薛莲花^1,2,3,,
赵侃^1,2,3,,,
崔英方⁴,
梁怡佳^1,2,3,
杨少华^1,2,3,
汪永进^1,2,3
1. 南京师范大学地理科学学院, 江苏 南京 210023
2. 虚拟地理环境教育部重点实验室(南京师范大学), 江苏 南京 210023
3. 江苏省地理信息资源开发与利用协同创新中心, 江苏 南京 210023
4. 南京旅游职业学院, 江苏 南京 211100

基金项目: 国家自然科学基金项目（批准号：41702180、41571102和41572151）和江苏省研究生科研与实践创新计划项目（批准号：KYCX19_0789）共同资助


详细信息

作者简介: 薛莲花, 女, 23岁, 硕士研究生, 自然地理学专业, E-mail:lianhuax@foxmail.com

通讯作者: 赵侃, E-mail:09371@njnu.edu.cn

中图分类号: P597⁺.2;P532

收稿日期:2020-02-10
修回日期:2020-05-06
刊出日期:2020-07-30

ABRUPT CHANGES OF EAST ASIAN SUMMER MONSOON OVER THE PAST TWO MILLENNIA FROM STALAGMITE RECORD IN LUOSHUI CAVE,HUBEI PROVINCE

Xue Lianhua^1,2,3,,
Zhao Kan^1,2,3,,,
Cui Yingfang⁴,
Liang Yijia^1,2,3,
Yang Shaohua^1,2,3,
Wang Yongjin^1,2,3
1. School of Geography, Nanjing Normal University, Nanjing 210023, Jiangsu
2. Key Laboratory of Virtual Geographic Environment(Nanjing Normal University), Ministry of Education, Nanjing 210023, Jiangsu
3. Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application, Nanjing 210023, Jiangsu
4. Nanjing Institute of Tourism&Hospitality, Nanjing 211100, Jiangsu


More Information

Corresponding author: Zhao Kan,E-mail:09371@njnu.edu.cn

MSC: P597⁺.2;P532

--> Received Date: 10 February 2020
Revised Date: 06 May 2020
Publish Date: 30 July 2020


摘要
摘要:基于湖北落水洞石笋（LS45）7个²³⁰Th年代结果和260个氧同位素测试数据，重建了近2000年来平均分辨率为6 a的东亚夏季风变化序列，该序列在280~800 A.D.、800~1400 A.D.和1400~1850 A.D.季风强度呈弱-强-弱的演变特征，分别对应于黑暗时代冷期（DACP）、中世纪暖期（MWP）和小冰期（LIA）3个典型气候期。LS45记录显示近2000年来东亚夏季风强度总体呈减弱趋势，并叠加数次百年尺度的振荡旋回。其中DACP和LIA并非持续几个世纪的连续弱季风时期，且内部还存在明显的数十年尺度强弱波动，δ¹⁸O振幅范围约为0.6 ‰。在DACP向MWP转变期间，δ¹⁸O值快速负偏，持续时间约40~50 a，变化幅度约0.7 ‰，指示夏季风突然增强。和尚洞、万象洞、Dandak洞的石笋记录以及Laguna Pallcacocha沉积物红度记录均显示了这一快速转变过程，暗示大尺度大气环流可能发生快速转型。进一步将中国石笋记录与太阳活动、厄尔尼诺、大西洋海表温度和北半球温度指标记录进行对比，发现这些记录之间存在良好对应关系和相似特征，表明百年-十年际尺度季风变化可能与太阳活动、厄尔尼诺-南方涛动（ENSO）和大西洋多年代际震荡（AMO）变化密切相关。因此，本文推测ENSO和AMO可能是太阳活动影响亚洲季风变化的关键因子。
关键词: 落水洞/
中世纪暖期/
季风气候突变/
石笋/
ENSO

