摘要
通过高密度AMS14C测年构建黔西高原野鸡坪泥炭YJP01钻孔的年代框架,基于多环境代用指标分析,并结合多元统计分析,探究野鸡坪泥炭中主要地球化学元素来源及其环境指示意义,恢复该区中世纪暖期至小冰期详细的气候变化过程.结合已有研究成果,解析西南地区及临近区域在这 2个时期气候条件的空间格局及其影响因素.结果表明:① 野鸡坪地区中世纪暖期(1 200―1450年)和小冰期(1 450―1880年)的气候特征分别为暖湿和冷干,与周边地区的古气候记录具有较好的一致性;② 西南地区在这 2个气候特征时期存在"暖湿-冷干"和"暖干-冷湿"2种温湿度组合模式,在空间上存在一条分界线并呈现东西分异模式;③ 西风南支位置的南北移动对西南地区过去千年的温湿度组合模式具有明显影响.
Abstract
The past millennium represents a critical period for global change research,yet there remains a lack of consensus on the temperature-humidity patterns and the driving mechanisms due to differences in research methodologies and proxy records.The Medieval Warm Period(MWP)and the Little Ice Age(LIA)are widely recognized as significant climate episodes during this time,but the temperature-humidity patterns associated with these periods vary regionally.In particular,the spatial differences and influencing factors in southwestern China remain understudied.The western Guizhou Plateau(WGP),situated in the northeast of the Yunnan-Guizhou Plateau within the hinterland of the Wumeng Mountains,is particularly sensitive to climate and envir-onmental changes.The Yejiping peat,located in the subalpine karst region of the WGP and influenced by the southern branch of the westerlies,offers a highly detailed and continuous record of climate variability during the MWP and LIA.In this study,we measured the water content,loss on ignition(LOI),and carbonate content of sediments from the Yejiping peat core(YJP01).High-resolution,continuous X-ray fluorescence core scan-ning was utilized to determine the geochemical element content and chromaticity of the samples.By analyzing the activity,content,and ratios of geochemical elements,and applying multivariate statistical techniques such as cluster and correlation analyses,we identified the sources of the primary elements in the Yejiping peat sedi-ments and their environmental implications.A robust chronological framework was established using high-density AMS14C dating,enabling us to reconstruct a detailed paleoclimate evolution from the MWP to the LIA on the WGP.This study also discusses the spatial patterns of climate variability during the MWP and LIA.Our results revealed the following key findings:1)Multiple proxies from the Yejiping peat indicate that the climate was warm and humid during the MWP(1 200-1 450)and cold and dry during the LIA(1 450-1880),which aligns with other regional paleoclimate records.2)The"warm-wet and cold-dry"as well as"warm-dry and cold-wet"climate characteristics coexisted in southwestern China during the MWP and LIA,demonstrating a clear spatial differentiation between the eastern and western regions of the area.3)The movement of the westerlies,particularly their shifts northward or southward,significantly influenced the hydrothermal patterns in south-western China throughout the past millennium.This study,therefore,provides a comprehensive understanding of regional climate variability and its controlling mechanisms during key climatic periods,contributing valu-able insights into the broader picture of global climate evolution.
维普
万方数据