北京平原区第四纪古气候变化

CHANGES OF QUATERNARY PALEOCLIMATES IN THE PLAIN AREA OF BEIJING

本文在怀柔HR88—01孔岩心地层划分的基础上,较系统地论述了上新世—晚更新世地层中所含孢粉、介形虫、软体化石的组合类型,重矿物、粘土矿物和部分地球化学元素的组合变化特征,并对其所代表的古气候环境进行了分析。初步认为:(1)上新世,本区气候以湿热为特征,气温较现在高4～5℃;(2)早更新世,气候明显变冷,具体表现为两寒夹一暖,寒冷气温较现在低7～8℃;(3)中更新世,冷、暖波动表现为暖—冷—暖—冷变化特点。寒期气温较现在低6℃左右,暖期比现在约高1～2℃;(4)晚更新世,气候以干冷为特征,气温较现在低5℃左右。

According to the stratigraphic classification based on the cores from well HR_(88-01) of Huirou, the paper systematically deals with the changes of the fossil assemblage types of sporopollen, ostracods and mollusks and assemblages of heavy minerals, clay minerals and some geochemical elements and analyzes the paleoclimate types represented by them. The following speculations have been made: (1) in the Pliocene the climate was wet and hot with temperatures 4～5℃ higher than the present ones; (2) in the Early Pleistocene the climate became obviously cold, which was manifested by a warm season sandwiched between two cold seasons, with the temperatures of the cold season 7～8℃ lower than the present ones; (3) in the Middle Pleistocene the temperatures fluctuated, manifested by warm-coldwarm-cold, with the temperatures of the cold season 6℃ or so lower than the present ones and those of the warm season about 1～2℃ higher than the present ones; (4)in the Late Pleistocene, the climate was dry and cold, with the temperatures about 5℃ lower than the present ones.