滇西南澜沧江带热水塘下二叠统沉积特征及构造古地理意义

SEDIMENTARY CHARACTERIS TICS AND TECTONIC PALAEOGEOGRAPHY OF THE LOWER PERMIAN N RESHUITANG OF LANCANGJIANG ZONE SOUTHWESTERN YRNNAN

热水塘下二叠统位于滇西南澜沧江带西区，为一套弧前深水斜坡盆地环境的碎屑浊流、等深流沉积组合，其物源主要来自东侧的大陆火山岛弧。它们和更东的龙洞河组，形成澜沧江带海西期“弧前－火山弧－弧后”的构造古地理格局，表明思茅地块西侧在晚石炭世—早二叠世为活动大陆边缘，标志着滇西南古特提斯洋板块自西向东的俯冲作用。

The early Permian stratum in.Reshuitang ,located in the west of Lancangjiang zone n southwestern Yunnan,is a series of clastic turbidites and contourites association deposlted in the forearc deep-water slope basin.Its provenance is the eastern continental volcanic island-arc.They,and Longdonghe formation ,formed“forearc-volcanic arc-backarc”pattern of tectonic palaeogeography during Hercynian in Lancangjiang zone. It showed that western margin of simao bolck was active margin during the later carboniferous to the early Permian which represents the eastern subduction of Palaeotethys plate in southwestern Yunnan.