大兴安岭南部上二叠统林西组新认识

NEW UNDERSTANDING OF THE UPPER PERMIAN LINXI FORMATION IN SOUTHERN DAXINGANLING REGION,CHINA

在综合分析前人资料和野外实际工作的基础上,根据岩石组合特征,将林西组大致分为两部分:下部为一套灰色、灰紫色、黄褐色的河流相砾岩、砂砾岩组合,含Paracalamites sp.,Eichwaldia sp.,Pecopterissp.等植物化石,分布于研究区南部的林西地区,推测为盆地的边缘相沉积,同时期盆地内部可能存在海陆交互相沉积;上部为黑、灰、绿为主色调的砂岩、板岩组合,含晚二叠世植物化石Paracalamites sp.,Pecopteris sp.,Cladophlebis sp.,Noeggerathiopsis cf.cylovaensis等及双壳类Palaeanodonta-Palaeomutela组合.在研究区广泛分布,但厚度及岩石组合特征横向变化较大,局部地区上部层位有火山岩,反映沉积环境比较复杂.

Based on a systematic study of previous data and field survey,the authors divided the Linxi Formation into two lithologic members from bottom to top.The first member,mainly distributed in Linxi area,is dominated by gray-purple fluvial sandstone and conglomerate,containing plants of Paracalamites sp.,Eichwaldia sp.and Pecopteris sp.The second member,widely spreading in the southern part of Daxinganling region,consists mostly of black gray sandstone-slate with volcanic rocks at the upper part,containing abundant fossils of bivalves and plants such as Palaeanodonta-Palaeomutela assemblage,as well as Paracalamites,Pecopteris,Cladophlebis and Noeggerathiopsis.