HR: 0800h
AN: B21B-0880    [Abstracts]
TI: Stable isotope and chemical composition of pearls - Biomineralization in cultured pearl oysters in Ago Bay, Japan -
AU: * Kawahata, H
EM: h.kawahata@aist.go.jp
AF: Geological Survey of Japan, AIST, Higashi 1-1-1, Tsukuba, Ibaraki, 3058567 Japan
AU: * Kawahata, H
EM: h.kawahata@aist.go.jp
AF: Graduate School of Science, Tohoku University, Sendai, Miyagi, 3050031 Japan
AU: Inoue, M
AF: Graduate School of Science, Tohoku University, Sendai, Miyagi, 3050031 Japan
AU: Suzuki, A
AF: Geological Survey of Japan, AIST, Higashi 1-1-1, Tsukuba, Ibaraki, 3058567 Japan
AB: 1. The oxygen isotopic composition of the pearl suggests that these pearls were produced around 23 degree centigrade, mainly in June, which is consistent with their occurrence in the field. In spite of high growth rate (higher than 0.2-1 g per year), where coral skeleton (~0.1 g per year) often presents non-equilibrium isotope partitioning, the pearls show complete or close to equilibrium condition. 2. The pearl samples showed rather scattered delta carbon 13 values (-1.04 - +0.47per mil, av. -0.16per mil) compared with delta oxygen 18 values. The delta carbon 13 values are ~-2.9per mil lower than those calculated from those in offshore water. It may be affected by low-delta carbon 13 waters due to degradation of organic matter in the Ba or by low-delta carbon 13 food. In the latter case, a simple mass balance calculation gives respiration component of 14%. 3. 12 trace elements of bulk pearl samples were classified into 4 groups: Group 1 (Co, Cr, Pb), Group 2 (Ba, Cs, U), Group 3 (Cu, Sn, V) and Group 4 (other elements such as Mn, Rb, Mo).Comparison with coral chemistry suggests that proteinous organic matter contain abundant Ba and Mn and significant amount of elements of Group.
DE: 4806 Carbon cycling
DE: 4825 Geochemistry
DE: 4870 Stable isotopes
DE: 4875 Trace elements
SC: Biogeosciences [B]
MN: 2004 AGU Fall Meeting