PHYTOGEOGRAPHY OF THE LATE PERMIAN MIXED FLORA OF NORTHERN CHINA

The large areas to the north of the mountain ranges along with Mts. Kunlun-Altun-Qilian-Qinling-Dabie are composed of a number of major tectonic blocks including Junggar, Tarim, Jiamusi-Mongolia, Qilian-Alxa and North China Blocks and some micro-terrains during the Permian. These areas are known as a mixed floral realm during the late Permian. Based on a systematic analysis of the fossil plants yielded in these areas, six phytoprovinces are recognized;1) Junggar-North Tarim Angaran-Cathaysian Phytoprovince;2)Beishan-Badain Jaran Angaran-Cathaysian Phytoprovince;3) Xingmeng(northestern China) Angaran-Cathaysian Phytoprovince;4) South Tarim Angaran-Euramerican Phytoprovince;5) Qilian-Alxa Cathaysian-Angaran Phytoprovince;6) North China Euramerican-Cathaysian-Angaran Phytoprovince. According to palaeomagnetic data and floral evolution, the movements of these blocks in the Paleo-Tethys and Palaeo-Asian Oceans are briefly summarized. They generally drifted from lower latitude tropical-subtropical rain forest climate zone to high latitude temperate and arid climate zone in the northern hemisphere through Carboniferous and Permian and finally collided forming part of Pangaea. It is concluded that the formation of these late Permian mixed floral provinces mostly resulted from the movement and collision of these blocks. During middle and late Permian, the Pangaea as a larged united continent led to migration and interchange of the floras from all of these previously isolated blocks, and finally resulted in mixed floras and even yielded abundant local taxa.

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