Abstract: There occur a series of fine clastic sedimentary rock and mediumbasic volcanic rocks assemblies (including the spite and metabasic basalt) in Genhe area of North Daxing’anling Mts.,belong to Moergen Formation.The studies on their geochemical characteristis show that basic valcanic rorks high contents of Na₂O,K₂O,TiO₂,w(Fe₂O₃)/w(FeO)=0.8(average) (belong to alkaline series).Enrichment in LREE and with insignificant Eu anormalies ;compared with MORB,their lightly depleted in Ti， Y， Yb,but more enriched in others elements are similar to those of ocean intraplate basalts. Their initial w(⁸⁷Sr)/w(⁸⁶Sr) value is 0.7043,the ε_Nd(t) value is 3.00,indicate that their source region are related to mantlesource.Based on above data,this paper proposes that the activity of mantle plume lead to basic volcanic rocks formed,reflecting of Hawaiitype oceanic island tectonic enviroment.

Key words: North Daxing’anling Mts., Early Carboniferous, mantle plume, oceanic island, basalts