The Shenquan sodic volcanic rocks, outcropped in the east of Lizhuang village in Tancheng County, Shandong Province, are tectonically located in the southern parts of the Yishu deep fault zone. The volcanic rocks comprise a shield volcano, and lithologically consist mainly of trachyandensite. Zircon LA-ICP-MS U-Pb dating yields an age of 96.5±1.4 Ma, which is younger than the ages of the widespread potassic rocks within the region, indicating an evolutionary trend from potassic to sodic for the Mesozoic volcanic rocks along the Yishu deep fault zone and its adjacent areas. Chemically, the Shenquan volcanic rocks have high alkali content (Na₂O+K₂O=10.34%～11.95%) and are obviously enriched in sodium (Na₂O/K₂O=1.76～3.92); they can be assigned to typical sodic volcanic rocks on the basis of various discrimination schemes. Geochemically, the rocks contain relatively high concentrations of rare earth elements (ΣREE=411.3×10^-6～456.3×10^-6), and are enriched in LREE and LILE (e. g., Rb, Ba, Th), and depleted in HFSE (e. g., Ti, Nb, Ta). They show right-oblique chondrite-normalized REE patterns and display some negative Pb anomalies in the primitive mantle-normalized trace element spidergrams. These rocks have enriched Sr-Nd isotopic compositions [I_Sr=0.706 8～0.707 7, εNd(t)=-16.66～-16.82], similar to that of the Mesozoic mafic rocks in Shandong, indicating that they were probably derived from an enriched lithospheric mantle. Based on a synthesis of geology and geochemistry, the authors hold that the mantle source of the Shenquan sodic volcanic rocks might have undergone multiple enrichment events induced by source contamination of continental crustal materials both from deep subduction of the Yangtze Craton and from lithospheric delamination of the North China Craton. During Late Cretaceous, the continued extension of Tanlu Fault induced the upwelling of asthenospheric melts which further modified the previously enriched mantle. Decompression partial melting of these multiply-modified mantle sources and further differentiation of the magmas finally generated the Shenquan sodic volcanic rocks.