| 云南高海拔湖泊对末次冰消期气候突变的响应 |
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| 引用本文： | 孙晓双,张灿,柴轶凡,赵成.云南高海拔湖泊对末次冰消期气候突变的响应[J].第四纪研究,2019,39(4):975-984. |
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| 作者姓名： | 孙晓双 张灿 柴轶凡 赵成 |
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| 作者单位： | 中国科学院南京地理与湖泊研究所,湖泊与环境国家重点实验室,江苏 南京210008;中国科学院大学,北京100049;中国科学院南京地理与湖泊研究所,湖泊与环境国家重点实验室,江苏 南京210008 |
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| 摘 要： | 气象观测资料表明,在当前全球暖化背景下高海拔地区的增温速率更快,其气候对全球气候变化的响应更为敏感.但是,高海拔地区如何响应快速气候事件,由于古气候古环境重建资料在高海拔地区较少,这一问题还没有很好的回答.为此选择云南省高山湖泊错恰湖为研究对象(海拔约3960 m),分析了湖泊沉积岩芯(深度范围90~244 cm)中正构烷烃的分布特征,重建了末次冰消期(19000~9500 a B. P.)沉积物有机质来源的变化,进而推断古气候演变.在17800~17000 a B. P.,错恰湖有机质以陆源输入为主,水生贡献相对减少,气候以暖湿为主;在17000~15100 a B. P.,水生有机质的贡献的比例增加,气候以冷干为主;在15100~12700 a B. P.,湖泊沉积有机质的陆源贡献增加,水生贡献相对减少,气候相对暖湿;在12700~11400 a B. P.时段,湖泊沉积水生有机质来源相对增多,气候相对冷干.与其他区域和全球气候记录对比发现,错恰湖的沉积记录指示的气候变化事件,受高纬冰量以及北大西洋驱动的西南季风突变所影响,在末次冰消期记录的4个明显的千年尺度气候事件,在时间上与First warmth、 H1、 B-A和YD事件相对应.与云南地区其他湖泊记录对比发现,小型湖泊或高海拔湖泊对这些全球快速气候事件的响应更加敏感.
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| 关 键 词： | 西南季风 末次冰消期 高海拔湖泊-错恰湖 正构烷烃 古气候 |
High-altitude lake sediments in response to abrupt climatic events during the last deglaciation in Southwestern China |
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| Sun Xiaoshuang,Zhang Can,Chai Yifan,Zhao Cheng.High-altitude lake sediments in response to abrupt climatic events during the last deglaciation in Southwestern China[J].Quaternary Sciences,2019,39(4):975-984. |
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| Authors: | Sun Xiaoshuang Zhang Can Chai Yifan Zhao Cheng |
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| Institution: | (State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, Jiangsu;University of Chinese Academy of Sciences, Beijing 100049) |
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| Abstract: | Modern instrumental data show that high-elevation regions, such as the Tibetan Plateau and its surrounding areas, are more sensitive to global climate change than anywhere else in the world.However, little is known about the climate and environmental responses to abrupt degalcial global climate events in high-elevation regions, largely due to the lack of high quality paleoclimate and paleoenvironment reconstructions.Here, we present results of n-alkane distributions inferred from a sediment core collected from Lake Cuoqia (27°24'N, 99°46'E;3960 m) in Hengduan Mountain, Yunnan Province, Southwestern China, in order to reconstruct and evaluate climate and environmental responses to abrupt deglacial climate events in high-elevation regions.We collected a 244-cm-long core from the lake center under a water depth of ca.26 m in May 2015, using a Uwitech Corer system, and then sectioned at 1-cm intervals in the laboratory.The high-altitude Lake Cuoqia adjoined Tibetan Plateau in the Yunnan of China southwest monsoon region was chosen to reconstruct the climatic events.In this study, we focus on the period of the last deglaciation, equivalent to the depth interval between 90~244 cm.The chronology of the core was established by 6 AMS-14C dates of terrestrial plant fragments at Beta Laboratory, which shows the analyzed section spans from 19000 a B.P.to 9500 a B.P.We analyzed the n-alkanes distribtution of this section of the core, at every 1-cm interval in State Key Laboratory of Lake Science and Environment in Nanjing Institute of Geography and Limnology.The n-alkane molecules of Cuoqia Lake range from nC17 to nC33, with ACL values of 23.74~28.11 and Paq values of 0.31~0.82.Long-and mid-chain n-alkanes show a significant odd predomination, while short-chain n-alkanes do not show this.From 17800 a B.P.to 17000 a B.P., our data indicate that the organic matter of lake sediments was mainly from terrestrial inputs with relative low aquatic sourced organic contributions, suggesting a relatively warm and humid climate.From 17000 a B.P.to 15100 a B.P., the increased contribution of aquatic organic matter indicated a relatively cold and dry climate.From 15100 a B.P.to 12700 a B.P., the increased contribution of terrestrial organic matter suggested a relatively warm and humid climate.From 12700 a B.P.to 11400 a B.P., the increased aquatic contributions showed a relatively cold and dry condition.The four distinct millennial-scale climatic events recorded by our data likely correspond to the well-documented First warmth、Heinrich 1 event (H1)、B?lling-Alller?d (B-A) and Younger Dryas (YD) events, probably related to high-latitude climate and abrupt variations in Atlantic Meridional Overturning Circulation and Indian Ocean Sea Surface temperatures.Together with other published reconstructions from lakes at different elevations in Yunnan, we conclude that small lakes from higher-elevation sites are more sensitive to these abrupt climatic events during the last deglaciation. |
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| Keywords: | southwestern monsoon last deglaciation high-altitude lake of Cuoqia n-alkanes paleoclimate |
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