The geochemical characteristics of Late-Triassic volcanic rocks from Wengshui in Zhongdian area, Yunnan and tectonic significant
云南中甸地区翁水晚三叠世火山岩地球化学特征及其构造意义

It has not been reported at present of arc magmatic activities for Late Triassic in northern zhongdian arc of Sanjiang tectonic belt. Our petrological and chronological researches show that the intermediate-acid magmatic activity of Indosinian developed in Wengshui areas of Zhongdian arc; zircon U-Pb dating indicates that the volcanic rocks in Wengshui area were erupted at 211.1±1.5Ma, which is similar to ages of other Indosinian volcanic rocks and ore-bearing porphyric rocks in southern Zhongdian area. The Wengshui volcanic rocks mainly consist of andesites and show depletion of high field strength elements such as Nb, Ta, Ti similar to arc volcanic rocks. Compared with Lannitang-Langdu andesites from southern area of Zhongdian arc, the both clearly show compositional signature of an arc volcanic rock. Combining their age and tectonic background, we conclude that Wengshui andesites, Lannitang-Langdu andesites and ore-bearing porphyric rocks from Zhongdian area were most likely formed by a same tectono-magmatic event, which were generated by westward subduction of the Ganzi-Litang in Late-Triassic.