张伟宏^1,,,
张振球^2,3,,,
陈剑舜¹,
周汪洋¹,
邵庆丰³,
李凤全¹,
王天阳¹
1. 浙江师范大学地理与环境科学学院, 浙江 金华 321004
2. 南京师范大学生命科学学院, 江苏 南京 210023
3. 南京师范大学地理科学学院, 江苏 南京 210023

基金项目: 国家自然科学基金项目（批准号：41602350和41971111）和浙江省自然科学基金项目（批准号：LY20D020001）共同资助


详细信息

作者简介: 张伟宏, 女, 33岁, 讲师, 第四纪地质学专业, E-mail:zhangwh@zjnu.cn

通讯作者: 张伟宏, E-mail:zhangwh@zjnu.cn; 张振球, E-mail:zhangzhenqiu163@163.com

中图分类号: P597⁺.2;P532

收稿日期:2020-01-28
修回日期:2020-04-21
刊出日期:2020-07-30

Variability of the East Asian summer monsoon during the Last Glacier Maximum recorded by a stalagmite oxygen isotope record in Chongqing, Southwestern China

Zhang Weihong^1,,,
Zhang Zhenqiu^2,3,,,
Chen Jianshun¹,
Zhou Wangyang¹,
Shao Qingfeng³,
Li Fengquan¹,
Wang Tianyang¹
1. College of Geography and Environmental Sciences, Zhejiang Normal University, Jinhua 321004, Zhejiang
2. College of Life Sciences, Nanjing Normal University, Nanjing 210023, Jiangsu
3. College of Geography, Nanjing Normal University, Nanjing 210023, Jiangsu


More Information

Corresponding authors: Zhang Weihong,E-mail:zhangwh@zjnu.cn ; Zhang Zhenqiu,E-mail:zhangzhenqiu163@163.com

MSC: P597⁺.2;P532

--> Received Date: 28 January 2020
Revised Date: 21 April 2020
Publish Date: 30 July 2020


摘要
摘要:基于重庆小山岩洞XSY1石笋的5个²³⁰Th年龄和582个氧同位素数据，重建了23134~19345 a B.P.期间分辨率约6.5 a的东亚夏季风变化历史。此石笋δ¹⁸O记录的长期趋势逐渐负偏，在其上叠加了一系列千年-百年尺度季风振荡，呈现为4谷3峰的结构形态。重庆XSY1和南京MSD石笋δ¹⁸O记录在数百年尺度的反相关系表明冰盛期时东亚大陆东部水汽并非来自印度洋。与北高纬记录对比显示东亚季风的增强与减弱基本对应格陵兰温度的升高与降低时期，暗示在冰量最大时期东亚季风与北高纬气候仍密切联系。此外，XSY1的δ¹⁸O与冰芯¹⁰Be通量亦存在明显的对应关系，表明太阳活动对东亚季风的调控作用受冰量边界条件影响较小。功率谱分析结果显示出1011 a、722 a、460 a、337 a和163 a的周期，与太阳活动周期相近，进一步确认太阳活动对东亚季风的驱动作用。石笋XSY1与澳大利亚石笋MC-S2 δ¹⁸O记录在千年尺度呈反相位变化，表明冰盛期时东亚季风与全球其他气候系统的动力联系。
关键词: 末次冰盛期/
石笋/
氧同位素/
东亚夏季风/
太阳活动

Abstract:A highly resolved and precisely dated record characterizes in detail the East Asian Summer Monsoon (EASM) during the Last Glacial Maximum (LGM). Here we report a stalagmite (no. XSY1) δ¹⁸O record from Xiaoshanyan Cave (29°42'N, 108°22'E; 456 m above sea level). This cave is located in Shizhu Tujia Autonomous County, Chongqing, Southwestern China. The area is climatically dominated by the EASM, featured by warm and wet summer, as well as cold and dry winter. The annual precipitation is more than 1110 mm in the region, most of which falls during the summer seasons. Vegetation above Xiaoshanyan Cave is dense and is mostly composed of deciduous plants. The temperature and relative humidity are 17.4℃ and 100% inside the cave, respectively. The stalagmite XSY1 is 832 mm in length. When halved along its growth axis and polished, the sample becomes ivory in the upper section of 0~600 mm and fuscous in the lower part of 600~823 mm.
A total of 5 ²³⁰Th dates were measured on the stalagmite XYS1. The ²³⁰Th dating were conducted by Thermo-Finnigan Neptune multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS) at Nanjing Normal University. The ²³⁰Th dating results indicate that a growth hiatus took place at the depth of 590~600 mm. In this study, the upper continuous section is focused on. We drilled 582 subsamples for stable isotope analyses along the central growth axis using a dental drill with a diameter of 0.5 mm. The δ¹⁸O measurements were performed by Finnigan-MAT-253 mass spectrometer at Nanjing Normal University. Precision of δ¹⁸O values is 0.06 ‰, at 1-sigma level.
We reconstruct an evolutionary history of the EASM during the period of 23134~19345 a B.P. based on the 5²³⁰Th ages and 582 δ¹⁸O data. The XSY1 δ¹⁸O values vary from -7.51 ‰ to -6.11 ‰ and the averaging value is -6.77 ‰. The δ¹⁸O record displays a long-term decreasing trend overall, which indicates a gradually intensifying EASM during the LGM. This long-term trend is interrupted by a series of multi-centennial to millennial δ¹⁸O oscillations, marked by 4 valleys and 3 peaks in shape. We find that the XSY1 δ¹⁸O variation is anti-phased with the stalagmite MSD δ¹⁸O record from Hulu Cave, eastern China on the multi-centennial scale. This relationship indicates that moistures at least in coastal East Asia were not totally from the Indian Ocean during the LGM. If the moisture had been from the remote Indian Ocean, both the stalagmite δ¹⁸O records would fluctuate in the same direction. The anti-phased behavior may be caused by ocean-atmosphere interactions in the Pacific Ocean, such as ENSO-like circulations. This is because the ENSO-like circulations regulate relative intensity of the Indian and East Asian monsoon. In addition, the XSY1 δ¹⁸O record correlates well with the GISP2 ice core δ¹⁸O and ¹⁰Be records on the centennial scale. The good correlations point to tight links of the EASM to the North Atlantic climate and solar activity during the LGM. The solar influence is further supported by spectral analyses of the XSY1 δ¹⁸O record. The analysis exhibits significant cycles at 1011 a, 722 a, 460 a, 337 a and 163 a at the 90% confidence level, close to solar cycles. Moreover, additional comparisons reveals that the EASM fluctuated reversely with the hydroclimate change in the Southern Australia on the millennial scale. This phenomenon indicates a dynamic connection of the EASM with the global climate system during the LGM.
Key words:Last Glacial Maximum/
stalagmite/
oxygen isotope/
East Asian summer monsoon/
solar activity



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