There is a widespread exposure of Diabase—gabbro basic intrusive rock groups in the peripheral area of the Dongchuan copper deposit on thewestern margin of the Yangtze block. However, there is no unified understanding of their genesis, age, and ore bearing potential. Results:This article presents a study on the petrology, petrogeochemistry, and isotopes of diabase—gabbro rocks in the peripheral area of the Dongchuan Copper Mine. The results obtained a zircon LA- ICP- MS U- Pb age of 800.4±7.0 Ma (MSWD=0.0085, n=20), indicating that the widely exposed basic intrusive rock group around the Dongchuan Copper Mine was emplaced in the middle Neoproterozoic period, indicating the existence of magmatic events in the middle Neoproterozoic period in the Dongchuan Copper Mine area. The basic intrusive rock group exhibits high MgO (5.11%~7.77%, average 6.23%), high TiO2 (2.04%~2.95%, average 2.60%), and rich alkali (2.30%~3.39%, average 2.97%) geochemical characteristics, exhibiting slightly alkaline potassium rich titanium basalt. The basic intrusive rock group is enriched with large ion radius elements such as K, Rb, and Ba, while high field strength elements such as Ta, Nb, Zr, and Hf are not significantly depleted. The distribution patterns of trace and rare earth elements are consistent with typical oceanic island basalt (OIB) and formed in an extensional tectonic background.Zircon Lu—Hf isotopes and (La/Sm) N — (Tb/Yb) N studies indicate that the Xiaoyixi basic rock mass is a product of low degree partial melting of ≤5% lower mantle garnet peridotite in the Middle Mesoproterozoic era, and there may be a small amount of crustal material mixed in later stages. Conclusions:The formation of the Xiaoyixi basic rock mass may be related to the mantle plume activity that caused the rupture of the Rodinia supercontinent in the middle Neoproterozoic, and is an important petrological and magmatic record of the Nanhua rift .