青海循化盆地晚更新世沉积序列与古气候

河流阶地作为河谷中常见地貌, 其堆积物特征对气候变化过程研究具有重要的意义.通过对循化黄河Ⅲ级阶地剖面沉积特征、粒度、磁化率、孢粉以及光释光测年的研究, 初步厘定循化黄河Ⅲ级阶地形成时代为75 ka.循化盆地晚更新世气候演化可以大致划分为6个阶段: 120~114 ka, 气候暖湿; 114~105 ka, 气候较为干冷; 105~98 ka, 气候较暖湿; 98~85 ka, 气候转为温凉; 85~75 ka, 气候暖湿; 75~63 ka, 气候干冷.这6个阶段分别与MIS5e-4段相对应. 

Sedimentary Sequences and Paleoclimate of Late Pleistocene in Xunhua Basin, Qinghai Province

Sedimentological analyses of the third terrace along the banks of the Yellow River in Xunhua basin have yielded results that have more than regional significance. They are concerned with the reaction of rivers to climatic changes in the Pleistocene. Based on the field investigations, granularity, magnetic susceptibility, palynological records and optically stimulated luminescence (OSL) dating, the age of the third terrace was revealed. It shows that the Yellow River incised during the transition from interglacial to glacial. Evidences show that the paleoclimate and environment in Xunhua basin during the Late Pleistocene can be roughly divided into six stages: (1) 120—114 ka, the climate was warm and moist; (2) 114—105 ka, the climate turned cool and dry; (3) 105—98 ka, the climate was relatively warm and humid; (4) 98-85 ka, the climate turned cool and temperature; (5) 85—75 ka, the climate was warm and humid; (6) 75—63 ka, the climate was cold and dry, which can be compared with high-resolution ice core and marine oxygen isotope climate series.