阿坝盆地黄土记录的青藏高原东部末次冰期环境变化

Environmental changes during the last glacial in the Eastern Tibetan Plateau revealed by loess sediments in the Aba Basin

青藏高原东部广泛分布的风成黄土沉积是记录过去气候变化和大气粉尘活动历史的重要陆地档案,恢复和重建其环境记录可以为深入理解高原环境演化过程和机制提供重要证据。本研究基于石英光释光测年建立了阿坝盆地各莫黄土剖面的年代框架,并利用多种环境代用指标重建了阿坝黄土记录的青藏高原东部约47 ka以来的环境变化历史。黄土磁化率、色度和碳酸盐记录表明深海氧同位素3阶段(MIS3)中晚期印度夏季风加强,青藏高原环境相对湿润。粒度重建结果记录了4次海因里希(Heinrich)事件和新仙女木(YD)事件,表明青藏高原末次冰期粉尘活动强烈,气候变化具有快速波动的特征。区域记录对比显示,北半球高纬地区气候系统对青藏高原地区快速气候变化有重要影响,大西洋经向翻转环流可能是高原地区粉尘活动和气候变化的主要控制因素。该研究为更好地认识青藏高原末次冰期环境演化过程提供了重要证据。

Loess deposits are widespread in the Eastern Tibetan Plateau(TP),and act as crucial terrestrial archives for past climate changes and dust activity.Studying their environmental signatures in detail offers valuable evidence to unravel the TP's environmental evolution processes and mechanisms.This study employs quartz optically stimulated luminescence dating to establish a robust chronology for the Gemo loess sequence in the Aba Basin.Utilizing multiple environmental proxies,we reconstructed the environmental change history since~47 ka in the Aba Basin.Magnetic susceptibility,color index,and carbonate content records suggest a strengthened Indian summer monsoon during the Marine Isotope Stage 3,leading to a relatively humid Tibetan Plateau.The grain size records of the Gemo loess revealed four Heinrich events and Younger Dryas event,indicating the periods of intense dust activity and rapid climate change on the TP during the last glacial period.Comparisons with regional records highlight the significant influence of high-latitude climate system in the Northern Hemisphere on rapid climate change in the TP.Our results suggest that the Atlantic Meridional Overturning Circulation may be the controlling factor of dust activity and climate change in the TP.This study provided crucial evidence for deep understanding of the environmental evolution in TP during the last glacial period.