论文部分内容阅读
思茅地块西缘的龙洞河组为一套火山—沉积岩系 ,原定时代为晚石炭世 ,被认为属南澜沧江洋弧后盆地沉积。现在龙洞河组层状硅质岩断片中发现了晚泥盆世放射虫化石 ,在细碧角斑岩之硅质岩夹层中发现了早石炭世放射虫动物群 ,表明龙洞河组不全是晚石炭世地层 ,而是由晚古生代的一些地层断片组成。思茅地块西缘深水沉积盆地的演化始于泥盆纪 ,应为滇西南古特提斯多岛洋的一个分支 ,向南可能与泰国难河带对比。
The Longdonghe Formation in the western margin of Simao block is a set of volcanic-sedimentary rock series. Originally scheduled for the Late Carboniferous, it was considered to be a sedimentary deposit of the South Lancang Ocean arc back-arc basin. Now that the Late Devonian radiolarian fossils were found in the layered siliceous rock fragments of the Longdonghe Formation, the Early Carboniferous radiolarian fauna was found in the siliceous intercalated layers of the Penipejar porphyry, indicating that the Longdonghe Formation was incomplete Carboniferous strata, but by a number of Late Paleozoic stratigraphic fragments. The evolution of the deep-water sedimentary basin in the western margin of the Simao block began in the Devonian and should be a branch of the ancient Tethys Island in southwestern Yunnan, possibly to the south of Thailand.