山西榆社-太谷盆地上新世中晚期的植被与环境

山西中、东部的榆社、太谷盆地发育了良好的上新世河湖相地层，其丰富的植物、鱼类和哺乳类化石为我们提供了一个古植被和古环境研究的理想场所。根据榆社盆地磁笥年表以及化石组合特征，榆社、太谷盆地约为5．5MaBP以来的套沉积、榆社张村组与太谷小白组的沉积时代相当，大约形成于3．5－2．3MaBP。从大约4．4MaBP开始，较高含量的云杉、冷杉花粉显示研究区已有暗针叶林生长，从3．5MaBP开始，暗针叶林有了较大的发展，存在大面积的暗针叶林纯林。大致从上新世中期的4．4MaBP开始，气候已经开始变冷，并有较明显的干湿波动，蒿、藜为主的干草原大约从2．3MaBP开始繁盛，表明研究区转变为干冷气候。

PALEOVEGETATION AND PALEOENVIRONMENT IN MIDDLE LATE PLIOCENE YUSHE AND TAIGU BASINS, EASTERN SHANXI,CHINA

In the middle-eastern Shanxi plateau,China,there developed sets of late Cenozoic lacustrine sediments that involved rich fossils of pollen,plants,fishes and mammalian in intermountain basins, which presents us a nice site to study paleovegetation and paleoenvironment.According to the magnetostratigraphic age table and comparing the combination characteristics of fossils,the Pliocene sequences were known to develop during 5.5 MaBP in Yushe and Taigu basins.As a result,Zhangcun formation and Xiaobai formation were deduced to have the similar age zone ranging from 3.5 MaBP to 2.3 MaBP.The increase of Picea and Abies shows that there lived motane coniferous trees during about 4.4 MaBP.High percentage of Picea and Abies since 3.6 MaBP indicates that the forest of Picea and Abies had a rapid development,and the big proportion forest of motane conifers existed in study area.The climate began to become cold from 4.4 MaBP.In the mean time,the climate fluctuation of wet and dry existed during the middle-late Pliocene.The blooming of steppe dominated by Artemisia and Chenopodiaceae indicates that climate has developed toward the cold and dry since 2.3 MaBP.