大同盆地地处我国季风影响的北部边缘, 第四纪以来盆地内发育厚层的河湖相地层, 其上覆盖马兰黄土或全新世沉积, 蕴含着丰富的气候环境变迁信息, 是研究气候环境变化的理想场所. 在对盆地内地层考察的基础上, 对晚近地质时期河湖相与风成相互层沉积剖面的磁化率、粒度变化进行了分析. 结果表明: 220 ka BP以来大同盆地气候变化经历了中更新世(220~199 ka BP)暖湿期、中更新世(199~138 ka BP)干冷期、末次间冰期(138~71 ka BP)暖湿期、末次冰期(71~11 ka BP)干冷期、全新世(11 ka BP至今)频繁的干冷暖湿波动变化过程, 每个阶段仍有次一级的气候波动. 大同盆地这种气候变化与深海氧同位素以及我国北方萨拉乌苏河地区、岱海等地揭示的气候变化有很好的对应, 反映出本区气候变化是对全球冰期-间冰期气候波动的响应.
英文摘要:
Datong Basin is located in an edge of East Asian monsoon zone, North China, and is characterized by a fragile ecotone, which sensitively responses to global change. So, the basin is an ideal site for researching global change in China. Commonly, magnetic susceptibility would well reflect environment change and has been widely applied to research Quaternary environment and climate change. A profile (DT Profile) in Datong Basin was ideally selected to study the climate change in North China. The magnetic susceptibility in the profile all indicated that the climate in North China has been very unstable since the middle Pleistocene, with frequent climate changes in different time periods. The climates in the Ice Age or in the Interglacial Period were unstable. The climate indexes in the DT Profile showed that there were several climatic fluctuations in each phase. These climate changes were well accordant with the global climate change reflected by the deep-sea oxygen isotope records and the records in polar ice cores, as well as that recorded in desert and loess depositions and evidences from the Salawusu River basin and Daihai Lake, showing a consistency in time of climate change between the study area and outside. The main factors that control the climate of the study area is East Asian monsoon.