中国晚始新世—早渐新世地层孢粉组合及其古气候特征

始新世—渐新世是从65Ma恐龙绝灭以来新生代地球历史上最重要的事件, 此时地球从“暖室”过渡到“冰室”, 全球气候突变, 南极冰首次出现, 气候突变引起生物的大绝灭, 而我国的孢粉组合也有明显的变化特征.根据我国各个区始新世晚期—渐新世早期地层中孢粉组合的演化规律来探讨当时我国的古气候变化规律, 研究认为中国从始新世晚期到渐新世早期总体上亚热带、热带植物成分丰度和分异度都降低, 温带植物如桦科和榆科花粉大增, 耐寒山地针叶植物大量发育, 干旱类型植物增加, 草本植物开始繁盛.这些反映了从始新世晚期到渐新世早期植被组成由热带亚热带常绿阔叶树为主的针阔叶林转变为落叶树为主的针阔混交林, 说明晚始新世气候温暖湿润过渡到早渐新世气候变干变冷.孢粉植物群所反映的我国气候变化趋势与全球气候变化趋势一致, 说明我国的陆地也受全球构造的演变和南极大陆冰盖的影响. 

Palynology Assemblages and Paleoclimatic Character of the Late Eocene to the Early Oligocene in China

The transition from the Eocene to the Oligocene is the most significant interval in Earth history since the dinosaurs died out around 65 Ma. During this interval the earth's climate changed from a "greenhouse" to an "icehouse". Global temperature plummeted and the first Antarctic icecap appeared. These climatic stresses triggered plant and animal extinction. The palynology in China also reflects these trends. Based on a study of the development of palynology and the flora from the Late Eocene to Early Oligocene in China, it is suggested that the diversity and abundance of tropical and subtropical plants significantly decreased, and temperate plants such as Betulaeae and Ulmaceae increased. Montane conifers also greatly increased, and at the same time the abundance of arid plants and herbaceous plants rose. The palynological assemblages from the Late Eocene to Early Oligocene reflect the floral changes that occurred, from coniferous and broad-leaved forest dominated by tropical and subtropical evergreen plants to coniferous and broad-leaved forest dominated by deciduous plants. The paleoclimate conditions in the Late Eocene to Early Oligocene changed from warm and wet to drier and cooler. This trend coincides with world climate at that time, which means that the Chinese mainland was influenced by the global transition and the development of the continental icecap over Antarctica.