Acta Geographica Sinica ›› 2021, Vol. 76 ›› Issue (3): 539-549.doi: 10.11821/dlxb202103004

• Climate Change and Land Surface Processes • Previous Articles     Next Articles

Environmental magnetic record of East Asian summer monsoon variability on the Chinese Loess Plateau since 16 ka BP

LIANG Xiao1,2(), YANG Pingguo1(), YAO Jiao2, ZHANG Peng2, ZHANG Jianhui2, SUN Pengfei3, AO Hong2   

  1. 1. School of Life Science, Shanxi Normal University, Linfen 041004, Shanxi, China
    2. Institute of Earth and Environment, CAS, Xi'an 710061, China
    3. School of Earth Science and Engineering, Hebei Universityof Engineering, Handan 056038, Hebei, China
  • Received:2020-01-06 Revised:2020-12-06 Online:2021-03-25 Published:2021-05-25
  • Contact: YANG Pingguo E-mail:liangsosou@126.com;lfypg@126.com
  • Supported by:
    Key Research Program of Frontier Sciences of Chinese Academy of Sciences(QYZDB-SSW-DQC021)

Abstract:

Climate change since the last deglaciation period is an important topic of Quaternary paleoclimate research. Eolian Holocene paleosols (S0) and last glacial loess (L1) on the western Loess Plateau margin have high sedimentation rates and provide valuable materials for the study of East Asian monsoon climate change since the last glacial deglaciation. Here we report high-resolution environmental magnetic records spanning the last 16 ka for the whole S0 and the uppermost L1 from the Hepingzhen section in the western Chinese Loess Plateau. Environmental magnetic results suggest that the magnetic properties of the Hepingzhen loess section are dominated by fine-grained magnetite, including superparamagnetic (SP), single-domain (SD), and fine pseudo single-domain (PSD) magnetite particles. The magnetic susceptibility and frequency dependent magnetic susceptibility records show identical variability during the last 16 ka. This consistent variability suggests that they are both influenced by content of pedogenic fine-grained (SP, SD, and fine PSD) magnetite particles, which is similar to the loess accumulations on the eastern Chinese Loess Plateau. Therefore, the magnetic susceptibility and frequency dependent magnetic susceptibility records of the Hepingzhen loess section can be also used to infer the soil pedogenic intensity and summer monsoon precipitation that dominates regional pedogenesis, as the case for the eastern Chinese Loess Plateau. The summer monsoon rainfall variation inferred from the Hepingzhen loess magnetic susceptibility and frequency dependent magnetic susceptibility records is consistent with that inferred from South China stalagmite oxygen isotope data during the last 16 ka. Both the western Chinese Loess Plateau and South China precipitation is suggested to be substantially lower during the last glacial period than in the Holocene. Precipitation was high during the BØlling-AllerØd Warming (BA, 15-13 ka BP), and low during the Younger Dryas (YD, ~12 ka BP). The highest precipitation occurred in the early Holocene (~11 ka BP), with a long-term decreasing trend from early to late Holocene. Combining a detailed land-sea comparison, we suggest that the variation of East Asian monsoon precipitation between 16 ka and 11 ka was affected by combined solar radiation and regional temperature of the northern hemisphere, while the long-term summer monsoon precipitation during the last 11 ka was dominated by a decreasing trend in solar radiation.

Key words: environmental magnetism, loess deposits, last deglaciation, East Asian monsoon