吉林延边地区柯岛群之由来及再认识

Origin and further understanding on Kedao Group from Yanbian area,Jilin

吉林延边地区柯岛群为一套陆源碎屑岩建造,但在较长时间内被误认为是早二叠世海相火山岩系;近年来,其岩石地层学含义虽得到了恢复,但又被许多学者赋予了"混杂岩"的构造地层学含义。据笔者研究,柯岛群为一套陆相陆源碎屑岩,具有冲积扇河流湖盆的沉积相组合,以相同的沉积岩组合、构造背景及生物特征(P-P动物群)在区域上可与吉中地区芦家屯组对比,时代属早三叠世,是晚华力西造山作用后造山阶段拉张盆地产物。

Kedao Group in Yanbian area is a set of terrigenous clastic rocks which has been recognized as marine volcanic deposits in Early Permian for a long time. In recent years, the lithostratigraphic meaning of Kedao Group has been recovered, but the tecto-stratigraphic meaning of ＂mixtite＂ has been given by some geologists. The authors consider that Kedao Group is a set of continental, terrigenous clastic rocks with alluvial, fluvial and lacustrine deposits on basis of recent studies. The Kedao Group can be compared with Lujiatun Formation in the center part of Jilin according to the same sedimentary rock assemblage, tectonic setting and biological characteristic （ Paraeonodonta-Paraeomutela fauna）, and its geological age belongs to the Early Triassic, which is a product of the pull-apart basin in the orogenic stage after the Late Variscan orogenesis.