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辽宁本溪高分辨率石笋氧同位素记录的东亚夏季风“2.8 ka”事件

Variability of Eastern Asian summer monsoon during 2.8 ka climate event recorded in a stalagmite oxygen isotope sequence from Miaodong Cave, Northeastern China
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摘要 本研究利用辽宁本溪庙洞石笋MD12,通过230Th定年和高分辨率氧同位素分析,并集成庙洞另一支石笋MD11序列,重建了3.04~2.60 ka B.P.时期辽东地区夏季风(降水)变化历史。该石笋氧同位素序列记录了2.8 ka事件的详细过程,事件的核心阶段起止时间约为2.76~2.66 ka B.P.,中心点位于2.68 ka B.P.,稍微晚于西南石笋氧同位素记录(约2.71 ka B.P.),但是在事件的开始时间上,庙洞石笋氧同位素记录比西南石笋氧同位素记录晚了约100年。因此,庙洞石笋氧同位素记录与西南石笋氧同位素记录中显示的缓慢减弱-快速增强模式不同,2.8 ka事件在辽东石笋氧同位素记录中表现为快速减弱-突然增强的变化模式,与太阳活动代用指标一致变化,支持太阳活动是2.8 ka弱季风事件驱动因子的观点。庙洞石笋氧同位素快速响应太阳活动的变化特征,说明其动力学机制可能是太阳活动减弱导致北半球高纬度地区温度降低,然后通过大气"遥相关"作用影响东亚夏季风。 The 2.8 ka cold event is one of well known abruptly climate events during the Late Holocene. Previous documents showed weak Eastern Asian Summer Monsoon(EASM) and less precipitation in the northern margin of EASM area during 2.8 ka event. The forcing of this event has been pointed to Solar activity, but the detail forcing mechanism is still unclear. Considering the significantly negative excursion of solar activity during 2.8 ka, high resolution record of EASM with well age constraining is helpful for us to better understand this mechanism. In this study, stalagmite MD12 from Miaodong Cave(41°03'N, 125°31'E), Northeastern China were analyzed. The mineral composition of stalagmite MD12 is pure calcite. Total of 5 230Th dating were performed on MC-ICPMS. Total of 90 subsamples for stable isotope measurement were drilled(80 along the vertical growth axle and 10 along horizontal layer at 2 depths for "Hendy Test"), and analysed with MAT 253 coupling with Gasbench-Ⅱ. The MD12 isotope sequence covers interval of 2.92~2.60 ka B. P. The MD12 sequence was then composited with the other published oxgen isotope time series also from Miaodong cave, named MD11, to build the Miaodong stalagmite oxygen isotope sequence covering 3.04~2.60 ka B. P. The variability of Miaodong stalagmite oxygen isotope is interpreted as change of EASM intensity or monsoon precipitation in this area. Based on these ages with low errors(two sigma, 18 to 25 years), the Miaodong record give a detail evolution of EASM and precise transfer time of 2.8 ka event. From 2.88 ka B. P. to 2.62 ka B. P., the Miaodong record exhibits two weak EASM intervals, 2.81~2.87 ka B. P. and 2.76~2.66 ka B. P. respectively. The later one, covering about 110 years, is the key interval of 2.8 ka event, and exhibits a symmetrical shifting process. The EASM abruptly decrease at around 2.76 ka B. P., and reached its worst state at about 2.68 ka B. P., following by an abruptly strengthening process. This transfer point(2.68 ka B. P.) is little younger than those stalagmite
作者 蔡炳贵 李苗发 王芳 王立胜 王学锋 马志邦 闫禹 Cai Binggui;Li Miaofa;Wang Fang;Wang Lisheng;Wang Xuefeng;Ma Zhibang;Yan Yu(Key Laboratory for Humid Subtropical Eco-geographical Processes of the Ministry of Education, Fujian Normal University, Fuzhou 350007, Fujian;Institute of Geography, Fujian Normal University, Fuzhou 350007, Fujian;School of Geographical Sciences, Fujian Normal University, Fuzhou 350007, Fujian;Key Laboratory of Cenozoic Geology and Environment, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029)
出处 《第四纪研究》 CAS CSCD 北大核心 2019年第3期755-764,共10页 Quaternary Sciences
基金 国家重点基础研究发展计划项目(批准号:2017YFA0603401) 国家自然科学基金项目(批准号:41661144021和41272197) 福建师范大学校创新团队基金项目(批准号:IRTL1705)共同资助.
关键词 2.8 ka事件 东亚夏季风 石笋 氧同位素 中国东北 2.8 ka Event Eastern Asian Summer Monsoon(EASM) stalagmite oxygen isotope Northeastern China
作者简介 第一作者:蔡炳贵,男,44岁,副研究员,全球变化与第四纪环境演变研究,E-mail:bg-cai@fjnu.edu.cn,bingguicai@qq.com.
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