regional tectonic stage in East Asia). Six plutons are recognized in the Jiangligou region. Plutons IV (246 ± 3 Ma) and V (252 ± 2 Ma) record Early Triassic magmatism, and Plutons I (238 ± 1 Ma), II (216 ± 2 Ma), III (216 ± 2 Ma), and VI (224 ± 2 Ma) correspond to Middle-Late Triassic magmatic activity. Furthermore, the data from this study indicate that a Th/U ratio > 0.4 serves as a more effective criterion for identifying reliable magmatic zircons. Our data indicate that the Jiangligou Plutonic Complex represents a multi-stage magmatic system generated in response to the tectonic evolution of the West Qinling, spanning from the late subduction of the Mianlue Ocean to the peak collision between the North China and Yangtze blocks during the Indosinian orogeny. The region is dominated by a collisional setting, with magmas primarily derived from crustal remelting. This study provides key chronological and geochemical constraints on the Indosinian tectonic–magmatic evolution of West Qinling.