Abstract The subduction of the Paleo‐Pacific Plate beneath the NE Asian continental margin induced extensive magmatism, providing an excellent opportunity to investigate the interplay between plate dynamics, arc magmatism, continental crust formation, and porphyry mineralization. Here, we integrate mineralogical, geochronological, geochemical, and isotopic analyses of diverse Early Cretaceous magmatic assemblages in the Yanbian Fold Belt (NE China), aiming to reconstruct the evolution of a transcrustal magmatic plumbing system and constrain the key factors controlling porphyry mineralization during slab rollback. Dioritic enclaves (∼123 Ma) represent rapidly ascending mantle‐derived magmas that underwent magma mixing/mingling and quenching before solidification. Granitic intrusions (∼118 Ma) with low Sr/Y were attributed to a depleted crustal source with plagioclase and biotite fractionation. Mafic dikes (∼116 Ma) from a bimodal suite originated from a slab‐fluid‐metasomatized lithospheric mantle with increased input from the depleted mantle, whereas felsic dikes (∼115 Ma) with high Sr/Y resulted from melting of a juvenile lower crust under garnet amphibolite facies conditions. These rock assemblages record back‐arc crustal growth, reworking, and maturation. Compared with earlier (peaking at ∼130 Ma) back‐arc magmatism farther west in the Great Xing'an Range, our newly identified bimodal magmatism (initiated at ∼118 Ma) in the Yanbian area reveals a rapid rollback of ∼600 km within ∼12 Myr. Moreover, the late Early Cretaceous magmas exhibit significantly higher magmatic oxygen fugacity (ΔFMQ > +1, where FMQ is the fayalite‐magnetite‐quartz oxygen fugacity buffer) than their Jurassic counterparts (with ΔFMQ values generally below +0.5), paralleling regional porphyry‐related mineralization and revealing the critical role of slab rollback in modulating arc magmatic fertility. Our findings highlight how transient rollback episodes can generate diverse magmatic differentiation pathways and metallogenic triggers in supra‐subduction zone settings.
Wang et al. (2026) studied this question.