Geology And Geochemistry Characteristic Study Of Emeishan Basalt In Yuexi Area, Sichuan Province

The Permian to Triassic basalt Distributed in Yunnan, Guizhou and Sichuan, which has always been concerned by many scholars. Emeishan large igneous province basically located in the western margin of the Yangtze Block, and now, it is one of the few large igneous province recognized by the international geological community. In terms of mineral distribution in our country, Emei large igneous province is typical mineral concentrated area in Southwest China. Because its origin mainly associated with the activities of the mantle plume, its obviously feature is a large number of volcanic magma rock series produced in a short time. So the study of the Emeishan basalts has indicative significance in the evolutions, genesis, geological effects of mantle plume, Emei large igneous province will become a ideal place for studying mantle plume.Field measured by cross-sectional analysis found that the region Emeishan Basalt Formation thickness 1571.25 m. With the overlying strata was Xujiahe parallel unconformity contact with the underlying positive new group for the eruption unconformity relationship. Combined with field observations and previous information will be divided into three sections. Yuexi Emeishan Basalt Formation is mainly overflow facies, and then eruptive facies.Thesis on the Yuexi region of Emeishan basalt microscopic petrographic, geochemical experimental analysis of experimental data by defining the content of major elements of the range. Detailed analysis of the data, while beyond a reasonable range of samples interpreted accordingly. Illustrated by Huck, TAS diagram, silicon-analysis of major elements and other properties of potassium FIG. Rare earth element fractionation situation sensitively reflect the causes and characteristics of the source rocks. Yuexi Emeishan Basalt REE patterns showed a diagram of the right-wing type, while the mainland is enriched in light rare earth alkaline basalts of rightist slash. Trace elements LILE elements K, Sr, Ba strongly depleted, and Rb, LREE enrichment relative. While the high field strength elements Nb, P, Ce strongly depleted, Th, Zr, HREE relative enrichment. But LILE elements K, Yb larger fluctuation range Sr, Ba and heavy rare earth elements, combined with the corresponding sample microscopic observation and analysis ruled out the eclipse becomes basically possible, it should be caused by a preliminary judgment magma assimilation effect.In the terms of magma source, the analysis results showed that the Yuexi Emeishan basalt originated in garnet phase melt from high pressure conditions, which have high crystallization temperature. As the depth cha nge, the pressure,temperature and melting degree decrease, and formed the basalt. At the same time, preliminary determine the Yuexi Emeishan basalt is not derived from the lithospheric mantle but the mantle plume.