The evolution history of Asian monsoon and westerly winds over the past 14,000 years: Evidence from grain size of ash in the Hongyuan peat on the eastern Qinghai-Tibetan Plateau
The evolution history of Asian monsoon and westerly winds over the past 14,000 years: Evidence from grain size of ash in the Hongyuan peat on the eastern Qinghai-Tibetan Plateau
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DOI：
10.1016/j.palaeo.2023.111814
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发表时间：
2023-09
期刊：
影响因子：
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通讯作者：
Yongyong Bai;Mengxiu Zeng;Fengquan Li;Yougui Song;Yongqiu Wu;Jianghong Wu;Cheng Zhu;Haijun Peng
中科院分区：
文献类型：
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作者：
Yongyong Bai;Mengxiu Zeng;Fengquan Li;Yougui Song;Yongqiu Wu;Jianghong Wu;Cheng Zhu;Haijun Peng
亚洲季风和西风在不同时间尺度上的关系一直是一个有争议的话题。若尔盖湿地位于青藏高原东部，是我国最大的高原湿地，对环境变化极为敏感。虽然在该地区进行了几次古环境重建，但对粒度的综合研究仍然有限。本研究对该地区红原泥炭HY2014剖面沉积物中灰分的粒度进行了系统的研究。该剖面中的灰分成分主要是粘土和粉砂颗粒，含砂量非常低。除底层沉积物呈单峰型外，粒度频率曲线总体上呈双峰型。利用端元（EM）模式，结合前人的研究成果，重建了末次冰消期以来的大气环流。确定了三种不同的EM。EM1表明长距离悬浮物主要由WWs输送。EM2与低空环流有关，并与亚洲夏季风（ASM）的减少有关。EM3代表通过亚洲冬季风（AWM）进入湿地的物质。研究结果表明，在冰消后期，若尔盖湿地经历了寒冷干旱的气候条件，其AWM强度较强。此外，WWs和ASM发挥主导作用，而AWM逐渐减弱，在全新世期间，其强度在不同的时间间隔变化。结果还表明，WWs和ASM之间的正相关，以及WWs和AWM之间的负相关。
The relationship between the Asian monsoon and westerly winds (WWs) on various temporal scales remains a topic of debate. The Zoige wetland, situated to the east of the Qinghai-Tibetan Plateau, is the largest highland wetland in China and highly sensitive to environmental changes. While several paleoenvironmental reconstructions have been conducted in this region, comprehensive investigations into grain size are still limited. In this study, we conducted a systematic investigation of grain size in ash from the sediments of the Hongyuan peat HY2014 profile in this area. The ash composition in this profile was primarily clay and silt particles, with a very low sand content. The grain size frequency curves generally exhibited a bimodal modality, except for the sediments in the bottom layers which displayed a single-peak pattern. By employing the end-member (EM) model and considering previous research findings, we reconstructed the atmospheric circulation since the last deglaciation. Three distinct EMs were identified. EM1 indicated long-distance suspended materials primarily transported by WWs. EM2 was associated with low-altitude circulation and linked to a decrease in the Asian summer monsoon (ASM). EM3 represented materials transported into the wetland via the Asian winter monsoon (AWM). Our results suggested that during the late deglacial period, characterized by strong AWM intensity, the Zoige wetland experienced cold and arid conditions. Moreover, the WWs and ASM exerted dominant influences, while the AWM gradually weakened during the Holocene, with variations in their intensities across different time intervals. The results also revealed a positive correlation between WWs and ASM, as well as a negative correlation between WWs and AWM.