δ13Corg)等古环境替代指标的测试。实验结果显示,L*LOI550TOC3个有机碳含量指标同步变化,共同指示该钻孔序列经历了3个沉积环境演变阶段,即末次盛冰期晚期(2115 cal ka BP)河流—冲积相沉积阶段、冰消期至早中全新世(154 cal ka BP)高湖面湖泊—沼泽相沉积阶段和晚全新世(4 cal ka BP以来)洪冲积相沉积阶段。近2万年以来草海湖沼面积经历的收缩→扩张→收缩演变过程与石笋氧同位素变化基本吻合,表明季风降雨是引起草海湖泊水体和周边生态系统变化的主要因素。δ13Corg指标变化范围为-29.28‰~-24.19‰,表明草海盆地周围植被组成在末次盛冰期以来C4草本虽然略有增加,但均以C3植物为主。同时,TOCδ13Corg指标证明了B/A冰消期暖事件对盆地边缘区的湿地泥炭富集起到关键作用,而多指标揭示了近4 ka以来水域变浅并发展成为冲积环境的过程,也可能与石笋记录的夏季风减弱所带来的降水量减少有关。"/> δ13Corg). The environment proxies(L*、TOC and LOI550)varied synchronously,indicating three distinct intervals of lake level since the Last Glacial Maximum(LGM),i.e. riverine alluvial facies,lake-wetland facies and shallow water alluvial facies respectively from 21~15 ka BP,15~4 cal ka BP and after 4 cal ka BP. This change pattern is similar to the variation of speleothem δ18O records from the south China. The δ13Corg values,varying between-29.28‰ and-24.19‰,suggest C3 plant domination in regional vegetation,despite a possible moderate C4 plant increase during the LGM. The TOC and δ13Corg records show an important change at B/A event implying the local ecosystem and lake level are sensitive to the deglacial warming. There was an abrupt change in all proxy records at around 4 ka BP which may indicate a weakening summer monsoon indicated by the speleothem δ18O records."/> Palaeoenvironment changes during the past 21 ka inferred from organic geochemical records of Caohai Lake,Guizhou Province
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JOPC  2019, Vol. 21 Issue (6): 1025-1034    DOI: 10.7605/gdlxb.2019.06.070
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Palaeoenvironment changes during the past 21 ka inferred from organic geochemical records of Caohai Lake,Guizhou Province
Gong Xiao-Fei1, Chen Cong1, Tang Yong-Jie1, Huang Kang-You1, Yue Yuan-Fu2, Liang Kai-Xuan1, Zheng Zhuo1
1 School of Earth Sciences and Engineering,Sun Yat-sen University,Guangzhou 510275,China;
2 School of Marine Sciences, Guangxi University,Nanning 530004,China
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Copyright 2009 Journal of Palaeogeography Editorial