Carbonatite-alkaline complexes are commonly derived from the mantle. However, whether the source is litho-spheric or asthenospheric mantle remains debated. In order to better understand this issue, this paper conducts a Sr-Nd-O isotopic study on the Early Cretaceous, Weishan REE-rich syenite-(carbonatite) complex, Northern China. Two types of apatite are identified from the Weishan complex, namely magmatic and xenocrystic apatite. In-situ Sr-Nd isotopic analyses on magmatic apatite yielded (Sr-87/Sr-86)(i) from 0.70690 to 0.70719, and epsilon(Nd)(t) from -7.6 to -8.8. The pristine calcite from carbonatite has similar (Sr-87/Sr-86)(i) (0.70727-0.70739) with magmatic apatite. In-situ oxygen isotopic analyses on zircon yielded delta O-18(VSMOW)(parts per thousand) from 5.9 to 6.7 parts per thousand. Previous studies reveal that coeval, mantle lithosphere-derived rocks in the region have more enriched Sr (Sr-87/(86)Sri greater than 0.709) and Nd [epsilon(Nd)(t) - 12] isotopes than the Weishan complex; whereas the asthenosphere-derived rocks in the region are characterized by depleted Sr-Nd isotopes (Sr-87/Sr-86(i) < 0.706; epsilon(Nd)(t) greater than 0) and low delta O-18(VSMOW) values (mostly < 5.4 parts per thousand. It is well known that Northern China experienced destruction in the Early Mesozoic, which was accompanied with asthenosphere upwelling along trans-lithosphere faults. Considering that the Weishan complex locates adjacent to the trans-lithosphere Tanlu fault, generation of the complex may be related to asthenosphere-lithosphere interaction. Notably, the Weishan complex differs from coeval REE-barren carbonatites in that its source involved asthenosphere-derived components; hence, involvement of asthenosphere-derived components may be important for the formation of such a REE-rich complex. In general, this study highlights the importance of lithosphere-asthenosphere interaction in supplying necessary heat and materials for the generation of the Weishan complex.