摘要
末次冰消期以来,我国东部季风区和西部干旱区分别呈现出"季风"和"西风"的两种降水模式。柴达木盆地位于二者的过渡区,由于缺乏可靠年代控制下的定量古气候记录,末次冰消期以来该盆地植被和降水变化的过程和模式,以及全新世适宜期季风降水是否影响到该区域至今仍存争议。本研究通过柴达木盆地东北部可鲁克湖西侧湿地深520 cm的沉积物钻孔14 cal.ka B.P.以来的孢粉记录,重建了植被和降水演化历史。结果显示青藏高原东北部干旱-半干旱区末次冰消期和早全新世(约14.1~8.0 cal.ka B.P.)以旱生灌丛-荒漠草原植被为主,降水量从约28 mm增至约249 mm;中全新世(约8.0~3.9 cal.ka B.P.)草原植被扩张到末次冰消期以来的最高水平,降水显著增加,最高值可达约292 mm;晚全新世(约3.9~0.3 cal.ka B.P.)荒漠草原再次扩张,降水量大幅度下降至约20 mm。可鲁克湖区降水过程呈现典型的东亚"季风模式",显示在全新世适宜期东亚季风的影响范围可以向西推进到柴达木盆地东北部。分析认为,柴达木盆地东北部的降水变化受北半球太阳辐射量变化、高纬冰盖及青藏高原热动力强迫的协同影响。
There are"monsoonal"and"westerlies"precipitation patterns in Eastern and Northwestern China since the Last Deglaciation.But the comprehensive history of variations in vegetation and precipitation over the transition area and whether the monsoonal precipitation has been imposed on this region in the"Holocene Climatic Optimum"(HCO)remains controversial.Quantitative paleoclimatic reconstruction is crucial for understanding the dominant atmospheric circulations which controlled northeastern Tibetan Plateau(NETP)during the Holocene.In this study,the Locally weighted weighted averaging(LWWA)method was applied to the pollen archive from a 520 cm long peatland core(37°15'10.91″N,96°51'06.06″E)on the west side of Hurleg Lake(37°14'~37°19'N,96°50'~96°58'E)in NETP and the vegetational succession and mean annual precipitation history have been yielded.An opening landscape of vegetation dominated by xerophytic shrubs and desert grassland was showed in the last glacial period and the Early Holocene(about 14.1~8.0 cal.ka B.P.),the precipitation increased markedly from 28 mm to 249 mm.During the Middle Holocene(about 8.0~3.9 cal.ka B.P.),a wettest climate prevailed over the lake area,the steppe vegetation expanded substantially and the precipitation reached the maximum value of 292 mm,which matched the HCO.A degenerated trend in the late Holocene(about 3.9~0.3 cal.ka B.P.)was noted by increased desert grassland composition,precipitation decreased steeply to 20 mm.The precipitation variation of Hurleg Lake area exhibited canonical East Asian summer monsoon(EASM)pattern and the variations of Northern Hemisphere insolation,the magnitude of ice-sheet as well as the thermodynamic forcing of the Tibetan Plateau orchestrated the"monsoonal"precipitation pattern of northeastern Qaidam Basin during the Holocene.The EASM rain belt has been migrated northwestward to the eastern Qaidam Basin during the HCO.Our finding shows there would be more precipitation in the northeastern Qaidam Basin,thriving the steppe vegetation thus increa
作者
余英浩
金映豫
徐德克
王永莉
李浩
汪亘
崔安宁
魏志福
YU Yinghao;JIN Yingyu;XU Deke;WANG Yongli;LI Hao;WANG Gen;CUI Anning;WEI Zhifu(Key Laboratory of Cenozoic Geology and Environment,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029;College of Earth and Planetary Sciences,University of Chinese Academy of Sciences,Beijing 100049;Innovation Academy for Earth Science,Chinese Academy of Sciences,Beijing 100029;Center for Excellence in Life and Paleoenvironment,CAS Beijing 100044;Key Laboratory of Petroleum Resources,Northwest Institute of Eco-Environment and Resources,Chinese Academy of Sciences,Lanzhou 730000,Gansu)
出处
《第四纪研究》
CAS
CSCD
北大核心
2021年第5期1229-1243,共15页
Quaternary Sciences
基金
中国科学院(B类和A类)战略性先导科技专项项目(批准号:XDB26000000和XDA2007010103)
国家自然科学基金项目(批准号:41771237、42071103和41888101)
国家重点基础研究发展计划项目(批准号:2017YFA0603403)共同资助。
关键词
孢粉
古植被
古气候定量重建
全新世适宜期
柴达木盆地
pollen
paleo-vegetation
quantitative climate reconstruction
Holocene Climatic Optimum
Qaidam Basin
