Research ArticleCLIMATOLOGY

Combined high- and low-latitude forcing of East Asian monsoon precipitation variability in the Pliocene warm period

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Science Advances  13 Nov 2020:
Vol. 6, no. 46, eabc2414
DOI: 10.1126/sciadv.abc2414
  • Fig. 1 Location, regional geological settings, and investigated sections.

    (A) The study area is located in the monsoon-dominated semihumid region of China. The black solid line is the 400-mm isohyet, which separates the monsoon semiarid and semihumid regions, and the red star shows location of the study area in China. (B) Location of the Weihe Basin; the rectangle corresponds to the area of the geological map shown in (C). (C) Geological map with localities mentioned in the text. (D) The major lithology of the upper part of the CGC sequence is thick yellowish-red sandy mudstone with interbedded yellow conglomeratic sand layers, or occasionally gravel layers. The loess-paleosol sequence is seen above the dashed line. (Photo credit: Yichao Wang, School of Geography and Ocean Science, Nanjing University.) (E) The middle part of the CGC sequence is mainly composed of three conglomeratic sand and gravel layers interbedded with two reddish-brown mudstone layer. (Photo credit: Huayu Lu, School of Geography and Ocean Science, Nanjing University.) (F) The lithology of the lower part mainly comprises frequent alternations of fine-grained massive sandy mudstone, conglomeratic massive sandstone, and massive or crudely bedded sand clast-supported conglomerate. (Photo credit: Yichao Wang, School of Geography and Ocean Science, Nanjing University.)

  • Fig. 2 Lithostratigraphy, magnetostratigraphy, and magnetic susceptibility of the CGC sequence and correlation with the geomagnetic polarity time scale (21).

    High magnetic susceptibility values correlate with coarse-grained deposits, reflecting flooding intensity, and the type and quantity of the magnetic minerals in the source area may influence the magnetic susceptibility variations, although they are not discussed in detail in this paper.

  • Fig. 3 East Asian monsoon precipitation during 6.73 to 2.58 Ma BP.

    (A) Grain size fraction of >63-μm (this study). (B) Mean grain size from this study. (C) MAT (mean annual temperature) and MAP (mean annual precipitation) of the Weihe Basin, from Wang et al. (26). (D) Global cooling trend recorded by the benthic δ18O composite record of Zachos et al. (11). PDB, Pee Dee belemnite. (E) Band-pass filter of 100-ka of the mean grain size time series from this study. (F) Earth orbital eccentricity of 100 ka band-pass–filtered during 7.0 to 2.5 Ma BP from Laskar et al. (23).

  • Fig. 4 Results of spectral analysis of East Asian monsoon precipitation variations during the Pliocene.

    (A) Wavelet analysis results of the mean grain size time series from this study; the reddish color indicates strong power, and the ~100-, ~41-, and ~20-ka periodicities are indicated by horizontal white lines. (B) REDFIT power spectrum analysis results for the interval of 2.58 to 6.73 Ma BP from this study. Blackman-Tukey spectrum analysis results of the mean grain size time series during 2.58 to 6.73 Ma BP (C), 2.58 to 3.4 Ma BP (D), and 3.4 to 6.73 Ma BP (E), from this study. The 80, 90, and 95% confidence levels are labeled with thick green, red, and blue lines, respectively.

Supplementary Materials

  • Supplementary Materials

    Combined high- and low-latitude forcing of East Asian monsoon precipitation variability in the Pliocene warm period

    Yichao Wang, Huayu Lu, Kexin Wang, Yao Wang, Yongxiang Li, Steven Clemens, Hengzhi Lv, Zihan Huang, Hanlin Wang, Xuzhi Hu, Fuzhi Lu, Hanzhi Zhang

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    • Supplementary Materials Part 1 and Part 2
    • Figs. S1 to S8
    • Table S1
    • Legend for data S1
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