Detailed field observations have identified basic and granitic plutons in Kumux area, whose intersections resulted in a white-black mosaic pattern at the surface. Geochemical analyses demonstrate that both granite and gabbro are strongly enriched in LREE and incompatible elements and depleted in HREE and other compatible elements. Very high Sr content and low Rb/Sr ratio of the gabbros can be attributed to some contamination of Sr-enriched fluids derived from sedimentary rocks. Such a geochemical feature suggests that the gabbros were derived from an enriched mantle wedge area in a magma arc environment. Weak fractionation of HREE indicates garnet crystallization during partial melting of the enriched mantle wedge. CL observations and SHRIMP U-Pb analyses of granitic zircons reveal that the granite is of S-type resulting from remelting of meta-sedimentary rocks at about 396 Ma. Taking into account the geological data from peripheral areas, the authors have reached the following conclusions: (1) the intensely deformed plutons of the Kumux area resulted from the northward subduction of the Paleo South Tianshan Ocean under the Central Tianshan terrane, (2) during the subduction, the Kumux area was located on the subduction-related continental magma arc zone, and (3) the boundary between the South Tianshan unit and the Central Tianshan unit should be re-located to the south of the Kumux and the north of the Yushugou ophiolite slice.