Abstract:Objectives: After a regional geological survey of 1∶50 000, new mafic—ultramafic alkaline rock bodies were newly discovered in the Dianzhong area of Eshan County. The lithology is garnet- containing apatite rock and syenite. Petrogeochemistry shows that the SiO2content of the rock is 42.74% ~ 45.11%, which generally has high MgO (8.78% ~ 11.13%), iron- rich (full iron content), low TiO2(0.88% ~ 2.45%), and low Na2O (0.17% ~ 0.62%), alkali- rich characteristics. Results:Enrichment of large ion lithophilic elements (LILE) such as Rb, Ba, Sr, and Th, relative loss of high field strength elements (HFSE) such as Nb, Zr, Ti, Hf and heavy rare earth elements Yb, Y, during the magma formation process, it had a moderate degree of partial melting (about 10% to 15%), and experienced significant crystal differentiation in the later stage. Zircon U- Pb LA- ICP- MS dating of pyroxene and gabbro, 260.2 ± 1.6 Ma (MSWD = 0.4, n = 10) and 264.0 ± 1.3 Ma (MSWD = 2.4, n= 23).Conclusions:Belongs to the late Middle Permian, and has similar geochemical characteristics and emplacement age to the Emeishan basalt. Based on the regional data and the above characteristics, this paper believes that the mafic—ultramafic alkaline rock in the Dianzhong area of Eshan County belongs to the product of the Emeishan mantle plume. This discovery is of great significance for enriching the data of the Emeishan large igneous province.