乔治王岛菲尔德斯半岛早第三纪植物群及其环境意义

TERTIARY FLORA ON F1LDES PENINSULA OF KING GEORGE ISLAND, ANTARCTICA AND ITS ENVIRON-MENTAL SIGNIFICANCE

南极乔治王岛菲尔德斯半岛化石山植物群的发现是研究该地区新生代地质历史的一件大事。通过层位对比、化石特征、植物群组合面貌的研究,认为该植物层的时代为始新世末期至渐新世早、中期,当时为温暖偏干的温带或亚热带疏林环境。

Some impressions of stems and leaves were found in the layers enbedded in the grey-purple volcanic debris on Fossil Hill, 1.5 km northwest of the Chinese Great Wall Station on Fildes Peninsula of King George Island, Antarctica. Analysis and identification of the fossils led us to find Banksia cf. oblongifolia Cav., Sterculia Sp., Paliurus Sp., cf. Araucaria Sp., Cupressites Sp. and etc., After the stratigraphic correlation of the layers containing the impressions and study of the characteristics of the fossils, we believe that the plants lived in late Eocene and early and middle Oligocene Epoches. Inaddition in this area Dicotylophyllum corifolium, Dicutylophyllum Sp. 1,D,sp. 2 were found, as Li Haomin (1988) reported. All leaves of these plants were leathered. The leaves of the fossils we found are leathered or saw-edged Banksia cf. oblongifolia and others. They are mainly distributed at present in Oceania of the Southern Hemisphere. Since Banksia tends to live in arid areas, the botany community may reflect sparse wood environments in temperate or subtropical zone, showing warm and arid climate. About the fossil leaf forms from King George Island were discribed by Barton (1963) in his report. 15 of the 21 Dicotyledonous leaf forms in the collections have non-entire margins, two have entire. Eleven of the 17 dicotyledonous leaf forms from the western king George Island have non-entire margins. All four described forms from eastern King George Island have non-entire margins. Most of the leaves from western King George Island are small. The non-entire margins and small leaf forms are also dominant in the leaf forms from Fossil Hill. The study shows that in modern temperate flora about 90 per cent of decotyledonous species have non-entire margins, and that the converse is usually true under tropical conditions. Present cool climates are also generally characterized by a higher proportion of small leaves. The preponderance of small non-entire fossil dicotyledonous leaves at King George Island seems to point towards a temperate climate.