内蒙古乌达煤田早二叠世山西组湿地植被群落演替序列

THE SUCCESSION SEQUENCE OF EARLY PERMIAN WETLAND VEGETATIONAL COMMUNITIES IN THE SHANXI FORMATION OF THE WUDA COALFIELD,INNER MONGOLIA

基于对内蒙古乌达地区早二叠世山西组2号煤相邻地层的野外工作,系统采集植物化石12属、14种。根据沉积环境及植物古生态学分析,识别出生长于该地区早二叠世三角洲平原环境下的植被群落演替序列,包括由早及晚5个群落,即:1)Lepidodendron incertum Sze et Lee群落,代表最初开始形成2号煤层的植被;2)Lepidodendron incertum-Lepidodendron posthumii Jongm.et Goth.群落,反映2号煤下段煤层在停止成煤作用之前的沼泽植被;3)Stigmaria ficoides(Sternb.)Brongn.-Calamites suckowii Brongn.群落,反映泛滥平原上碎屑沼泽与河流之间的广大湿地所生长的植被;4)Lepidodendron incertum-Calamites suckowii群落,代表该区泛滥平原上碎屑沼泽植被;5)Pecopteris taiyuanensis Halle-Emplectopteris triangularis Halle-Taeniopteris serrulata Halle群落,反映天然堤及河流上游泛滥平原中的植被生态群落。植物群落整体面貌为典型的华夏植物群(如织羊齿、大量的带羊齿以及东方鳞木类)。当前群落演替序列反映了二叠纪华夏植物群成煤向碎屑景观的演替状况,以及华夏区成煤植被的稳定性。

Five sequential vegetational communities preserved in a delta plain setting are recognized in the coal measure strata of the Coal 2in the Shanxi Formation of the Wuda Coalfield,Inner Mongolia.They are：1）Lepidodendron incertum Flora representing the vegetation that started to form the Coal2; 2） Lepidodendron incertum-Lepidodendron posthumii Flora,that is the last phase of the swampy vegetation forming the lower part of the Coal 2;3）Stigmaria ficoides-Calamites suckowii Flora demonstrating the vegetation living in the spacious wetland between the clastic swamp and river;4）Lepidodendron incertum-Calamites suckowii Flora,living on the clastic swamp on the floodplain;5）Pecopteris taiyuanensis-Emplectopteris triangularis-Taeniopteris serrulata Flora,that represents the vegetation on natural levee and the floodplain of the upstream.Fossil plants of these five floras are systematically examined and collected,including 14 species of 12 genera.In general,they are all typically Cathaysian elements,such as Emplectopteris,abundant Taeniopteris,and so called Oriental Lepidophytes.These floras promote our understanding on the peat-forming to clastic landscapes and vegetational evolution,and particularly the relative stability of the coal-forming floras in Cathaysia.