西北冰洋中更新世以来黏土矿物变化特征及其反映的洋流和冰盖演化  

Variations in clay mineral composition in the western Arctic Ocean since the mid-Pleistocene:Implications on changes in circulation and ice sheet development

作　　者：徐仁辉 王汝建[1] 肖文申[1] 董林森 刘焱光 Xu Renhui;Wang Rujian;Xiao Wenshen;Dong Linsen;Liu Yanguang(State Key Laboratory of Marine Geology,Tongji University,Shanghai 200092,China;First Institute of Oceanography,Ministry of Natural Resources,Qingdao 266061,China)

机构地区：[1]同济大学海洋地质国家重点实验室,上海200092 [2]自然资源部第一海洋研究所,山东青岛266061

出　　处：《海洋学报》2020年第9期50-60,共11页

基　　金：国家自然科学基金(41776187,41030859);南北极环境综合考察与评估专项(CHINARE2012-2016-03-02)。

摘　　要：本文通过对中国第七次北极考察在西北冰洋阿尔法脊南部钻取的ARC7-LIC岩芯沉积物的XRF Ca/Al比值、冰筏碎屑和黏土矿物等研究,重建了中更新世以来研究区沉积物源和周边冰盖的演化历史。ARC7-LIC岩芯黏土矿物组合类型变化显示:深海氧同位素(MIS)29~13期黏土矿物组合主要以西伯利亚物源区为主,而MIS 12期以来以北美物源为主。黏土矿物组合的变化,反映中布容期前后洋流模式的改变。同时,MIS 12期高含量的蒙脱石可能来自北美物源。物源指标对比显示,劳伦冰盖在MIS 16期首次向西北冰洋大规模排泄冰山,并且从MIS 12期开始,西北冰洋周围冰盖的进退幅度增大。在MIS 6期、4期和3期,Ca/Al和高岭石含量的不协同变化指示北美冰盖的发育具有区域差异性,位于阿拉斯加北部和麦肯齐河流域的冰盖较班克斯岛−维多利亚岛一侧更发育,崩解的冰山能将高岭石带到研究区沉积下来。In this study,we investigated clay mineral assemblages together with other provenance indicators of Core ARC7-LIC retrieved from the southern Alpha Ridge,in order to reveal the changes in sediment deposition,ocean circulation in the western Arctic Ocean,and the development of surrounding ice sheet through the mid-late Pleistocene(~MIS 29).Changes in clay mineral composition in Core ARC7-LIC suggest a transition of Siberian sourced material during MIS 29−13 towards a North American sourced material during MIS 12−1.This transition reflects the change of the circulation in the western Arctic Ocean before and after the Mid-Brunhes Event,which features an amplification of glacial-interglacial cycles in the post Mid-Brunhes Event.An exceptionally high smectite peak characterizes MIS 12,which is inferred to be from North American source.Laurentide ice sheet discharges icebergs and fine material in the western Arctic Ocean since MIS 16.The amplitude of ice sheet growth and decay increases since MIS 12.During MIS 6,4 and 3,the asynchronous variations of Ca/Al and kaolinite suggest heterogeneous development of Laurentide ice sheet on the Canadian Arctic Archipelago and Alaska-Mackenzie sides.

关 键 词：西北冰洋 黏土矿物 物源 波弗特环流 穿极流 北极冰盖 

分 类 号：P736.21[天文地球—海洋地质]