甘肃窑街寺湾沟－炭洞沟红层孢粉组合、地质时代与生态环境

对窑街寺湾沟－炭洞沟红层孢粉和地层层序及时代进行了系统分析与对比研究。在该剖面中划分出２个孢粉组合:①双束松粉属－无口器粉属－杉粉属－栎粉属－瘤面海金砂孢属组合，时代为早渐新世；②双束松粉属－拟桦粉属－栎粉属－藜粉属－瘤面海金沙孢属组合，属中渐新世。研究表明:窑街寺湾沟－炭洞沟红层剖面的层位位于朱儿庄剖面之上，整个窑街地区的红层剖面属始新统－中渐新统；窑街地区始新世孢粉组合与中国东、西部地区孢粉组合相似，均发育以亚热带和暖温带植物为主的亚热带型落叶阔叶林，气候炎热；始新世晚期至早渐新世则演变为以暖温带落叶阔叶树种为主的针阔叶混交林植被，气候温暖湿润；中渐新世为暖温带落叶阔叶林，气候较温暖湿润。区域对比分析表明，从渐新世早期中国东、西部植被开始出现差异并逐渐加大，该时期也许是中国新构造运动的一个重要时期。

The Red Bed Sporo-pollen Assemblages、Geological Age and Ecological Environment from Siwangou-Tandonggou of Yaojie,Gansu

This paper includes a systematic analysis and correlation study on the sporo-pollen assemblage, stratigraphic sequence and geochronology of the Siwangou red bed section in Yaojie,Gansu. The following sporo-pollen assemblages may be recongnized in the Siwangou section (in ascending order ):① Pinuspollenites-Inaperturopollenites-Taxodiaceaepollenites-Quercoidites-Lygodioisporites assemblage,which may be assigned to Early Oligocene;② Betu laceoipollenites- Quercoidites-Chenopodipollis -Lygodioisporites assemblage,which belongs to Middle Oligocene. The results of this study show that, the geological age of the red bed section belongs to Eocene-Middle Oligocene; the Eocene sporo-pollen assemblages of Yaojie are approximately similar to those of the east region and the west region of China,which indicate a subtropical broadleaf and deciduous forest, mainly composed of the subtropical and warm temperate taxa, and a burning hot climate; from Late Eocene to Early Oligocene, the vegetation of Yao ne evolved to warm temperate mixed broadleaf and needleaf forests, mainly composed of the warm broadleaf and deciduous plants, presumably associated with warm and humid conditions; the Middle-Oligocene sporo-pollen records of Yaojie reflect comparatively warm and wet climates, which indicate that temperate broadleaf and deciduous forests are mainly constituted by Betulaceoipollenites and Quercoidites. The region correlation analysis shows that since Early Oligocene a trend toward difference of vegetation and climate has been on the increase between east and west region of China. Early Oligocene may be an important age of neotectonic movement in China.