The high-δ18O signature of Early Cretaceous lithospheric mantle beneath the North China Craton: Role of plate subduction

The Early Cretaceous was a pivotal phase in the evolution of the North China Craton, during which cratonic destruction reached its zenith and was marked by a fundamental transformation of the subcontinental lithospheric mantle (SCLM) in composition and physicochemical properties. The subduction of the Paleo-Pacific plate and the subsequent formation of the eastern Asian Big Mantle Wedge (BMW) have been widely credited with the decratonization of the North China Craton. However, the spatial extent of these deep processes across the North China Craton, as well as the cratonic responses to successive Phanerozoic circum-craton plate subduction events, remains debated. Here, we report in situ major element and oxygen isotope compositions of olivine xenocrysts hosted by Miocene basalts from Xiyang−Pingding in the central North China Craton. By integrating available oxygen isotope data from olivine in xenoliths, xenocrysts, and phenocrysts from 133−0.6 Ma mantle-derived rocks in the North China Craton, we aim to clarify the effects of plate subduction and Big Mantle Wedge development on the Archean lithospheric keel. The SCLM beneath Xiyang−Pingding mainly comprises ancient, refractory mantle, with a minor proportion of fertile, modified mantle. Its δ18O values (5.09‰−5.84‰), slightly above the normal mantle range, predominantly recorded metasomatic enrichment by melts derived from the Paleo-Pacific plate during flat-slab subduction. High δ18O signatures persisted during the formation and evolution of the eastern and northeastern Asian Big Mantle Wedge systems. The Early Cretaceous SCLM beneath the North China Craton shows uniformly high δ18O imprints, reflecting multistage mantle modification induced by surrounding plate subduction events since the early Paleozoic and likely providing the impetus for the destruction of the North China Craton.