Geological Significance and Volcanic Features of Wulang Formation of Lower-Middle Permian in Bayinjulike Area, Xinyuan County, Xinjiang

The continental volcanic rocks of Wulang formation of Lower-Middle Permian displayed a planar spatial distribution in the Bayinjulike area. Wulang formation is divided into upper unit (P₁w²) and lower unit (P₁w¹), where the upper formation is a bimodal volcanic combination of basic volcanic rocks and acid volcanic rocks, constructed by the main body volcanic rocks of Wulang formation. The major elements show that the volcanic rocks of Wulang formation are alkaline series. Characterized by strong enrichment of Ba, Th, Ta, and other enrichment of Ce, Hf, Zr and Sm, the distribution feature of trace elements is double uplift, which is basically identical with geochemical pattern of within plate alkaline basalts. Rare earth elements distribution curve inclines to the right, the LREE concentrated obviously, while HREE slightly enriched in the rhyolite, and relatively depleted in the basalt. Discrimination diagrams in further clarifies that the group volcanic rock formed in the intraplate evolution environment. The comparative study on the formation inferred that volcanic rocks of Wulang formation in Bayinjulike area formed in the early-middle Permian.