1. School of the Earth Sciences and Resources, China University of Geosciences, Beijing 100083, China;
2. Shandong Institute of Geological Survey, Jinan 250013, China;
3. Institute of Earth Sciences, China University of Geosciences, Beijing 100083, China

There are many intermediate-basic dikes which intersect the mineralization belts in Songjiagou gold deposit. Detailed zircon LA-ICP-MS U-Pb geochronology, petrology and geochemistry have been carried out for these intermediate-basic dikes.The results show that the dykes can be divided into pre-metallogenic and post-metallogenic dykes, which consist of diabase and diorite respectively.The ΣREE contents of the two types of dykes are relatively high, the LREE/HREE ratio of the pre-metallogenic dike ranges from 12.76 to 15.52，and the LREE/HREE ratio of the post-metallogenic dike is 18.72.Both are characterized by relative enrichment of LREE and depletion of HREE.The pre-metallogenic and post-metallogenic dikes are enriched in large ion lithophile elements(Rb, Ba) and high field-strength elements (U, Th), but depleted in Nb, Ti and other high field-strength elements, which show the characteristics of intraplate basalts mixed with crustal materials.The zircon U-Pb ages of the pre-metallogenic dikes range from 518 to 802 Ma, which belongs to the captured zircons, while the zircon U-Pb age of the post-metallogenic dyke is (121±5)Ma.Combined with the maximum sedimentary age of Laiyang Group (130±2 Ma)，it is concluded that the Songjiagou gold deposit was formed in 121~130 Ma.