Wang Yichao, Lu Huayu, Wang Kexin, Wang Yao, Li Yongxiang, Clemens Steven, Lv Hengzhi, Huang Zihan, Wang Hanlin, Hu Xuzhi, Lu Fuzhi, Zhang Hanzhi
School of Geography and Ocean Science, Nanjing University, Nanjing 210023, China.
School of Earth Sciences and Engineering, Nanjing University, Nanjing 210023, China.
Sci Adv. 2020 Nov 13;6(46). doi: 10.1126/sciadv.abc2414. Print 2020 Nov.
East Asian monsoon variability in the Pliocene warm world has not been sufficiently studied because of the lack of direct records. We present a high-resolution precipitation record from Pliocene fluvial-lacustrine sequences in the Weihe Basin, Central China, a region sensitive to the East Asian monsoon. The record shows an abrupt monsoon shift at ~4.2 million years ago, interpreted as the result of high-latitude cooling, with an extratropical temperature decrease across a critical threshold. The precipitation time series exhibits a pronounced ~100-thousand year periodicity and the presence of precession and half-precession cycles, which suggest low-latitude forcing. The synchronous phase but mismatched amplitudes of the East Asian monsoon precipitation proxy and eccentricity suggest a nonlinear but sensitive precipitation response to temperature forcing in the Pliocene warm world. These observations highlight the role of high- and low-latitude forcing of East Asian monsoon variations on tectonic and orbital time scales.
由于缺乏直接记录，上新世温暖世界中东亚季风的变率尚未得到充分研究。我们展示了来自中国中部渭河盆地的上新世河流-湖泊序列的高分辨率降水记录，该地区对东亚季风敏感。该记录显示在约420万年前季风发生了突然转变，这被解释为高纬度变冷的结果，温带温度下降超过了一个临界阈值。降水时间序列呈现出明显的约10万年周期以及岁差和半岁差周期，这表明存在低纬度强迫作用。东亚季风降水代理指标与偏心率的同步相位但不匹配的振幅表明，在上新世温暖世界中，降水对温度强迫的响应是非线性但敏感的。这些观测结果突出了高、低纬度强迫在构造和轨道时间尺度上对东亚季风变化的作用。
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