【作者】 兰源红；

【导师】 田明中；

【作者基本信息】 中国地质大学(北京) ， 第四纪地质学， 2017， 博士

【摘要】 论文基于对达里诺尔古湖地区典型沉积剖面进行的野外观察和实测,运用光释光测年法(OSL)和电子自旋共振法(ESR)建立其年代格架,探讨研究区的古气候与古环境,尤其是古大湖的形成和演化。通过环境代用指标的分析,对研究区中-晚更新世的古气候和古环境进行了恢复,获得的主要认识有:(1)达里诺尔地区8个湖相剖面的发现和分析为研究该地区古大湖以及内蒙古高原第四纪沉积环境及古气候演化提供了更多的证据支持。(2)根据剖面JP1湖相沉积物的沉积相特征、粒度特征和元素地球化学特征,结合年代学测试,重建了达里诺尔地区210ka以来的气候演化历史,将研究区的气候演化划分为四个大阶段,即第一阶段:210～149 ka,第二阶段:149～72 ka,第三阶段:72～60 ka,第四阶段:60～26 ka;依次经历了干燥炎热—温暖湿润—寒冷干燥—温暖湿润的变化历程。同时发现研究区晚更新世的气候演化与青藏高原古里雅冰芯的气候记录呈现一致的变化趋势,即均在MIS5和MIS3时期显示温暖湿润气候,在MIS4时期显示干旱寒冷气候。(3)通过研究8个湖相剖面的沉积特征和粒度特征,结合年代学测试,揭示了研究区晚更新世古湖演化的证据及其演化历程。研究区在MIS5时期形成古大湖并出现高湖面,MIS4时期古湖收缩,MIS3时期古湖再次发育并出现最高湖面形成超级大湖,经棚-达里诺尔古湖,湖水位达到海拔1300米;LGM时期古湖大幅收缩甚至一度解体,12.96～11.69 ka时期,古湖又一次出现高水位形成次一级的古大湖,经棚-福盛号古湖,湖水位达到1200米。(4)重建了经棚-达里诺尔超级大湖在MIS3期间最高水位时的水域范围,其覆盖了达里诺尔盆地和西拉木伦河上游的大部分区域,面积达到约3000平方千米;也重建了经棚-福盛号古湖最高水位时期的水域范围,仅覆盖了西拉木伦河上游的部分区域,面积为约600平方千米。更多还原

【Abstract】 Based on field measurement on 8 typical sedimentary sections in Dali Nor area,and chronostratigraphic framework created by OSL and ESR,this paper discussed the formation and evolution of palaeo-Lake.And by using analysis on the environmental proxies,middle-late Pleistocene lake evolution and paleoclimate changes were recovered.The study shows that:(1)According to detailed geomorphology and sedimentology research of eight sections in field,this dissertation found more evidence for the existence of the palaeo-lake.(2)According to the lithofacies,granulometry,geochemistry analyses and chronology of section JP1,the palaeoclimatic evolution in Dali Nor since 210 ka was recovered.The evolution was divided into four stages,i.e.,Ⅰ:210～149 ka,Ⅱ:149～72 ka,Ⅲ:72～60ka,Ⅳ:60～26 ka,and experienced hot-dry,warn-wet,cold-dry and warn-wet climate orderly.(3)The lithofacies and granulometry of 8 lacustrine sections in Dali Nor area uncovered the evolutionary precess of palaeolake.The palaeolake formed high water level in MIS5,shrunk in MIS4 and recovered in MIS3.Also in the MIS3,the palaeolake developed the highest water level above 1300 m and became a huge palaeolake Jingpeng-Dali Nor.The palaeolake shrunk sharply in the LGM and recovered later.During 12.96～11.69 ka,the palaeolake appeared another high water level above 1200 m and a new stage of palaeolake Jingpeng-Fushenghao.(4)This paper reconstructed the water region of huge Jingpeng-Dali Nor palaeolake at its highest water level,which covered the Dali Nor basin and the upstream area of Xilamulun River and reached almost 3000 km~2.The water region of palaeolake Jingpeng-Fushenghao was also reconstructed at its high water level,which covered the part region of the upstream area of Xilamulun River and reached almost600 km~2.更多还原