云南澜沧地区澜沧岩群变质岩石类型特征与原岩恢复

CHARACTERISTICS OF METAMORPHIC ROCK TYPES AND ORIGINAL ROCK RESTORATION OF THE LANCANG ROCK GROUP IN LANCANG AREA,YUNNAN PROVINCE

云南澜沧地区澜沧岩群出露于昌宁-孟连结合带西部,划分为曼来岩组片岩,原岩为泥岩、粉砂质泥质岩、泥质粉砂岩类;惠民岩组钠长千枚岩,原岩为流纹岩;南坑河岩组变质石英砂岩,原岩为石英砂岩。为一套含火山陆源碎屑沉积,其沉积环境为被动陆缘。澜沧岩群变质带经历了三期变形变质作用,早期为加里东期,主变质时期为华力西期,后期局部叠加印支期动力变质作用。

The Lancang rock group in the Lancang area,Yunnan Province,crops out in the western part of the Changning-Menglian junction zone.It is a set of volcanic terrestrial clastic sediments formed in a passive continental margin environment,consisting of Manlaiyan Formation schist(original rock is mudstone,silty argillaceous rock,and muddy siltstone),Huiminyan Formation sodium feldspar phyllite(original rock is rhyolite),and Nankenghe Formation metamorphic quartz sandstone(original rock is quartz sandstone).The metamorphic belt of the Lancang rock Group has undergone three stages of deformation and metamorphism,including the Caledonian period,the main metamorphic period of the Variscan period,and the late partial superposition of the Indosinian dynamic metamorphism.