Metamorphic And Deformation Characteristics In Northwest Yunnan Province Of Nu River Chongshan Group Metamorphic Complex

In this paper,through the systematical research of inside and outside,to the mountains to group of metamorphic complex field geological,chronology,geochemistry and metamorphic deformation characteristics,based on the system,and basic find out lofty mountain group of the original rock types,metamorphic complex diagenetic environment,The metamorphism and metamorphic period of its diagenetic rocks are divided into the following conclusions:?1?The metamorphic complex of Chongshan Group is a set of metamorphic rock assemblages,consisting mainly of felsic metamorphic rocks and some of the intercalated argillaceous metamorphic rocks.The primary rocks are composed of acid igneous rocks and continental clastic complex sandstone,which are mainly composed of volcanic-sedimentary rocks.?2?Gneiss in Chongshan metamorphic complex,mylonite as acid igneous rock,black cloud plagioclastic schist as continental clastic complex sandstone,forming tectonic environment of active continental margin.?3?The U-Pb age data of the samples in this study are mainly concentrated in P₁?286.6±2.9Ma?282.2±3.0Ma?and T₃?234.4±3.8Ma?232.4±2.8Ma?206.6±5.6Ma?periods,indicating the tectonic hydrothermal events caused by collision and compression of several microcontinental blocks,such as the Yangtze plate,in the Hercynian-Indosinian stage and the subtractive closure of the PaleoTethys main ocean basin.It has important influence on this area.?4?The early stage of the metamorphic complex of chongshan group is the regional metamorphism of amphibole facies in Jinning period.Regional metamorphism of high greenish-schist facies in the middle stage;Late dynamic metamorphism.?5?The main deformation of metamorphic complex in chongshan group can be divided into four stages:the deformation of plagioclase and biotite schist in the first stage;The second stage is the ductile deformation of late intrusive granite.The third stage of deformation is the brittle ductile deformation under regional slip.The fourth stage is the brittle deformation caused by the eastward thrust of the lancang river structural belt.