冀克家^1,2,,
朱二雷¹,
储国强³,
侯居峙^1,4,,
1. 中国科学院青藏高原研究所高寒生态重点实验室, 北京 100101
2. 中国科学院大学, 北京 100049
3. 中国科学院地质与地球物理研究所, 中国科学院新生代地质与环境重点实验室, 北京 100029
4. 中国科学院青藏高原地球科学卓越创新中心, 北京 100101

基金项目: 国家自然科学基金项目（批准号：41772178和91747207）和国家重点研发计划项目（批准号：2018YFA0606400）共同资助


详细信息

作者简介: 冀克家, 男, 29岁, 博士研究生, 古气候环境变化和生物标志化合物研究, E-mail: jikejia@itpcas.ac.cn

通讯作者: 侯居峙, E-mail: houjz@itpcas.ac.cn

中图分类号: P426.6;P941.78

收稿日期:2020-11-08
修回日期:2021-01-16
刊出日期:2021-03-30

Precipitation record based on varve chronology in Jiang Co on the central Tibetan Plateau during the past 2000 years

JI Kejia^1,2,,
ZHU Erlei¹,
CHU Guoqiang³,
HOU Juzhi^1,4,,
1. Key Laboratory of Alpine Ecology, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100101
2. University of Chinese Academy of Sciences, Beijing 100049
3. Key Laboratory of Cenozoic Geology and Environment, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029
4. CAS Center for Excellence in Tibetan Plateau Earth Sciences, Beijing 100101


More Information

Corresponding author: HOU Juzhi,E-mail:houjz@itpcas.ac.cn

MSC: P426.6;P941.78

--> Received Date: 08 November 2020
Revised Date: 16 January 2021
Publish Date: 30 March 2021


摘要
摘要:青藏高原由于其环境的脆弱性容易受到气候变化和人类活动的影响，重建这一地区过去2000年高分辨率的气候变化记录有助于增加我们对气候变化和人类活动之间关系的理解。本文通过对江错湖泊一根长达101 cm的岩芯沉积物纹层分析，重建了青藏高原中部过去2000年的纹层年代序列和降水变化。利用岩相显微镜和电子探针显微分析仪分析发现，沉积物中发育了良好的碎屑-有机质年纹层，纹层层偶主要由粗颗粒碎屑层和细颗粒碎屑层组成，其间极薄的有机质层是鉴定年纹层的标志。江错的年纹层年代序列与独立的核素测年（²¹⁰Pb、¹³⁷Cs和¹⁴C）结果基本一致，证明了年纹层的可靠性。基于对年纹层形成机制的分析，提出粗颗粒厚度百分比（coarse%）作为指示降水的新指标，粗颗粒物质主要由降水产生的径流将外源物质搬运到湖中，降水越多，搬运能力越强，粗粒颗粒物质相对含量也越多。这一指标与当地现代气象观测记录对比发现有较好的一致性。江错过去2000年的降水记录具有78~80 a和112~123 a两个百年尺度的周期波动特征，可能与Gleissberg太阳活动有关。在过去2000年中，该地区呈现出中世纪暖期（公元1000~1400年）降水多，小冰期（公元1400~1900年）降水少，现代暖期（公元1900年至今）降水多的特点，这与该地区其他的降水记录一致。
关键词: 青藏高原/
纹层年代/
江错/
降水

Abstract:The environment of the Tibetan Plateau(TP) is susceptible to climate change and human activities. It is essential to reconstruct a high-resolution climate record during the past 2000 years in this region, helping us to enhance the understanding of climate-human interaction. Jiang Co(31°33'N, 90°49'E; 4630 m a.s.l.) is located in the east of the town of Bange, central TP. Jiang Co is a monomictic lake with a surface area of 36 km² and a catchment area of 310 km². The maximum depth is 25 m. The lake is fed mainly by precipitation via three seasonal rivers in the rainy season(June-September) from west, northeast, and south, respectively.
A 101 cm long core of Jiang Co(JC15) was obtained by gravity corer, which was used for varve analysis and AMS ¹⁴C, ²¹⁰Pb, and ¹³⁷Cs dating. Clastic-biogenic varves are comprised of two laminae, a coarse-grain and a fine-grain layer, observed by a petrographic microscope and Electron Probe Micro Analyzer. The total varve counting number is 1963 A.D. with an error of 2.7% from 81 A.D. to 2015 A.D.. Three AMS ¹⁴C ages are 4085 a B.P., 4460 a B.P., and 5350 a B.P. at the depth of 29.5~30.0 cm, 59.5~60.0 cm, and 99~100 cm, respectively. The varve chronology is supported by independent ²¹⁰Pb ages by CRS model, ¹³⁷Cs age by 1963-peak, and ¹⁴C ages by Bacon model. The percent thickness of the coarse-grain layer within a single varve was used as a proxy for precipitation, as more coarse grains are transported mainly by increasing runoff. This precipitation record is highly correlated with the precipitation amount recorded at the Bange Meteorological Station between 1957~2015 A.D.. During the past 2000 years, the precipitation record reconstructed from Jiang Co sediments shows centennial-scale fluctuations of 78~80 years and 112~123 years that are consistent with other records in the region, possibly influenced by the solar activity of Gleissberg. The precipitation record shows a characteristic of wet Medieval Warm Period(1000~1400 A.D.) and Current Warm Period(1900 A.D.~now) and dry Little Ice Age(1400~1900 A.D.).
Key words:Tibetan Plateau/
varve chronology/
Jiang Co/
precipitation



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