1． College of Earth Sciences，Jilin University，Changchun 130061，China; 2． Ｒesearch Center of Palaeontology ＆ Stratigraphy，Jilin University，Changchun 130026，China

Zircon LA- ICP- MS U- Pb age and whole- rock geochemistry data are presented for the Dongxigao dio- rite porphyries in Pingyi，western Shandong，to restrict its petrogenesis． The zircons from the Dongxigao diorite porphyries exhibit striped absorption and oscillatory growth zoning in the cathodoluminescence images，which have upward- type characteristics of rare earth elements (ＲEEs) with positive anomaly of Ce and negative anomaly of Eu，and have high Th/U ratios (0． 06- 0.91)，indicating its magma origin． Zircon LA- ICP- MS U- Pb dating indicates that 207 Pb/ 206 Pb ages of 16 spots of zircons are between 2 476 Ma and 2 701 Ma，yielding a weighted mean age of 2 481 ±8 Ma，which represents the formation age of Dongxigao diorite porphyries，i.e. Late Neoarchaean． Geochemically，the samples have low contents of SiO 2 (54.94% and 54.86%) and high amounts of MgO (7.19% and 7.58%) and Mg # values (66． 47 and 67． 59)． Additionally，the Dongxigao dio- rite porphyries show enrichment of LＲEEs and prominent negative Eu anomaly (δEu = 0.89 and 0.91)，and they are characterized by enrichment of large ion lithophile elements (LILEs) (e.g. Cs，Ｒb and Ba)，deple- tion of high field strength elements (HFSEs) (e.g. Nb，Ta，Zr，Hf and Ti)，and positive anomaly of K and Pb． The results imply that the Dongxigao diorite porphyries dominantly derived from partial melting of enriched lithospheric mantle with attributes of arc magma，and the magma source area was mixed with amounts of conti- nental crust material，it suggests that they formed in transformation tectonic setting changing from compression to intraplate extension．