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ON THE PERMIAN PHYTOGEOGRAPHY OF W.HENAN-N.ANHUI REGION

Wang Jun1, Sun Bai-nian2, Shen Guang-long3   

  1. 1. Nanjing Institute of Geology and Palaeontology,Academia Sinica,Najing 210008; 2. Department of Geology,Lanzhou University, Lanzhou 730000; 3. Department of Geology,Northwest University,Xi’an 710069
  • Received:1999-03-20 Revised:1999-03-20 Online:1999-03-20 Published:1999-03-20

Abstract: Statistica1 method has been used in a comprehensive study of the Permian focal1 plants from W.Henan-N.Al1hui region. The results of this study are summarized in the attached table and compared to the fossil plants from North and South China. Four Permian plant assemblages have been recognized in this area,which are: (1)Neuropteris pseudovata-Lepidoderdron szeianum assemblage in the early stage of the Early Permian (the middle and upper parts of Taiyuan Formation) (2)Emplectopteris triangularls-Cathaysiopieris whitei-Lobatannularia sinensis assemblage in the middle stage of the Early Permian (the Shanxi Formation) (3)Gigantopteris lagrelii-Lobatannularia ensifolia-Fascipeters hallei assemblage in the late stage of the Early Permian (the Lower Shihhotse Formation). (4)Gigantopteris nicotianaefolia-Lobatannularie multifolia-Psygmophyllum multipartitum assemblage at the early stage the Late Permian (the Upper Shihhotse Formation). The major components of each p1ant assemblage are compared quantitatively in the Figure 1. The Permian flora of the W.Henan-N.Anhui region is characterized by its endemic features, especially in the late stage of the Early Permian and the early stage of the Late Permian. However,as far as the number of species is concerned, the species occurring only in the W.Henan-N.Anhui region are usually less than those occurring both in this region and N.Chian,i.e.,A≤B+C. Therefore, this region could be regarded as a phytoprovince in the N.China Phytoarea,rather than a phytoarea with the same rank as N. China and S. China regions. This conclusion is further supported by an analysis of thecommon species and the Simpson coefficients (see table 1) among these plant assemblages in the W.Henan-N.Anhui region,N.China and S.China,because the fossil flora of W .Hena n-N.Anhui region generally possess a closer relation to that of N.China than S.China throughout Permian period. As an independent phytoprovince in the N.China Phytoarea,the fossil flora in this region possesses certain transitional features be tweed the flora in N.China and S.China Phytoareas. For example, Gigantonoclea and Gigantopteris, which are considered respectively the representative as member of the Gigantopterids in N.China and S.China, co-exist primarily in the W.Hen an-N.Anhui region. The development of the W.Henan-N.Anhui phyroprovince is probably related to the movement (drifting, rotating)of the N.China and Yangtze blocks and is consistent with the Permian coal beds containing this fossil flora and bearing the feature of “northern stratigraphic type and southern sedimentary facies”.