The Woniusi Group Basalt Of Xiyi Yuannan Lead And Zinc Mining Area’s Geochemical And Chronology Characteristics

The Woniusi group basalt, which is mainly distributed in the baoshan area, western Yunnan province, is a part of the Mount-Emei’s large igneous province(LIP). Based on the previous work, we have carried out a study on the petrological and geochemical characteristics, LA-ICP-MS zircon U-Pb chronology, and also identified the tectonic environmenof the Woniusi group basalt, Based on the above results, contrast with the features of the basalt from Mount-Emei, the following conclusions can be obtained:(1)The Woniusi group basalt show enrichments in light REEs and depletions in heavy REEs., and moderate negative Nb, Ti anomalies, but no obvious Eu negative anomaly.. The feature of the low content of the rare earth element(∑<120μg/g)and the low Ti/Y ratio( <500) is similar to the low-titanium basult from the Mount-Emei.(2)The figures of Zr/Y-Zr,V-Ti/1000,Th/Hf-Ta/Hf presented that the Woniusi group basalt is continental crust migmatization.(3)Previous studies showed that the eruption time of Mount-Emei’s LIP mainly in 255~265Ma, while the most active time of mantle plume was in 260 Ma. The weighted mean LA-ICP-MS U-Pb age of the Woniusi group basalt is 261.3±1.2Ma(1σ)which was consistent with the eruption time of Mount-Emei’s LIP.Combined with the paleomagnetic characteristics and the above results, it can be concluded that the Woniusi group basalt is the product and signifcant conponent of Mount-Emei’s LIP, as both of them share the temporal and spatial coherence along with the same occurring environment.