晚古生代特提斯区热带、亚热带植物群的东西分异

EAST-WEST DIFFERENTIATION OF LATE PALAEOZOIC TETHYAN TROPICAL-SUBTROPICAL FLORAS

关键词:  晚古生代  欧美植物区  东西分异

Key words:  Late Palaeozoic  Euramerican floral province  east-west differentiation

摘要:

从早石炭世开始,地球出现明显受气候带控制的植物分区现象,产生了分别代表南、北温一寒带的冈瓦纳植物区和安加拉植物区以及夹在其间的代表热带、亚热带的欧美植物区(广义)。
随着南、北大陆在特提斯西部的汇聚,广义的欧美植物区在晚石炭世产生了东西分异,形成了西部狭义的欧美植物区和东部的华夏植物区。本文从分析东、西两植物区的生态特征、演化阶段、古构造格局的重组和古地理环境等因素入手,探讨了两植物区之间的区别及其分异的原因。可以认为植物区的东西分异是由气候的东西分异造成的,而气候的东西分异则是由于特提斯西部的板块汇聚造成的,它促使西部特提斯地区转变为干旱的大陆性气候,而东部特提斯地区为裂解阶段,保持着潮湿的海洋性气候。

Abstract:

The floral provinciation apparently controlled by climatic zones appeared on the Earth from the Early Carboniferous onwards,forming three floral provinces,i,e.,the Gondwana floral province which represents the southern temporate and/or frigid zones,the Angara floral province which represents the northern temperate and/or frigid zones,and the Euramerican floral province (sensu lato) which represents the tropical-subtropical zones.
With the convergence of the Laurasia and Gondwana continental landmasses in western Tethys during the Late Carboniferous,the Euramerican floras(sensu lato)were differentiated in the eastern and western parts,resulting in the formation of two floral provinces,i,e.,the Euramerican floral province (sensu stricto) in the west and Cathaysian floral province in the east.The differences between the two floral provinces and the origin of the east-west differentiation are probed in this paper on the basis of the ecological characteristics and evolutional stages of the two floral provinces,the reconstruction of palaeotectonic framework and the palaeogeographical environments.It is suggested that the floral differentiation was caused by the east-west climatic differentiation which,in turn,resulted from the plate convergence in western Tethys giving rising to the dry continental climates in the west,while the climates in the east remained to be the humid marine climates.