基于粒度端元分析重建共和沙地风沙活动历史  

Reconstruction of the aeolian activity history of the Gonghe sandy land based on grain size end-member analysis

作　　者：张兆康 鄂崇毅[1,2,3] 徐春霞 史运坤 张晶 ZHANG Zhaokang;E Chongyi;XU Chunxia;SHI Yunkun;ZHANG Jing(Key Laboratory of Tibetan Plateau Land Surface Processes and Ecological Conservation(Ministry of Education),Qinghai Normal University,Xining 810008,China;Qinghai Provincial Key Laboratory of Physical Geography and Environmental Process,College of Geographical Science,Qinghai Normal University,Xining 810008,China;Academy of Plateau Science and Sustainability,People's Government of Qinghai Province and Beijing Normal University,Xining 810008,China)

机构地区：[1]青海师范大学,青藏高原地表过程与生态保育教育部重点实验室,西宁810008 [2]青海师范大学地理科学学院,青海省自然地理与环境过程重点实验室,西宁810008 [3]高原科学与可持续发展研究院,西宁810008

出　　处：《第四纪研究》2025年第1期62-73,共12页Quaternary Sciences

基　　金：青海省自然科学基金项目(批准号:2021-ZJ-918);国家自然科学基金项目(批准号:42171011)共同资助。

摘　　要：共和沙地位于青藏高原东北缘,东亚夏季风影响范围的边界区域,对气候变化响应敏感。粒度参数是指示区域环境变化的重要指标,但其在共和沙地中的指征意义尚不明晰,本研究基于高密度光释光年代与参数化端元分析模型方法,并结合磁化率、元素地球化学等环境指标对木格滩沙地东南部约4.1 m厚的那交全新世风成剖面进行粒度数据集的解离,明确各端元组的指征意义,重建该区域风沙演变过程。研究发现:1)那交剖面粒度共解离为3个端元组,EM1指示成壤作用和东亚夏季风强度;EM2代表较大范围区域风沙活动强度;EM3表征木格滩沙地的扩张收缩变化强度;2)利用高密度光释光年代重建的沉积速率曲线结果揭示了该区域在11~10 ka、约1.5 ka为高沉积速率阶段,5.0~1.5 ka为沉积间断时期,可能受侵蚀作用影响;3)通过与已发表的可靠环境指标对比,重建共和盆地过去环境变化过程,并将其分为3个主要阶段。阶段一:12~9 ka风沙活动呈现增强的趋势;阶段二:9~5 ka期间,风沙活动显著减少,与此同时,成壤作用增强,指示气候转变为较暖湿的状态,但由于此时期较强的太阳辐射和蒸发作用的影响,EM3含量占比较高,表明木格滩沙地可能未被完全固定;阶段三:1.5 ka以来,共和盆地的环境受到冷干气候和逐渐增强的人类活动的双重影响,风沙活动再次活跃,特别是在木格滩沙地,沙地的扩张尤为显著。The Gonghe sandy land(35°27'~36°56'N,98°46'~102°22'E)on the northeastern Qinghai-Tibetan Plateau,situated at the boundary of the East Asian summer monsoon's influence,is a key area for studying Holocene aeolian sedimentation and offers insights into past environmental and climate changes.This research aims to clarify the aeolian processes and environmental dynamics in the Gonghe sandy land by analyzing sedimentary records.By focusing on grain size parameter as the key indicator of regional environmental shifts,this study seeks to enhance the understanding of climatic fluctuations and human impacts in this sensitive region.A typical aeolian profile,Najiao(NJ:35°40'23.15″N,101°5'49.04″E;elevation 3629 m),was collected from the leeward side of the prevailing winds on the southeastern edge of the Mugetan sandy land in the Gonghe sandy land.The profile,with a thickness of 4.1 meters,involved collecting 18 optically stimulated luminescence(OSL)dating samples at 10/40 cm intervals to construct a chronological framework.Additionally,108 environmental samples were collected at 2/5 cm intervals for analyzing grain size,magnetic susceptibility,and elemental geochemistry.These analyses were complemented by the End-member analysis to categorize grain size distributions into three end-member groups(EM1,EM2,EM3),representing distinct environmental processes.EM1 indicates soil formation influenced by the East Asian summer monsoon,EM2 denotes regional aeolian activity,and EM3 reflects the fluctuations of the Mugetan sandy land.High-resolution OSL dating identified periods of significant deposition rates at 11~10 ka and ca.1.5 ka,with a notable decrease from 5.0~1.5 ka,indicating depositional hiatus.The study delineates three key phases of environmental change:(1)From 12 ka to 9 ka,marked by intensified aeolian activity and cold,dry conditions;(2)From 9 ka to 5 ka,characterized by reduced aeolian activity and increased soil formation under warmer,more humid conditions;and(3)Since 1.5 ka,renewed aeolian activity driven by

关 键 词：端元分析 共和沙地 人类活动 全新世 

分 类 号：P534.632[天文地球—第四纪地质学] P512.21[天文地球—古生物学与地层学] P941.73[天文地球—地质学]