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本文在总结渭河谷地 2 0多个孢粉剖面的基础上 ,依据古地磁资料确定其时代 ,并在空间和时间上进行孢粉组合对比 ,从而建立了 1 0个区域孢粉组合带。由此提出 3.5 Ma BP以来孢粉植物群的演化经历了 5个阶段 :由阔叶林—针叶林—森林草原与草原—森林草原与荒漠草原—草原—森林草原与草原。这 5个阶段标志着地表环境系统发生巨大变革 ,变革时间为 2 .5 Ma BP,2 .0 Ma BP,1 .4/ 1 .6 Ma BP和0 .8Ma BP。
Based on the summary of more than 20 sporo-pollen profiles in the Weihe River valley, the paper determined the age based on the paleomagnetic data and compared the sporopollen assemblages in space and time so as to establish 10 sporopollen assemblages. It is suggested that the evolution of sporopollen assemblages in 3.5 Ma BP has undergone five stages: broad-leaved forest-coniferous forest-forest steppe and steppe-forest steppe and desert steppe-steppe-steppe steppe and grassland. These five phases marked a dramatic change in the surface environment system, with a change time of 2.5 Ma BP, 2.0 Ma BP, 1.4 / 1.6 Ma BP and 0.8 Ma BP.