100 k.y. pacing of the East Asian summer monsoon over the past five glacial cycles inferred from land snails
100 k.y. pacing of the East Asian summer monsoon over the past five glacial cycles inferred from land snails
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100 公里
DOI：
10.1130/g50243.1
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发表时间：
2023-02-01
期刊：
影响因子：
5.8
通讯作者：
Chen, Jun
中科院分区：
文献类型：
--
作者：
Bao, Rui;Sheng, Xuefen;Chen, Jun
中更新世转型之后轨道强迫作用对东亚夏季风（EASM）的影响存在争议。中国洞穴的δ18O记录仅显示出类似于20千年周期的低纬度特征，而中国黄土的成土指标记录则以高纬度100千年周期为主。这种差异可能源于代用指标的多成分来源，特别是对于黄土沉积中的成土信号，其中主要的气候信号受到成土作用的平滑、淋溶以及沉积速率变化的影响，而沉积速率也受到100千年周期的强迫。我们基于蜗牛壳的δ13C值（δ13Cshell）呈现了一份来自中国黄土高原中部过去470千年的东亚夏季风记录，该记录消除了上述过程的影响，专门记录了当地过去东亚夏季风的降水情况。δ13Cshell记录以100千年周期为主，间冰期的值比冰期更为贫化。在海洋同位素阶段（MIS）11末期，基于δ13Cshell的降水在北半球MIS 11超级间冰期气候之后仍保持在间冰期水平，尽管全球范围内已经进入冰期。总体而言，我们的δ13Cshell记录与高北纬冰量变化高度耦合，可能支持东亚夏季风的高纬度强迫作用。
The effects of orbital forcing on the East Asian summer monsoon (EASM) after the mid -Pleistocene transition are controversial. Chinese cave 618O records only show low-latitude similar to 20 k.y. cycles, while pedogenic proxy records from Chinese loess are dominated by high -latitude 100 k.y. cycles. This discrepancy may result from the multicomponent origin of proxies, particularly for pedogenic signals in loess deposits, where the primary climatic signals are modified by pedogenic smoothing, leaching, and changes in sedimentation rate, and the latter are also being forced by 100 k.y. cycles. We present an EASM record spanning the past 470 k.y. from the central Chinese Loess Plateau based on the 613C values of land snail shells (613Cshell), which eliminates the influence of the above processes and exclusively records the local past EASM precipitation. The 613Cshell record is dominated by the 100 k.y. cycle, with more depleted values during interglacials compared to glacials. At the end of marine isotope stage (MIS) 11, 613Cshell-based precipitation remained at an interglacial level following the MIS 11 super-interglacial climate in the Northern Hemisphere, although a gla-cial period had commenced on a global basis. Overall, our 613Cshell record is highly coupled with high-northern-latitude ice-volume variations, possibly supporting the high-latitude forcing of the EASM.