HR: 0830h
AN: PP11A-0210    [PDF]
TI: Calibration of Mg/Ca, Sr/Ca and Ba/Ca in Sedeiment Trap Planktonic Foraminiferal Shells and Seawater
AU: * Huang, K
EM: l4890107@ccmail.ncku.edu.tw
AF: Department of Earth Sciences, National Cheng Kung University, 1, Ta-Hsueh Road, Tainan, 701 Taiwan
AU: You, C
EM: cfy20@mail.ncku.edu.tw
AF: Department of Earth Sciences, National Cheng Kung University, 1, Ta-Hsueh Road, Tainan, 701 Taiwan
AU: Lin, H
EM: hllin@mail.nsysu.edu.tw
AF: Institute of Marine Geology and Chemistry, National Sun Yat-Sen University, 70, Lien-Hai Road, Kaohsiung, 804 Taiwan
AU: Shieh, Y
EM: ytshieh@eden.tpm.gov.tw
AF: Taiwan Museum, 2, Xiang-Yang Road, Taipei, 100 Taiwan
AU: Li, M
EM: mdli20@mail.ncku.edu.tw
AF: Department of Earth Sciences, National Cheng Kung University, 1, Ta-Hsueh Road, Tainan, 701 Taiwan
AB: Mg/Ca, Sr/Ca and Ba/Ca in foraminiferal calcite are important proxies for reconstructing the past hydrological properties in the ocean. Paired Mg/Ca and $\delta$$^{18}$O measurements on single foraminiferal species are especially of great merit in estimating both temperature and $\delta$$^{18}$O in seawater. However, only a paucity of data is available for the purpose of direct calibration between seawater and foraminiferal shells compositions. Several species of planktonic foraminifera (250-350$\mu$m) obtained from the plankton tow and sediment trap (between 14 Oct. 2000 and 20 Mar. 2002) near the central ocean basin of the South China Sea (SCS) were hand picked and cleaned thoroughly for high precision trace element/calcium ratios determination using a HR-ICP-MS (Element II, Thermo- Fannigan) installed at NCKU. The SCS located between Southeast Asia Continent and Western Pacific Ocean is an ideal place for assessing the relationships between foraminiferal shells chemistry and properties of ambient seawater, because of its distinctive intra-annual variability in T and S in terms of both the spatial and temporal distributions. Seawater profile samples were collected using CTD rosette sampler over the plankton tow and trap deployment periods. This allows us to examine if calcite shells reached isotopic equilibrium with surrounding seawater and to calibrate precisely of Mg/Ca thermometry in foraminiferal shells and other climatic proxies. The preliminary results indicate: (1) Mg/Ca of all species show a significant relationship with instrumental T calculated from habitat depths of each species, Mg/Ca = 0.43 exp 0.075 T (r= 0.76). (2) The Sr/Ca ratios display gradual decreasing trends with dwelling depth, which are similar to the distributions in seawater profiles. (3) The Ba/Ca of thermocline- dwelling species show large variations compared with other depth dwellers.
DE: 3344 Paleoclimatology
DE: 3670 Minor and trace element composition
DE: 4267 Paleoceanography
DE: 4271 Physical and chemical properties of seawater
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2003 Fall Meeting