| 16 ka以来黄土高原东亚夏季风变化的环境磁学记录 |
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| 引用本文： | 梁潇,杨萍果,姚娇,张鹏,张建辉,孙鹏飞,敖红.16 ka以来黄土高原东亚夏季风变化的环境磁学记录[J].地理学报,2021,76(3):539-549. |
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| 作者姓名： | 梁潇 杨萍果 姚娇 张鹏 张建辉 孙鹏飞 敖红 |
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| 作者单位： | 1.山西师范大学生命科学学院,临汾 0410042.中国科学院地球环境研究所 黄土与第四纪地质国家重点实验室,西安 7100613.河北工程大学地球科学与工程学院,邯郸 056038 |
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| 基金项目： | 中国科学院前沿科学重点研究计划(QYZDB-SSW-DQC021)。 |
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| 摘 要： | 末次冰消期以来的气候变化是第四纪古气候研究的重要内容。本文对黄土高原西部和平镇剖面16 ka以来的黄土沉积序列（厚度为3.5 m）进行了高分辨率环境磁学研究。结果表明：该黄土序列的磁性颗粒主要由细颗粒磁铁矿主导。其磁化率和频率磁化率具有相同的变化特征,与黄土高原中部和东部的黄土磁化率变化机制一致,即黄土高原西部和平镇黄土的磁化率和频率磁化率仍然受成土作用形成的细颗粒磁铁矿控制,因此其磁化率和频率磁化率仍然可以反映季风降雨的变化特征,并且其反映的16 ka以来季风降雨变化与南方石笋氧同位素记录的季风变化特征一致。通过详细的海陆综合对比,本文认为16 ka至11 ka间东亚季风降雨的变化受到北半球太阳辐射和北半球区域温度的共同影响,而11 ka之后的夏季风降雨减少主要受太阳辐射降低的影响。
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| 关 键 词： | 环境磁学 黄土沉积序列 末次冰消期 东亚季风 |
| 收稿时间： | 2020-01-06 |
| 修稿时间： | 2020-12-06 |
Environmental magnetic record of East Asian summer monsoon variability on the Chinese Loess Plateau since 16 ka BP |
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| LIANG Xiao,YANG Pingguo,YAO Jiao,ZHANG Peng,ZHANG Jianhui,SUN Pengfei,AO Hong.Environmental magnetic record of East Asian summer monsoon variability on the Chinese Loess Plateau since 16 ka BP[J].Acta Geographica Sinica,2021,76(3):539-549. |
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| Authors: | LIANG Xiao YANG Pingguo YAO Jiao ZHANG Peng ZHANG Jianhui SUN Pengfei AO Hong |
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| Institution: | 1. School of Life Science, Shanxi Normal University, Linfen 041004, Shanxi, China2. Institute of Earth and Environment, CAS, Xi'an 710061, China3. School of Earth Science and Engineering, Hebei Universityof Engineering, Handan 056038, Hebei, China |
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| 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. |
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| Keywords: | environmental magnetism loess deposits last deglaciation East Asian monsoon |
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