The meta basic volcanics, lying at the Southeast of Xilinhot area, distributed in the east of the Hinggan Mongolian orogenic belt in Inner Mongolia, are the amphibolite part of Xilin Gol complex. From the amphibolite, by LA MC ICP MS Zircon U Pb Dating technique, this paper gets two formation ages: (334.5±3.5) Ma and (323.4±2.4)Ma, which belong to late Carboniferous epoch. Geochemical ananlysis shows that the meta basic volcanics are characterized by relatively high Fe (TFeO=6.07%~10.55%), high Mg (MgO=3.90%~11.29%), high Al (Al2O.3=12.68%~17.22%), low Ti (TiO2=056%~169%), high Na low K (K2O+Na2O=212%~737%, K2O/Na2O=002~ 059), belonging to calc alkaline basalt or andesite. These metabasic volcanics are also characterized by relatively low in REE content(ΣREE=15.97×10-6~176.0×10-6), relatively light fractionation between LREE and HREE(LREE/HREE=0.77~6.26), no obvious Eu negative anomaly(δEu=048~113) and particular strong enrichment in large ion lithophile elements (Rb, Th, U and K) and depletion in high field strength elements (Zr, Hf, Nb and Ta), showing an affinity to MORB, suggesting that their original rock mostly are island arc basalt or andesite. Further, The Isr and εNd(t) values are 0701828~0704096 and +283~+661，which implies that they could be derived from the depleted lithospheric mantle. In a word, it is presumedly determined that their primary magma may originate from depleted mantle wedge which was metasomatosed due to the subduction of plate. They may result from island arc magmatism. Based on these results, it is inferred that these volcanics were melting products of the metasomatized mantle wedge formed during the Paleo Asian Ocean subduction northward. And therefore in late Carboniferous the Paleo Asian Ocean was not closed in study area but was in its subduction stage.