Geochemical Characteristics of Permian Volcanic Rocks from Jianshui , Southeast Yunnan and Their Tectonic Implication
滇东南建水二叠纪火山岩地球化学特征及其构造意义

The Permian volcanic rocks from Jianshui area tectonically intruded into southwest part of Shizong-Mile fault belt.It is mainly comprised of basalts,basaltic andesites,andesites and a little picrites.Geological and geochemical characteristics show that they are formed in back-arc environment,matching Carboniferous pillow lava from Jianshui area.These imply that Yangtze block and Cathaysia block occurred plate-subduction in late Paleozoic forming the island-arc volcanic rocks,and that they produced back-arc extension in Permian,then formed back-arc basins.From late Paleozoic to early Mesozoic,there was a complex trench-arc-basin system between Yangtze and Cathaysia blocks.