摘要
由青藏高原东北边缘两剖面中，孢粉记录所反映的气候旋回与深海氧同位素记录对比，两者之间有良好的对照性，据此可划出２２个主要旋回和部分次一级旋回．根据孢粉组合分析，早更新世早期是第四纪期间水热条件最为优越的时期，２２ＭａＢＰ以来气候向干冷发展，１８～１７７ＭａＢＰ湿润程度最高，１７～１６ＭａＢＰ前后，伴随黄土沉积出现，植被与环境发生历史性转折．
The northeast margin of the Tibetan Plateau is the juncture of three large physiographical regions of China, highly sensitive to global climate change. Same reliable information on the chronology and environmental evolution have been gotten through a systematic research on a series of Quaternary sections in this region recent years. A set of palynologic records from continuous Quaternary strata with the highest resolution so far in China have been obtained based on sporo-pollen analysis of the sections at Dongshanding in Linxia and at Yandonggou in Lanzhou, the typical regions for studying, because of their particular localities, their continuous, thick basin-fill sediments, spanning the whole of the late Cenozoic, and their abundant sporo-pollen fossils and datable gypsum crystals. The sporo-pollen assemblages were systematically studied in combination with the researches in paleomagnetism, magnetic susceptibility, geochemical analysis etc. The results are valuable to analyse the confused palynological information in the early Quaternary. The climatic cycles reflected by the sporo-pollen records of the two sections in the northeast margin of the Tibetan Plateau have a better correspondence to the deep sea oxygen isotope records. According to the sporo-pollen assemblage analysis, 22 main and secondary cycles were recognized and the best humidity and temperate condition appeared in the early Pleistocene during the Quaternary. The climate has become to dry-cold since 2 2 Ma BP. with the most moist level between 1 8～1 77 Ma BP. A historic turning appeared in about 1 7～1 6 Ma BP. together with appearance of loess sediment.
出处
《冰川冻土》
CSCD
北大核心
1998年第2期141-149,共9页
Journal of Glaciology and Geocryology
基金
国家攀登计划项目
