摘要：

在河北秦皇岛柳江盆地石炭一二叠纪地层中发现古植物化石44属86种。其中，真蕨纲和种子蕨纲居首要位置，占古植物群属种总数的41.8%，楔叶纲次之，占18.6%。石松纲植物居第三位，占11.6%。种子化石占11.6% ，其他依次为瓢叶纲4.7%、苏铁纲4.6%、科达纲2.3%、银杏纲2.3%、松柏纲2.3%。此古植物群属种丰富，华夏植物群的特点明显，纵向上可划分成6个古植物组合，即Linopteris neuropteroides-Lepidodendron galeatum组合，Neuropteris plicata-Lepidodendron posthumii组合，Lobatannularia sinensis-Annularia stellata组合，Pecopteris anderssonii-Pterophyllum daihoense组合，Cladophlebis permica-Psygmophyllum multipartitum组合和Ullmannia bronnii-Walchia bipinnata组合。该古植物群演化具有阶段性，组合的变化与古地理6个演化阶段相适应：第一阶段（本溪组）深潮下带、湖、三角洲、河流环境交替出现；第二阶段（太原组）潮下带、潮坪、三角洲环境交替出现；第三阶段（山西组）河道、沼泽、天然堤、决口扇环境交替出现；第四阶段（下石盒子组）沼泽、河道、砂坝环境交替出现；第五阶段（上石盒子组）从干旱陆相河漫湖、天然堤、泛滥平原、河口砂坝逐步转变为多层叠覆边滩和心滩环境；第六阶段（石千峰组）为干旱条件下大型湖泊三角洲、天然堤、边滩交替出现。这反映了植物群演化与古地理环境演化的同步性。

Abstract:

The fossil plants studied  in  this  paper  were  collected  from the Upper  Carboniferous and Permian in  Liujiang Basin, Hebei  Province. This  flora was composed of 86 species in 44 genera  belonging to Filicopsida (41.8%), Cycadopsida  (4.6%), Cordaitopsida  (2.3%), Ginkgopsida (2.3%)  and  Coniferae  2.3%.x Many fossil plants had  the characteristics of Cathaysia flora.  The  flora could be divided into six assemblages in ascending order:Linoptleris neuropleroides-Lepidodiendron galeatum, Neuropteris plicata-Lepidodendron posthumii, Lobatannularia sinensis-Annularia stellata, Pecopteris anderssonii-Pterophyllum daihoense, Cladophlebis permica-Psygmophyllum multipartitumand Uilmannia bronnii-Walchia bipinnata assemblages. According to the sedimentary characteristics and plant assemblages, the evolution  of the flora  could be divided into six stages. In the first stage(Benxi Formation) deep subtidal，lagoon,delta and river occurred allernativelyIn the second stage (Taiyuan  Formation), subtidal，tidal flat and delta occurred alternativelyIn the third stage (Shanxi Formation), swamp, distributary channel, natural levee,and crevasse splay occurred alternatively. In the fourth stage (Lower Shihezi Formation), swamp, distributary channel, and sand bar occurred alternatively. In the fifth satge(Upper Shihezi Formation), large lake lake, natural levee,and river mouth bar changed to point bars and central bars. In the sixth stage(Shiqianfeng Formation), large lake delta, natural levee, river mouth bar and point bar ocurred alternatively.Key wordsLiujiang Basin, Carboniferous,Permian, Cathaysia flora, evolution  of paleaogeographyAbout the authorYang Tongsheng，born in  1958，graduated  from China  University of Geosciences(Beijing) and  obtained Ph. D. degree in 1999.Now he is an  associate  professor,and   is  engaged in paleobotany，sedimentary  environments  and  paleoecology.