大兴安岭地区嫩北农场一带晚古生代火山岩地层的厘定

大兴安岭嫩北农场一带出露一套以中酸性火山熔岩为主的晚古生代地层.前人对这套地层划分、时代归属存有很大分歧.原因是:一方面区域上火山岩出露厚度大、露头不连续、区域植被茂盛,顶底多为断层接触或被第四系所覆盖;另一方面由于存在于火山岩地层中的化石较少或缺少精确的同位素年代学数据.本文在新近研究成果的基础上,依据地层岩石组合对比及锆石U-Pb年代学资料,将这套晚古生代地层进行了重新厘定为大石寨组.

DETERMINATION OF THE LATE PALEOZOIC VOLCANIC STRATA AROUND THE NENBEI FARM IN DAXINGANLING REGION

A set of Late Paleozoic strata, dominated by acid-intermediate volcanic lava, is outcropped around the Nenbei Farm in Daxinganling region. Previously, the stratigraphic division and age of the strata have been great differences. The reasons for this are as follows: On the one hand, the volcanic rocks in the area are great in thickness, discontinuously outcropped and covered by vegetation, with top and bottom mostly contacted with faults or covered with Quaternary sediments. On the other hand, there is less fossils in the volcanic rocks, or lack of precise isotopic geochronological data. Based on recent research results and comparison between the rock assemblages on zircon U-Pb geochronology, these Late Paleozoic strata are reassigned.