YuezhaoPipasi metamorphic volcanic rocks are exposed between the Devonian strata and the preSinian Bikou Group in Wudu county of Gansu Province. Based on geochemical classification, volcanic rocks can be divided into bimodal and alkaline. The bimodal volcanic rocks consist mainly of dacitic rhyolite and tholeiitic basalts characterized by low K and high Na concentration. The REE distribution partterns of tholeiitic basalts show the flat style and their trace elements geochemistry is similar to MORB. But the low Nd and high Th concentration imply contamination by the continental crust in magma process. All above evidences suggest that the YuezhaoPipasi metamorphic volcanic rocks were the products of transition from continental rift to matured oceanic basin, implying that the volcanic rock may be the west branch of the MianLue paleoocean