摘要
报道江西临江镇晚始新世临江组内发现的含Palibinia植物群。详细记述了Palibinia属的研究历史 ,其地质、地理分布以及其命名问题。从其叶形态、伴生的蒸发岩以及植被的分异度等确认Palibinia为旱生植物 ,并对其所代表的干旱气候形成机制予以探讨。文中描述了该植物群中的 6种主要植物化石 。
Fossils of the extinct genus Palibinia are widely distributed in low and middle latitudes (from 23°—37 °N ) of China, i.e. Guangdong, Hunan, Hubei, Jiangxi, Jiangsu, Southwest of Shandong, Henan, Sichuan, Shaanxi, Ningxia and Gansu. In Jiangxi Province only one specimen of Palibinia from the drillcore was reported by Li (1979) before this study. Recently some new fossil plants were discovered from a section near Linjiang Town in Northwestern Jiangxi. Near half of the specimens of the flora are Palibinia . In addition, there are leaves of Nelumbo , Lauraceae, Betulaceae and some other hydrophytes, and perhaps, the fruits of Nelumbo as well. Because of the poor preservation here only a few species of this flora can be identified and described. Nevertheless, Palibinia and Nelumbo are described and discussed in some detail in the present paper. The leaves of Palibinia are tiny (usually no more than 0.5 cm in width) and very thick in texture, mostly appearing in the Paleogene sediments of red beds, or light colored ones intercalated with red beds. The sediments yielding Palibinia often contain gypsum, sylvite and other evaporites. These facts show that this kind of plants might have grown in an arid condition (or seasonal arid area). The stratigraphical and geographical distribution of Palibinia in China (see textfig.1) suggests that a dry or periodical dry climate was in low and middle latitude area of China in Paleogene, especially in Middle and Late Paleocene and Early and Middle Eocene. On the other hand, some contemporaneous warm temperate floras with subtropical elements such as Cycas anomostoma Y. S. Liu, Sabalites chinensis Endo were reported from higher latitude areas, e.g. Fushun and other localities of Northern China. Therefore,the present authors deduce that the climatic differentiation from low to high latitudes in China is caused mainly by different physical geographical conditions existing in East Asia before the uplift of Qinghai Xizang Plateau (QTP). The Fushun flora and other similar floras in the high latitude areas in the Northern Hemisphere e.g. the flora in Gdansk (54.23 °N , 18.40 °E ), containing the fossil flowers of Cinnamomum protypum (Menge) Conw. and C. felixii Conw. in amber imply that the polar area in Paleocene and Eocene was probably smaller than it is at present. According to the meteological rule, while planet polar front and depression arrive in the high latitude area, dry and hot climate would develop in low and middle latitudes at the same time. Our conclusions agree with two of the results of an improved CCMI/NCAR climate dynamic model test of Chen Longxun et al . (1999). They are: 1. before the initial stage of the Qinghai Xizang Plateau uplift (40—50Ma BP) “the simulated Chinese climate is dry and hot with little rainfall in the most regions aside from some of West China”;2. “The effect of the plateau uplift on the Chinese climate predominantly makes the place colder”, about 10°C decline in temperature in the Eastern part of China. Our conclusions are in concordance with the result of the climate model test,which may explain the reason of the existence of the hot and dry climate in low and middle latitude area of China in Paleocene and Eocene (most probably, in Cretaceous as well) and of the abrupt disappearance of Palibinia in China after that time. Acknowledgements The authors are greatly indebted to Prof. Zhou Zhiyan for his support and help in many aspects. We should like to thank Prof. Liu Gengwu for critical reading of the manuscript and valuable comments. We thank Mr. Ren Yugao for drawing textfigure and Mr. Yuan Ruming for taking photos. This study was financially supported by the National Natural Science Foundation of China (Project No. 39930020).
出处
《古生物学报》
CAS
CSCD
北大核心
2002年第1期119-129,共11页
Acta Palaeontologica Sinica
基金
国家自然科学基金 (No .39930 0 2 0 )资助课题
