Pedogenic carbonate isotope record of vegetational evolution since late Miocene in Loess Plateau

作     者：Shiling Yang Zhongli Ding Zhaoyan Gu Jimin Sun Shangfa Xiong 

作者机构：Chinese Acad Sci Inst Geol Beijing 100029 Peoples R China 

出 版 物：《Chinese Science Bulletin》 (中国科学通报)

年 卷 期：1999年第44卷第11期

页      面：1034-1038页

核心收录：

学科分类：070903[理学-古生物学与地层学(含：古人类学)] 0709[理学-地质学] 07[理学] 

基　　金：Science Foundation of China 

主　　题：pedogenic carbonate palaeovegetation shift atmospheric CO2 concentrations. 

摘      要：lsotopic analyses for paleovegetational evolution have been carried out on samples of the pedogenic carbonate nodules in the Red Clay-Loess sequence at Lingtai （35°N）, the Loess Plateau. Stable carbon isotopic composition indicates that （ ⅰ ） C4 plants might be present at least by7.0 Ma; （ ⅱ ） C4 plants expanded gradually between ～4.0 and ～3.2 Ma, and their biomass fraction was up to 50%; and （ ⅲ ） the biomass of C4 vegetation since ～2.0 Ma seems to have been decreased to the level （about 20%） before 4.0 Ma. C4 plant expansion at Lingtai cannot be fully understood with the global C4 expansion model because it occurred much later up to 3.0 Ma than in Pakistan, which indicates that some changes in the regional climatic system may also contribute to C3/C4 shift except changes in atmospheric CO2 concentrations and temperature. The latitudinal zone for C3/C4 transition seems to move southwards slightly in East Asia, compared with the case in North America where 37°N is the ideal