On the basis of petrogeochemical data, the volcanic lavas of Baimianxia Formation can be classified into two major parts. These are a high TiO2 (>1%) type situated in lower part with highgrade metamorphism; and low TiO2(<1%) type situated in upper part with lowgrade metamorphism. The volcanic rocks in lower part has dominantly tholeiitic lavas with chondrite normalized REE patterns exhibiting high REE contents （∑REE=83.4~180.8μg/g）, high LREE/HREE ratios （LREE/HREE=2.17~5.85）and weak negative Eu anomaly(δEu=0.79~1.01), also the trace element patterns display weak NbTa anomalies with respect to Th, K, La, Ce, elemental and isotopic data is similar to the signatures of within plate lavas and suggest the lavas in lower part originated from within plate setting. In contrast, the volcanic rocks in upper part exhibit low REE contents, low LREE/HREE ratios, and pronounced NbTa anomalies with respect to Th, K, La, Ce, these are typical arc or continental arc signature. While the basalts and andesites in Sanwan Formation show flat or LREE depletion patterns, similar to NMORB, together with the rock associations, we suggest these lavas formed in backarc basin setting. LAICPMS zircon UPb dating for basalts in upper part of Baimianxia Formation and elemental and SrNd isotopic data suggest the age of lavas in lower part of Baimianxian Formation is 1144Ma or so, and which originated form and asthenospheric oceanicislandbasaltlike mantle source within the garnet stability field with fractional crystallization and crustal contamination and continental lithospheric mantle also contributing significantly to the formation the the lavas. Instead, the lavas in upper part of Baimianxia Formation formed about 437Ma and maybe continued to late Paleozoic, they may originate from arc or continental arc in response to aqueous fluids or melt expelled from a subducting slab, and the partial melting occurred in garnet stability field. The samples of basalts and andesites show they are derived from depleted mantle source similar to NMORB. Finally, we can conclude that the lavas in upper part of Baimianxia Formation represent the geological records of riftrelated volcanism in middle Proterozoic. Whereas, the lavas in upper part of Baimianxia Formation and Sanwan Fromation may be generated by the oceanic and continental conversion occurred in Paleozoic.