Abstract:Here, we derive a precisely ²³⁰Th-dated and high-resolution stalagmite δ¹⁸O record from the Luoshui Cave (29°44'N, 109°7'E; 1071 m), Enshi, Hubei Province, Central China. This study region is located at the south slope of Daba Mountain Range and the northern edge of the subtropical monsoon region. The mean annual temperature in the cave is approximately 14.5℃ with relative humidity close to 97%.
The stalagmite (LS45) was collected in the chamber with a total length of about 237 mm. This sample is divided into two sections of 0~130 mm and 130~237 mm because of growth hiatus at the depth of 130 mm, so, the section of 0 mm to 130 mm is the research area. Besides, the growth rate is stable throughout the entire stalagmite, as is by the ²³⁰Th dating results.
When halved and polished, it is composed of pure and transparent calcite with homogeneous lithological characteristics. We present a continuous high-resolution record of EASM evolution from 280 A.D. to 1850 A.D., roughly contains three periods of Dark Times Cold Period (DACP), Medieval Warm Period (MWP) and Little Ice Age (LIA). This paleoclimate time sequence was established by 7 precise ²³⁰Th dates and 260 stable oxygen isotope ratios (δ¹⁸O). The dating measurements were then conducted by multi-collector inductively coupled plasma mass spectrometer (MC-ICP-MS) at the Isotope Laboratory of Nanjing Normal University, the error is ±2 sigma, and Isotope Geochemistry Laboratory at the Earth Observatory of Singapore, Nanyang Technological University. The oxygen isotopic analyses were run at the Isotope Laboratory of Nanjing Normal University with Finnigan MAT-253 mass spectrometer. Precisions for δ¹⁸O is ±0.06 ‰ and ±0.05 ‰ for δ¹³C.
The δ¹⁸O values of the stalagmite (LS45) vary from -8.2 ‰~-7.3 ‰ and its maximum amplitude is close to 0.9 ‰, the average value is about -7.7 ‰, and the overall fluctuation range is small. The average δ¹⁸O values during the periods of 800~1400 A.D. is negative, implying relatively stronger ASM and corresponding to the period of MWP. And the average δ¹⁸O values during the periods of 280~800 A.D. and 1400~1850 A.D. is positive, implying relatively weaker ASM, corresponding to the period of DACP and LIA respectively. The general trend of δ¹⁸O record from stalagmite LS45 is temporally consistent with the stalagmite records from the Heshang Cave in Hubei, the Wanxiang Cave in Gansu, the Dandak Cave in India and a record of red colour intensity of sedimentary in Laguna Pallcacocha within dating errors.
The LS45 δ¹⁸O record shows that the intensity of Asian summer monsoon (ASM) has decreased in the past 2000 years in general. Three episodes reflected in our record show weak-strong-weak pattern of monsoon, and is punctuated by several centennial-interannual scale oscillations throughout the entire studied interval. It is observed that ASM is strongly weakened during the DACP and LIA. However, we found that DACP and LIA were not continuous cold periods lasting for several centuries, and there were regular secondary fluctuations of warm and cold times within them. These two episodes, also recognized in other stalagmite records, corresponds to weak solar activities. But the factors of the monsoon system on the centennial-decadal scale are very complicated. Besides, at the transition from DACP to MWP, ASM strengthened abruptly, taking place in about 40 years, indicating a rapid atmospheric circulation transition. This fast process is also mirrored in Heshang Cave, Wanxiang Cave, Dandak Cave records and a record of red colour intensity of sedimentary in Laguna Pallcacocha, within dating errors. The abrupt monsoonal shift is consistent with a fast warming in the Atlantic sea surface temperature (SST) and Northern Hemisphere temperature, a sharp strengthening of both El-Ni?o activities and solar activities, this indicates that this mutation process is related to the increase of solar activity, Atlantic Multidecadal Oscillation (AMO) and the increase of El Ni?o -Southern Oscillation (ENSO) activity. In addition, ENSO and AMO may be important amplification mechanisms and transmission mechanisms of solar activity signals regulating the East Asian summer monsoon.
Key words:Luoshui Cave/
Medieval Warm Period/
abrupt monsoonal shifts/
stalagmite/
ENSO



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