Geochemical evidence for terrigenous sediment recycling in the Late Permian subcontinental lithospheric mantle of the northern North China Craton

Understanding the recycling process of subducted slab in subduction zones is vital to deciphering the heterogeneity of cratonic mantle and the variable compositions of continental arc igneous rocks. This study presents a comprehensive analysis of zircon U-Pb ages, Hf-O isotopes, hornblende major elements, whole-rock major and trace elements, as well as Sr-Nd-Hf isotopes of mafic igneous rocks from the northern North China Craton. These data constrain metasomatic processes in the cratonic mantle. The Late Permian mafic igneous rocks (ca. 254−252 Ma) studied are characterized by arc-like trace element signatures and enriched whole-rock Sr-Nd-Hf isotopes, with (⁸⁷Sr/⁸⁶Sr)_i ratios of 0.7063−0.7076, ε_Nd(t) values of −18.0 to −9.3, and ε_Hf(t) values of −29.7 to +0.5. In addition, they also have elevated zircon δ¹⁸O values of 5.9‰−7.0‰, and variable zircon ε_Hf(t) values of −19.4 to +6.0. These features suggest the rocks were derived from an enriched mantle with the involvement of terrigenous sediments. We propose that the subcontinental lithospheric mantle of the northern North China Craton was mainly metasomatized by terrigenous sediment-derived hydrous melt during the southward subduction of the Paleo-Asian Ocean. Moreover, partial melting of the metasomatic mantle may be triggered by the slab rollback related to the closure of the Paleo-Asian Ocean in the Late Permian, which resulted in the formation of the mafic igneous rocks studied. Thus, the Late Permian igneous rocks studied provide petrological and geochemical evidence of the crust-mantle interaction during the subduction of the Paleo-Asian Ocean.