Key Laboratory of Mineral Resources in Western China (Gansu Province), School of Earth Sciences, Lanzhou University, Lanzhou 730000, China.
Key Laboratory of Western China's Environmental System (Ministry of Education), College of Earth and Environmental Sciences, Lanzhou University, Lanzhou 730000, China;
Proc Natl Acad Sci U S A. 2021 Oct 26;118(43). doi: 10.1073/pnas.2107055118.
The East Asian summer monsoon and the precipitation it brings are relevant for millions of people. Because of the monsoon's importance, there has been a substantial amount of work attempting to describe the driving mechanisms behind its past variability. However, discrepancies exist, with speleothem-based East Asian monsoon reconstructions differing from those based on loess records from the Chinese Loess Plateau during the late Quaternary. The periodicity of wet and dry phases experienced by desert areas that lie on the periphery of the East Asian monsoon's influence offer another independent view of monsoonal variability. Here, we provide environmental records based on magnetic parameters for the last 3 million years from the Tengger Desert, China, one such marginal arid region. Our results reveal wet-dry cycles at a dominant frequency of 405 kiloyears, with drier intervals corresponding to eccentricity minima. These findings are consistent with previous reconstructions of East Asian summer and North African summer monsoon precipitation variability. Our records emphasize the dominant role of eccentricity in forcing East Asian monsoonal precipitation as well as monsoonal-derived environmental fluctuations experienced in peripheral desert areas. These results challenge the traditional view that high-latitude ice sheets are the primary driver of East Asian monsoon precipitation during the Quaternary based on Chinese loess records.
东亚夏季风和它带来的降水与数百万人息息相关。由于季风的重要性，人们已经做了大量的工作来描述其过去变化的驱动机制。然而，存在差异，洞穴石笋记录的东亚季风重建与第四纪中国黄土高原黄土记录的东亚季风重建不同。位于东亚季风影响边缘的沙漠地区的干湿阶段的周期性为季风变化提供了另一种独立的观点。在这里，我们提供了过去 300 万年来自中国腾格里沙漠的基于磁参数的环境记录，这是一个边缘干旱地区。我们的结果揭示了主导频率为 40.5 千年的干湿循环，较干燥的间隔对应于偏心率最小值。这些发现与之前对东亚夏季风和北非夏季风降水变化的重建一致。我们的记录强调了偏心率在强迫东亚季风降水以及在边缘沙漠地区经历的季风衍生环境波动方面的主导作用。这些结果挑战了基于中国黄土记录的传统观点，即高纬冰盖是第四纪东亚季风降水的主要驱动因素。
