山西榆社盆地,上新世河湖相地层十分发育,植物化石丰富。上新世早—中期的代表性植物有:Magnolia Liquidambar, Platycarya和Tsuga等,说明当时的榆社地区为北亚热带森林景观,但已有向干冷方向发展的趋势。上新世晚期,榆社地区为暖温带落叶阔叶林景观,同现在华北南部的植被相似。河湖的广泛分布和植被的特征表明,上新世的榆社地区属于季风气候,一年之中季节性的干湿变化和冷暖变化十分明显。
This paper deals with the lacustrine sedimentary facies and the flora to reconstruct the Pliocene paleoenvironment in Yushe basin.Yushe basin is a dentritic saucer-like synclinal basin in eastern Shanxi Plateau. The flu-vio-lacustrine sediments of Late Conozoic, ranging from Pliocene to Early Pleistocene, are spread in the basin. This ancient lacustrine basin has been dissected into undulating hills due to subsequent uplift of the area. As a result, the Late Conozic Deposits are widely exposed. The fluvio-lacustrine deposits are grouped into the Yushe group which includes Lower Pliocene, Upper Pliocene and Lowre Pleistocene. It is worthy to note that the down-warped lacustrine basin exhibits various types of sedimentary facies.The paleobotany is commonly regarded as one of the most valid indicators for paleoenvironment. We have noted that a great number of Plant fossils was found which are seldom seen elsewhere. The pliocene flora were mainly Quercus, Area, Zolkova and Ulmus ect. All this indicated the warm temperature and monsoon climate at that time.The Early and Middle Pliocene formations contain seme representative plants, such as Magnolia. Liquidambar, Platycarya and Tsuga. etc. This Shows Yushe area was a forest landscape of northern subtropical zone at that time, but it had a tendency towards dry and cold climate different from the subtropical forest landscape of Miocene in Shanwang area.During Late Pliocene, Yushe area was a landscape of deciduous and broadleaf forest of warm temperature zone the vegetation was alike with the present one in the south of North China. The widespreading of fluvio-lacustrine and characteristic vegetation in Yushe Pliocene suggested that the climate belongs to monsoon climate with marked seasonal climate change from dry to humid and cold/warm seasonal alternation during a year.