末次冰消期以来白令海盆的冰筏碎屑事件与古海洋学演变记录  

ICE-RAFTED DETRITUS EVENTS AND PALEOCEANOGRAPHIC RECORDS IN THE BERING BASIN SINCE THE LAST DEGLACIATION

作　　者：陈志华[1,2] 陈毅[1,3] 王汝建[4] 黄元辉[1,2] 刘欣德 王磊[4] 邹建军[1,2] 

机构地区：[1]国家海洋局第一海洋研究所,山东青岛266061 [2]海洋沉积与环境地质国家海洋局重点实验室,山东青岛266061 [3]中国科学院青藏高原研究所,北京100085 [4]同济大学海洋地质国家重点实验室,上海200092

出　　处：《极地研究》2014年第1期17-28,共12页Chinese Journal of Polar Research

基　　金：国家自然科学基金项目(40176136;41106166);南北极环境综合考察与评估专项(CHINARE2012-01-02;CHINARE 2013-01-02;CHINARE2013-04-01;CHINARE2013-03-02)资助

摘　　要：通过对白令海盆中部BR02岩芯高分辨率的颜色、粒度和元素地球化学地层的研究发现:(1)该岩芯较为完整地记录了末次盛冰期结束以来(约16.3 ka BP)的多期冰筏碎屑事件,包括H1、OD、YD和北方2期,其中以H1和YD最为显著,反映了末次冰消期以来该地区海冰/冰山以及区域性冰川的消长变化;(2)BR02岩芯上部17—25 cm段出现富Mn、富Ba的氧化型沉积,说明在全新世高海面时期,白令海与北太平洋、北冰洋之间的水体交换达到极点,白令海环流加强,海盆底层水含氧状况明显改善,并引发海洋生产力增加;(3)CaO、Na2O、Sr、Zr及Na2O/K2O比值的分布说明,海盆冰筏碎屑主要来自富碳酸盐的育空河流域,其次为阿拉斯加半岛和阿留申群岛等火山岩区;岩芯上部Na2O/K2O比值的递增暗示10 ka BP以来与火山物质输运有关的北太平洋入流(阿拉斯加流)可能增加。From a high-resolution study of sediment grain size, color reflectance and elemental stratigraphy of core BR02, which was dredged from the central part of the Bering Basin, we came to the following conclusions. （ 1 ） Core BR02 provides perfect records of the ice-rafted detritus （IRD） events that have happened since 16.3 ka BP at the end of the Last Glacial Maximum, including the H1, OD, YD and Boreal 2 events, of which H1 and YD are the most significant. These IRD events all happened during cold episodes or stadials, and indicate changes in sea ice/icebergs in the sea and local glaciers in the surrounding lands. （2） The interval of Mn- and Ba-rich sediments at 17--25 cm in the upper part of BR02 indicates that water exchange between the North Pacific Ocean, the Bering Sea, and the Arctic Ocean increased to its highest level during the Holocene high-sea-level period, which induced changes in the circulation and seabed redox and an increase in marine productivity in the Bering Basin. （3） The concentrations of CaO, Na20, Sr and Zr and the Na2O/K2O ratio indicate that the IRD was mainly derived from the Yukon River drainage, and secondarily from the volcanic province that includes the Alaska Peninsula and the Aleutian Islands. Meanwhile, the gradual increase in the Na2O/K2O ratio in the upper part of the core indicates that the circulation, especially the influence of the Alaska Current on sediments, has been enhanced since 10 ka BP.

关 键 词：白令海盆 末次冰消期 冰筏碎屑事件 底层水富氧事件 古海流 

分 类 号：P736[天文地球—海洋地质]