南京雨花台组的孢粉组合及其时代的探讨

<正> 南京附近(包括六合、江宁和江浦)的一套胶结较松散,以棕红、黄、灰色砂砾岩为主的河湖相沉积物;刘季辰、赵汝钧(1924)以雨花台砂砾层为典型剖面,建立雨花台组,时代为始新世。近年来,找到不少化石,从一些动植物化石看,证明了这套砂砾层为同相异期的产物。如江宁方山的洞玄观组,发现安琪马,时代属中新世;浦镇猪头山的砂砾岩,夏树

Sporo-pollen assemblage from the Yuhuatai Formation of Nanjing and its geological age

The Yuhuatai Formation, with its stratotype in southern Nanjing and composed of sands and gravels, was established by Liu Ju-chen and Zhao Ru-jin in 1924. No fossils were found from this formation, and therefore, its geological age is still in dispute. Bi Zhi-guo et al. (1977) suggested that this formation be correlated with the lower part of the Liuhe Formation (Early Pliocene) and the name of the Yuhuatai Formation be abolished due to lack of fossils, while Xia Shu-fang et al. (1981) considered if to be lower .Pleistocene based on the lith. logical peculiarity, geomorphological position and the contact relationship between the upper and lower beds of the formation.From this formation a sporo-pollen assemblage was obtained in 1977. In this assemblage, Finns is extremely abundant, and the pollen grains of deciduous trees, such as Ulmus, Betula, Alnus, Qu-ercus, Populus, Salix, Corylus, Juglans, Carya, Liquidambar, Rhus, Pterocarya, Fagus, Castanea and Ostrya were found. The pollen grains of evergreen broad-leafed trees, such as Hex and Trocho-dendron also occur in this assemblage. There are a plenty of herbaceous pollen grains, constituting 18-41% of the assemblage, such as Artemisia, Cruciferae, Gramineae, Labiatae, Chenopodium, Li-laceae and Cyperaceae. Judging from the characteristics of this assemblage, the present writers think that this assemblage may be Late Pliocene.