Late Eocene pollen records and palaeoenvironmental changes in northern Tibetan Plateau  

作　　者：MIAO YunFa FANG XiaoMin SONG ZhiChen WU FuLi HAN WenXia DAI Shuang SONG ChunHui 

机构地区：[1]Institute of Tibetan Plateau Research,Chinese Academy of Sciences,Beijing 100085,China [2]National Laboratory of Western China Environmental Systerms of Education of China&Department of Geography,Lanzhou University,Lanzhou 730000,China [3]Nanjing Institute of Geology and Palaeontology,Chinese Academy of Sciences,Nanjing 210008,China

出　　处：《Science China Earth Sciences》2008年第8期1089-1098,共10页中国科学（地球科学英文版）

基　　金：the National Key Program for Developing Basic Sciences (Grant No. 2005CB422001);the National Science Foundation of China (Grant Nos. 40334038, 40421101);the President Fund of Chinese Academy of Sciences

摘　　要：The Eocene palaeovegetation landscape and palaeoclimate reconstructed from the pollen records in the Jiuquan Basin, northwest China provide some important information on the early uplift of the Tibetan Plateau and the origin and evolution of the aridification in northwest China. The records show the arid-semiarid scrubs with open forest palynofloras controlled by the subtropical high existed in northwest China during the 40.2-33.4 Ma. Four pollen assemblages are found: Nitrariadites-Cheno-podipollis-Pinaceae assemblage (40.2-37.9 Ma) is followed by Chenopodipollis-Nitrariadites assemblage (37.9-34.6 Ma), Pinuspollenites & Abietineaepollenites-Chenopodipollis assemblage (34.6-33.9 Ma), and Chenopodipollis-Nitrariadites assemblage (33.9-33.4 Ma). The percentage of thermophilic types is in anti-correlation with that of the dry types, which means the palaeoclimate is relatively warmwet or cold-dry during most of that time. Such aridity may be related to the water vapor reduction and the planetary wind system movement northward in response to the cooling caused by small-ephemeral icesheets.The Eocene palaeovegetation landscape and palaeoclimate reconstructed from the pollen records in the Jiuquan Basin, northwest China provide some important information on the early uplift of the Tibetan Plateau and the origin and evolution of the aridification in northwest China. The records show the arid-semiarid scrubs with open forest palynofloras controlled by the subtropical high existed in northwest China during the 40.2–33.4 Ma. Four pollen assemblages are found: Nitrariadites-Cheno-podipollis-Pinaceae assemblage (40.2–37.9 Ma) is followed by Chenopodipollis-Nitrariadites assemblage (37.9–34.6 Ma), Pinuspollenites & Abietineaepollenites-Chenopodipollis assemblage (34.6–33.9 Ma), and Chenopodipollis-Nitrariadites assemblage (33.9–33.4 Ma). The percentage of thermophilic types is in anti-correlation with that of the dry types, which means the palaeoclimate is relatively warm-wet or cold-dry during most of that time. Such aridity may be related to the water vapor reduction and the planetary wind system movement northward in response to the cooling caused by small-ephemeral ice-sheets.

关 键 词：Tibetan Plateau POLLEN records EOCENE PLANETARY ARID zone PALAEOENVIRONMENT cooling 

分 类 号：P534.63[天文地球—第四纪地质学]