中原地区荥阳盆地末次冰消期以来的气候与环境变化  

Climate and environmental changes since the last deglaciation in the Xingyang Basin of the Central China Plains

作　　者：刘畅[1,2] 冯兆东 冉敏 裴宏业 惠争闯 LIU Chang;FENG Zhaodong;RAN Min;PEI Hongye;HUI Zhengchuang(College of Geography and Environmental Science,Henan University,Kaifeng 475004,Henan,China;Key Laboratory of Earth System Observation and Simulation of Henan Province,Kaifeng 475004,Henan,China)

机构地区：[1]河南大学地理与环境学院,开封475004 [2]河南省地球系统观测与模拟重点实验室,开封475004

出　　处：《地理学报》2024年第9期2261-2279,共19页Acta Geographica Sinica

基　　金：国家重点研发计划(2020YFC1521605)。

摘　　要：为进一步理解末次冰消期以来东亚夏季风(EASM)变化的时空特征,特别是中原地区全新世EASM的时空格局及其驱动机制,在AMS14C年代的支持下,本文基于荥阳盆地湖相-湿地相剖面的正构烷烃和沉积学指标(粒度和总有机碳),重建了荥阳盆地~17.8 cal ka BP以来的气候与环境变化历史。重建结果表明,~17.8-~11.7 cal ka BP是草原环境下的黄土状堆积阶段。~11.7-~8.5 cal ka BP为湿地沉积时段,是森林和湿地扩展的时期。~8.5-~2.8 cal ka BP为湖泊存在时段,木本植物和水生植物丰度达到最高后波动降低。~2.8-~2.4 cal ka BP为湿地存在阶段,菌藻类和/或微生物、沉水浮游植物的烷烃贡献量很大。~2.4-~1.1 cal ka BP为草原环境下的黄土沉积时段。本文进一步基于荥阳盆地长链正构烷烃的平均碳链长(ACL_(27-33),简称ACL)和C_(27+29)/C_(31+33)比值,结合渑池盆地木本花粉百分含量和禾本科/(蒿属+藜科)比值,重建了中原地区全新世以来湿度变化,并与长江中下游地区和中国北方地区(指黄河以北地区)的全新世湿度序列进行了对比。对比结果显示,全新世中期的干旱时段(~7.0-~4.0 cal ka BP或~8.0-~5.0 cal ka BP)与长江中下游地区全新世中期的干旱时段基本对应。这一时段的干旱对应于厄尔尼诺-南方涛动(ENSO)强度的较低值(即La Nino态)时段和赤道西太平洋SST较高温时段。控制上述EASM影响区的中国中部地区全新世湿度空间格局的主要机制可能是ENSO状态以及由ENSO调控的亚热带西太平洋高压(WPSH)的南北向移动。In order to depict the spatiotemporal patterns of EASM variations(EASM:East Asian Summer Monsoon)since the last deglaciation,we analyzed n-alkane compositions and sedimentological characteristics of a lacustrine-wetland section(namely ZWZ-1 section)in the Xingyang Basin of the Central China Plains.We also reconstructed the climatic and environmental changes since~17.8 cal ka BP on the basis of the analytical results.The reconstruction displayed five-staged variations:(1)~17.8-~11.7 cal ka BP was a period of loess-like sediment accumulation under a steppe-dominating environment;(2)~11.7-~8.5 cal ka BP was a period of wetland deposition,during which the n-alkane-indicated forest and wetland expanded;(3)~8.5-~2.8 cal ka BP was a period of lacustrine deposition and also a period of maximal woody and aquatic plant n-alkane components;(4)~2.8-~2.4 cal ka BP was again a period of wetland deposition when the n-alkane components of bacteria,algae/microorganisms and submerged phytoplankton increased dramatically;(5)~2.4-~1.1 cal ka BP was a loess deposition period under a steppe-dominating environment.We also compared the Holocene moisture sequences(ZWZ-1 section and MC-1 section)from the Central China Plains with those from the middle and lower reaches of the Yangtze River and also with those from northern China.The moisture sequence at ZWZ-1 section was based on the average chain length of long-chain n-alkanes(ACL_(27-33))and C_(27+29)/C_(31+33) ratio and the moisture sequence at MC-1 section was based on tree pollen(%)and Poaceae/(Artemisia+Chenopodiaceae)ratio.Our comparison shows that the mid-Holocene drought(~7.0-~4.0 cal ka BP or~8.0-~5.0 cal ka BP)in the Central China Plains chronologically corresponded with the mid-Holocene drought in the middle and lower reaches of the Yangtze River.It seems that the mid-Holocene drought in the entire central China(including the middle and lower reaches of the Yangtze River and the Central China Plains)was causally associated with lowered El Niño-Southern Oscillation(ENSO)intens

关 键 词：荥阳盆地 正构烷烃 全新世 东亚夏季风 厄尔尼诺—南方涛动 

分 类 号：P534.632[天文地球—第四纪地质学] P532[天文地球—古生物学与地层学] P512.2[天文地球—地质学]