唐古拉山东段布加岗日南坡小冰期冰进的^(10)Be暴露测年研究  

^(10)Be surface exposure dating of Little Ice Age glacial events on the southern slope of Bujia Gangri,eastern Tanggula Mountains

作　　者：赵井东 邱锦坤 季卉晗 郭万钦 刘瑞连 麻浩男 ZHAO Jingdong;QIU Jinkun;JI Huihan;GUO Wanqin;LIU Ruilian;MA Haonan(State Key Laboratory of Cryospheric Science,Northwest Institute of Eco-Environment and Resources,Chinese Academy of Sciences,Lanzhou 730000,China;Key Laboratory of Western China’s Environmental Systems,Ministry of Education,Lanzhou University,Lanzhou 730000 China;School of Geography,Liaoning Normal University,Dalian 116029,China)

机构地区：[1]中国科学院西北生态环境资源研究院冰冻圈科学国家重点实验室,甘肃兰州730000 [2]兰州大学资源环境学院西部环境教育部重点实验室,甘肃兰州730000 [3]辽宁师范大学地理科学学院,辽宁大连116029

出　　处：《冰川冻土》2022年第4期1109-1118,共10页Journal of Glaciology and Geocryology

基　　金：第二次青藏高原综合科学考察研究项目(2019QZKK0201);国家自然科学基金项目(41830644,42071013,42041006)资助。

摘　　要：高寒地区形态独特的冰川侵蚀与沉积地形是过去冰川变化最直接的证据,包含有重要的古气候环境变化信息。根据山地冰川沉积序列,通常将分布在现代冰碛地形外围形态较完好的多列冰碛垄的形成时间推定为小冰期。小冰期冰进的时间与规模是理解与重建近千年以来古气候环境变化的基础及较准确预测未来气候环境变化的关键。本研究应用^(10)Be暴露测年技术对唐古拉山东段布加岗日南坡拥曲河源区西(主)谷与东(悬)谷中基于地貌关系与沉积序列推定为小冰期的第一套冰碛垄M_(W1)与M_(E1)进行定年。测得MW1冰碛垄4个样品的^(10)Be年龄分别为(155±23)a、(197±27)a、(218±26)a和(273±31)a;ME1冰碛垄3个样品的^(10)Be年龄分别为(262±30)a、(186±28)a和(131±25)a。使用P-CAAT法分析得出它们的年龄为(203±52)a(n=4)和(162±58)a(n=3)。地貌关系、沉积序列、冰碛垄的形态特征、土壤发育与植被覆盖以及测年结果等共同表明拥曲河源区西谷与东谷中的第一套冰碛垄形成于小冰期。结合周边地区的研究成果及古气候环境代用指标可以推断降温是这次冰进的主因。The spectacular glacial erosional and depositional landforms on the Tibetan Plateau(TP)and its surrounding mountains are direct imprints of the Quaternary glaciations and contain essential information of palaeoclimate change and landscape evolution.According to the glacial sequences in the TP and its surroundings,the moraine complexes with fresh-looking tills,distribute beyond the modern glacial landforms are assumed to be formed during Little Ice Age(LIA)glacial advance.The timing and extent of this glacial advance is critical to understand the spatiotemporal variation of ancient glaciers and palaeoclimate change during the past millennium.Here,the first moraine complexes in the west(main)and east(hanging)valleys of Yongqu River valley,which originates from the southern slope of Bujia Gangri were investigated by terrestrial in situ cosmogenic nuclides(TCN)^(10)Be surface exposure dating techniques.Their ages are(203±52)years(M_(W1),n=4)and(162±58)years(M_(E1),n=3).Our dating results,position,geomorphological and sedimentary relationship,characteristics of boulders and moraines,soil development and vegetation coverage and other features demonstrate that the first set of moraines were formed during the LIA glacial advance.This glacial event is synchronous with those in the TP and its surroundings.Combining the climate proxies in the TP and its surroundings,it is reasonable to infer that the cooling during LIA was a main control factor to force this glacial advance.

关 键 词：小冰期 ^(10)Be暴露测年 唐古拉山 

分 类 号：P534.63[天文地球—第四纪地质学] P343.6[天文地球—古生物学与地层学]