摘要
在末次冰期发生的6次海因里希事件(Heinrich事件,简称H事件)中,H6事件发生年代最早,对其研究较少,利用高分辨率石笋记录研究H6事件期间的气候环境变化,有助于理解高低纬度气候变化对H事件的响应过程。本文基于重庆市金佛洞石笋JF2017铀系测年数据和碳同位素数据,重建H6事件期间中国西南地区季风气候环境的演化过程。结果显示:石笋JF2017的δ13C值在61811±204 a B.P.~59716±159 a B.P.时段显著偏重,持续大约2095 a,暗示该时段季风减弱和生态植被退化,对应北大西洋H6事件。H6事件期间,石笋JF2017的δ13C记录在61811~60848 a B.P.期间开始先逐渐偏重至最大值,随后发生短时间尺度的波动变化;最后在60848~59716 a B.P.期间缓慢偏轻至H6事件结束,整体呈现先逐渐偏重后又缓慢偏轻的趋势,内部存在百年际尺度的气候震荡,表明H6事件期间当地气候不稳定。石笋JF2017记录的百年际尺度的季风气候变化可能与热带辐合带和北大西洋经向翻转环流密切相关。
Of the six Heinrich events(H event for short)occurring during the last glacial period,H6 event has been less studied due to its earliest occurrence time.However,using high-resolution stalagmite records to study climate and environmental changes during H6 event can help people understand the response of climate change at high and low latitudes to the H events.In recent years,much progress has been made in terms of studies on paleoclimate and environmental changes with use of stalagmiteδ13C records.Besides,some stalagmiteδ13C records have been used to study the climate change of the events on a millennium scale during the last glacial period,but there is no detailed record of the high-resolution climate change in Southwest China during the H6 event.In this case,the JF2017 stalagmiteδ13C may provide an excellent proxy for exploring the climate and environmental change during H6 event.Based on the dating data of uranium series and carbon isotope data of JF2017 stalagmite in Jinfo Cave,we analyzed the climate significance indicated by stalagmiteδ13C,and reconstructed the evolution process of the monsoon climate environment in Southwest China during H6 event. Developed from the Jinfo-Yangzi Cave system, Jinfo Cave is located in Jinfo Mountain, Nanchuan district,Chongqing, Southwest China, with an altitude of 2,080 m. The Jinfo Mountain area belongs to subtropical humidmonsoon climate, which is jointly affected by the Indian Summer Monsoon and the East Asian Summer Monsoon(ASM). In this study, the age samples of stalagmites were tested by Neptune Plus Multi-receiver Plasma InductivelyCoupled Mass Spectrometry (MC-ICP-MS), and the carbon isotopes of stalagmites were tested by Delta-V-Plus gasisotope ratio mass spectrometer and carbonate automatic sampling device Kiel-IV online. The experimental results arebased on Vienna Pee Dee Belemnite (V-PDB) with δ13C experimental analysis error<0.06 ‰(2σ). According to dataanalysis, the variation range of stalagmite JF2017 δ13C is from -1.44 ‰ to -4.92 ‰, with an average value of -3.40 ‰.JF2017 stalagmite δ13C fluctuates significantly, and change amplitude is -3.48 ‰. JF2017 stalagmite δ13C records showthat the value mainly presents a negative-positive-negative-positive trend during the period of 63,000-58,000 a B.P.Due to the complex influence factors of stalagmite δ13C, we compared JF2017 stalagmite δ13C records with JFYK7stalagmite δ18O records in Yangkou Cave which belongs to the same cave system as Jinfo Cave in order to furtheranalyze the climate significance of stalagmite JF2017 δ13C. The comparison indicates a similar variation between thestalagmite stable isotope records of Yangkou Cave and JF2017 stalagmite δ13C records. Through previous research,JFYK7 stalagmite δ18O is indicative of variations in ASM intensity, and the positive shift in stalagmite δ18Ocorresponds to weakened ASM. In this study, we observed that the stalagmite JF2017 δ13C value was slightly positive,corresponding to the positive JFYK7 stalagmite δ18O. Therefore, under the background of weakening ASM, JF2017stalagmite δ13C records can reflect the change of ecological environment caused by the change of regional hydrologicalclimate. In addition, the comparison between JF2017 stalagmite and the stalagmites from other caves indicate thatJF2017 stalagmite δ13C records were comparable with other climate records during H6 event. From 61,811 a B.P.to60,848 a B.P., the values gradually became heavier, reaching to the maximum, and then fluctuated on a short-timescale. Finally, from 60,848 a B.P. to 59,716 a B.P., they became slightly lighter to the end of H6 event. Thecomparison between JF2017 stalagmite δ13C and other relevant records in the rest of the world shows fluctuations inthe stalagmite δ13C record, so do the corresponding ITCZ and AMOC. This study shows that the stalagmite JF2017 δ13C value was significantly heavier during the 61,811 ± 204 a B.P.-59,716 ± 159 a B.P. period, lasting for about 2,095 a, which may suggest that the monsoon weakened and theecological vegetation degraded during this period. This result corresponds to the North Atlantic H6 event. During H6event, stalagmite JF2017 δ13C records became heavy to the maximum value during the period of 61,811-60,848 a B.P.,followed by the fluctuation change on the short-time scale. During the period of 60,848-59,716 a B.P., the valuesslowly became lighter to the end of the H6 event. The trend of becoming light after a gradual increase of weight and aclimate shock inside on a centennial scale indicate that the local climate was unstable during H6 event. The monsoonclimate change on a centennial scale recorded by stalagmite JF2017 may be closely related to the IntertropicalConvergence Zone (ITCZ) and the North Atlantic meridional overturning circulation (AMOC).
作者
组里塞斯
杨勋林
王勇
胡明广
许奕滨
Zulisaisi;YANG Xunlin;WANG Yong;HU Mingguang;XU Yibin(School of Geographical Sciences,Southwest University/National Observation and Research Station of Karst Ecosystem in Jinfo Mountain of Chongqing,Chongqing 400715,China;Chongqing Key Laboratory of Karst Environment,Chongqing 400715,China;Nanchuan Field Scientific Observation&Research Base of Karst Eco-environment,Ministry of Natural Resources of the People’s Republic of China,Chongqing 400715,China)
出处
《中国岩溶》
CAS
CSCD
北大核心
2023年第3期590-602,共13页
Carsologica Sinica
基金
国家自然科学基金项目(41971109,41572158)
国家重点研发计划项目(2016YFC0502301)。
