季风亚洲末次冰期的古冰川遗迹

GLACIAL RELICS OF MONSOONAL ASIA IN THE LAST GLACIATION

季风亚洲末次冰期可统一称为大理冰期,古冰川首次出现于东亚海岸山地,内陆高山高原则冰川规模缩小。早期大理冰期冰川规模大于晚期,是季风亚洲的特色。古雪线在亚洲东海岸形成向南弯曲的大槽,是大理冰期夏季风衰弱、海陆的干湿对比加剧以及东亚大槽南移的结果。53000—27000 aB.P.之间为萨拉乌苏-卡尔金斯克大间冰段,气候冷暖多变,西伯利亚冻土融化,华北平原为喜冷云杉林占据,内陆湖水面普遍升高。构造运动对古冰川发育有明显影响。青藏高原大冰盖是不存在的。

On the whole, the Last Glaciation in monsoonal Asia should be termed as the Dali Glaciation which is quite in accord with the Zyryanka Glaciation in Northeast Asia. Twenty-one sites of glacial remnants with credible evidence have been briefly discussed in this paper. Glaciers developed on the coastal mountains of monsoonal Asia for the first time. However, the size of the glaciers of the Dali Glaciation were generally smaller, except for those in the southeastern Qinghai-Xizang (Tipet) plateau and the mountains in Northeast Asia where the conditions for palaeoglacire development were more favourable. The Last Glaciation is characterized by smaller glacier in the late Dali Glaciation compared to that of the earlier period in monsoonal Asia. Between the earlier and late Dali Glaciation, there was Megainterstadial, during which the climate was changable and the water levels of inland lakes reached the highest in the Late Pleistocene. It was cold and humid in the North China Plain where cold-resistant species like Picea and Abies were extensively distributed. In Siberia, the climate became warm and permafrost melted during the Salawusu-Karginsky Megainstadial. The snow line of the Dali Glaciation curved southward to form a big trough in the region near the Pacific Ocean. This shows that the difference of humidity between continent and ocean increased. This indicated that summer monsoon receded and the East Asia Trough moved southward. The Last Glaciation in monsoonal Asia developed under the impact of intense neotectonic uplift. In this paper the author suggests that no large ice-sheet covered the Qinnghai-Xizang plateau during the Pleistocene.