银川盆地中更新世以来的孢粉植物群古气候旋回探讨

STUDY ON PALYNOFLORA AND PALEOCLIMATIC CYCLES SINCE MID-PLEISTOCENE IN YINCHUAN BASIN

利用银川地区孢粉时间序列的随机数字滤波分析的研究成果 ,应用频谱分析方法探讨银川盆地孢粉植物群气候波动特征 ,确定 0 .80MaB .P .以来存在 6 0× 10 4 a、30× 10 4 a、10 (或 6 )× 10 4 a的准周期 ,依据孢粉植物群的时空分布建立了该区多重气候旋回模型。该模型将该区 0 .80MaB .P .以来的气候划分为 1个 0 .6 0Ma的气候幕 ,3个 0 .30Ma的气候期 ,10个 0 .10 (0 .0 6 )Ma的气候段。并且讨论了模型与自然环境演变的关系 ,指出 0 .80～ 0 .5 5MaB .P .期间为冷凉旋回 ,0 .5 5～ 0 .2 0MaB .P .期间为暖温旋回 ,0 .2 0MaB .P .

The study results of sporopollen time sequence in Yinchuan basin by the random digital filtering method and the characteristics of palynoflora climatic fluctuation by frequency spectrum analysis method show that there existed 60×10 4 a, 30×10 4 a and 10 (or 6)×10 4 a periods since 0.80 Ma B. P. In the light of temporal-spatial distribution of the palynoflora, the climatic multicyclic model in the study area has been established. The climate over past 0.80 Ma can be divided into 1 climatic episode (0.60 Ma), 3 climatic periods (0.30 Ma) and 10 climatic subperiods (0.10 or 0.06 Ma). The relation between the model and the change of natural environment has also been discussed. In author's opinion, the period of 0.80～0.55 Ma B. P. is the cold cycling, 0.55～0.20 Ma B. P. is the temperate-warm cycling and 0.20 Ma B. P. up to now is the cold cycling again.