A comparative study of boron isotopes and trace elements of the marine foraminifers during the last glacial maximum and Holocene  

作　　者：NI YunYan 1,2 1 Research Institute of Petroleum Exploration and Development,PetroChina,Beijing 100083,China 2 Bristol Isotope Group,Department of Earth Sciences,Bristol University,Wills Memorial Building,Queens Road,Bristol BS8 1RJ,United Kingdom 

出　　处：《Science China Earth Sciences》2010年第1期91-100,共10页中国科学（地球科学英文版）

基　　金：funded by ORS fellowship supplemented by he Department of Earth Scieces,University of Bristol to Ni R. Y.;National Natural Science Foundation of China (Grant No.40703014)

摘　　要：Boron isotopic compositions in marine planktonic foraminifers can record changes in seawater pH and hence provide a new tool to reconstruct the changes of paleo-atmospheric PCO2.Here a comparative study was done on boron isotopes and trace element abundances of planktonic foraminifers,Globigerinoides sacculifer and Globigerinoides ruber from three tropical ODP sites,Site 806B,Site 664C and Site 999A.It is demonstrated here that G.ruber is a better species to be used for downcore boron isotope analyses on glacial-interglacial scales,particularly since G.sacculifer is prone to dissolution causing unexpectedly light boron isotopes during glacial times.It has been shown that the trace elements composition of foraminifers (i.e.,Mg/Ca,U/Ca,B/Ca,and Li/Ca) can reflect the variations of seawater temperature and/or [CO3 2-].However,all of these systems are highly species de-pendent and affected by other vital effects,and it is therefore important to perform necessary calibrations when applying them to the downcore analyses.Boron isotopic compositions in marine planktonic foraminifers can record changes in seawater pH and hence provide a new tool to reconstruct the changes of paleo-atmospheric PCO2.Here a comparative study was done on boron isotopes and trace element abundances of planktonic foraminifers,Globigerinoides sacculifer and Globigerinoides ruber from three tropical ODP sites,Site 806B,Site 664C and Site 999A.It is demonstrated here that G.ruber is a better species to be used for downcore boron isotope analyses on glacial-interglacial scales,particularly since G.sacculifer is prone to dissolution causing unexpectedly light boron isotopes during glacial times.It has been shown that the trace elements composition of foraminifers (i.e.,Mg/Ca,U/Ca,B/Ca,and Li/Ca) can reflect the variations of seawater temperature and/or [CO3 2-].However,all of these systems are highly species de-pendent and affected by other vital effects,and it is therefore important to perform necessary calibrations when applying them to the downcore analyses.

关 键 词：FORAMINIFERS boron ISOTOPE trace element last GLACIAL maximum atmospheric PCO2 

分 类 号：P597[天文地球—地球化学]