There exists the thick-bedded formation of Hercynian marine volcanicrocks in southern Hulun Buir League,Inner Mongolia.The basic volcanic rocksof Late Devonian Lower Daminshan Formation(D3x)with a steeply-dippingREE distribution curve are complex of theoleiite and alkaline bsalt,indicating that their formation environment from the middle Devonian to the Early stageof Late Devonian was originally a peroiod of back-are rifting in the continent margin and that they might be products of partial melting of the mantle .Theiron magma debris discovered for the first time in the debris tuff at the top of the formation also supports this conclusion.The basic-acid rocks of Late Devonian Upper Daminshan Formation (D3s)are considered as arc calc-alkaline volcanic series that resulted from the crystallization and differentiation of magma,Their tectonic environment was probably an volcanic arc along the active contiDental margin, similar to things of andes Mountains.The Lower Carboniferous volcanc rocks are of alkaline series that erupted in an intraplate environment. Studies of petroloraery,petrochemistry rare earth elements as well as geote-ctonic environment fail to support the argument that the metallogenic condi-tion is very favorable for the formation of marine volcanics-hosted copperdeposits.