Copper and zinc isotope variations in ferromanganese crusts and their isotopic fractionation mechanism  

作　　者：Lianhua He Jihua Liu Hui Zhang Jingjing Gao Aimei Zhu Ying Zhang 

机构地区：[1]Key Laboratory of Marine Geology and Metallogeny,First Institute of Oceanography,Ministry of Natural Resources,Qingdao 266061,China [2]Laboratory for Marine Geology,Pilot National Laboratory for Marine Science and Technology(Qingdao),Qingdao 266061,China

出　　处：《Acta Oceanologica Sinica》2021年第9期43-52,共10页海洋学报（英文版）

基　　金：The Shandong Provincial Natural Science Foundation of China under contract No.ZR2014DP009;the China Ocean Mineral Resource Research and Development Association Research Program under contract Nos DY135-N-1-03,DY135-C1-1-04 and DY135-R2-1-03;the Fund of the Construction and Operation of Test and Technical Support System for Natural Resources Investigation and Evaluation。

摘　　要：Ferromanganese(Fe-Mn)crusts are potential archives of the Cu and Zn isotope compositions of seawater through time.In this study,the Cu and Zn isotopes of the top surface of 28 Fe-Mn crusts and 2 Fe-Mn nodules were analysed by MC-ICP-MS using combined sample-standard bracketing for mass bias correction.The Zn isotope compositions of the top surface of Fe-Mn crusts are in the range of 0.71‰to 1.08‰,with a mean δ^(66)Zn value of 0.94‰±0.21‰(2 SD,n=28).The δ^(65)Cu values of the top surface of Fe-Mn crusts range from 0.33‰to0.73‰,with a mean value of 0.58‰±0.20‰(2 SD,n=28).The Cu isotope compositions of Fe-Mn crusts are isotopically lighter than that of dissolved Cu in deep seawater(0.58‰vs.0.9‰).In contrast,the δ^(66)Zn values of Fe-Mn crusts appear to be isotopically heavy compared to deep seawater(0.94‰±0.21‰vs.0.51‰±0.14‰).The isotope fractionation between Fe-Mn crusts and seawater is attributed to equilibrium partitioning between the sorption to crusts and the organic-ligand-bound Cu and Zn in seawater.The Cu and Zn isotopes in the top surface of Fe-Mn crusts are not a direct reflection of the Cu and Zn isotopes,but a function of Cu and Zn isotopes in modern seawater.This study proposes that Fe-Mn crusts have the potential to be archives for paleoceanography through Cu and Zn isotope analysis.

关 键 词：ferromanganese crusts Cu isotopes Zn isotopes PALEOCEANOGRAPHY 

分 类 号：P597[天文地球—地球化学] P736.44[天文地球—地质学]