Morphotype dependence of Globigerinoides ruber(white)and Trilobatus sacculifer Mg/Ca ratios in the western tropical Pacific:implications for reconstructing the mixed-layer depth  

作　　者：Qi Jia Tiegang Li Zhifang Xiong Bingbin Qin 

机构地区：[1]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》2023年第11期35-43,共9页海洋学报（英文版）

基　　金：The National Natural Science Foundation of China under contract Nos 41830539 and 41906063;the Marine S&T Fund of Shandong Province for Pilot National Laboratory for Marine Science and Technology(Qingdao)under contract No.2022QNLM050203;the Taishan Scholars Project Funding under contract No.ts20190963。

摘　　要：Planktonic foraminifer Globigerinoides ruber(white)and Trilobatus sacculifer are the most frequently used mixedlayer dwelling species for reconstructing past oceanic environments.Specifically,the Mg/Ca ratios of these two foraminiferal species have been used for reconstructing tropical/subtropical changes in sea surface temperature(SST).However,these two species have different morphotypes,of which the spatial and temporal differences in Mg/Ca ratios and their influencing factors are still unclear.Our objective is to investigate the potential differences between the Mg/Ca ratios of these different morphotypes of G.ruber(white)and T.sacculifer in the western Philippine Sea(WPS)and determine their implications for the reconstruction of SST and upper-ocean structure.Mg/Ca measurements are made on two basic morphotypes of G.ruber(white)[sensu stricto(s.s.)and sensu lato(s.l.)]and T.sacculifer[with(w)and without(w/o)a sac-like final chamber]on samples of Site MD06-3047B from the WPS.Our results reveal that Mg/Ca ratios of different G.ruber morphotypes show consistent differences;and those of T.sacculifer morphotypes show staged variations since MIS 3.It is suggested to select a single morphotype for reconstructing SST changes using the Mg/Ca ratios of G.ruber and T.sacculifer in the WPS.Furthermore,the Mg/Ca ratios between G.ruber s.s.and G.ruber s.l.[Δ(Mg/Ca)_(G.ruber s.s.-s.l.)]downcore MD06-3047B covaries with indexes of summer monsoon.Combining with the core-top results,showing regional variation of differences in theΔ(Mg/Ca)_(G.ruber s.s.-s.l.)over the western tropical Pacific,we propose thatΔ(Mg/Ca)_(G.ruber s.s.-s.l.)may tend to reflect summer mixed layer depth.

关 键 词：MORPHOTYPES Globigerinoides ruber(white) Trilobatus sacculifer Mg/Ca ratios mixed-layer depth 

分 类 号：Q915[天文地球—古生物学与地层学]