The Jiaodong Peninsula of eastern Shandong Province comprises the Jiaobei terrain of North China affinity and the Sulu ultrahigh-pressure metamorphic terrain. In this study, we present zircon U-Pb ages, major- and trace-element data, and Sr-Nd-Pb isotopic compositions of intermediate to mafic dikes from the Linglong region of the Jiaobei terrain and the Rushan region of the Sulu terrain to discuss the nature of the mantle source(s) beneath eastern China during the Early Cretaceous. Zircon U-Pb dating yields Early Cretaceous dike emplacement ages ranging from ∼124 to ∼120 Ma for the Linglong region and from ∼118 to ∼108 Ma for the Rushan region. Dikes from both regions are all potassic, with “arc-like” trace-element distributions as well as high unradiogenic Pb isotopic composition, low initial εNd values (−19.64 to −10.80), and high radiogenic 87Sr/86Sr ratios (0.7075–0.7112), suggesting the involvement of an extensively enriched mantle component. Such isotopic characteristics are found in contemporaneous intermediate to mafic intrusive rocks in the whole Shandong Province and are explained in terms of a Triassic northwestward-subduction model of the Yangtze Block beneath the North China Block. The dikes from the Linglong and Rushan regions have low Nb/U and Ce/Pb ratios, implying the involvement of upper-continental-crustal material. Combined with the southward younging of zircon U-Pb ages through Shandong Province, we suppose that the enriched mantle source beneath the Jiaodong Peninsula was formed by metasomatism of silicic melts or fluids derived from the subducted Yangtze continental crust during the Triassic, followed by decompression melting of this mantle during the Early Cretaceous due to rollback of the subducted Paleo-Pacific plate.

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