滇西施甸地区卧牛寺组火山岩的地质时代及喷发环境

Age and Eruption Environment of Volcanic Rock from Woniusi Formation in Shidian,Western Yunnan Province

前人将施甸地区卧牛寺组火山岩与北部保山地区卧牛寺组火山岩等同起来,认为是海相喷发的产物。本次调查工作揭示,施甸地区卧牛寺组缺乏沉积夹层,与北部保山地区卧牛寺组火山岩喷发环境存在明显差异,其岩石学、地球化学、宏观地质特征均表明,施甸地区卧牛寺组火山岩具大陆溢流相喷发机制,为陆相喷发产物。同时,年龄测定结果(264 Ma)及其与下伏和上覆地层的接触关系表明,卧牛寺组火山岩的喷发时期为早二叠世,为卧牛寺组地质时代的确定提供了重要依据。

In previous studies on volcanic rock of Woniusi Formation in Shidian region, some researchers have proposed it has close relation with the marine volcanic activity as in Baoshan region, north Yunnan Province. However, the inexistence of sediment strata and characteristics of petrology, geochemistry and geology indicate that the eruption environment is significantly different between the two regions. It is showed that the Woniusi Formation form in continental eruption setting and associated with the continental flood magma in Shidian region. In addition, the age （264 Ma） of volcanic rock from Woniusi Formation and the contact relationship with upper and lower strata suggest the Woniusi Formation might be formed in Early Permian, and these provide new evidence for the formation age of Woniusi Formation.