通过对内蒙古黄旗海陈家村剖面进行AMS~(14)C测年,建立了14.5cal. ka BP以来的年代框架,综合粒度、磁化率及地球化学指标分析其环境变化。研究结果表明: 黄旗海自14.5cal. ka BP以来经历了四个环境变化阶段: 14.5 - 10.6cal. ka BP,沉积物以粉砂为主,残积系数与Fe~(3+) /Fe~(2+)值较低,表明水动力、风化作用较弱,气候相对寒冷; 10.6 - 7.8cal. ka BP,残积系数不断增大,指示化学风化作用不断加强,气候由寒冷转为温暖,期间伴随干冷事件发生; 7.8 - 3.9cal. ka BP,粉砂及砂粒级含量较高,层理发育,指示强弱交替的水动力条件,残积系数、Fe~(3+)/Fe~(2+)增速加快,指示气候温暖湿润; 3.9 - 0.9cal. ka BP,砂含量及平均粒径减小,残积系数也降低,指示化学风化程度减弱,湖泊水动力减弱,水位下降,气候转为干冷。末次冰消期以来黄旗海环境演化与全球气候变化具有一致性,同时由于其所处地理位置与水文条件等局部地域差异,导致典型气候变化事件在起止时间上存在一定差异性。
英文摘要:
Based on AMS 14C dating of sediments,the regional age framework since 14.5cal. ka BP was established through the CJC section in Huangqihai,Inner Mongolia,north China. By combining the feature of grain size,magnetic susceptibility and geochemistry,the environmental changes in Huangqihai during the past 14500 years were analyzed. The results show that the environmental changes of the area can be divided into four stages as follows: 14.5 - 10.6cal. ka BP,when the sediment was mainly silt,the eluvial coefficient and Fe~(3+)/Fe~(2+) were low,indicating relatively weak chemical weathering with cold climate; 10.6 - 7.8cal. ka BP,when the eluvial coefficient was decreasing,the hydrodynamic force and the weathering became stronger,the climate became warm and arid; 7.8 - 3.9cal. ka BP,when the eluvial coefficient and Fe~(3+)/Fe~(2+) increased quickly with increased volumes of silt and sand, indicating warm and wet climate; about 3.9 - 0.9cal. ka BP,when the weathering and hydrodynamic force became weaker,the lake water level became lower gradually,the climate was dry and cold. The environmental changes of Huangqihai since the last deglaciation were consistent with global climate change. But the division of typical events was different because of the location and hydrological conditions.