中更新世全球最大冰期与中国沙漠扩张

位于青藏高原和西北干旱区交界带的沙沟黄土剖面, 详细记录了0.8 Ma BP以来东亚季风系统和沙漠演化的历史. L6黄土层中, 中值粒径和砂粒含量表明当时冬季风极端强盛, 沙漠大规模扩张, 其范围仅次于末次冰期最盛期. 在0.6～0.7 Ma BP以前(即深海氧同位素MIS16阶段), 北半球高纬度大陆冰盖大规模扩展, 全球冰量达到最大, 并且西伯利亚冰盖的扩展, 还使得西伯利亚高压增强; 同时, 青藏高原上也发育了最大规模的冰川, 从而强化了西风和东亚冬季风. 其结果造成了中国季风边缘区的沙漠扩张. 虽然全球冰量和青藏高原是影响沙漠演化的重要因素, 但在不同的时段其机制可能有所不同, 也不能忽略其它因素的影响.

The Maximum Glaciation and Desert Expansion in China during MIS16

The Shagou loess section, which is situated in the border between the Tibetan Plateau and northwest arid region of China, records the detail of climate changes and desert evolution over the past 0\^83 Ma BP. Median grain size and sand content in the L6 loess layer indicate that winter monsoon greatly enhanced and desert extremely expanded at that time. During the MIS16, ice sheets in the Northern Hemisphere extended largely, and the global ice volume reached the Maximum since the mid\|Pleistocene climate transition. The expansion of northern Siberian ice sheet also reinforced the Siberian High during MIS16. At the same time, the Maximum glaciation developed in the Tibetan Plateau greatly adjusted the westerly and amplified winter monsoon via the Siberian High. Responding to the maximum of global ice volume, as a climate background, and the Maximum Glaciation in the Tibetan Plateau, as an amplifier of the winter monsoon and westerly, deserts in East China expanded extremely. Global ice volume and the Tibetan Plateau are the two important factors influencing desert evolution among others.