Early Cretaceous Magmatism in the Great Xing'an Range, NE China: Constraints on the Subduction and Rollback of the Paleo‐Pacific Plate

ABSTRACT

This study presents new zircon U–Pb–Hf isotopic and whole‐rock geochemical data for Early Cretaceous igneous rocks in the Great Xing'an Range, NE China, with the aim of constraining the subduction and rollback history of the Paleo‐Pacific Plate. The results indicate that late Early Cretaceous magmatism (ca. 130–112 Ma) involved both intermediate and felsic magmas. Trachyandesite was derived from a depleted mantle wedge metasomatized by subduction‐related fluids, whereas trachydacite, dacite and granite porphyries were generated mainly by melting of newly accreted lower crust. Combined with the final emplacement of the Raohe Accretionary Complex and coeval calc‐alkaline magmatism in eastern NE China, these data indicate that the late Early Cretaceous magmatism formed in a back‐arc extensional setting related to westward subduction of the Paleo‐Pacific Plate. From ca. 112 Ma to the Late Cretaceous, the eastward narrowing of magmatism records rollback of the Paleo‐Pacific Plate.