亚北极太平洋阿拉斯加湾50kaBP以来放射虫组合指示的古海洋变化  

PALEOCEANOGRAPHIC CHANGES SINCE 50kaBP INFERRED FROM RADIOLARIAN ASSEMBLAGES IN GULF OF ALASKA,SUBARCTIC PACIFIC

作　　者：张海峰[1,2] 王汝建[2] 肖文申[2] 李文宝[2,3] 

机构地区：[1]国家海洋局海洋生态系统与生物地球化学重点实验室,杭州310012 [2]同济大学海洋地质国家重点实验室,上海200092 [3]内蒙古农业大学水资源保护与利用自治区重点实验室,呼和浩特010018

出　　处：《海洋地质与第四纪地质》2015年第3期23-36,共14页Marine Geology & Quaternary Geology

基　　金：国家自然科学基金重点项目(41030859);国家自然科学基金中俄合作与交流项目(41211120173);南北极环境综合考察与评估专项项目(CHINARE2015-03-02);国家海洋局极地考察办公室对外合作支持项目(IC201105);中国地质调查局地质调查工作项目(水[2015]02-013-012)

摘　　要：利用SO202-INOPEX航次在亚北极太平洋阿拉斯加湾获取的沉积物岩心,以及基于AMS14 C测年数据建立的年龄模式,开展了50kaBP以来放射虫的古海洋学研究,获得如下认识:(1)Cycladophora davisiana是阿拉斯加湾最具代表性的优势种放射虫,其次是Siphocampe arachnea和Acanthodesmia micropora;(2)对放射虫的统计数据进行Q型因子分析,提取出4个方差极大因子,可以代表不同的水团甚至是水体的混合作用,其中C.davisiana作为中层水团演化的替代性指标,对冰期-间冰期旋回和快速气候变化事件的响应较为敏感,其变化特征表明该区中层水团的演化主要受控于亚北极太平洋NPIW形成源区及其输送机制的变化;(3)基于放射虫标志种Ceratospyris borealis,Actinomma boreale/leptodermum和Rhizoplegma boreale的变化特征及其环境指示意义,认为50kaBP以来阿拉斯加湾上层海洋环境的变化具有阶段性:LGM之前,该区海洋表层生产力相对稳定,海冰消长与冰融水脉冲明显地响应于冰阶-间冰阶等气候旋回;LGM期间,受大陆冰盖、大气环流和海洋环流变化的综合影响,冰融水事件以及海冰持续增加、生产力明显下降的状况可能较少出现;LGM以来,在B-A和YD等快速气候变化事件的影响下,冰融水脉冲引起表层生产力快速增加,气候快速变冷则造成生产力急剧降低。The paleoceanographic record of radiolarian assemblage for the past 50 ka is investigated using a box core（SO202-27-6）obtained from the Gulf of Alaska,subarctic Pacific during the R/V Sonne cruise SO202-INOPEX.Ten AMS14 C data are used for establishing the stratigraphic age model.The study suggests that：（1）Cycladophora davisianais the most dominant radiolarian specie in the Gulf of Alaska during the past 50 ka,followed by Siphocampe arachnea and Acanthodesmia micropora.（2）The Q-mode factor analysis obtains 4maximum variance factors,which represent different radiolarian assemblages.Among them,C.davisianacan be used as a proxy for intermediate water of the Gulf of Alaska,which was sensitive to the rapid climate change of glacial-interglacial cycle,and the variable pattern reveals that the evolution of intermediate water was controlled by the formation and transportation of NPIW from subarctic Pacific.（3）Based on the indicative radiolarian species for environmental changes,such as Ceratospyris borealis,Actinomma boreale/leptodermum and Rhizoplegma boreal,we argue that the upper ocean conditions in the Gulf of Alaska underwent periodic changes during the past 50 ka.Before LGM,relatively stable surface productivity,sea-ice expansion and retreat,and melt-water pulse（MWP）responded clearly to the interstadial（GI）to stadial（GS）cycles.During LGM,under the conditions of complex ice sheet effects,atmospheric circulation and oceanic currents,there were rarely WMP,continuous sea-ice extension and limited productivity in the Gulf of Alaska.Since LGM,rapid increase and decrease in surface productivity was caused by rich-nutrient water from MWP and by rapid cooling event,respectively.

关 键 词：放射虫组合 中层水团演化 上层海洋环境 50kaBP以来 阿拉斯加湾 

分 类 号：P736.22[天文地球—海洋地质]